The clutch plates are seized again on my 76 T140 after sitting through the winter. I doubt they’re worn, the bike only has 12k miles on it. Should I clean them again and try to do a better job or should I replace them? Any tips to keep them from sticking over the winter?
mpayson
Clutch plates - replace or clean them again?
Hi MPayson,
There are several options:
1) If overwintering then cable tie the clutch lever to the bars, so the plates remain separated while parked up.
2) change the primary oil before overwintering, so the plates sit in cleaner condition.
3) The most expensive but usually the best solution is to replace the clutch with a 7 plate conversion, it's a no stick, no drag upgrade,that works astonishingly well.
Regards
Peg.
There are several options:
1) If overwintering then cable tie the clutch lever to the bars, so the plates remain separated while parked up.
2) change the primary oil before overwintering, so the plates sit in cleaner condition.
3) The most expensive but usually the best solution is to replace the clutch with a 7 plate conversion, it's a no stick, no drag upgrade,that works astonishingly well.
Regards
Peg.
Hi mpayson, friction clutch plates can become saturated with oil, which is a contributor to the sticking condition. I would suggest removing them for inspection. You can use a couple of magnets to withdraw them from the clutch basket when they are stuck together in groups and difficult to remove with a bent pick. Check the tabs for deformation and also measure the thickness of the friction material on each plate. 12000 miles is a lot of service on friction plates, so be prepared to replace them. I've never been able to find a minimum thickness specification in any Triumph workshop manuals, but I once read in an old BSA manual that .141" is the minimum thickness for a 57-1362 clutch plate. The new 57-1362 Emgo reproductions (which I prefer) measure about .155" thick. If your plates are reusable and are to be put back into service, you can soak them in your parts washer tank with a suitable solvent, clean them off and let them dry out in the sun. I have never been a fan of soaking friction plates in new oil prior to fitment into vintage BSA or Triumph clutches, although that is the accepted practice with many modern clutches. Hope this helps.
-Dave
-Dave
It might pay you to tie the clutch lever in so the plates are loose over Winter. These sticking plates seem to be a USA problem as mine have never stuck. Just wheel it out the garage,start up and snick into gear. Try a new set of the very cheap unbranded plates on ebay. They have been the best ones i have used. Very light lever pull using the thinner 650 springs and no clutch slip even using the 750 kit. This piece of aluminium may be helping
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I have been very happy with my clutch operation for many years. A 2 finger pull on the lever although i can do it with one finger. Standard cable and lever, all cheap friction and plain plates and the standard 6 plate system. I used to get some slip years ago until fitting these cheap plates. I do slightly roughen the plain plates and a little oil on new plates. Still not able to see why some bikes get stuck plates during storage. Neither of my old bikes get stuck. The BSA has been sat for about 6 Months now and i expect to be able to start up and ride away as it always has done.
I've had some pretty good luck freeing up plates after sitting all winter by starting the bike, then just holding in the clutch while blipping the throttle as I warm it up. The cold gear lube gives enough resistance to free up the plates. Of course, if they are truly stuck, you might have to pull the clutch apart. However, I found simply holding the clutch in to be more effective than trying ti kick start it with the clutch in. Once they are freed up, for daily use I just pull the clutch in and kick through to make sure they are free. It works for me, even after a long NY winter!
Agree Peg, my Aerco 7 plate is a joy to have. Never sticks, I never have to clutch and kick to free it up before starting. I can always get first when running in neutral and two finger pull feels like most other bikes, no heaviness at all.
Aerco are from a UK company (Velocette), plenty dealers in the UK, try Burton Bike bits for one.
My last Bonnie, I fitted a NH 7 plate conversion as well as an SRM billet plate. Once set up, it operated flawlessly. With my T160, I yearn for the ease of adjustment in the Bonnie's (but this may be just down to lack of knowledge/experience with the T160)
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But surely you did think of improving it Geoff, with your 650 springs and billet pressure plate? 
I have an Aerco kit on mine with original steels (plus one cheap eBay one). If I leave the bike for a few weeks I’ll need to free it off before starting, if I start it and drop it into gear it will make a fair clunk.
A cable tie on the clutch lever can just pull the lever halfway and will not damage the cable in any way.
Removing the plates is made much easier using the telescopic magnetic pick up tools available at low cost. At 180 degree apart they come out very easily.
Just try a new set of those low cost plates and see the results.
A 7 plate set up might be better, it will certainly cost a lot more and it might cause you a few problems fitting and setting it up if you have no experience with them.
Having used the basic plates since 1978 without any difficulty, i stick with what works for me.
I have had clutch slip in the past so it can happen that the oil contaminates the plates. Usually the slip starts at 4000 rpm just when you are overtaking a car.
We pay about £40 for a set of friction plates here and the plain plates are a bit less. I expect they are Emgo being sold at the various autojumbles but no seller will say what they are.
You will have the 750 thicker springs which make the lever quite hard to pull in. I am able to use 650 springs which are less strong and using a 750 kit. Me and the passenger weigh around 26 stone. The clutch does very well without any slip or stick.
Use V-twin oil in the USA.
Many here have fitted 7 plates and Peg and Don have carried out a few conversions with input here. I expect Don has videos as well as good explanation of fitting it.
Removing the plates is made much easier using the telescopic magnetic pick up tools available at low cost. At 180 degree apart they come out very easily.
Just try a new set of those low cost plates and see the results.
A 7 plate set up might be better, it will certainly cost a lot more and it might cause you a few problems fitting and setting it up if you have no experience with them.
Having used the basic plates since 1978 without any difficulty, i stick with what works for me.
I have had clutch slip in the past so it can happen that the oil contaminates the plates. Usually the slip starts at 4000 rpm just when you are overtaking a car.
We pay about £40 for a set of friction plates here and the plain plates are a bit less. I expect they are Emgo being sold at the various autojumbles but no seller will say what they are.
You will have the 750 thicker springs which make the lever quite hard to pull in. I am able to use 650 springs which are less strong and using a 750 kit. Me and the passenger weigh around 26 stone. The clutch does very well without any slip or stick.
Use V-twin oil in the USA.
Many here have fitted 7 plates and Peg and Don have carried out a few conversions with input here. I expect Don has videos as well as good explanation of fitting it.
Hi mpayson, I'm most interested in this. Exactly what oil are you using?
Do you know where you bought your last set of plates? What brand are they?
My experience is Emgo plates with the extra thickness end up being too thick. Emgo steel plates are extra thin to compensate for the thicker friction. I find the top plate is just ready to fall off the cush hub will lever pulled. I would not recommend Embo plates unless you get Emgo plain steel also. Yes, I have personal experience with Emgo. Ended up returning them.
Unfortunately Bonneville Shop is out of Aerco. Aerco is in my mind the best plate in the world. No drag, no slip. A bit more durable than Hyde under same riding conditions.
Hyde 7 plate is very close 2nd in my personal experience which I have a lot of.
The difference between Aerco & Hyde is the inner diameter of the friction pads & Hyde has more slots, but that doesn't seem to matter. I don't know that the friction material on Hyde & Aerco is the same, but it sure looks & acts the same. Soak either plate in oil you will use in primary until pads are saturated. This is stated in Hyde instructions. I do it on 100% of the clutches I install. It will NOT make plates stick. You should ALWAYS free clutch before starting cold or hot. Just do it.
Aerco works very well with stock steel pressure plate. Hyde works ok with steel pressure plate but the larger outside diameter of MAP alloy pressure plate is very desirable with Hyde. MAP alloy is slight advantage with Aerco. This is all due to the friction pad circle inside diameter of 7 plate friction pads. If you choose MAP alloy, call & ask for just the plate, no rod. The ball bearing is only real advantage on dry primary. Transfer your adjusting screw to new pressure plate, Threads are the same. MAP is the only current seller in the world of the larger OD pressure plate. Check eBay for good used MAP or Britech. Britech is currently out of production. The open design of some plates looks sexy but is of no advantage one way or the other.
The OD of pressure plate matters a fair amount with Hyde plates. The smaller diameter pressure plates tend to miss or mostly miss pressure circle of friction pads, due to the larger ID of friction pads. The causes plain steel plate flex of top several plates & results in more uneven wear of steel plate & friction pads. Again this mostly matters with Hyde. The wear of steel plate photos is with Hyde friction & original steel pressure plate. So you can see smaller OD alloy pressure plate is not good for the 7 plate kits.
I most strongly recommend new smooth steel plain plates. DO NOT ROUGHEN SMOOTH PLATES! The etched plates just promote faster friction plate wear & grip no better with the Aerco or Hyde 7 plate friction material.
The Bonneville shop alloy plate is actually smaller OD than the original steel pressure plate. That becomes a step backwards with 7 plate kits. So if you want alloy it's only MAP that's an improvement over original steel.
Quick look shows Hyde is in stock. Converting pounds price comes to $181US + shipping. There will be no tax. You'll also need plain steel plates. I get my plain from Bonneville Shop.
Just today, a few hours ago, returned from 94 mile lunch ride. Was thinking about this the whole way. If you could only ride my bike, John's bike, Dave's bike & several others, you'd not believe a Triumph clutch could work so good & have reasonable lever effort at the same time. The 7 plates properly set up are a dream come true & durable as well.
Would I use a Hyde again? Absolutely.
There is a lot that goes into installing a 7 plate. Generally you can't just stick them in, They must be fitted, especially the first plate to be sure it fits right. The springs to get no slip & easy effort must be to correct 650 spec. Bonneville shop Harris UK made 57-1830 are the only ones I've found to original spec. At least the ones I bought 6 months ago were. Kibblewhite C630 thrust washer is the only one that I've found that truly lasts long term. Easily 30000 miles. This matters as it effects spring tension.
Obviously worn out basket or cush hub parts must be replaced or no plates will help.
We'll get into the minute details should you choose a 7 plate. In my experience 7 plate is the real solution.
Here are some photos to illustrate what I'm talking about. Britech & MAP alloy are the same OD.
Don
Do you know where you bought your last set of plates? What brand are they?
My experience is Emgo plates with the extra thickness end up being too thick. Emgo steel plates are extra thin to compensate for the thicker friction. I find the top plate is just ready to fall off the cush hub will lever pulled. I would not recommend Embo plates unless you get Emgo plain steel also. Yes, I have personal experience with Emgo. Ended up returning them.
Unfortunately Bonneville Shop is out of Aerco. Aerco is in my mind the best plate in the world. No drag, no slip. A bit more durable than Hyde under same riding conditions.
Hyde 7 plate is very close 2nd in my personal experience which I have a lot of.
The difference between Aerco & Hyde is the inner diameter of the friction pads & Hyde has more slots, but that doesn't seem to matter. I don't know that the friction material on Hyde & Aerco is the same, but it sure looks & acts the same. Soak either plate in oil you will use in primary until pads are saturated. This is stated in Hyde instructions. I do it on 100% of the clutches I install. It will NOT make plates stick. You should ALWAYS free clutch before starting cold or hot. Just do it.
Aerco works very well with stock steel pressure plate. Hyde works ok with steel pressure plate but the larger outside diameter of MAP alloy pressure plate is very desirable with Hyde. MAP alloy is slight advantage with Aerco. This is all due to the friction pad circle inside diameter of 7 plate friction pads. If you choose MAP alloy, call & ask for just the plate, no rod. The ball bearing is only real advantage on dry primary. Transfer your adjusting screw to new pressure plate, Threads are the same. MAP is the only current seller in the world of the larger OD pressure plate. Check eBay for good used MAP or Britech. Britech is currently out of production. The open design of some plates looks sexy but is of no advantage one way or the other.
The OD of pressure plate matters a fair amount with Hyde plates. The smaller diameter pressure plates tend to miss or mostly miss pressure circle of friction pads, due to the larger ID of friction pads. The causes plain steel plate flex of top several plates & results in more uneven wear of steel plate & friction pads. Again this mostly matters with Hyde. The wear of steel plate photos is with Hyde friction & original steel pressure plate. So you can see smaller OD alloy pressure plate is not good for the 7 plate kits.
I most strongly recommend new smooth steel plain plates. DO NOT ROUGHEN SMOOTH PLATES! The etched plates just promote faster friction plate wear & grip no better with the Aerco or Hyde 7 plate friction material.
The Bonneville shop alloy plate is actually smaller OD than the original steel pressure plate. That becomes a step backwards with 7 plate kits. So if you want alloy it's only MAP that's an improvement over original steel.
Quick look shows Hyde is in stock. Converting pounds price comes to $181US + shipping. There will be no tax. You'll also need plain steel plates. I get my plain from Bonneville Shop.
Just today, a few hours ago, returned from 94 mile lunch ride. Was thinking about this the whole way. If you could only ride my bike, John's bike, Dave's bike & several others, you'd not believe a Triumph clutch could work so good & have reasonable lever effort at the same time. The 7 plates properly set up are a dream come true & durable as well.
Would I use a Hyde again? Absolutely.
There is a lot that goes into installing a 7 plate. Generally you can't just stick them in, They must be fitted, especially the first plate to be sure it fits right. The springs to get no slip & easy effort must be to correct 650 spec. Bonneville shop Harris UK made 57-1830 are the only ones I've found to original spec. At least the ones I bought 6 months ago were. Kibblewhite C630 thrust washer is the only one that I've found that truly lasts long term. Easily 30000 miles. This matters as it effects spring tension.
Obviously worn out basket or cush hub parts must be replaced or no plates will help.
We'll get into the minute details should you choose a 7 plate. In my experience 7 plate is the real solution.
Here are some photos to illustrate what I'm talking about. Britech & MAP alloy are the same OD.
Don
Attachments
Some great information and pictures there Don. A lot of readers appreciate your effort and help
It is engine oil in the primary case, not 80/90 gear oil. If you are new to these bikes, i would simply fit the new 6 plate direct replacements and go out and ride it away. Then, later on in its life and you have learned a lot more, take a look at the 7 plate if the 6 plate is not good enough. Never use gear oil in the primary as it will get into the engine oil. Not only that, it would stick the plates together just because it is thick oil
This has been a wonderful and really informative thread. Great discussion on the differences in pressure plates. I can see now why different plates can have an effect.
I would like to stand back a bit and make sure I understand the big picture fully. For the 750's, they have stronger springs with higher lever effort and are prone to slipping. So the 7 plate conversion, using the lighter 650 springs will reduce lever effort while reducing slip - a win-win. For the 650's, there would be no reduction in lever effort since they are the same springs. The advantage of a 7 plate in a 650 would only be reduced slippage, and perhaps less sticking due to the quality of the materials they use - although a stock 6 plate in good condition is not prone to slippage - correct? So when it comes time to renew the clutch in my 650, I guess the 7 plate would be an option just for fun, but not really essential.
Do I have this right?
I suppose one other possibility for a 650 is to put a 7 plate kit in and use slightly weaker springs than stock, for an even lighter clutch pull - say for when my daughter rides it? Is that something anyone has done?
I would like to stand back a bit and make sure I understand the big picture fully. For the 750's, they have stronger springs with higher lever effort and are prone to slipping. So the 7 plate conversion, using the lighter 650 springs will reduce lever effort while reducing slip - a win-win. For the 650's, there would be no reduction in lever effort since they are the same springs. The advantage of a 7 plate in a 650 would only be reduced slippage, and perhaps less sticking due to the quality of the materials they use - although a stock 6 plate in good condition is not prone to slippage - correct? So when it comes time to renew the clutch in my 650, I guess the 7 plate would be an option just for fun, but not really essential.
Do I have this right?
I suppose one other possibility for a 650 is to put a 7 plate kit in and use slightly weaker springs than stock, for an even lighter clutch pull - say for when my daughter rides it? Is that something anyone has done?
Hi,
Hth.
Regards,
Standard 500 springs are weaker than standard 650 springs, and available from a Triumph parts dealer.
Hth.
Regards,
You have grasped quite a lot there. I have a 650 engine with 750 cylinders so its a bit more power than a 650 or T140. I use the cheap plates and lighter 650 springs. I get no slipping and no sticking plates and possibly the large aluminium outer cover helps. The only thing i need to do for maintenance is adjust the cable every year or so about 1mm .My lever can be pulled in with one finger but more comfortable to use 2. It is a very light clutch for a T120 but heavier than any modern bike. I carry a heavy load with a passenger so i need no slippage when overtaking and it just grips. My spring adjusters are quite far in to get a bit more tension while still having a light lever pull. I expect the 7 plate does benefit as people have found but for really light clutch action, you could use a hydraulic system.
This all depends on how the bike is used. I can ride most hills in my area in top gear with a passenger with ease so i only need the clutch a few times to stop or if traffic slows up. On my annual club runs i use the clutch a lot due to other riders running slow and braking.
If you have a clutch that is hard work, a 7 plate may improve it a lot. I cannot fault the 6 plate i have so will keep it. I have spent a long time with this bike and the identical one i had back in 1978 so i can just put it together without looking at books. Eventually, i found what works perfectly for me. I do have fairly strong fingers as i have worked manually all my life.
All of what has been said seems to work for that individual. I still feel the aluminium plate is the second best non standard part of my bike. Number one best part is the 750 conversion.
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This all depends on how the bike is used. I can ride most hills in my area in top gear with a passenger with ease so i only need the clutch a few times to stop or if traffic slows up. On my annual club runs i use the clutch a lot due to other riders running slow and braking.
If you have a clutch that is hard work, a 7 plate may improve it a lot. I cannot fault the 6 plate i have so will keep it. I have spent a long time with this bike and the identical one i had back in 1978 so i can just put it together without looking at books. Eventually, i found what works perfectly for me. I do have fairly strong fingers as i have worked manually all my life.
All of what has been said seems to work for that individual. I still feel the aluminium plate is the second best non standard part of my bike. Number one best part is the 750 conversion.
My answer is: Use EMGO friction plates, ride the bike as often as possible, and if you know the bike will sit more than a month, tie back the clutch lever.
Those are the best plates I've ever used, and I've used MAP, Barnett, and another well-known brand (can't remember the name).
I've told the story many times, I have them in my '65/66/67/68/69/70 Bonneville 650 race bike, and after 3 starts learning how to hook up the clutch at the starting line, I was never beaten to turn one (quite often by 750 triples and fours). Still have the same plates in there since 2007, and they'll unstick with 2 or 3 kicks and I can holeshot again.
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Those are the best plates I've ever used, and I've used MAP, Barnett, and another well-known brand (can't remember the name).
I've told the story many times, I have them in my '65/66/67/68/69/70 Bonneville 650 race bike, and after 3 starts learning how to hook up the clutch at the starting line, I was never beaten to turn one (quite often by 750 triples and fours). Still have the same plates in there since 2007, and they'll unstick with 2 or 3 kicks and I can holeshot again.
Hi All, This is a big subject.
There can be other ways than mine. I’ll just share my experience.
T140 springs are shorter & stiffer than 650 springs. They do not allow slip at all set to factory tension. This was with original factory cork plates. The down side is the huge, and I mean huge increase in lever effort, which is also hard on clutch cable.
I and others tried 650 springs on T140 & it has a propensity to slip. Even going with tighter spring adjustment.
It is often thought T140 doesn’t make make more power, but in my experience but the way the power comes on makes clutch more prone to slip.
You can back off T140 springs to get less lever effort with 750 springs. I have not perfected that. Getting the right amount of spring tension. Doing some experiments the way the lever pulls is just different the way the spring ramps up (for lack of a better term).
Cable brand & lube is a part of lever effort. I will only use Barnett cables as the ends are swaged (crimped) on steel. I’ve never seen or heard of end pulling off Barnett cable. They are lined with some sort of “plastic “, however I’ve found lubing with motor oil (I use Mobil Vtwin 20-50), reduces cable friction another level. Oil has caused zero damage to liner on John’s Bonnie, after 10 years & over 20k miles.
The advantage of hydraulic clutch actuator is no cable friction. For most users, with lubed Barnett cable cable friction will not be a problem.
There’s more of course! Lever shape…. Stretched out finger’s don’t have much power. Close to grip they have more power. A dog leg lever that starts close to grip can be easier to pull due to that. There is free lunch, to pull the same inches of cable the fulcrum must be greater, which increases lever effort. Still dog leg can feel easier.
However if you want stock looking lever & switch console if used, dog leg is not an option.
Now we are back to getting inside the clutch.
John Healy wrote an article on 7 plate clutch & how the friction circle works to increase grip. Search Vintage Bike Magazine & find link.
The factory pressure plate flex is not an issue. The pressure face is only about 1/8-3/16” wide. But… since it presses on the center of the friction circle it doesn’t flex top few steel plates very much. The normal diameter alloy plates have wider pressure face so press flatter. This gives small advantage with stock 6 plate pressure pads.
But on 7 plate the friction pads are smaller. The pads have the inner diameter removed. This changes things. I am not a fan of the SRM plate as the OD is not enlarged to compensate for the friction circle of the smaller pads.
With Hyde plates. Riding MAP size pressure plate back to back compared to stock steel PP I can feel a decided difference in the way the clutch takes up. Suppose you’re getting on freeway up hill on ramp. You wind motor to 5500 & shift quickly then full throttle again. The MAP plate locks clutch solidly. The factory Steel PP allows a teeny tiny bit of slip before it hooks up solid. The factory PP is just at the ID of friction circle, so top cutch plates take more flex.
Moving to Aerco which the ID is smaller. The advantage of MAP plate is reduced. But the smaller diameter of the SRM is not hardly an advantage over the steel.
Doing the exact same road test comparing MAP to original PP, the MAP hooks up harder, but not much.
If I wasn’t really paying attention for minute details I’d not noticed it.
I think the MAP plate is about $60US without bearing. I feel it’s with the cost using Aerco plates, as it optimizes operation. If you you can’t afford that you’ll get good service with original PP.
If you chose Hyde, I feel MAP plate is almost a must. Still John has over 20k miles on his Hyde with original steel PP.
If you use 6 plate clutch you must keep 750 springs.
Springs on the market place is very challenging. Most sellers market springs as if they all the same. But with many of these springs you might as well buy from the hardware store. Seems that’s what they do??
That’s why I specifically mentioned those exact springs from Bonneville Shop. With a known spring tension, you can set spring nuts to a known depth & get repeatable good results.
Calculating spring depth is a new subject we’ll get into later.
The smaller friction pads allows for easier freeing, along with modern friction pad material. My friends Hyde clutch sat for nearly a year. Freed easily first kick. Same with Aerco.
pressure plate lift matters. When you lift .100-118” good things happen. That’s another subject also.
Finally factory on the later T140 used a special sort of 7 plate. Maybe call it a 13 plate? Normally you install friction plate first. But on the factory one friction pads were glued to the back of basket. They made the steel if all plates a little thinner. This allowed thicker friction pads than used in the modern 7 plate kit.
The factory reverted to 650 springs for easier lever effort. That was the whole point. It worked well. If friction material wore out, the basket slots were worn out anyway. All went well until factory parts were all sold out. Now those owners are installing early basket & modern 7 plate kit. Nobody I know of is reproducing the factory version.
Personally when I’m asked to do clutch job it gets 7 plate + any worn out parts. If they don’t agree, won’t work with them. The 7 plates work that good. Especially for T140.
Don
There can be other ways than mine. I’ll just share my experience.
T140 springs are shorter & stiffer than 650 springs. They do not allow slip at all set to factory tension. This was with original factory cork plates. The down side is the huge, and I mean huge increase in lever effort, which is also hard on clutch cable.
I and others tried 650 springs on T140 & it has a propensity to slip. Even going with tighter spring adjustment.
It is often thought T140 doesn’t make make more power, but in my experience but the way the power comes on makes clutch more prone to slip.
You can back off T140 springs to get less lever effort with 750 springs. I have not perfected that. Getting the right amount of spring tension. Doing some experiments the way the lever pulls is just different the way the spring ramps up (for lack of a better term).
Cable brand & lube is a part of lever effort. I will only use Barnett cables as the ends are swaged (crimped) on steel. I’ve never seen or heard of end pulling off Barnett cable. They are lined with some sort of “plastic “, however I’ve found lubing with motor oil (I use Mobil Vtwin 20-50), reduces cable friction another level. Oil has caused zero damage to liner on John’s Bonnie, after 10 years & over 20k miles.
The advantage of hydraulic clutch actuator is no cable friction. For most users, with lubed Barnett cable cable friction will not be a problem.
There’s more of course! Lever shape…. Stretched out finger’s don’t have much power. Close to grip they have more power. A dog leg lever that starts close to grip can be easier to pull due to that. There is free lunch, to pull the same inches of cable the fulcrum must be greater, which increases lever effort. Still dog leg can feel easier.
However if you want stock looking lever & switch console if used, dog leg is not an option.
Now we are back to getting inside the clutch.
John Healy wrote an article on 7 plate clutch & how the friction circle works to increase grip. Search Vintage Bike Magazine & find link.
The factory pressure plate flex is not an issue. The pressure face is only about 1/8-3/16” wide. But… since it presses on the center of the friction circle it doesn’t flex top few steel plates very much. The normal diameter alloy plates have wider pressure face so press flatter. This gives small advantage with stock 6 plate pressure pads.
But on 7 plate the friction pads are smaller. The pads have the inner diameter removed. This changes things. I am not a fan of the SRM plate as the OD is not enlarged to compensate for the friction circle of the smaller pads.
With Hyde plates. Riding MAP size pressure plate back to back compared to stock steel PP I can feel a decided difference in the way the clutch takes up. Suppose you’re getting on freeway up hill on ramp. You wind motor to 5500 & shift quickly then full throttle again. The MAP plate locks clutch solidly. The factory Steel PP allows a teeny tiny bit of slip before it hooks up solid. The factory PP is just at the ID of friction circle, so top cutch plates take more flex.
Moving to Aerco which the ID is smaller. The advantage of MAP plate is reduced. But the smaller diameter of the SRM is not hardly an advantage over the steel.
Doing the exact same road test comparing MAP to original PP, the MAP hooks up harder, but not much.
If I wasn’t really paying attention for minute details I’d not noticed it.
I think the MAP plate is about $60US without bearing. I feel it’s with the cost using Aerco plates, as it optimizes operation. If you you can’t afford that you’ll get good service with original PP.
If you chose Hyde, I feel MAP plate is almost a must. Still John has over 20k miles on his Hyde with original steel PP.
If you use 6 plate clutch you must keep 750 springs.
Springs on the market place is very challenging. Most sellers market springs as if they all the same. But with many of these springs you might as well buy from the hardware store. Seems that’s what they do??
That’s why I specifically mentioned those exact springs from Bonneville Shop. With a known spring tension, you can set spring nuts to a known depth & get repeatable good results.
Calculating spring depth is a new subject we’ll get into later.
The smaller friction pads allows for easier freeing, along with modern friction pad material. My friends Hyde clutch sat for nearly a year. Freed easily first kick. Same with Aerco.
pressure plate lift matters. When you lift .100-118” good things happen. That’s another subject also.
Finally factory on the later T140 used a special sort of 7 plate. Maybe call it a 13 plate? Normally you install friction plate first. But on the factory one friction pads were glued to the back of basket. They made the steel if all plates a little thinner. This allowed thicker friction pads than used in the modern 7 plate kit.
The factory reverted to 650 springs for easier lever effort. That was the whole point. It worked well. If friction material wore out, the basket slots were worn out anyway. All went well until factory parts were all sold out. Now those owners are installing early basket & modern 7 plate kit. Nobody I know of is reproducing the factory version.
Personally when I’m asked to do clutch job it gets 7 plate + any worn out parts. If they don’t agree, won’t work with them. The 7 plates work that good. Especially for T140.
Don
A habit I got into, and have never broken, is going into neutral from 2nd while coasting to a stop.
But a plus 1 for the 7 plate clutch.
But a plus 1 for the 7 plate clutch.
possibly ive missed it?
no one has mentioned greasing- not oiling- the friction plates before install. i do this routinely with a lithium based white grease, and it makes the clutch smoother, at least initially.
i dont ever have the clutch sticking problems people here describe, and i do nothing special when i lay the bike up for the winter.
no one has mentioned greasing- not oiling- the friction plates before install. i do this routinely with a lithium based white grease, and it makes the clutch smoother, at least initially.
i dont ever have the clutch sticking problems people here describe, and i do nothing special when i lay the bike up for the winter.
Norman Hyde has them in stock at £168 and i expect the company will post to the USA. Montys does not sell them. Have a look around some of the British spares shops.
Hi All, Let me explain my opinions more clearly regarding pressure plate outside diameter.
Even the original steel pressure plate works fine. I personally covered many thousands of miles using one as others I know have as well.
The photos I posted of plain plate wear pattern shows the short coming of the smaller diameter pressure plate. Yes they still work fine.
The plates have close to the same miles on them.
It's true a smaller diameter pressure plate will work fine. However, if you're going to install 7 plate I feel the larger diameter of the MAP plate optimizes the advantages of the 7 plate kit. My very strong feeling is, if you are going to buy alloy plate for a 7 plate kit, MAP plate is the way to go due to the larger diameter. Again my opinion from my experience, & I stand by that.
Going back 10 years. Here's how I got involved with 7 plate in the first place. My bike was pulling ends off of clutch cable. Usually upper end. I did not yet know about the strength advantage of Barnett. That was suggested by John Healy some years ago. At the same time with my urban area & constant shifting in the local canyons my arthritis was really flaring up in my hands & fingers. A life time of being a mechanic wore them out I suppose. Having done lots of 650 clutches I had lots of junk plates & some original 650 springs on hand. I knew 750 (twin) springs had different part #, but didn't know the difference as I'd not taken a 750 clutch apart. After my brand new Venhill cable end pulled off 5 blocks from home at the end of a 300 mile ride, in the dark, I'd had it! I needed a solution. Searching web I discovered 7 plate kits. John Healy was US distributor of Venhill. He covered cable under warranty & suggested Barnett is stronger with the swaged steel ends, I might have better service with Barnett. At the same time I asked what he knew about 7 plate kits. He knows all there is to know. I was not flush with cash at the time & truthfully wasn't convinced it was as good as reported. They were not so popular then as now. Still costly though.
I decided to try just 650 springs. The lever effort was huge relief to my hand/fingers. But I was experiencing some clutch slip. It became obvious the 7 plate was the only solution. So I ordered Hyde from UK. At the time it was suggested to just use steel pressure plate. I did that. My stash of original 650 springs was from mid 70s. I got fresh set from JRC engineering to use with new 7 plate kit. Lever effort was easy. Too easy as it turned out. After 500 miles or so I noticed slight clutch slip. I decided to keep it under observation. At about 100 miles I removed cover & turned springs a little deeper. This was good for some thousands of miles. Then far from home I noticed it slipping at times. Of course, I always maintained correct rod adjustment & lever play. Then I had to go up a big grade at speed with cars tailgating. About 2 miles. Half way I down shifted to reduce slip. Damage was done though. I got home & saw plates were worn to glue. I'd had a bad feeling about this, but wanted lightest lever effort possible. So I got another Hyde 7 plate. I'd been auto transmission man at work for many years. I know wet clutches pretty well.
I wanted a way to determine a new spring depth that would give enough tension to never slip, yet have acceptable lever effort. I determined from an original set of nearly new cork plates & all 6 steel plates measured about 1.400" stacked thickness. We called this stack height at work. The working clearance of plates is very important on auto transmissions, so this was measured on every clutch pack.
Laying out all clutch parts from small hub on main shaft including internal clutch hub parts I determined what actually determines the fitted stack height in relation to the end of the studs. From that determined I could use 1.400" as a baseline. Measuring the thickness of new clutches of various brands I soon learned it's a crap shoot. From 1.300 to over 1.500". Then I was able to calculate the fitted spring nut depth on studs. Measuring studs I found them to be fairly close in length. Not really a variable. But the thickness of thrust washer was a variable. Also the thickness of spider/back plate in cush hub was a variable. If these parts are not to spec of thickness or worn you must compensate by going deeper with spring nuts. If clutch plate stack height is thinner than 1.400 you must compensate by going deeper with nuts. The new cork plates were kind of smooth & didn't seem to wear in much, but modern friction pads wear in at first to wear the fuzz off. This must be compensated for by going deeper with spring nuts. Remember we are still wanting least lever effort as possible without slip. So we don't just crank nuts down willy nilly. New 7 plate kit stack height is quite variable. From 1.380 to 1.330 I've seen so far. This must be compensated for. In the mean time I did some clutch work on bikes with worn plates. Owner didn't want new. Perfect, bikes to test my theories. 6 plate kits worn to near 1.275". Sure enough the deeper formula for nuts figured off 1.400 made plates work fine again. Mind you they are still worn thin, but gripped fine.
Next chapter.... I ran the 2nd Hyde many thousands of miles. Then I got terrible rattle from primary. I installed new cush rubbers. Basket & hub were grooved & already filed once. Heavy wear on spider & back plate of cush hub. Chain adjuster was well arched. No change at all with refiling grooves or new rubbers. But I was noticing how the plates had worn uneven. I already knew steel pressure plate was too small of OD. On automatic transmissions the pressure plate is hydraulicly actuated with very high oil pressures. The pressure plate is full width & circle to prevent steel plate flex inside of clutch. Or with the bell type pressure plates with thin face the top steel plate is a good 1/4" thick to prevent flex. So I knew what was happening. I needed a larger diameter pressure plate. But checked the diameter from vendors world wide all were the same as steel at best & most were actually smaller! That's a step backwards!
By happen stance I worked on friend's bike that had Hyde & Britech pressure plate. Just the right size to fully cover friction pads. Remember there is not a lot room inside primary cover. Alloy plates barely fit. They were about $120 on line, but none available. So I contacted Jaye at Britech. Jaye is super smart & interesting man. He knows clutches & racing inside & out. Funny thing, he explained to me about how automatic transmissions have pressure plate over the full circle of friction pads & that was a problem with the Hyde plates. Nobody was addressing this problem so he decided to have some made. His machinist basically was retiring & not producing any. He had only one left... It was his first prototype he took to the shows. All polished high gloss. He felt sorry for me & sold it to me. I was so lucky. If you know him call him & ask what happened to his prototype pressure plate. There is certainly a market for his plate, but like many of us he was wanting to wind down his work life.
Here is photo of the plate.
Again these are my opinions & why I hold them as such. Other things work, that has been shown.
Don
Even the original steel pressure plate works fine. I personally covered many thousands of miles using one as others I know have as well.
The photos I posted of plain plate wear pattern shows the short coming of the smaller diameter pressure plate. Yes they still work fine.
The plates have close to the same miles on them.
It's true a smaller diameter pressure plate will work fine. However, if you're going to install 7 plate I feel the larger diameter of the MAP plate optimizes the advantages of the 7 plate kit. My very strong feeling is, if you are going to buy alloy plate for a 7 plate kit, MAP plate is the way to go due to the larger diameter. Again my opinion from my experience, & I stand by that.
Going back 10 years. Here's how I got involved with 7 plate in the first place. My bike was pulling ends off of clutch cable. Usually upper end. I did not yet know about the strength advantage of Barnett. That was suggested by John Healy some years ago. At the same time with my urban area & constant shifting in the local canyons my arthritis was really flaring up in my hands & fingers. A life time of being a mechanic wore them out I suppose. Having done lots of 650 clutches I had lots of junk plates & some original 650 springs on hand. I knew 750 (twin) springs had different part #, but didn't know the difference as I'd not taken a 750 clutch apart. After my brand new Venhill cable end pulled off 5 blocks from home at the end of a 300 mile ride, in the dark, I'd had it! I needed a solution. Searching web I discovered 7 plate kits. John Healy was US distributor of Venhill. He covered cable under warranty & suggested Barnett is stronger with the swaged steel ends, I might have better service with Barnett. At the same time I asked what he knew about 7 plate kits. He knows all there is to know. I was not flush with cash at the time & truthfully wasn't convinced it was as good as reported. They were not so popular then as now. Still costly though.
I decided to try just 650 springs. The lever effort was huge relief to my hand/fingers. But I was experiencing some clutch slip. It became obvious the 7 plate was the only solution. So I ordered Hyde from UK. At the time it was suggested to just use steel pressure plate. I did that. My stash of original 650 springs was from mid 70s. I got fresh set from JRC engineering to use with new 7 plate kit. Lever effort was easy. Too easy as it turned out. After 500 miles or so I noticed slight clutch slip. I decided to keep it under observation. At about 100 miles I removed cover & turned springs a little deeper. This was good for some thousands of miles. Then far from home I noticed it slipping at times. Of course, I always maintained correct rod adjustment & lever play. Then I had to go up a big grade at speed with cars tailgating. About 2 miles. Half way I down shifted to reduce slip. Damage was done though. I got home & saw plates were worn to glue. I'd had a bad feeling about this, but wanted lightest lever effort possible. So I got another Hyde 7 plate. I'd been auto transmission man at work for many years. I know wet clutches pretty well.
I wanted a way to determine a new spring depth that would give enough tension to never slip, yet have acceptable lever effort. I determined from an original set of nearly new cork plates & all 6 steel plates measured about 1.400" stacked thickness. We called this stack height at work. The working clearance of plates is very important on auto transmissions, so this was measured on every clutch pack.
Laying out all clutch parts from small hub on main shaft including internal clutch hub parts I determined what actually determines the fitted stack height in relation to the end of the studs. From that determined I could use 1.400" as a baseline. Measuring the thickness of new clutches of various brands I soon learned it's a crap shoot. From 1.300 to over 1.500". Then I was able to calculate the fitted spring nut depth on studs. Measuring studs I found them to be fairly close in length. Not really a variable. But the thickness of thrust washer was a variable. Also the thickness of spider/back plate in cush hub was a variable. If these parts are not to spec of thickness or worn you must compensate by going deeper with spring nuts. If clutch plate stack height is thinner than 1.400 you must compensate by going deeper with nuts. The new cork plates were kind of smooth & didn't seem to wear in much, but modern friction pads wear in at first to wear the fuzz off. This must be compensated for by going deeper with spring nuts. Remember we are still wanting least lever effort as possible without slip. So we don't just crank nuts down willy nilly. New 7 plate kit stack height is quite variable. From 1.380 to 1.330 I've seen so far. This must be compensated for. In the mean time I did some clutch work on bikes with worn plates. Owner didn't want new. Perfect, bikes to test my theories. 6 plate kits worn to near 1.275". Sure enough the deeper formula for nuts figured off 1.400 made plates work fine again. Mind you they are still worn thin, but gripped fine.
Next chapter.... I ran the 2nd Hyde many thousands of miles. Then I got terrible rattle from primary. I installed new cush rubbers. Basket & hub were grooved & already filed once. Heavy wear on spider & back plate of cush hub. Chain adjuster was well arched. No change at all with refiling grooves or new rubbers. But I was noticing how the plates had worn uneven. I already knew steel pressure plate was too small of OD. On automatic transmissions the pressure plate is hydraulicly actuated with very high oil pressures. The pressure plate is full width & circle to prevent steel plate flex inside of clutch. Or with the bell type pressure plates with thin face the top steel plate is a good 1/4" thick to prevent flex. So I knew what was happening. I needed a larger diameter pressure plate. But checked the diameter from vendors world wide all were the same as steel at best & most were actually smaller! That's a step backwards!
By happen stance I worked on friend's bike that had Hyde & Britech pressure plate. Just the right size to fully cover friction pads. Remember there is not a lot room inside primary cover. Alloy plates barely fit. They were about $120 on line, but none available. So I contacted Jaye at Britech. Jaye is super smart & interesting man. He knows clutches & racing inside & out. Funny thing, he explained to me about how automatic transmissions have pressure plate over the full circle of friction pads & that was a problem with the Hyde plates. Nobody was addressing this problem so he decided to have some made. His machinist basically was retiring & not producing any. He had only one left... It was his first prototype he took to the shows. All polished high gloss. He felt sorry for me & sold it to me. I was so lucky. If you know him call him & ask what happened to his prototype pressure plate. There is certainly a market for his plate, but like many of us he was wanting to wind down his work life.
Here is photo of the plate.
Again these are my opinions & why I hold them as such. Other things work, that has been shown.
Don
Attachments
Hi All, For the record, I've never seen sticking clutch plates in my riding circle in the San Fransico Bay area. Either in the '70s or now days. My bike sat for 43 years in spare room. Was using Castrol GTX 20-50 oil. I & many of my riding friends are using Mobli1 vtwin 20-50. Clutches love it. Easy free & no slip.
Don
Don
@TR7RVMan Don
Thank you very much for a very interesting and informative post. Probably above my head and capabilities, but great reading nonetheless.
I am an amateur hamfisted spanner guy who somehow have managed to keep most of my bikes going over 40 odd years. Learning new stuff with the Triple but still a long way to go.
I love reading the technical posts on this site posted by the regulars, and whilst most of it goes over my head, I like to think I pick up some residual knowledge from them, so thanks again and keep posting
Thank you very much for a very interesting and informative post. Probably above my head and capabilities, but great reading nonetheless.
I am an amateur hamfisted spanner guy who somehow have managed to keep most of my bikes going over 40 odd years. Learning new stuff with the Triple but still a long way to go.
I love reading the technical posts on this site posted by the regulars, and whilst most of it goes over my head, I like to think I pick up some residual knowledge from them, so thanks again and keep posting
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