Triumph Rat Motorcycle Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
395 Posts
Discussion Starter #1
Hi all,

I have a clutch that slips. It is a Norman Hyde supplied 7 plate item. I stripped it today to inspect the plates and it does not appear to have much wear at all but I cannot be sure.

However, the spring retainers were not screwed down very far so when I put it all back together I set it up, as per the workshop manual (the screws are also now roughly flush with the retainer outer faces), and making sure the cover plate was level (slowly turning the engine and using a dial gauge).

Took her for a run but whilst a little better, she still slips at high revs, full throttle, under load in 4th and 5th. So, I am wondering snout my options:

1. I can try screwing the retainers further in (but they are close to binding).

2. Fit stronger springs (have tried both T120 and T140).

3. Get a new, quality 7-plate clutch.

4. Find/buy an uprated/competition clutch.

For context: My engine is strong. PO had the engine built up with balanced crank, line-bored mains, corrello forged rods and pistons, gas-flowed competition head, Hyde tappets, Hyde half-race cams, alloy barrels and PR tubes, lightened push rods, 1.5 headers, Norton non-baffle pea shooters and other bits n bobs. A rolling road printout, in the pile of receipts I got with the bike, shows 61.8bhp at the crank. Not bad from a 40 year old archaic twin ?

So, do I need a stronger clutch and if so, can anyone recommend one please?

Cheers,
Ian
 

·
Registered
Joined
·
1,738 Posts
I have a 7 plate unit on my TSS....and it goes quite hard. So I don't think the 7 plate conversion is your issue. And your springs shouldn't be binding with the adjusters flush IMO.

Only change is I am also running with an SRM alloy PP, but I can't see it being the difference tbh.
How did they measure the hp at the crank? It would need some very fancy gear and on a bench with a test bed/hub dyno setup. Usually its on a dyno and done at the rear wheel. But either way, 61.8 is pretty good.
 

·
Registered
Joined
·
3,262 Posts
Hi Boggie, I have a fair amount of experience with Hyde 7 Plate.

A few thoughts. Several things can cause slip. Things are not adding up for what you've done. You should not have slip.

First make for certain you are using an oil known to not cause slip. Don't fool around. Use a good motorcycle oil that specifically states for wet clutch.

If you have had slip at all I expect the friction pads have taken damage. This can be compensated for by spring tension so long as friction pad is not worn to steel. Guessing is a hard way to tell spring tension. It can be calculated if you have a Vernier caliper. If you don't have one, you need one. Not costly. $20 US on eBay.

Verify all 14 plates are still flat.

Take all 14 plates. Stack together as you would install them, but make sure friction plate on top. Place on flat surface like edge of bench or table. Slide edge of plates over edge of table enough that you can measure the thickness of stack. About 3/4 of pad width hanging over edge.
Take one hand & spread fingers such you press plates tightly together. With other hand holding calipers measure thickness of stack.

New will be close to 1.400". Will call 1.400" nominal. I expect you will be thinner due to wear. Suppose you have 1.315". Subtract your thickness from 1.400". That would be .085". Record this amount.

Clean all plates in petrol & dry with a cloth. Inspect each friction plate closely. If you see one that is thinner than others (which is common). Place this thin side into basket first. Oil all plates well, trust me, soak them well. Friction & steel. Stack in the other plates as normally would.

Inspect your springs. 650 springs will be close to 1-13/16 long, 9.5 coils, wire diameter .098" part # 57-1830.
750 springs are 1-3/4" long, 7.5 coils, wire diameter .112" part # 57-4644.
Make sure you don't have 500 springs. Some sellers seem to think all springs are the same & interchangeable. They are not! You must measure to see what you have. You should be able to use 650 springs, but if you are making big power, you must go to 750 springs.

Your plates are installed. You've verified you have the springs you want to use. Now install the spring nuts with dome flush with end of studs. Take your calipers & slide depth gauge out .085 in my example case. YOU will use your number calculated from your stack height. Back to my case I'll go .085 deeper with nuts using the depth gauge as my guide. Then in your case of slip I'd go deeper on one or two nuts to correct wobble. Don't back off in your case for wobble correction. Will drag bad during first start up, but when excess oil comes off plates in a few blocks will not drag. This procedure compensates for worn or thinner plates that genuine Triumph were. Many new plates are thinner or thicker than originals were.

No need to roughen plain plates with Hyde or Aerco clutches.

Back off clutch lever all the way. Turn in rod screw until plates begin to lift. Back off. Turn in gently until it just stops. Back off 5/8 turn, lock nut counter holding screw. Adjust clutch lever play. 1/16-1/8" for now. Always make sure lever has some play.

If your basket & hub are grooved it doesn't allow plates to press together properly. Grooved clutches never work right.

I just had personal experience with this. It has been said worn spider in cush hub causes slip & drag. I have become to believe this is true. It also causes too much end play in clutch basket. This for sure is true. What I don't know is how much wear is enough to cause slip when everything else is good. I'm still working that formula out. I can say without question after installing all new clutch parts & & 7 plate the operation is fantastic. It has certainly reduced drag & seems to grab tighter.

Give this some thought & see if it helps.

Even with my old Hyde 7 plate it did not slip at all after I started using the 1.400" nominal factor on 7 plates that slipped. I have put worn Hyde plates together from old clutch jobs & used the formula & again no slip.

If a Hyde slips it's almost always not enough spring tension or incorrect oil.

On a side note, what pressure plate are you using?

I'm currently experimenting with large diameter Britech pressure plate. OD is 5.770" (5-11/16'). Pressure face is 1/2" wide. This centers full pressure face over Hyde pads. The steel Triumph plate actually works quite well with Hyde, but it's biased to the inner diameter of friction pads. I've notice the outer few steel plates flex slightly causing uneven wear. The steel plate is 5-3/8 OD with 1/8" pressure face.

I recently installed Aerco 7 plate with steel pressure plate. As we speak I'm installing the Britech pressure plate. Should be riding by Monday night. I'll report the difference. However I expect the full pressure contact of the Britech would make the outer 3-4 plates more efficient. Be careful of which alloy plate you get. Have the OD measured. Many are the same or smaller OD than 5-3/8. That won't help you. Smaller is a step backwards. I'm also most interested to see how the open design of most alloy plates effects the oiling of the plates. I believe in both Hyde & Aerco. They really work well. They tend to slip less than standard clutch.

Either you stack height to spring tension factor is off or you have some bad wear in spider/basket area. Or... the oil. Or combination.
Don
 

·
Premium Member
Joined
·
9,753 Posts
A dial gauge to get a true pressure plate is OTT. A bit of bent wire is fine
Are you sure that your clutch mechanism is set up right? Ie lever to gearbox?

I have NH 1/2 race and use T120 springs with no clutch slip, 7 plate clutch and alli pressure plate
 

·
Registered
Joined
·
1,415 Posts
I have a T140 with for sure more power than any stock T140...It has a 7 plate Aerco clutch, stock pressure plate, 650 springs tightened down before coil bind, the studs protrude through the nuts a few threads....And...I use Valvoline VR1 20/50 oil, it is not Jaso rated an carries a warning it may no be suitable for wet clutches...My bike has no clutch slip at full throttle high rpm shifts or roll on in higher gears, it frees easiy when cold...
This leads me to believe the Aero clutch is the best choice because it's not fussy thing ...
 

·
Registered
Joined
·
395 Posts
Discussion Starter #6
I have a 7 plate unit on my TSS....and it goes quite hard. So I don't think the 7 plate conversion is your issue. And your springs shouldn't be binding with the adjusters flush IMO.

Only change is I am also running with an SRM alloy PP, but I can't see it being the difference tbh.
Interesting, thanks. I doubt that too and there are many tweaked bikes out there using 7 plate clutches, so either the clutch needs replacing or (more likely) I haven't quite got it setup right yet. The adjusters are not quite flush yet so there might be an extra turn in there.

How did they measure the hp at the crank? It would need some very fancy gear and on a bench with a test bed/hub dyno setup. Usually its on a dyno and done at the rear wheel. But either way, 61.8 is pretty good.
The power readings came from a rolling road. If I understand the process correctly; the initial RWHP measurement is taken at the wheel on the power run, then transmission loss is measured on the run down. The rolling road software then calculates engine power using these two figures.

I am told the calculation is pretty accurate, any variance is down to atmospheric conditions such as height above sea level, temperature and humidity. Of course there are variations between different rolling roads so who knows which one is accurate.... ?

Cheers,
Ian
 

·
Registered
Joined
·
395 Posts
Discussion Starter #7
Hi Boggie, I have a fair amount of experience with Hyde 7 Plate.

A few thoughts. Several things can cause slip. Things are not adding up for what you've done. You should not have slip.

First make for certain you are using an oil known to not cause slip. Don't fool around. Use a good motorcycle oil that specifically states for wet clutch.

If you have had slip at all I expect the friction pads have taken damage. This can be compensated for by spring tension so long as friction pad is not worn to steel. Guessing is a hard way to tell spring tension. It can be calculated if you have a Vernier caliper. If you don't have one, you need one. Not costly. $20 US on eBay.

Verify all 14 plates are still flat.

Take all 14 plates. Stack together as you would install them, but make sure friction plate on top. Place on flat surface like edge of bench or table. Slide edge of plates over edge of table enough that you can measure the thickness of stack. About 3/4 of pad width hanging over edge.
Take one hand & spread fingers such you press plates tightly together. With other hand holding calipers measure thickness of stack.

New will be close to 1.400". Will call 1.400" nominal. I expect you will be thinner due to wear. Suppose you have 1.315". Subtract your thickness from 1.400". That would be .085". Record this amount.

Clean all plates in petrol & dry with a cloth. Inspect each friction plate closely. If you see one that is thinner than others (which is common). Place this thin side into basket first. Oil all plates well, trust me, soak them well. Friction & steel. Stack in the other plates as normally would.

Inspect your springs. 650 springs will be close to 1-13/16 long, 9.5 coils, wire diameter .098" part # 57-1830.
750 springs are 1-3/4" long, 7.5 coils, wire diameter .112" part # 57-4644.
Make sure you don't have 500 springs. Some sellers seem to think all springs are the same & interchangeable. They are not! You must measure to see what you have. You should be able to use 650 springs, but if you are making big power, you must go to 750 springs.

Your plates are installed. You've verified you have the springs you want to use. Now install the spring nuts with dome flush with end of studs. Take your calipers & slide depth gauge out .085 in my example case. YOU will use your number calculated from your stack height. Back to my case I'll go .085 deeper with nuts using the depth gauge as my guide. Then in your case of slip I'd go deeper on one or two nuts to correct wobble. Don't back off in your case for wobble correction. Will drag bad during first start up, but when excess oil comes off plates in a few blocks will not drag. This procedure compensates for worn or thinner plates that genuine Triumph were. Many new plates are thinner or thicker than originals were.

No need to roughen plain plates with Hyde or Aerco clutches.

Back off clutch lever all the way. Turn in rod screw until plates begin to lift. Back off. Turn in gently until it just stops. Back off 5/8 turn, lock nut counter holding screw. Adjust clutch lever play. 1/16-1/8" for now. Always make sure lever has some play.

If your basket & hub are grooved it doesn't allow plates to press together properly. Grooved clutches never work right.

I just had personal experience with this. It has been said worn spider in cush hub causes slip & drag. I have become to believe this is true. It also causes too much end play in clutch basket. This for sure is true. What I don't know is how much wear is enough to cause slip when everything else is good. I'm still working that formula out. I can say without question after installing all new clutch parts & & 7 plate the operation is fantastic. It has certainly reduced drag & seems to grab tighter.

Give this some thought & see if it helps.

Even with my old Hyde 7 plate it did not slip at all after I started using the 1.400" nominal factor on 7 plates that slipped. I have put worn Hyde plates together from old clutch jobs & used the formula & again no slip.

If a Hyde slips it's almost always not enough spring tension or incorrect oil.

On a side note, what pressure plate are you using?

I'm currently experimenting with large diameter Britech pressure plate. OD is 5.770" (5-11/16'). Pressure face is 1/2" wide. This centers full pressure face over Hyde pads. The steel Triumph plate actually works quite well with Hyde, but it's biased to the inner diameter of friction pads. I've notice the outer few steel plates flex slightly causing uneven wear. The steel plate is 5-3/8 OD with 1/8" pressure face.

I recently installed Aerco 7 plate with steel pressure plate. As we speak I'm installing the Britech pressure plate. Should be riding by Monday night. I'll report the difference. However I expect the full pressure contact of the Britech would make the outer 3-4 plates more efficient. Be careful of which alloy plate you get. Have the OD measured. Many are the same or smaller OD than 5-3/8. That won't help you. Smaller is a step backwards. I'm also most interested to see how the open design of most alloy plates effects the oiling of the plates. I believe in both Hyde & Aerco. They really work well. They tend to slip less than standard clutch.

Either you stack height to spring tension factor is off or you have some bad wear in spider/basket area. Or... the oil. Or combination.
Don
Thanks Don!
Some really useful info in there!

I am using Millers 20w50 Classic Motorcycle oil but there is no mention of compatibility with wet plate clutches, or not. I will do some research. However, it slipped before I serviced it too. The PO used Rock Oil Classic SAE50.

I had T140 springs in there and it was slipping but I noted that the adjusters were not flush. They were roughly level with the bottom of the slot. Perhaps the PO didn't have the correct tool (or modified large screwdriver) so had only done them up as far as possible with a standard screwdriver....

The original clutch was heavy too, even after replacing the cable with a Venhill featherweight. So, based on information I read somewhere on the forum, I experimanted by swapping the springs for T120 items, as I heard that this produces a lighter clutch lever action. I set these with the adjuster rod just below the top surface of the spring cap nuts and made sure they were all level.

Pressure plate is the original Triumph, as far as I can tell. I am really interested to here how you get on with your alternative combinations.

I have definitely improved the slip, compared to how it was before I started experimenting but it is still there. Perhaps my next step is to refit the T140 springs and tighten the caps up more than I have currently. Setting them so that the threaded bar is level with the top, rather than just below. If that does not resolve the issue then I might fit a whole new clutch, after checking for grooves / wear you noted above.

Cheers,
Ian
 

·
Registered
Joined
·
395 Posts
Discussion Starter #8
A dial gauge to get a true pressure plate is OTT. A bit of bent wire is fine
Are you sure that your clutch mechanism is set up right? Ie lever to gearbox?

I have NH 1/2 race and use T120 springs with no clutch slip, 7 plate clutch and alli pressure plate
Thanks Dave,
Agreed, I should have used anwire. My dial gauge is far too accurate and I ended up fiddling for far too long...ever to gearbox is all set up as per the workshop manual with cable slack and adjuster screwed out 1 turn from lifting the plate. Thanks for the recommendation on clutch plates ?
Cheers,
Ian
 

·
Premium Member
Joined
·
9,753 Posts
I'm not sure that my Ali clutch plate offers any advantage but it was shiny !
There have been discussions over whether the Ali is lighter than the original steel, and whether the Ali provides a more even pressure on the plates than the standard
Plewsy on here (Lunad on YouTube has very good videos on adjustments

 

·
Registered
Joined
·
5,432 Posts
I use Barnett alloy friction plates with good results. I have reverted to a 6 plate set up with 650 springs with good results. My bike is still running the original motor, to my knowledge never rebuilt. Im sure it doesn’t have as much power as your built up ones , but it runs well. I use Barnett plates because I’ve had good results with them not sticking when cold as well as not slipping under power. I always thoroughly deburr the hub and basket so all the plates move easily. I change out any plates that aren’t flat. I rub them all on a sheet of glass with Emory cloth on it as my flatness indicator, then wash them.
 

·
Registered
Joined
·
395 Posts
Discussion Starter #11
I have a T140 with for sure more power than any stock T140...It has a 7 plate Aerco clutch, stock pressure plate, 650 springs tightened down before coil bind, the studs protrude through the nuts a few threads....And...I use Valvoline VR1 20/50 oil, it is not Jaso rated an carries a warning it may no be suitable for wet clutches...My bike has no clutch slip at full throttle high rpm shifts or roll on in higher gears, it frees easiy when cold...
This leads me to believe the Aero clutch is the best choice because it's not fussy thing ...
Sounds like this may be a good option if I fo for a replacement. My thinking is that if the T140 springs, screwed down as far as I can does not address the issue, I will strip the clutch, check the basket and hub for wear and it they are ok, fit a complete net 7-plate clutch and potentially one of the pressure plates Don is experimenting with.
Cheers,
Ian
 

·
Registered
Joined
·
395 Posts
Discussion Starter #12
I'm not sure that my Ali clutch plate offers any advantage but it was shiny !
There have been discussions over whether the Ali is lighter than the original steel, and whether the Ali provides a more even pressure on the plates than the standard
Plewsy on here (Lunad on YouTube has very good videos on adjustments

Agreed, I am subscribed to his channel! :)
 

·
Registered
Joined
·
1,415 Posts
Obviously, everything needs to be in reasonably good shape as mentioned by Don and others ....But sometimes you think a part is worn, replace it with new, and a month later it seems worn again...It's like the part wears to the limit quickly and then stays like that for a long time..:wink2:
 

·
Registered
Joined
·
3,262 Posts
Hi Boggie, No, don't just tighten springs. Your first step is measure clutch stack. That will tell you where your base spring setting should be.

I'd like to know what that number is.

Right now you are grasping at straws. I don't recommend that.

At the same time, wear of thrust washer & little hub flange is a part of that factor... So this gets more complicated. I didn't want to mention that prior. I still want to know your stack height before compensating for other worn parts. I have personal experience with worn spider & know you can overcome some slip from that wear by going tighter on springs.

The problem is, as was most correctly pointed out the wear man not be a factor in your problems.

Replacement cush hubs & baskets are not close to the quality of original Triumph parts. So don't jump into replacing genuine parts until they are shown bad.
Don
 

·
Registered
Joined
·
1,415 Posts
Replacement cush hubs & baskets are not close to the quality of original Triumph parts. So don't jump into replacing genuine parts until they are shown bad.
Don
And that is a problem,poor quality replacement parts..And sometimes the high qualty parts are a problem.
When I built the Triumph 650 race bike about 7 years I used Barnett clutch plates, 6, running in ATF...After the first series of dyno runs the clutch would not release. The plates were stuck so bad I had to pull the basket and dump out the pack and literally pry them apart ( I believe Barneet has revised plate material)...John Healy read ny complaints and we spoke on the phone..He advised inexpensive Tiawan cork friction discs and plates, 750 springs just short of coil bind...he said it'll be fine if slipping the clutch off the line is kept to a minimum. I did as he recomended running the plates first in ATF and later 10-40 bike oil...The bike needs a primary chain every 5 or so runs but the clutch has never been a problem with about 62 or so HP at the flywheel..
 

·
Registered
Joined
·
395 Posts
Discussion Starter #17
Hi Boggie, No, don't just tighten springs. Your first step is measure clutch stack. That will tell you where your base spring setting should be.

I'd like to know what that number is.

Right now you are grasping at straws. I don't recommend that.

At the same time, wear of thrust washer & little hub flange is a part of that factor... So this gets more complicated. I didn't want to mention that prior. I still want to know your stack height before compensating for other worn parts. I have personal experience with worn spider & know you can overcome some slip from that wear by going tighter on springs.

The problem is, as was most correctly pointed out the wear man not be a factor in your problems.

Replacement cush hubs & baskets are not close to the quality of original Triumph parts. So don't jump into replacing genuine parts until they are shown bad.
Don
Thanks Don

You are absolutely right; I need to do this properly. Time is my issue though; it is rare I get the change to spend large amounts of it on the Bonnie. I have 2 other restorations, my job and Dad-taxi duties to juggle. Hence my thoughts to tighten the springs and see....

I will try to make some time next weekend and report back. Reading your comprehensive explanation / process it looks like a 3-4 hour job but it has to be done and I would really like a good look at the basket and hub.

Thanks,
Ian
 

·
Registered
Joined
·
3,262 Posts
Hi Ian, I would just start with removing clutch plates & measure stack height. That will only take about extra 1/2 hour. Then you'll not be guessing on spring tension.

You will then know the next step. If notching is acceptable, and spring tension was not tight enough, you know correcting spring tension is reasonable next step & would be expected to correct slip.

If tension was already tight enough or notching is excessive, you know you'll need to do a full tear down & repairs.

Doing another guess on spring adjustment is not productive way to go.

Also, please take very clear detailed photos of grooves on basket & hub while plates are out. That will give us an idea of what you have & be able to make a recommendation.
Don
 

·
Registered
Joined
·
395 Posts
Discussion Starter #19
Will do Don, really appreciate the advice and info. I should be able to find some time next weekend. Will report back with measurements and photos then.
Cheers,
Ian
 
1 - 19 of 19 Posts
Top