1975 T140V clutch query - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 20 (permalink) Old 07-10-2019, 08:39 AM Thread Starter
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1975 T140V clutch query

The clutch on my 1975 T140V is very stiff to say the least. I have put a new clutch cable and adjusted springs etc but no real change. Is there an actual alternative full clutch that anyone could recommend that would make it easier to use?
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post #2 of 20 (permalink) Old 07-10-2019, 01:02 PM
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Just had a discussion about this a few month ago.

I run 650 springs on my 79, and 500 springs on my 68. They can have tendency to slip if I get aggressive with the throttle, but they are a much easier pull. There are a lot good suggestion on this thread;


https://www.triumphrat.net/classic-v...iscussion.html
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post #3 of 20 (permalink) Old 07-10-2019, 02:33 PM
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Ensuring that the lever fulcrum is correct helps. Then adjust everything by the book.

Keep tight bends out of the cable. I use a venhill featherlight.

I use a 7 plate conversion with 650 springs. I also use an alloy pressure plate but I am not so sure that it actually does something.
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post #4 of 20 (permalink) Old 07-11-2019, 02:05 AM
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Hi nhojk1, I don't know of a direct clutch that makes lever pull easier. However I have quite a bit of experience with this. I'll give you my thoughts. I think a 1975 would have same levers as my '73.??

I would agree the T140 clutch lever can be very hard to pull. They were very hard from new. A root cause was the 750 clutch springs were very much stiffer than 650 springs.

I would most strongly recommend lubing your new cable. Either with engine oil hanging cable like shop manual shows or a dedicated clutch cable lube that is injected into cable with a tool & aerosol can of cable lube. Lube perch pivot & upper cable end pivot in lever. That is always the starting point.

Are you using original perch or a replacement of some type? The distance from lever pivot to cable end center point is very important. I believe it should be 7/8".

Some owners use dogleg levers which can change the pivot didtance, but that's another subject.

I installed 650 springs as test with original clutch plates. I got acceptable lever effort, but the clutch would slip at times. I put 750 springs back in.

I installed Norman Hyde 7 plate +1 clutch kit & put the 750 springs back it. Normally I adjust the spring nuts flush with dome of nuts. It was said you back off nut until the studs were flush with slots. Over time I found backing nuts off like this tended to allow micro slip which reduced friction pad life, leading to premature slip. However it gave a very nice lever pull. Now I accept a little harder pull & put studs flush with domes. This has proven to be the best compromise.

Changing to an alloy pressure plate won't change lever pull one way or the other. Unless you want an alloy one for some other reason there is no reason not to reuse the steel plate.

Many alloy pressure plates have a smaller outside diameter which actually press the clutch stack in a less desirable fashion as the inside diameter of the friction pads is much greater than on stock clutch. So some of the alloy plates miss pressing on the friction pads to a greater extent than the original Triumph steel one. But the alloy ones still work ok. I've never had a problem with the steel ones so I just reuse them unless they have some sort of damage or are bent. Put on flat surface to check for bending as you would a clutch plate.

The 7 plate kits are simple install. You reuse rod, adjusting screw, pressure plate & all adjustments are like the original 6 plate.

Some sellers seem to think 650 & 750 springs are interchangeable. They are not! 57-1830 650 springs have 9.5 coils & are 1-3/16" long in real life.

57-4644 750 springs have 7.5 coils & are 1-3/4" long in real life. The wire in 750 springs is fatter also. .112" compared to .098" for 650 springs.

Ask seller to measure springs to be sure you don't get sent 750 springs. You want 57-1830. They can count the coils too.

I've found with all the T140 clutches I've been involved with. The correct lever pivot length, properly lubed new cable, 7 plate clutch with 650 springs has given the owners a clutch they can live with & ride all day. An added bonus is the clutch cable has less strain on it, so it doesn't break as easily. You could always back off the springs slightly as I did at first & live with shorter clutch life. It was still about 10k+ miles.

All this is assuming the ball cam is in good shape & adjuster screw is not hitting the inspection cover in primary cover or something odd.

Peg has installed a hydraulic clutch system to replace the cable. Maybe she will jump in & elaborate on that. I've never felt that conversion so I don't know how much it helps.

I hear good reports about Areco 7 plate kits also, but I have no personal experience with them.

The friction pads on 7 plate are very thin, so you can get the extra plates in the same space as the 6 plate takes.

Don
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post #5 of 20 (permalink) Old 07-11-2019, 03:12 PM
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One thing that it could be is that the actuation mechanism in the gearbox cover might have been replaced at some time with a 79 on one.
They have the same part number but the later one has an X added. It's designed for the 79 on levers
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post #6 of 20 (permalink) Old 07-11-2019, 06:13 PM
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Hi Dave, How much difference do you find it makes? Codeman installed one on '76 T140. Didn't seem to notice a real difference. Clutch released fine with the X cam. The old cam was very worn at the pivot causing a lot of lost motion & low lift.

Seems like the X cam is often sold under prior part #.
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post #7 of 20 (permalink) Old 07-11-2019, 06:27 PM
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650 springs will make for a lighter pull on the lever. They are smaller diameter metal. Try a set. It might slip a little in 3rd gear if you give it a large throttle but not in the other gears. Routing cable loose and without any sharp turns helps as does a venhill featherlight cable and an alloy cover much the same as Daves set up. I still use 6 plates.

Now,where did that bit fall off ?
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post #8 of 20 (permalink) Old 07-11-2019, 07:03 PM
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Hi All, I've seat of the pants observed the way a T140/TR7V makes power is a little different. Pretty much all that changed 750 springs to 650 springs have experienced clutch slip overall under certain power bands.

This has always puzzled me. The T120T 750 so far as I know uses 650 springs with at least decent results. I know a few guys with Morgo 750 kits & 650 springs. Clutch works fine. The Morgo kits make more power the way I feel it riding bike than 650. Yet the clutch with 650 springs doesn't seem to slip.

650 & 750 clutches take the same clutch plates & pressure plate. Why does the T140 tend to slip with 650 springs? Does the short rods change the torque curve such it puts more torque through clutch for an instant?? I ride T120, TR6 now & then. When we swap bikes both riders are bewildered at how they can feel so differently the way motor runs.

Any thoughts or experiences?
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post #9 of 20 (permalink) Old 07-11-2019, 09:23 PM
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Quote:
Originally Posted by TR7RVMan View Post
Hi All, I've seat of the pants observed the way a T140/TR7V makes power is a little different. Pretty much all that changed 750 springs to 650 springs have experienced clutch slip overall under certain power bands.

This has always puzzled me. The T120T 750 so far as I know uses 650 springs with at least decent results. I know a few guys with Morgo 750 kits & 650 springs. Clutch works fine. The Morgo kits make more power the way I feel it riding bike than 650. Yet the clutch with 650 springs doesn't seem to slip.

650 & 750 clutches take the same clutch plates & pressure plate. Why does the T140 tend to slip with 650 springs? Does the short rods change the torque curve such it puts more torque through clutch for an instant?? I ride T120, TR6 now & then. When we swap bikes both riders are bewildered at how they can feel so differently the way motor runs.

Any thoughts or experiences?
Don
That is a good question, because my 68 650 seems to have as or more power than my 79 750. I have played around with springs on both of those bikes, and found the 500 springs work fine on the 650, and the 650 springs work fine on the 750. But the 750 springs are an extremely hard pull.
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post #10 of 20 (permalink) Old 07-12-2019, 02:56 PM
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Quote:
Originally Posted by TR7RVMan View Post
Hi Dave, How much difference do you find it makes? Codeman installed one on '76 T140. Didn't seem to notice a real difference. Clutch released fine with the X cam. The old cam was very worn at the pivot causing a lot of lost motion & low lift.

Seems like the X cam is often sold under prior part #.
Don
I honestly don't know but it equates to having the "wrong lever perch" even if the lever is original.
The lever and actuator work as one and mixing them up throws out the lift.
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