Moto Grand Prix
Main Motorcycle: 1973 Triumph TR7RV
Join Date: Oct 2013
Location: Pleasant Hill, CA USA
Other Motorcycle: 1964 Triumph Mountain Cub
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.