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Triumph TR6 - Clutch Master Cyl.

I will be needing a new clutch master and slave cyl. this coming Spring. I see 2 different master cyl's listed, one with a .70 bore and one with a .75 bore. I read something like one is better for pedal pressure, and the other is for slave travel or something like that. What is the big difference between the 2 besides bore diameter? Is one better than the other?
Robert

Robert
The early cars were fitted with the 0.75", after complaints from customers about the heavy clutch pedal it was reduced to 0.7", if your car is at present fitted with a 0.7" one [most are] I would replace it with the same. The 0.75" is a handy if your clutch takeup point is nearer the floor than you would like, it moves it up slightly but it does make for a heavier pedal.
Ron
R. Algie

Robert,

Ron is corect in all he says, I would just like to add that if you have installed a heavier pressure plate such as included with the "Magic Clutch" kit and you use the 0.75" MC your left leg will get a workout. I made the mistake of doing this to the wife's '75 when she was driving about 15 miles one way to work in city traffic. She was not a happy camper. She did autocrossed this car and had no issues on the track, but it was a bear for her in stop and go driving.

Quite honestly, I did not care for it in city driving either, way too heavy.

Don
Yellowdog

Robert,
Not to specifically contradict with what Don said, but I have a .70" bore on my "mostly" 1971 TR6. I removed an old Borg and Beck pressure plate of unknown origin with the TRF Magic Clutch kit plus accessories. The TRF kit I bought had a Sachs pressure plate and driven disc. I found that the Sachs plate was easier to push than the B&B. I also read an article either on VTR or old Buckeye where someone had graphed the release pressures of the Laycock, B&B and Sachs plates. The Sachs plate was either in the middle or at the bottom of the graph being lower than the B&B. I also replaced the bearing with the std. Koyo as well as the cross shaft, fork, pins, dowels in the rear plate and bell housing. I have not been able to put many miles on mine about 600 since the exchange but all is well.

In my experiences the Magic Clutch kit is fantastic and offer lighter pedal effort than the B&B. Others may have differing experiences.

Case in point, the 0.70" bore will work (as it was OEM for 6 out of the 7 yrs of production) but it does not offer the saftey margin (per Roger Williams)that the 0.75" bore does. Roger recommends it as a worth while upgrade to go with 0.75" bore.

Worn linkage and clevis pins, shaft bushings all add up to slop in the slave travel. Get your mechanical linkage in top shape and you can easily use either .70" or .75" bore.

Cheers! MRankin
MRankin

Robert-Also check out the hydraulic throw out bearing talked about in past post. there are a couple of posters who own this set up and I am sure will offer their thoughts.
Don
DON KELLY

Robert & MRankin,

My apologies for not being more specific. There were (still are) two different B&B pressure plates used in the TR6. The original plate had a relatively mild spring system that would equate to many modern vehicles. The aftermarket B&B was known to be quite a bit stiffer, to the tune of 15 - 30% depending on the pedal position. From what I have learned the Sachs plate spring is about 10 - 12% stiffer than the original B&B.

When I installed the Sachs plate in her car, an original style B&B was removed. That coupled with the fact that I chose that instant in time to replace the master cylinder with the 0.75" piston version led us to several spirited discussions about how I ruined her car. To restore order in the house I reinstalled the 0.70" master and we continue to live in peace and harmony.

I could not agree more with MRankin that if you are replacing a later style (aftermarket) B&B with a Sachs plate you will notice a marked ease in pedal effort. Again, my apologies for not being more specific.

Don
Yellowdog

Don,
Thanks for the clarification. I too remember now that the early B&B plates were good and the recent aftermarket B&B are the ones to avoid. I likely removed a non OEM B&B thus the extra effort. Funny what you think you remember and what you actually remember while typing.

Glad you have peace and harmony still. These cars have a way of getting between the "women" in our lives. But, one is a real good listener!

My wife has her edges about my TR6, but mostly she wants me to "just finish the darn thing and drive it".

I am trying! Cheers!
MRankin
MRankin

This thread was discussed between 18/09/2005 and 22/09/2005

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