TR6 TR6 Clutch master and slave

[vettedog72]

I have seen a few comments about bore size of the clutch master and I would like a knowledgeable member to enlighten me about the differences and interchangeability. Big bore master harder to operate? My '74 all ways took a mule kick to operate the clutch; don't have a clue about bore size.
Thanks in advance for the info.

 

[MDCanaday]

The bore size difference will cause some change in the feel of the unit. But if it really stiff be advised there have been a lot of clutches of poor quality sold for a number of years.Many have the wrong springs and are way too stiff.
The smaller bore master with the large bore slave might help some, worth a try at least.
md(mad dog)

 

[Alan_Myers]

Hi,

I agree with previous response. Smaller bore MC and/or larger bore SC will result in less pedal effort. TR4/4As used a .70 bore master cylinder. For some reason, it was changed to .75 on the TR6. One downside is that there is less adjustment possible with the larger bore. I've seen some discussion that the lack of adjustability might be one reason TR6 clutches are generally less reliable than the earlier cars. It's pretty easy to locate the Girling .70 bore CMC if you want to try one on your car. They are still manufactured and look just like the originals. (The .70 brake MC with the larger reservoir is much more difficult to find, may not be made any longer, but that's not what's used on your car, anyway.)

One caveat about going to the smaller bore, putting more pressure on your clutch. Be sure the shaft, yoke and linkage are all in good shape before doing so. One possible reason the larger bore was used on TR6 would be to help reduce the common problem of the pin in the throwout bearing yoke breaking. That's pretty easily protected against by using a good quality pin, making sure it fits well and is wired to keep it from loosening, and fitting a 1/4" grade 8 bolt to the opposite side of the yoke as a secondary attachment.

Cheers!

Alan