[TR] TR4 vs TR4A clutch items

[carlsereda]

Peter,
The 4A went to a 'diaphram' clutch (w/8"disc) versus the old-fashioned
3-finger style with 'coil springs' (w/9"disc). I believe this was to speed up
the 'action' - so it seems to me that the 4A hydraulics were sped up too. If
you have an original style TR4 clutch pressure plate you could probably use
either hydraulic system without feeling much difference (although I have
wondered myself if I could speed my original 4 clutch with 4A hydraulics - or
would I just be abusing the linkage in between?).
If you do have a TR4A clutch pressure plate installed I would stick with the
TR4A hydraulics to benefit from the faster clutching capability..
Regards,
Carl
'63 TR4 since '74 .. with the faster TR4A 4into2into1 exhaust manifold..

Cognescenti listerati,

I have a customer who is needing to re-plumb his clutch hydraulics. 
His car is a TR4, as we've determined through the years. It seems 
that what is on the car, though is 4A stuff. (lots of it)

Using various original TR manuals, and Moss, et. al., it seems that;

4s used 3/16 tubing and a rubber flex hose at the slave. The 
fittings would have been a 3/8-24 male single(bubble) flare into the 
master, a length of 3/16 tube, a 3/8-24 female nut single flare, 
rubber hose with a long 3/8-24 male fitting to accommodate a nut for 
a bracket. rubber hose (8") with a 3/8-24 straight fitting requiring 
a copper gasket at the slave.

Whereas
4As used 1/4" tubing and a stiffer kind of flex tubing a la 6s at the slave.

Both use the same master cylinders, and hence bore diameters.

My questions are: 1) am I correct in the above?

2) In other cars, when the line diameter changes from 3/16 to 1/4 
there is a concurrent change in bore diameters of either the master, 
or the slave, or both. Why not with the 4A, and are there 
advantages of 1 plumbing scheme over the other.

We are thinking that while this car has many parts of both 4s and 
4As, that it would be best to make it as much a true 4 as possible, 
unless there is a compelling reason to switch to 4A clutch piping. Pedal
feel?


Thanks for any help.

Peter C.