[Fot] Caliper questions

[Gt6steve at aol.com]

Hello Jack, I can take a stab at these questions as the GT6 uses the same 
ones.
I race a TR4 with Toyota calipers. I love them not because they give 
me much of a braking advantage but because the rubber parts are made 
of modern stuff and last more than a partial season. With stock 
calipers, I've always roasted the dust covers in two weekends and had 
to replace the sealing rings every season. However, my club is 
working to bring cars back to era correctness and wants me to switch 
back to the stock calipers.

I have found a set of TR6 calipers that I would like to use. They are 
dimensionally identical to the TR4's but vary in some details, and I 
can't find any TR4's.

I'd like some input from the collective wisdom of the FOT:

1. Question about calipers -- Are there any major advantages / 
disadvantages, TR4 or early TR6?
The Metric (late?) caliper uses a readily available pad as the dimensions 
match that of a 240Z.  Keep that a secret just between us though.  And the 500 or 
so FOTer's reading this.


2. Question about pistons -- My new calipers have the 1/4" pad 
retaining pins and are marked 16P, which means that they are the 
early TR6 calipers. However, they are fitted with the late dust 
covers with the extra spring retaining clip. Since I must buy new 
pistons, does anybody know the difference between the early and late pistons?

3. Dust cover question -- the last time I rebuilt stock TR4 calipers, 
when I tried to install the dust covers, I gave up after a couple of 
hours and assumed that they were made wrong, with a lip too big for 
the slot. Do others have this problem? If so, have you seen a 
downside to leaving the dust covers off?
I've left the dust covers off for about fifteen years now with no apparent 
issue.  They are just too much aggravation to put on.  That said, we don't race 
in the rain as often as you folks might.


4. I fully expect the bores to be totally corroded, so of course I'll 
have to split the calipers to clean them up. The manual says don't do 
it, but I don think I'll have a choice, and the o-ring is available 
from Moss. Is there anything really tricky about splitting the calipers?
The only trick is to be sure the square O-ring is thick enough for 
reassembly.  They often aren't.  Then just retorque the bolts to an upper range figure 
for the size.  Again, no apparent problem.


As ever, thanks in advance.



uncle jack 
Hope that helps, Steve