In a message dated 3/14/99 11:10:44 AM Eastern Standard Time,
dynamic@transport.com writes:
> Back when I was young and dumb I used to drive the TR6 QUITE hard on
> certain favorite twisty roads around Medford, Oregon. On TWO occasions I
> used the brakes hard enough in rapid succession to produce pad fade... hard
> pedal, but no stop!
Pete,
This is the one place where an increase in horsepower might require an
improvement in brakes. Not in braking POWER, but in fade resistance. With more
power and spirited back road driving, your average speed will be higher, which
means you will be slowing more often from higher speeds, so brake fade will
occur quicker.
> And Dan... Where d'you get the 4-pot calipers? You speak as though they
> were a direct bolt-on to the standard TR6 stuff.
On my car, they are virtual bolt-ons. On other TR6s, they may require a minor
bit of modifications. First of all, let me give credit where credit is due.
About a year or so ago, I asked the list for advice on brake up grades, and I
got a lot of good advice, but John Lye turned me on to this deal. He suggested
I use calipers from an 82 - 84 Toyota 4 wheel drive pickup truck. I just
walked into the auto parts store and said give me a pair of calipers for a
1982 4X4 Toyota pickup, and got the brake pad mounting hardware as well. I
paid $39 for each caliper, plus a $30 core charge, and about $15 for the
hardware. They were in the store the next day.
On my car (but I have reason to believe my car may be an oddity) the mounting
holes are EXACTLY the same size, and have EXACTLY the same spacing as the
holes on the stock TR6 (1975 brake setup). If I leave off the dust covers, no
further work is required - just bolt them on and go. The fluid fittings are
metric, so on your car, a change will be required, but my car has no fittings
or brake lines on it now anyway, so making the correct fittings will not be
any more work than making up the other fittings. The calipers are virtually
the same size as the TR calipers, so space is not a concern.
The mounting ears on the Toyota calipers are about 1/16 inch thicker than the
Triumph calipers, so if I wish to retain the dust covers, I have 3 options:
1) Take the calipers to a machine shop and have the 1/16 " milled off. If I do
this, all that is required is to trim about 1/4 in off each side of the dust
cover to clear the slightly longer Toyota caliper. This trimming will have to
be done whichever option I choose.
2) Cut off two of the dust cover mounting tabs, extend them 1/16 " and weld
them back on.
3) Place a 1/16" thick washer under the third dust cover mounting tab, and let
the dust cover move 1/16 " further away from the rotors. If I do this option,
I will have to trim the three suspension clearance holes in the dust covers a
little bit for additional clearance, as the covers will now be 1/16" closer to
the suspension components.
I am planning on using option no.1, as the caliper mounting bolts I have are
just marginally long enough for the other 2 options.
Which gets me to the reason I think my calipers are an oddity. The calipers
bolt to the suspension assembly using 7/16" UNF bolts. The holes in both the
Toyota and my TR6 calipers are 0.478" in diameter, whereas a 7/16" bolt has a
diameter of 0.437". The 7/16" bolts that came out of my car have a larger
diameter shank, 0.471" in diameter, which mates very nicely with the caliper
mounting hole, with nearly no slop. I ordered a new set of caliper mounting
bolts from TRF, and I got four non-standard 7/16" bolts. They were non-
standard in that the shanks were long enough to go clear through the caliper
mounting hole, rather than the standard 1/4" shank on a bolt of this length,
but the shanks were the same diameter as a standard bolt. This makes me think
that these bolts are indeed the proper bolts for a standard TR6. I called TRF
and asked about them, and was told they had sold lots of them, and had no
complaints.
If I were to use the standard bolts, I would have to machine thin sleeves for
each hole to eliminate excessive play, so I will just reuse the old bolts.
I'd be curious to hear what others have found with their brake caliper
mounting bolts on their TR6s. Are my bolts nonstandard? Are the caliper holes
non standard? Is every one that is buying new bolts using the wrong ones? Let
me know, please.
BTW, these calipers will give a 10 increase in braking pressure for a given
pedal pressure, and have about 50% more pad area than stock.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://members.aol.com/danmas/
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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