british-cars
[Top] [All Lists]

TR-8 brakes, state of things

To: british-cars@alliant
Subject: TR-8 brakes, state of things
From: muller@Alliant.COM (Jim Muller)
Date: Tue, 6 Mar 90 11:51:13 EST
Well, it appears that SOL mail is okay.  Today I came in to find absolutely
*no* bounced mail!  Either Internet figured out some process that violates
causality and sent me all of today's bounced mail this past weekend, or I
actually *fixed* all the problems for the time being (fat chance!), or the
rest of the email world is brain-dead today (mit-eddie?  earth to mit-eddie?
come in, mit-eddie...).  In any case, let's open the flood gates again...
One thing that will help this kind of problem is if your machine goes down,
let me know ASAP.  I know, you can't send me email if you r machine is down.
So have someone else do it.  Call up a friend...or just call me at work at
508-486-1290, or at home at 617-891-0258.  Thanks.

Last week I wrote:
>>I remember reading the Car&Driver review of TR-8 when it was new.  Seems to
>>me it was written by Pat Bedard, if that matters.  He (or they) went bonkers
>>over the car, especially the acceleration and handling, but were less than
>>impressed with the brakes.  They even pointed out as to how the diameter of
>>the rotors had been reduced from the TR-7, though the swept area was still
>>high.  They commented as to how they would have considered diameter to be
>>the more critical parameter.  It does suggest, though, that TR-7 brakes
>>might be a better choice, if the parts will fit.  Bill S., is this reasonable?

Bill Sohl responded:
>If Jim's info is correct, it might seem appropriate to use TR-7 brakes,
>but I'm not up to speed on the technical details of the TR-7 vs TR-8
>brakes.  Logically, however, it doesn't make sense that the
>engineers would have switched to a different, less effective,
>braking system for the TR-8, since production of both 7s and 8s
>was on the same assembly line and to do so would certainly have
>incurred greater production costs.

Well, that was exactly (almost) what the C&D writer thought.  I dug up my
old copy and have it here before me.  It was written by Don Sherman, not
Pat Bedard (my memory is going away...  what were we talking about?).  The
review was in August, 1980.  Dar green cover, picture of a metallic light
green TR-8 drophead and a yellow glider on the cover.  Lots of nice color
pictures of the TR-8 and (what's this?) one of a red(!) glider.

They liked the car but were concerned about the brakes.  They reported erratic
stopping distances, partly the result of the rear drums locking up first.
Their 70-0 distances varied from 228 to 240 feet, and in the bar-graph they
showed for comaprison to other cars, they listed Corvette 190 ft, Porsche 924
194 ft, Datsun 280-ZX 206 ft, and TR-8 228 ft.  Maybe the comaprisons to other
cars don't mean much since conditions may have been different.

The text of the article included:
"...Several crucial brake-component dimensions have been juggled since the
last TR7 we tested, but not all of them in the right direction.  The front
rotors are thicker by 50 percent (they're still non-vented, however), and
the front brake pads are 45 percent larger in surface area.  Unfortunately,
there's been a quarter-inch *reduction* [italics theirs] in front-brake rotor
diameter, the most critical dimension of all.  The TR8 weighs almost 200
pounds more than a TR7, and really could use fourteen-inch wheels and some
hellacious disc brakes all around.
   The last bit was just our token show of objectivity..."

I don't know about the 200 pound weight difference.  I thought the 3.5 V-8 was
supposed to be light...and it can't all be in bigger drive-line components,
can it?  Maybe some of it was because the last 7 they did was a coupe and the
8 was a drophead.  Also, I don't know if the TR-7's brakes were ever changed.
Seems to me that I saw TR-7 and 8 brake pads listed in a TRF catalogue, and
they were the same (there goes my memory again), which invalidates their 45%
surface area increase comment.  However the *rotors* are different.  They are
listed on successive lines in the TRF Christmas Catalogue, and they differ by
some $40 in price!  And it isn't clear whether the 7's brakes will fit on the
8's hubs or be compatible with the calipers.  Who knows why they did it?
Most likely it was an attempt to reduce weight.  I know they used several
different brake arragements on the LeMans cars so as to reduce weight when
possible.  Maybe C&D's car would have worked better if they had bothered to
adjust the rear drums.  Of course, this suggests that sampling aberations from
a sample size of 1 make most auto-journalism tests inconclusive, a fact that
they don't dare admit (but do on rare occasions when they can't explain, or
don't want to accept, some result)!

Jim Muller



<Prev in Thread] Current Thread [Next in Thread>
  • TR-8 brakes, state of things, Jim Muller <=