sounds like your front disc rotors need to be turned. i had this same issue
on an
american car and the problem was warped rotors. if there's no vibration without
braking, i
believe the issue is somewhere in the brake components. and if it's not the
rotors, i'd
look at the calipers and how they interact with the rotor.
my 2 cents....
Tom Di Iulio
1976 TR6
Denver, CO
----- Original Message -----
From: "Robert M. Sexton" <sexton@starmark.net>
To: "Triumph Mailing List" <triumphs@autox.team.net>
Sent: Friday, December 08, 2000 5:19 PM
Subject: TR6 Occasional Pulsation/Vibration Under Braking
>
> My 1976 Triumph TR6 has 33,700 miles (original) on it and I have just had
> some mechanical work done on the brakes, bushings, and stiffer springs
> (from TRF) including new brake rotors, stainless steel brake jumpers, new
> discs, new rear brake shoes, aluminum steering guide (from TRF), and
> electronic ignition. Also, the rear differential mounting was reinforced
> and cracks welded.
>
> I don't know whether everything is now stiffer in the suspension or what,
> but now there is a stronger pulsation of the brake pedal and shaking when
> normally (lightly) putting on the brakes --- sometimes. However, when
> braking hard, the brakes work fine without any shaking of roughness of the
> car. While driving under throttle, lightly touching the brake pedal
> generates a pulsation. Before the repairs to the brakes and suspension,
> only occasional shaking was noticed. The car drives and rides normally up
> to 70mph or so (highest that I tested it today) so the general balance of
> the wheels, tires, and suspension appear to be OK.
>
> The timing for this is not good since I wanted to take the TR6 for a few
> laps around VIR (http://www.virclub.com) tomorrow (Saturday, 09dec2000).
>
> The mechanic (very good sports car and formula racer mechanic) thought that
> machining the rear brake drums might help --- it did not.
>
> Our possible thoughts are as follows:
>
> 1. The front brass trunnions have slight play. Could this be the source
> of the vibration when the car weight is distributed in certain situations
> under light braking???
>
> 2. Something in the suspension or brakes???
>
> 3. Hydraulic brake cylinders and/or servo unit may be generating
>transients???
>
> Does anyone have any ideas, suggestions, or experience in this situation????
>
> Thanks for your help.
>
> Bob Sexton
> sexton@starmark.net
> 804.792.0167
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