Brake vibration

[jemgee]

Car has no vibration through steering wheel - except as front brakes start to bite - not severe but irritating

 

Everything is bolted up ok so surmise it could be pad kick back or worn/distorted discs - they do look a bit grooved not flat smooth.

 

Any thing else spring to mind?

[Alec Pringle]

Hi Mike,

 

an interesting cause of brake vibration that came up working on Tim Timmer's TR6 in Holland the weekend before last.

 

Previous owner had fitted new brake discs, but with hex bolts to the hub having a thread the whole length, as opposed to the originals which have a plain shank tightly fitting through the holes in the disc itself, and the remainder threaded.

 

Net result being that the threads had been gradually flattened as the disc hammered them under braking, and of course the vibration problem had been slowly getting worse as the disc fractionally rotated on the bolts. The offending bolts, although of imperial thread, had a metric head . . . .

 

Replacement with correct (old) bolts - problem sorted.

 

These bolts had presumably been supplied by one of the major TR specialists along with the rest of the new brake components.

 

Worth a check on your car perhaps ?

 

Cheers,

 

Alec

Edited April 21, 2011 by Alec Pringle

[Hasbeen]

I have had 2 causes of vibration under brakes in otherwise sound cars.

 

One was in a Brabham Repco

 

After a major rebuild, due to time constraints, a bloke who had no experience of fully adjustable racing suspensions was given the job of doing the wheel alignment.

 

The car was dreadful under brakes, shaking not only the steering wheel, & even the column when braking hard, but even the body.

 

Most of the front end was replaced before it was found he had set the front at 7 degrees castor. Everything else was good. Once this was reset to the design 3 degrees all shaking disappeared.

 

The other was a TR8, which was in excellent condition. It must have had an unreported knock, as it suddenly started shaking under brakes, & some conditions of bumpy road, at speeds lower than the famous TR7/8 shimmy.

 

This was traced to excessive toe in, which should be zero on them.

 

This shake was a lower frequency, but greater magnitude wobble than that usually caused by unbalanced wheels.

 

Unfortunately the only information I could get was that the toe in was "very" high. The wobble disappear completely after this was corrected.

[jemgee]

Thanks for the 2 suggestions. I had the tracking checked not long ago but I was intending to go back to the same local mechanic who I trust. I will have a chat with him about these possibilities and let you know what we find.