sticking front brakes

[lynchpin]

Hi all

I am sure that some of you will say you should have asked us first but after chasing the problem of the front brakes binding (mostly n/s) for a while we changed the front hoses incase this was the problem, no change,we had already done the calipers and master cylinder a few years ago when we replaced a faulty servo (yes I prefer to have one) which failed at Le mans.

Today we found that the system has a valve fitted on the tee piece at the split to the front/rear brakes which i assume keeps pressure in the front system to keep brake peddle pressure up, after stripping and cleaning the valve all is now good. The front brakes dont bind or snatch and the old girl seems to pull much better from a standstill, go on tell me I should have ask the forum.

cheers Phil..

[Paul Harvey]

you should have asked the Forum

[RogerH]

Definately

[ianc]

The valve is fitted to maintain a slight pressure to the front (disc) brakes to keep the pads rubbing gently against the discs.

That's the theory!

Dismantle this valve, remove and discard the innards, and replace the 'valve' in circuit (saves having to fit a longer length of bundy tubing and looks original!).

No more problems.

Ian Cornish

[lynchpin]

The position of the valve means it would keep some pressure in the whole system but the rear shoes obviously pull back because of the return springs,Everything is good now that its been cleaned out ,the peddle feels firm and does not require pumping to push the pads to discs so I assume its working.

If I need to later,what valve is available,I assume it would go in between master cylinder and tee,as the front brakes have a pipe to each caliper from the tee, or can you just remove the innards and not bother as other cars of the period with disc front brakes ie mini coopers etc never had one to my knowledge? Does the tr4a 5 or six have one?

 

Will ask in future honest Phil..

Edited July 11, 2013 by lynchpin

[peejay4A]

There's not one on the 4a or 6.

[stuart]

There are modern versions available though some are better than others.I have just had to use two to cure a long pedal on a car fitted with 4 pot calipers. Used some Nascar type ones, not cheap but works a treat, but to do it properly you do need to re-jig the pipe work.

Stuart.

[Paul Harvey]

I have just had to use two to cure a long pedal on a car fitted with 4 pot calipers. Used some Nascar type ones, not cheap but works a treat

There goes the budget, again.....

[ianc]

As I said before, and as advised by Neil Revington, it's unnecessary.

Dismantle, dispense with the innards and replace.

Ian Cornish

[Guest ntc]

Sorry Ian

Not so it serves a purpose

[lynchpin]

Interesting difference of opinions, the fact that its not used on the 4a which i think still only has a single curcuit system makes you assume its not needed, i can see that altering the system ie different calipers could bring with it other problems to solve so for now i will see how it goes now we have cleaned all the c**p out of the valve and pipes etc, not used the car since the repair so will keep an eye on it over this coming sunny tr weekend.

 

 

Thanks again Phil..

[stuart]

As Triumph were the first to introduce disc brakes on road cars and worked closely with the brake manufacturers in developing the system I very much doubt if they would have fitted the valve without a good reason after all it wouldnt have been a cheap unit to produce. Its not strictly speaking a restrictor valve (as described in the Moss parts book) but a residual pressure valve to keep a certain amount of line pressure in the system. Especially useful with some calipers that dont have close tolerances between the pistons and the bodies which will allow the pistons to relax from the discs too easily.

Stuart..