Discussion
Erm...bit of a wierd one this, but before I investigate further - I was just wondering if anyone has experienced this:
Changed the front pads and discs today (260mm). No problems with the calipers, they are in excellent condition, has a stone in one pad which scored a disc, so just decided to change the lot.
After fitting both discs and pads, I checked each side was turning freely before replacing the wheels. The disc and pads are correct and there's no leaks from the hoses.
I started the car to move it out and go for a drive to start to bed the pads in. The pedal is spongy (air - but from where?) and the brakes are seized solid - at the rear I think. Any ideas how this might have happened.
Now, its getting late so I've put the car back in the garage - and will have to wait until next weekend to figure it out.
My first job will be to bleed the system and then take a look at the rear calipers. I read in the bible about a valve to prevent the rears from locking before the fronts - is it possible pushing the pistons back at the front has pressurised the rear psitons and they are not freeing up?
Open to any ideas!!!
Changed the front pads and discs today (260mm). No problems with the calipers, they are in excellent condition, has a stone in one pad which scored a disc, so just decided to change the lot.
After fitting both discs and pads, I checked each side was turning freely before replacing the wheels. The disc and pads are correct and there's no leaks from the hoses.
I started the car to move it out and go for a drive to start to bed the pads in. The pedal is spongy (air - but from where?) and the brakes are seized solid - at the rear I think. Any ideas how this might have happened.
Now, its getting late so I've put the car back in the garage - and will have to wait until next weekend to figure it out.
My first job will be to bleed the system and then take a look at the rear calipers. I read in the bible about a valve to prevent the rears from locking before the fronts - is it possible pushing the pistons back at the front has pressurised the rear psitons and they are not freeing up?
Open to any ideas!!!
That sounds very strange. If it's a hydraulic problem then you can get the car moving for now by cracking open a bleed nipple to release the pressure. This will also tell you which end of the car has the problem.
This is a problem that can occur if the master cylinder pushrod is adjusted too tight and stops the m/c from coming back fully. However, you don't mention any work on that so I assume it's unchanged. This problem would also make it difficult/impossible to retract the pistons to replace the pads so I assume that's not what is going on.
It may be you have some other problem such as a sticking slider, snagged handbrake cable etc.
This is a problem that can occur if the master cylinder pushrod is adjusted too tight and stops the m/c from coming back fully. However, you don't mention any work on that so I assume it's unchanged. This problem would also make it difficult/impossible to retract the pistons to replace the pads so I assume that's not what is going on.
It may be you have some other problem such as a sticking slider, snagged handbrake cable etc.
LOL - I didn't leave the handbrake on (although I thought that at first!). It was, however, my wifes reaction to the problem - we all know how useful that kind of input can be when frustrated!!
I haven't done anything regarding the master cylinder, but have experienced a failure previously on an old Opel Manta - that was a case of no brakes as the master cylinder seals failed (whilst driving!!!).
When I get home on Saturday I'm going to take off the rears to inspect the calipers and will release a nipple to see if i can move the sliders. The only thing I can think is that I've pressurised one of the rear calipers and maybe a piston has seized (maybe a broken seal and corroded piston??).
Will post back next weekend, but welcome any thoughts in the meantime.
I haven't done anything regarding the master cylinder, but have experienced a failure previously on an old Opel Manta - that was a case of no brakes as the master cylinder seals failed (whilst driving!!!).
When I get home on Saturday I'm going to take off the rears to inspect the calipers and will release a nipple to see if i can move the sliders. The only thing I can think is that I've pressurised one of the rear calipers and maybe a piston has seized (maybe a broken seal and corroded piston??).
Will post back next weekend, but welcome any thoughts in the meantime.
I do prefer to bleed the calipers as the pistons are pushed back, so that the superheated fluid is ejected and top up the res with fresh fluid.
I do that because it requires less effort to push the pistons back, and it seems sensible to replace the most 'grotty' fluid, but it also seems as tho it would avoid any of the problems outlined also.
Dave
I do that because it requires less effort to push the pistons back, and it seems sensible to replace the most 'grotty' fluid, but it also seems as tho it would avoid any of the problems outlined also.
Dave
Found the problem!!!!
Before replacing the wheel and tightening up, I failed to notice that there is about 0.1mm clearance between the outer (fixed) part of the caliper. Once the wheel is tight the disc is clamped against the caliper.
Strange - the discs are RS Turbo 1.6 standard, which is the EBC listed replacement part. There is a section in the bible about a TVR specifc offset, mentioning removing the spacers between the caliper and the mouting bracket.
The disc is 24mm wide, and the caliper gap is 28mm, currently the disc is touching one side of the caliper.
On inspection I have 4mm spacers, reducing the width of the spacers would give me 2mm clearance either side of the disc, so it looks like I am going to have to root around for some spacers.
Has anyone else had to change/remove spacers when changing discs?
Just found this after searching for 'spacers' - hopefully may help someone in the future:
http://www.pistonheads.co.uk/gassing/topic.asp?t=1...
Before replacing the wheel and tightening up, I failed to notice that there is about 0.1mm clearance between the outer (fixed) part of the caliper. Once the wheel is tight the disc is clamped against the caliper.
Strange - the discs are RS Turbo 1.6 standard, which is the EBC listed replacement part. There is a section in the bible about a TVR specifc offset, mentioning removing the spacers between the caliper and the mouting bracket.
The disc is 24mm wide, and the caliper gap is 28mm, currently the disc is touching one side of the caliper.
On inspection I have 4mm spacers, reducing the width of the spacers would give me 2mm clearance either side of the disc, so it looks like I am going to have to root around for some spacers.
Has anyone else had to change/remove spacers when changing discs?
Just found this after searching for 'spacers' - hopefully may help someone in the future:
http://www.pistonheads.co.uk/gassing/topic.asp?t=1...
Edited by jeboa on Saturday 26th May 16:41
Hi Martin,
Not sure if it's too late, but thought I'd add my own recent experience with the joys of TVR brakes!
I've just replaced front/rear discs and pad. I ordered all my parts through a local car spares shop, going for the standard escort cossie rears and rs2000 fronts. When I fitted the fronts I had the same problem as you, the disc was too close to the caliper. I checked the old discs, and took them to the spares shop and it turned out they were Granada discs!! Apparently this was normal practice at TVR to fit whatever was handy at the time, spacing the caliper out where needed!
Anyway, cut a long story short, after a lot of messing around and part swapping, I ended up with Escort RS turbo fronts and took the spacer out altogether, perfect fit!
If you haven't already sorted it all out, it might be worth taking your old disc and spacer with you when getting your new discs, and check it with the RS Turbo discs, you might be pleasantly suprised!
Not sure if it's too late, but thought I'd add my own recent experience with the joys of TVR brakes!
I've just replaced front/rear discs and pad. I ordered all my parts through a local car spares shop, going for the standard escort cossie rears and rs2000 fronts. When I fitted the fronts I had the same problem as you, the disc was too close to the caliper. I checked the old discs, and took them to the spares shop and it turned out they were Granada discs!! Apparently this was normal practice at TVR to fit whatever was handy at the time, spacing the caliper out where needed!
Anyway, cut a long story short, after a lot of messing around and part swapping, I ended up with Escort RS turbo fronts and took the spacer out altogether, perfect fit!
If you haven't already sorted it all out, it might be worth taking your old disc and spacer with you when getting your new discs, and check it with the RS Turbo discs, you might be pleasantly suprised!
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