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Spongy Brake Pedal
Posted: 09/12/18 13:43
by ABleach
Hi all, i hope you can help me because i am loosing my mind!!!
Just fitted new disks, pads, calipers and braided lines to my rev 2 NA, i have bled the brakes to high heaven, no more bubbles. The pedal is hard when engine off, engine on and the pedal goes to the floor. Im assuming this is due to servo assistance. Any ideas?
Im guessing its master cylinder? but i cannot find a new replacement....
Many thanks
Re: Spongy Brake Pedal
Posted: 09/12/18 15:35
by peteV6R5
how long was the system dry for? sels can dry out and not recover.
how are you bleeding?
if you dont do both fronts before rears or both rears before fronts you can get into airlock issues.
2 of you (1 brake pedal 1 on bleed nipple) or using a pressurised bleed system .
feel like its not bled correctly. but guessing here
Re: Spongy Brake Pedal
Posted: 09/12/18 18:12
by ABleach
Hi mate, it was dry for about a month,
2 man method, am 100% sure that i am doing that right
Re: Spongy Brake Pedal
Posted: 09/12/18 21:37
by Snorkie
The fact that the pedal is alright without the engine running means you probably still have air in the system.
Some times you just need to leave it for a while (air saturated in fluid) best to leave overnight.
Buy a pressure or vacuum bleeder they will save you a load of time and trouble.
Pressure bleeder is better but vacuum is almost as good and easier to use.
Re: Spongy Brake Pedal
Posted: 10/12/18 11:16
by nick
I had trouble until I used a pressurised system. I think the handbrake mechanism contributes to the problem
Re: Spongy Brake Pedal
Posted: 10/12/18 16:36
by ABleach
Thing is, i took it into a garage and had them use a master bleeder on it, ended up getting no air out in the end, system fully bled over an hour yet the problem persists!
Re: Spongy Brake Pedal
Posted: 10/12/18 19:46
by abovetherim
Try bleeding with the engine running.
Rear left, rear right, front left then front right.
Check all the unions disturbed when fitting the brake lines top and bottom.
If the problem persists it may be that you have goosed the mater cylinder. The theory is that when 2 man bleeding you get to put your foot to the floor which can run the internal seals on part of the chamber that doesn't normally see wear. So this is rough/corroded and may damage/ flip a seal.
Re: Spongy Brake Pedal
Posted: 10/12/18 21:01
by ABleach
What would bleeding with the engine on do differently?
Yeah i am thinking master cylinder... no idea where i would get one though haha!
Re: Spongy Brake Pedal
Posted: 10/12/18 21:12
by jimi
nick wrote: ↑10/12/18 11:16
I think the handbrake mechanism contributes to the problem
How can it ?
Re: Spongy Brake Pedal
Posted: 10/12/18 21:14
by jimi
abovetherim wrote: ↑10/12/18 19:46
If the problem persists it may be that you have goosed the mater cylinder. The theory is that when 2 man bleeding you get to put your foot to the floor which can run the internal seals on part of the chamber that doesn't normally see wear. So this is rough/corroded and may damage/ flip a seal.
If that was the case then how is it holding a firm pedal with the engine off ? Have you tried the brakes on the road ? (very carefully
)
Re: Spongy Brake Pedal
Posted: 10/12/18 22:48
by abovetherim
jimi wrote: ↑10/12/18 21:14
abovetherim wrote: ↑10/12/18 19:46
If the problem persists it may be that you have goosed the mater cylinder. The theory is that when 2 man bleeding you get to put your foot to the floor which can run the internal seals on part of the chamber that doesn't normally see wear. So this is rough/corroded and may damage/ flip a seal.
If that was the case then how is it holding a firm pedal with the engine off ? Have you tried the brakes on the road ? (very carefully
)
Could be that only one seal is damaged and that the undamaged one gets hard enough to to hold the pedal but with servo assist it pushes a little more to feel the damaged one.
I have seen this once on a Capri and we diagnosed as one caliper was not moving at all off the pedal
Re: Spongy Brake Pedal
Posted: 10/12/18 22:52
by abovetherim
ABleach wrote: ↑10/12/18 21:01
What would bleeding with the engine on do differently?
Yeah i am thinking master cylinder... no idea where i would get one though haha!
If you want new then give tcbparts a call or general eBay.
If you happy with used then post a wanted as here or imoc or on the book of face if you are part of that.
Where are you? I know someone in Leicester that may have a used one stashed.
Re: Spongy Brake Pedal
Posted: 11/12/18 17:34
by MRHAPPY62
I have a good used one if you are near west sussex .
Re: Spongy Brake Pedal
Posted: 11/12/18 20:18
by ABleach
MRHAPPY62 wrote: ↑11/12/18 17:34
I have a good used one if you are near west sussex .
Am over in essex sadly bud, about 90 mile trip each way for me :(