Help :( R32 Hard Brake Pedal, Can't Find Out What It Causing It.

[Ten Four]

Heres the story:

Bought an unreg R32 GTS4 that had been sitting for a while. And now it wants to go over the pits and has failed twice for a hard brake pedal. So far this has been done:

Brakes bled

Front & Rear calipers reconditioned

New pads fitted

Master cylinder reconditioned

Rotors skimmed

Brake booster pressure tested

The brakes react to first part of pedal travel but go solid when trying to press hard, ie in a emergency stop. This is why pits said they won't pass it.

NOTE: Car has factory ABS fitted.

So far, can't get rid of the hard pedal. Beginning to suspect while booster has passed pressure test, it is miss-performing. Has anybody got one that they can lend me to test? Or if it comes to it, anyone have a good condition one to sell?

Anybody had this problem before? (Rmb ABS fitted)

0431 985 155 is my dad's phone number (Tony).

(I'm still on Ls)

[Ashy Larry]

Sounds like air in the system,

But if you have bled them, it should of corrected the problem.

There is a particular way you bleed the brakes with ABS as well.

Not sure if that is just for GTR though.

Other than that, I am stumped!

[Ten Four]

Yeah, it's been done by my mechanic who used to do ferraris lambos tractors (ex-barbagello) etc etc, basically fixes anything, except my line!

It doesn't feel like air cause if just driving normally, they are fine. Its when you brake to a certain point that it becomes rock solid and you really have to press hard for the car to stop. (Don't get me wrong, it stops really well, its just the hard pedal) The guy at the pits said sure, your average joe could stop the car, but he's referring to when say eg a girl is driving and they can't press the pedal, ie making it too dangerous.

I want the car on the road :| This is the only thing stopping it and its starting to annoy the hell out of me. Stupid skylines

Edited February 7, 2009 by Ten Four

[Flash89]

if you pump the breaks while the car is off it gets hard, does it go anysofter when you turn the car on???

[NA_Goodness]

Doesn sound like air in the system, that gives the opposite effect. You put your foot an the brake and nothing happens for a while because you're compressing the air.

Sadly, I cant think of what it might be.

[Ashy Larry]

Rhys,

Air in the system can in fact cause block peddle mate,

I understanded where you are coming from,

But to discount air from the system completely at this stage, may in fact lead you down the incorrect path.

There is a sequence that you have to bleed the brakes with ABS in a skyline if it is to be done properly.

There is write up for this in the GTR Manual that can be found online.

Once you have cleared the system completely, then can you move onto the next fault finding excercise.

Nav had a very similiar issue with his car.

Cheers

Mike

[Defective]

id be checking wheter or not any of the lines are twisted and or split

check slides are lubed

and how old is the brake fluid?

[ahh 33 s2]

maybe post the same questoin in the suspension braking and tyres forum... might geet a few brake gurus to give u a hot tip.

[Ten Four]

Thanks for the replies guys.

Flash, it's not much different, both on and off are pretty hard.

Mike, where is this guide? Otherwise the air has been pretty much discounted at this stage. Its acting more like the booster so I'm going to try get one (to a point its fine, after that its just hard). Cause the car still stops really well, its just the firm pedal.

Defective, the lines are not twisted or split cause each was tested. Brake fluid was replaced earlier today.

Ahh 33, I think I may just do that, thanks.

Edited February 7, 2009 by Ten Four

[Onthehunt]

Have you tried taking it and stopping by a couple of performance workshops to get their opinion on what it could be? They might have come across this issue before and know the solution.

[Ten Four]

Yeah mate, as a last resort I will probably end up taking it to a performance workshop. I'm sure the problem is something silly. If the brake boosters I've just bought and the disabling the ABS don't fix it, I'll take it to one.

[Flash89]

have you checked the vaccum line that is from your break booster to the engine??

[Pal]

sound like vacuum. like when u stall your car and the peddle goes hard and you gotta push it hard to stop?? (2 many hards in there me thinks )

[Ten Four]

Its not the vacuum line, we already tested that.

[Dsturbd]

The brakes react to first part of pedal travel but go solid when trying to press hard, ie in a emergency stop. This is why pits said they won't pass it.

Who idea was it to do the above mentioned repairs ??

Get a Brake specialist to check it out . ( a good one also )

[TAKUSHI]

Rhys,

Air in the system can in fact cause block peddle mate,

I understanded where you are coming from,

But to discount air from the system completely at this stage, may in fact lead you down the incorrect path.

There is a sequence that you have to bleed the brakes with ABS in a skyline if it is to be done properly.

There is write up for this in the GTR Manual that can be found online.

Once you have cleared the system completely, then can you move onto the next fault finding excercise.

Nav had a very similiar issue with his car.

Cheers

Mike

Mmm i know you might be the guy who gave me the warn on this but ima have to say fail on that one aye, as a mechanic i can say that air in system will cause a spongey pedal and lesser response upon application

Its sounding more like booster but also check where the vacuum line connects to the manifold, start it with that line off and make sure its sucking in air, also check that the booster vacuum hose isnt sucking closed under vacuum when you push the pedal

[Ten Four]

Dsturbed, the car had been sitting for 1.5 years so the above jobs were done as to be expected. However, it didn't change the brakes much.

Takushi, that has been done a few days ago.

Update: it isn't the ABS.....

Edited February 9, 2009 by Ten Four

[NISMOGTT]

Hey might sound odd but can you post up a pic of the brake booster....

i had a brake specialist test my old TX-5 booster and it was fine then i had the same problem..

i found there was a one way valve in the booster due to boost and it was the wrong way around so please check you dont have one or it is the right way around.... also you say you tested the line,,, did you actually start the car with a vacume tester on it then rev to boost to see the difference?? and what was the difference??

[Flash89]

i was thinking the same thing after i looked at how a break booster works

[Ten Four]

Hi guys, problem seems to have been solved.

Previously, the master cylinder must have been taken apart as a washer was missing and the piston was bigger than usual (looked like nothing was out of place...). Replaced washer and put a shorter piston and it seems to have solved the problem. In essence, the car still brakes just as well as before, just with a softer pedal now.

Will be visiting the pits tomorrow.. Cheers.

Edited February 10, 2009 by Ten Four