Outer Limits 4x4 Board

Hey guys i need some advice on what the problem could be with my
GQ shorty.

Driving my GQ the brake pedal started playing up going soft then hard all the time.

So i instantly thought brake booster, so i went and bought one from Hall 4X4 wreckers and changed it on the weekend and now the syptoms have changed to braking by itself.

When i lightly touch the brakes just to slow down a lil the pedals by itself presses to the floor and brakes very hard.

so i checked for vaccum leak but couldnt find anything, check the one way valve near the brake booster and all checks out.

anyone have any ideas on wtf it can be?????????

Petrol or diesel?

hi there it is a petrol with lpg

hmmmmmmm anyone with any ideas???

make sure there's no shit in the system.
many many yrs ago, rebuilt the master on a car, all went well.
went cruising that night, halfway through the nite the brakes when applied would lock on, and take forever to release.
tow hom etc, next day found a tiny bit of old rubber in the line, so totally fluched the whole system.

has your wheel bearings effed out on you to the point where diff oil leaked out through the wheel bearings and all through your brakes?

my hilux rear brakes did this and it was because the pads got contaminated by the diff oil which made the brakes stick on and come on very hard even when i just touched them...

Thanks for your replies.

The diff has a slight leak but not enough to make you worry about it but i will take off the pads and have a look.

At the same time i will try blow out the brake lines then bleed the whole system aswell hopefully this helps.

The brake booster has a sensitivity disc inside it to slow the reaction of the booster , if the front rod that contacts the master cylinder has been pulled out or let fall forwardthe disc can drop out of the holder and float around inside the booster . this causes freeplay in the pedal and harsh braking with no pedal feel .

hmm that more closely describes my symptoms.
So if the rod is pulled out and that disc has fallen out of place how do you fix it? Do i need to pull apart the booster? or just get a new booster?

You can buy a disc from the brake shop , someone who reconditions boosters would be your best shot . Then remove the front seal and piston rod , it will have a large end on it same size as the disc , put a little rubber grease on disc and stick it to the end , when you put it back in there is a cup the size of the end of the rod it sits inside this . put the seal back in and bobs your muthers uncle. just leave the old one floating round won't hurt anything. If you cant find a new disc you could try and fish the old one out but this can be hard to do. Good luck

cool thanx heaps ppl!!!!

In so many of these interesting threads we never find out what solution finally worked. So please let us know how you get on, TR3LOS351.

Sounds as if hi60 knows what he is talking about.


David

Another cause may be an internally split flexible brake hose. The fluid can pass through one way, then the pressure flares out the internal splits not allowing the fluid to return when you take your foot off the brake pedal.

kane077 wrote:Another cause may be an internally split flexible brake hose. The fluid can pass through one way, then the pressure flares out the internal splits not allowing the fluid to return when you take your foot off the brake pedal.

Would never have thought of that. Amazing what you can glean from these forums.

i checked my brake hoses they seem fine, got someone to press hard on the brakes while checking and i noticed that they all expand a lil front ones more than the back. so i take it this must be normal?? might just chase some new ones up for piece of mind.

i pulled off the brake booster and sounds like sumtin is rattling around inside. tried pulling it apart but its got like a retaining lock thing around the front seal where the mastercyl side is and i think i bent it so i got quoted $250 to get the booster reco-ed so i think i might just do that.

i'll be fitting the lines first then the booster too see which one is the problem.

piston on the caliper can get corroded also, I've had one seize on me. Also had front drivers jam up due to split hose as discribed above. disconnected the line and the piston let go. Crimped the hose and drove home on 3 brakes. got new hose now all good!