Braking Problems

[JimmyC Advanced Member Find all posts View Profile Close JimmyC]

G'day all,
Looking for anyone else who may be able to shed some light on this.
Had a service done last week and since then the brakes have been acting really weird. The service involved the replacement of a CV boot so the brake calipers came off but apparently weren't opened.
Anyway since then the first time I hit the brakes after not using them for a while (>30 seconds) the pedal is very soft and there is a lot of travel before they kick in. This is mostly prevalent at low speeds. Subsequent brake usage is completely normal if the brakes are used again within a short time. Once the brakes go without use for a little they go back to soft for the first push.
When stationary if I apply constant pressure to the pedal it sinks slowly to the floor.
There are no leaks on the brake lines and fluid is full and about 80% condition. This issue has come on suddenly.
It went back to the mechanic today and the brakes got bled but still the same issue. All my other research suggests that the master cylinder is failing but I can't find any mention of anyone else that has had the same issue, nor can I find any parts online which suggests to me that it is a very rare thing.

Can anyone point me in a direction as to anything else to try before I go chasing a master cylinder which i have a feeling will be big $$
Cheers.

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Hey,

Could be a sticky front piston in your calipers. Brake dyno test will reveal this.

Sticky pistons in Prado calipers are quite common.

Hope you get it sorted soon!

Best

Mark

[JimmyC Advanced Member Find all posts View Profile Close JimmyC]

So I got a price on a master brake cylinder today from Toyota... $1813 just for the part!!!!!! I'm now thinking it might be a leaking brake line. The caliper got taken off to do the CV boot and the issue started after that so there is the potential.
I'll also get the piston checked as Whitey suggested. Booked into a brake specialist on monday!

[Milkmanstan Lurker Find all posts View Profile Close Milkmanstan]

G'day all,
Looking for anyone else who may be able to shed some light on this.
Had a service done last week and since then the brakes have been acting really weird. The service involved the replacement of a CV boot so the brake calipers came off but apparently weren't opened.
Anyway since then the first time I hit the brakes after not using them for a while (>30 seconds) the pedal is very soft and there is a lot of travel before they kick in. This is mostly prevalent at low speeds. Subsequent brake usage is completely normal if the brakes are used again within a short time. Once the brakes go without use for a little they go back to soft for the first push.
When stationary if I apply constant pressure to the pedal it sinks slowly to the floor.
There are no leaks on the brake lines and fluid is full and about 80% condition. This issue has come on suddenly.
It went back to the mechanic today and the brakes got bled but still the same issue. All my other research suggests that the master cylinder is failing but I can't find any mention of anyone else that has had the same issue, nor can I find any parts online which suggests to me that it is a very rare thing.

Can anyone point me in a direction as to anything else to try before I go chasing a master cylinder which i have a feeling will be big $$
Cheers.

Hi,
I had similar problem with my brakes not biting and "long brake pedal" after I had my tyres replaced and aligned at Bob Jane. Lug nut were obviously overtightened. Solved it by 1) Cleaning the rotor and pads with brake cleaner( Lots of tyre shine used) 2) bleeding the brakes 3) pressing in the pistons 4) torqueing the wheel lug nuts to factory spec. ( warped rotor pushing piston back in when rotating??? 5) recalibrated steering angle

That seem to solve the problem, not sure which exact step fixed the problem but brakes are performing much better now. Maybe try these before replacing the master cylinder, and might also want to check that the brake caliper bolts are proper torqued too. Hope this helps.

Regards
Stan

[JimmyC Advanced Member Find all posts View Profile Close JimmyC]

Hi Stan,
Going to check the line myself for leaks tomorrow and see how that goes, I might try the brake clean too and check the pad alignment etc. Monday's booking is to check every other possible option before looking at the master. I feel that if it were the master the soft pedal would occur more randomly rather than only on the first push.

[Milkmanstan Lurker Find all posts View Profile Close Milkmanstan]

Hope you solve your brake problems. $1800 for a master cylinder? Maybe they added an extra zero by mistake either that or I'll really out of touch with inflation. Geez!

[JimmyC Advanced Member Find all posts View Profile Close JimmyC]

So a solution has been found!
I lifted the car up to clean all the brake lines and check for leaks. Upon putting the wheel back on I felt some big play in the wheel in all directions. Back up to the mechanic and it turns out my wheel bearing is kaput. There was no grinding noises or anything, the brake problem was the only clue. Apparently that was caused by the disc moving in relation to the calliper which pushed the pistons for the pads back causing the first push to be soft because it required to reset the piston before working.
A wheel bearing was found soon enough but they couldn't get some sort of ???sub-bearing??? off (I was half asleep when they rang me so didn't hear them too well), not sure what that was but apparently it needs to be pressed out? Anyway they couldn't get it off so need that part too. Being Alice Springs it won't get here til tues. Weekend holiday for the car!