[alien]

Righto...

First time i've had this happen so I'm not 100% on what it could be! Was a cold morning (about 5*C) and i felt like driving my sierra hard, so i did. lol I was doing a fair amount of hard braking, chuck it into a corner, accelerate hard, brake hard etc etc often slowing from 80km/hr or so in around 100m, taking a corner at about 40-50km/hr and accelerate back up again.

After doing this for about 10mins I braked to turn right and the car pulled left, released the brakes to make the turn and away it went.

I then repeated this a few times at different speeds and the effect was the same. Parked it at work, jumped in to drive home and it's been fine since.

I can only assume that i boiled the brake fluid or a caliper was sticking or not clamping properly due to the heat? It's 4-wheel disc so can't be a drum issue.

What's all your thoughts on possible causes and solutions? And don't say not to drive it like that, cos that ain't gonna happen =)

[Gwagensteve]

Sticking caliper

[alien]

Due to the heat you reckon? Or worth forking out to rebuild them?

[Gwagensteve]

Probably a sign it will start happening more frequently. That's my guess. If you boil the fluid you'll get no pedal, so it wasn't that.

[bohuler]

My sierra did the same thing after some 'hecktic' hills driving BUT I kept on driving and the next day the caliper locked on and seriously frucked itself. (nearly pulling the car and myself off the road and down a nasty as hill :S)
Either buy a rebuild kit (if you can get the one with new pistons go for that) or take it to a brake specialist and get them to rebuild the calipers. If they change the pistons make sure you get old ones back so you know they have done it right

Dave

[alien]

Ive not checked, but a guess is that the pads are running low so the piston's travelling further and there's some junk in there jamming it up... but then if it were that it'd be constant.

Pulling left while i push my foot down means the right side calliper/s is seizing open not shut too?

[Marko_SJ]

bohuler wrote:

My sierra did the same thing after some 'hecktic' hills driving BUT I kept on driving and the next day the caliper locked on and seriously frucked itself. (nearly pulling the car and myself off the road and down a nasty as hill :S)
Either buy a rebuild kit (if you can get the one with new pistons go for that) or take it to a brake specialist and get them to rebuild the calipers. If they change the pistons make sure you get old ones back so you know they have done it right

Dave

Can you rebuild them, and polish up the pistons?

Thats what I was told to do with motorcycle brake pistons.

Alien's description does not sound like what happened when I boiled the brakes in my commodore. I just progressively lost braking ability.

[fordem]

Marko_SJ wrote:

Alien's description does not sound like what happened when I boiled the brakes in my commodore. I just progressively lost braking ability.

Progressive loss of braking ability - aka brake fade - is more likely to be a friction surface (pad/rotor) issue, than a fluid boil issue - when the fluid boils, like Gwagensteve says, you'll have no brakes.

It takes a while to get the fluid up to boiling point (which will vary with the moisture content), but once you get it to that point, you're going to go from full-brakes to no-brakes in the blink of an eye - total brake failure, akin to fluid loss, with one exception, give it a chance to cool and they work again - that is, assuming that when they failed you didn't stuff the vehicle, so you get the chance to find they work after cooling off.

[MrRocky]

Just drop the calipers at perth brake parts they are the main supplier for all the mech shops ect...
I had them do my hz prem calipers $140ea
1 day turnaround

[MrRocky]

Perhaps an opportunity toupgrade to lwb vit discs and calipers ?

[Marko_SJ]

fordem wrote:

Marko_SJ wrote:

Alien's description does not sound like what happened when I boiled the brakes in my commodore. I just progressively lost braking ability.

Progressive loss of braking ability - aka brake fade - is more likely to be a friction surface (pad/rotor) issue, than a fluid boil issue - when the fluid boils, like Gwagensteve says, you'll have no brakes.

It takes a while to get the fluid up to boiling point (which will vary with the moisture content), but once you get it to that point, you're going to go from full-brakes to no-brakes in the blink of an eye - total brake failure, akin to fluid loss, with one exception, give it a chance to cool and they work again - that is, assuming that when they failed you didn't stuff the vehicle, so you get the chance to find they work after cooling off.

You are likely correct. I know I got them hot and they are pitifully undersized for the car but it may well have been the friction surface.

After driving around gently, my brakes came back... very slowly.

[4x4xzook]

My Sj70 did the same, after breaking suddenly behind a ute with a trailer that had no brake lights. It progressivly became worse, eventually locking on and pulling the car almost off the road...
Two mechanics looked at it and said i needed new calipers, i changed my master cylinder still the same problem.... ABS brake specialist gave me a pricey list.

So I decided to tackle it ony my own first. I changed the disc and pads. Also made sure i had plenty of that pbr caliper grease in, fitted the wheels and bled the brakes. It was like a new car again.
That pbr grease will cause the caliper to seize or pull more to one side. (That being the side thats drier and with less grease.)

[alien]

MrRocky wrote:

Perhaps an opportunity toupgrade to lwb vit discs and calipers ?

That's a no go - the caliper won't clear my hi-steer arms =) been there, done that.

I think my issue is the drivers side front is slightly "on" - i'll jack a wheel up tonight and have a feel of it, but that would explain that side heating up and fading more than the left side, causing it to pull left. I could smell a bit of brakes from the front drivers side this morning when i got to work and no smell from any of the other 4 wheels.

[alien]

15mins drive home from work and can smell brakes... so i park it up, take the drivers side wheel off, head inside and gather things, 15mins later i point the IR temp gun around the rotor / caliper and i'm getting readings for 110*C ! The passenger side is 30*C.

[alien]

FAIL: tried to undo the slide bolts to free them up, got about 5 turns in on the rear side and the bolt snapped inside the caliper. Off to suzistore for a new caliper in the morning! lol

[Gwagensteve]

Time to go vented IMHO.

[alien]

Eh? They don't make vented sierra rotors?

[J--A--C--K]

Vitara fronts , from a lwb are vented and bolt on

[alien]

aren't they a larger center bore though?

[jdk81]

I think they didn't acknowledge this post

alien wrote:

MrRocky wrote:

Perhaps an opportunity toupgrade to lwb vit discs and calipers ?

That's a no go - the caliper won't clear my hi-steer arms =) been there, done that.

[alien]

All fixed.. slide bolts were full of junk. Cleaned up, but of copper spray, back together (those rubber boots are a bitch) and all is well again.