GQ Brake Pistons

[Silver]

Now I read your post I think I may/should of written similar, but our mate had em already on the bench in bits.

G'day Robo and Rip'n'Shred.

Robo - we got a pretty good answer together in the end, I reckon! Thanks for your major part in it.

There are some gurus on here, I am not one of them in relation to patrol mechanicals, you may well be, Robo.

The gurus touch all the key points right up front all the time - the rest of just contribute what we can, based on experience, and it seems to be appreciated.

Rip'n'Shred - yep, for key safety systems, when in doubt, get expert help. A couple of good mechanics I know seem to forget how much they know from training and experience that helps them to diagnose and deal with problems. And they have manual skills and strength and tips and tricks as well, so they are a pleasure to watch at work.

Trolatron, all the best with your fix - be really interested to know what was holding the brake on, or why otherwise it got so hot

Out of left field, I guess there is a remote possibility that the heat is coming from a wheel bearing problem? I've seen car and trailer wheels depart from the car or trailer because the hub got so hot. Anyway, time and work will tell.

[rockndot]

I had a simalar problem also one day,
towing my Fathers big c/van out of home,(bush hill block)
when braking must have got a stone in behind the pad,
towed the van about 15 k's, noisey brake tap pedal ect, thinking that ford falcon he towes it with is gutsy.
when i stoped i had one hot wheel, one stuffed rotar, and a brake rebuild
But, slow and easy + gregorys manual, no problemo
But have to admit, i have spent plenty of time arround my mechanical mates,
so had seen heaps, but agree with others, if unsure on brakes, leave em for the brain trains.
cheers rock.

[Robo]

Up front, Sorry Rockndot.
Please anything but a Gregory manual.
Way way over priced for what's in em.
made that mistake years back (in my youth young and dumb) gregory very basic manual.
Next to useless for someone with some mech skills
Don't waste your money on gregory. my 2 c w.
There are far better manuals out there, Haynes or similar.
recently got a Max Ellery 1 as a gift for the out law for his tr##py, "opps" did I say that word.
Good manual covered alot of years many models and lots of info, diagnostics codes etc.
looks like recycled paper soft cover but the info in it impressed me. $44 on ebay.
Genuine manual probably best, and get one here.

[Rip'n'Shred]

Well done with the video, I'd never thought of that before.

Very hard to see detail but appears your doing well. Sometimes even minor pitting in the pistons can be bad. There is a lot of pressure behind those suckers.

Definitely replace all rubbers. Use wire brush to remove any build up or rust from slide pins, grease slides with rubber grease. Use clean new brake fluid on pistons to help insert with new seals, but only if you are ready to install straight away as brake fluid is hydroscopic (absorbs moisture in the air), otherwise rubber grease as previously mentioned.

Be sure to remove any excess grease. Does not play well with pads and discs.

Be a good time now to completely drain the brake fluid out of the vehicle if not already done. You don't want dirty old burnt fluid going anywhere near your rebuilt calipers. Refill and bleed very well after fitting all calipers back on. Use clean unopened bottle of correct grade of fluid. Don't mix synthetic and mineral brake fluids, big no no. don't even worry about synthetic, just good quality mineral will be fine.

The stuck piston. Usually use old brake pad against piston and use g clamp to very gently to push piston back in. if it requires force then stop, not good.

Discs. Any lip on the discs isn't good. After doing all this work, may as well get them machined. They will measure them too to ensure not too worn. Check very vigilantly for little cracks in discs, particularly the one that overheated.

Good luck. Feel free to ask any further questions. Thats what forums are for.

Mechanics do tend to forget what they have learnt.

[Silver]

Trolatron, your sliders in your video were much more free than mine - where crud had got in through the splits in the boots.

The video was a cracker of an idea, you seem to be a natural, and your camera person did a good job too!

[Trolatron]

Trolatron, your sliders in your video were much more free than mine - where crud had got in through the splits in the boots.

The video was a cracker of an idea, you seem to be a natural, and your camera person did a good job too!

Thanks Silver, I'll tell her you said she done a good job on the camera might help me get pionts back for swiping her dish washing pad and she missed 10 minutes of her favorite tv show Bones

PS : not bad for a mobile phone vid

[Robo]

Yes good advise I also have read this somewhere on the mineral and synthetic fluids.
You cant even try and completely drain and replace mineral.
If mineral fluid has been in system at all it's a no go to up grade, it has to be there from brand spanking new.

[werafa]

looking up in the manual - it says to lube the assembly with brake fluid. kinda makes sense too.

[werafa]

the replacement bolt in unit turned out to be for drum brakes. The seal kit was $24 per side

[Trolatron]

Thanks for all your input guys, I have now pulled all 4 calipers apart put new seal kits threw and rubber grease in with fresh brake oil and boy what a difference its made not that I was having problems pulling up in a hurry but it just all feels better threw the pedal and I gained 2 horse power now the brakes ain't dragging

Really happy with the results and I now have a much better understanding of how they work.


Cheers
Ray