JSpec brake calliper refurb

[stevie_b]

At least one of my JSpec callipers needs a refurb I think (nearside front), but I've hardly done any brake work on the car myself. Is there a How-to on here or elsewhere about it? I've searched on here and also on the internet at large (I figured the process is pretty similar regardless of car make/model), but I couldn't find anything that answered my questions.

 

Specifically, what the steps involved, and what does the refurb kit from Mr T include?

 

Here's what I'm guessing needs to be done (based on info in this thread):

1) remove relevant roadwheel

2) remove calliper from brake disc. I've done this before so I know how to do it.

 

It gets hazy from here on, so here goes:

3) depressurise the brake fluid? If so how?

4) Unplug the brake line from the calliper, bunging the end with something so brake fluid doesn't spill everywhere

5) Push the pistons out of their cylinders by hand? Is this possible or do I need to use the brake fluid (with brake line still attached) to pop them out?

6) remove the piston rubber seals

7) clean up all parts, but especially the piston bores with very fine sandpaper.

8) ensure the slider bolts are sliding freely. How free should they be? Hard to describe I know, but I could move mine maybe 2-3mm by hand with moderate force. If they're supposed to be looser than that or have more travel, please let me know.

9) do the cylinder bores need cleaning?

10) I'm assuming the refurb kit contains new rubber piston seals, so fit those

11) push the pistons back in place by hand

12) fit the brake line onto the calliper

13) bleed the brakes: do all 4 corners need bleeding even if I've only mucked about with one brake?

 

When I unplug the brake line from the calliper, roughly how much brake fluid should I expect to lose and what pressure would it be under? Is it going to squirting out all over the place?

 

Thanks in advance for any help.

[Nic]

Step by step guide in the service manual here http://www.turbosupras.com/pdfs/JZA80%20TSRM/BR.pdf

 

Part number for the front caliper refurb kit, the kit includes all new seals for both calipers.

 

http://img717.imageshack.us/img717/551/picture1qn.jpg

[stevie_b]

Thanks Nic!

 

The manual says to use compressed air to push the pistons out, which I don't have. What can I use instead? Something bodged together and pushed with a G-clamp?

[Nic]

Push them out using the brake pedal before removing the brake line or go down your local garage and use their airline.

[Digsy]

I used a cheap honing tool from Snap On in an electric drill to re-surface the piston bores in my calipers when I did a front and rear refurb a few years back, but it pays to be careful with the fronts because the piston housings are aluminium and can gaul up if you get it wrong.

 

It might be worth buying a tool to re tap the thread where the brake line connects as I found mine to be full of gunk. This will save all the crud from entering the cylinder when you screw the banjo bolt back in. I think it is M10x1mm but I can check next time I am in the garage.

 

The belows seals for the sliding pins can be pressed in using a vice. I squashed the rubber part into a large hex socket to protect it and then pressed the seal in using that. Before using this method I managed to split one seal by pressing on the rubber iteslf.

Edited July 5, 2012 by Digsy (see edit history)

[merckx]

You can leave the brake hose connected to the caliper and press the brake pedal to use hydraulic pressure to push them out.

 

Remove the pads.

 

Unbolt the caliper from the hub.

 

Remove the disc.

 

Bolt the caliper back to the hub to hold it in place while you're working on it.

 

If you now pressed the brake pedal the pistons could come flying out and maybe just one and not both!

 

So, you need to use a block of wood or similar to replace the discs and pads combined (a little narrower at a time and this will only allow the pistons to come out gradually. Obviously make sure it cannot fall out.

 

Easier to get someone else to now press the brake pedal, you can see how the pistons are pushing out.

 

One piston may come out before the other. You can use a pair of mole grips or something similar to pull the other out the last bit but you've got make sure you don't damage the piston. I would wrap the piston with a fair amount of tape first.

[nige-rz]

1. Unbolt wheel.

2. Remove caliper but leave brake line attached. *no need to remove disc as mentioned above. For me this wasn't necessary, it balances quite easily on top of disc.

3. Remove pads.

4. Start car, press brake pedal. (handy if someone else does this for you while you are looking at pistons.)

5. Freely moving pistons will fully extend and you'll see the dust boot become very stretched. I stopped at this point.

6. Remove caliper (clamp brake line with brake line clamp, don't worry there's no great pressure in the system), cut off dust boot and use pliers and padding to remove piston from the bore.

7. The problem is the seized pistons. They will not move. I used a g-clamp to force the piston back into caliper (after soaking in WD40), just to get it moving again. I then used step 4&5.

8. Use very fine grit paper to clean up piston and bore. **nb** don't use normal grease when reassembling. There's special red grease that comes with mr T's refurb kit. Was told normal grease can cause premature perishing of seals and dust boots.

9. Reassemble.

 

I'm on my phone so it's difficult to type out a full how to. It's a simple enough job, just take your time and be methodical. Any problems pm and I'll try my best to talk you through it.

 

Best of luck

[Nic]

Another tip, be careful unscrewing the bleed nipples, if they are corroded into the calipers they can easily sheer off when trying to loosen. If the threads are corroded soak with penetrating oil over night, then before removing them heat the caliper around the bleed nipple with a blow torch.

[stevie_b]

This is all excellent info folks.

 

Regarding the bleed nipples, when I come to re-assemble the callipers I guess it's prudent to apply something to the thread to prevent it seizing in the future. Copper grease?

[Robzki]

Copper grease can affect rubber seals and it generally gets cruddy and dry. Use 'red rubber' grease on brake parts. You will need a tub for rebuilding the calipers. apply it sparingly to seals etc. I have half a tub I could send you if you cover the postage but it can be found from motor factors etc cheaply. The banjos that connect to the caliper can be difficult to seal to stop the fluid leaking while you are rebuilding the calipers. I used some thick plasic bags and zip ties to wrap around them. You don't lose very much fluid, just make sure you keep the resovoir topped up.

 

I got my rebuild kit including the pistons from CW. Replace the brake fluid when you have finished if you know it hasn't been changed for a while.

 

Any questions just ask.

 

Rob

[Nic]

If you buy genuine parts from Toyota you should get a small bag of Lithium soap base glycol grease with the refurb kit.

 

Not sure how much the Toyota refurb kits are for the Supra in the UK - the one for my MR2 is stupidly expensive at £98! - this company does refurb kits, pistons, etc. at a fraction of that cost for the MR2, they also list parts for the Supra. I've used them before for parts and the quality is good. http://www.biggred.co.uk/catalogue.php

Edited July 6, 2012 by Nic (see edit history)

[Dnk]

I wouldn't bother refurbing j specs and just upgrade to the UK spec

[stevie_b]

Dnk: I have the stock 16" wheels and I think they'd foul the larger UK brakes.

[Dnk]

Yep your right they would need the 17's, time to upgrade your wheels as well

then Steve

 

UK spec 17's come up quite often and aren't silly expensive

 

I have a set in my garage with tyres on you could borrow till

you found some

 

Theres a set of 17" o/e wheels in the forsale section

Edited July 6, 2012 by Dnk (see edit history)

[Robzki]

Nothing wrong with jspecs unless you do a lot of track days. Mine lock the wheels on a very spirited drive, never had fade and they bite fine. They have been completely refurbed with new pistons etc, braided hoses and rbf660. Either refurb the jspecs or buy new UK or big brake. I certainly wouldn't be fitting s/h near 20 year old calipers unless they had new seals/pistons etc.

 

Oh and I have tried to test them to fade. I think that people trust old calipers with old fluid just because the concensus is that Uks are the ultimate. £600ish for ropey calipers always make me laugh.

 

Just my opinion

[Dnk]

Just to be clear i meant splash out and buy a new UK set up

[Robzki]

oh

[Dnk]

Have you got abs on your car Rob ?

[Nic]

Another option would be to send your calipers off to a brake rebuild company, they completely strip your calipers down, add coating and rebuild with new parts, http://www.biggred.co.uk/process.php get good reviews on the MR2 forums, here's a set an IMOC member had done.

 

Before

 

After

[Dnk]

The trouble is though Nic at the end of the day the caliper is still nearly 20 years old

and we've seen how fragile j specs are with quite a few failing round the bleed nipple.

 

I'd personally rather put the £320 cost to a new set up

Edited July 6, 2012 by Dnk (see edit history)

[Nic]

Hear what you're saying, didn't know about the bleed nipple issues.

[Robzki]

Have you got abs on your car Rob ?

 

yes?

 

Hear what you're saying, didn't know about the bleed nipple issues.

 

I've heard about it but didn't have any issues, and I'm a gorilla.

[Dnk]

Hear what you're saying, didn't know about the bleed nipple issues.

 

There's been a few on here where the casting has cracked around

the bleed nipple, more than likely due to the bleed nipple being

over tightened and there not being much material around the nipple

to deal with this.

 

This on its own is enough for me to want the UK 's as they are

a much better design and don't suffer with this problem

Edited July 6, 2012 by Dnk (see edit history)

[Digsy]

The J-spec brake caliper refurb kit for the REAR is about £40 (I just bought one from Toyota). The kit for the front will be slightly dearer. If you go for it you could easily remove, refurbish and rebuild both sides in a day, but I'd prefer to take my time and get everything nice and clean and paint the calipers while they are off the car.

 

Problem is that if you find something nasty like rust in the cylinder bore below the seal groove, then you are stranded until you can find a replacement caliper as there would be no point refurbing them.

 

I too have never had bleed nipple problems (and I have changed calipers zillions of times) but am aware of many that have.

Edited July 6, 2012 by Digsy (see edit history)

[The-Plethora]

I had the bleed nipple problem and it was getting through lots of fluid. I picked up a spare set of brakes from another user on here who said they were from a soarer (I think). Anyway they use the same pads front and back as the jspecs and the fronts are a different design and don't appear to suffer the same issue.

 

 

It would be nice to upgrade at some point but unless you are going round a track I think Jspecs are fine for most people.

Edited July 6, 2012 by The-Plethora (see edit history)