Brake Caliper Rebuild
- Thread starter Slomo
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
smittycrusher
"Hey big guy, you a golfer" - Roger Dorn
I had the same question back when I did mine. I never found an answer. I honestly can't remember what solution I came to. I know I did some reasoning to get to my solution but can't remember the mental process. I wish I could be more help.
Smitty
Smitty
Is it possible to measure the torque of taking the four bolts off? I'm not sure a torque wrench works both ways...
serenity
SILVER Star
ok this came up in chat too.
you can split calipers, you can replace those o-rings, there should be 2 in each caliper.
sandblast your calipers and clean with compressed air, linish your pistons or replace them if badly corroded. go to your local brake shop they will have the unobtainable o-rings. make sure all seals and o-rings are lubed up to prevent damage during fitting and initial operation, proper lube is available from brake shops.
to torque the calipers up use a 1/2" drive impact gun run with 80psi air pressure, or do all bolts up finger tight then place the caliper in a vice and using correct sized spanner (14mm?) do the bolts up as tight as possible by hand.
did this a few weeks ago at a shop under the supervision of a mechanic who specializes in brakes. he has been doing this for years without any issues.
you can split calipers, you can replace those o-rings, there should be 2 in each caliper.
sandblast your calipers and clean with compressed air, linish your pistons or replace them if badly corroded. go to your local brake shop they will have the unobtainable o-rings. make sure all seals and o-rings are lubed up to prevent damage during fitting and initial operation, proper lube is available from brake shops.
to torque the calipers up use a 1/2" drive impact gun run with 80psi air pressure, or do all bolts up finger tight then place the caliper in a vice and using correct sized spanner (14mm?) do the bolts up as tight as possible by hand.
did this a few weeks ago at a shop under the supervision of a mechanic who specializes in brakes. he has been doing this for years without any issues.
Skillet
Skillet
I am re-using my flat o-rings. they are perfect.
Lubing them up with brake fluid.
Lubing them up with brake fluid.
That can net you 400+ ft/lbs of torque. Might be a little much.
serenity
SILVER Star
i'll talk to my mechanic and get some info on that lube and the o-rings and check the torque settings. skillet, those o-rings may not be the correct thickness, they might look good but have been squashed after sitting between 2 pieces of steel for 15 odd years. company policy where i work is that all seals gaskets and o-rings are replaced on every service.
serenity
SILVER Star
alrighty. talked to my mechanic today.
on torque specs just as i said. he uses a 1/2" gun, if you are concerned about the torque drop your air pressures on your regulator. they don't have to be very tight though so you can just hold them in a vice and use a spanner to do them up. ensure all the o-rings are in properly and the calipers are up square and free from burrs of course.
the o-rings are 13mm OD, 8mm ID and 2mm thick they have a small raised edge on the OD and they are probably made from EPDM.
O-Ring Material Guide
as for assembly lube something like this will do. use it on all components, especially rubber seals
Wilwood High-Performance Disc Brakes - Brake Fluid & Assembly Lube
if you aren't sandblasting or acid washing your calipers make sure you clean up this part of the bore as this is the area that rusts and causes pistons to seize, also make sure you clean out the bores and galleries with brake cleaner. if you have the money and time get a machine shop to turn up new pistons from stainless. this removes the issue of bubbling chrome and reduces the chances of seizing. before assembly blow down the caliper halves with compressed air.
Glenn
on torque specs just as i said. he uses a 1/2" gun, if you are concerned about the torque drop your air pressures on your regulator. they don't have to be very tight though so you can just hold them in a vice and use a spanner to do them up. ensure all the o-rings are in properly and the calipers are up square and free from burrs of course.
the o-rings are 13mm OD, 8mm ID and 2mm thick they have a small raised edge on the OD and they are probably made from EPDM.
O-Ring Material Guide
as for assembly lube something like this will do. use it on all components, especially rubber seals
Wilwood High-Performance Disc Brakes - Brake Fluid & Assembly Lube
if you aren't sandblasting or acid washing your calipers make sure you clean up this part of the bore as this is the area that rusts and causes pistons to seize, also make sure you clean out the bores and galleries with brake cleaner. if you have the money and time get a machine shop to turn up new pistons from stainless. this removes the issue of bubbling chrome and reduces the chances of seizing. before assembly blow down the caliper halves with compressed air.
Glenn
Last edited:
Skillet
Skillet
All parts were cleaned, rust removed, new rebuild kit.
used "green grease" which is a synthetic waterproof grease.
maybe keep the rust down.
going to reassemble and torque to 61 ft lbs.
will report back if there are leaks, etc.
thanks for the input.
used "green grease" which is a synthetic waterproof grease.
maybe keep the rust down.
going to reassemble and torque to 61 ft lbs.
will report back if there are leaks, etc.
thanks for the input.
Skillet
Skillet
Follow up:
Everything completed as above. Also used red, HIGH TEMP loc-tite.
Multiple trips, hard driving, braking, long downhill grades, etc...
Not one drop leaked so far and the brakes function better than they ever have.
Hope this helps anyone considering this task.
Everything completed as above. Also used red, HIGH TEMP loc-tite.
Multiple trips, hard driving, braking, long downhill grades, etc...
Not one drop leaked so far and the brakes function better than they ever have.
Hope this helps anyone considering this task.
Is the small rubber piece circled in this pic a cap for the bleeder valve? It is something different than the small rubber cap that goes on the cylinder and I didn't see anything like it when taking them apart. Not sure where else it would go.
Thanks for any input.
Thanks for any input.
Yup - at least that's what I did with mine.
Yep, little nipple caps!
I found this thread via trusty Google. I have a 3/92 HZJ80 and the front calipers are both sticking quite badly, causing some drivabilty issues. I recently obtained a caliper rebuild kit and this thread contains the best guide on rebuilding calipers that I have seen.
Now a lot of Aussie people have told me I should look at upgrading the brakes to the later (8/92 and up) style with larger rotors, etc. and I may do that in the future.
I need to do all the front hub seals (genuine toyota is the way to go here apparently) but I'll deal with the sticking calipers first. Got new D694 tyres recently and fixed up a problem with the input flange for the rear diff a while back (it was waaay loose and the seal was also shot).
Next big challenge is the transmission which needs to come out to address clutch issues (I've replaced the MC and SC but still misbehaving) and a leaking rear main seal.
Anyway something someone mentioned to me was to use Silvo to clean up the piston surfaces and inside the bores of the caliper housings. Anyone tried that?
Craig.
Now a lot of Aussie people have told me I should look at upgrading the brakes to the later (8/92 and up) style with larger rotors, etc. and I may do that in the future.
I need to do all the front hub seals (genuine toyota is the way to go here apparently) but I'll deal with the sticking calipers first. Got new D694 tyres recently and fixed up a problem with the input flange for the rear diff a while back (it was waaay loose and the seal was also shot).
Next big challenge is the transmission which needs to come out to address clutch issues (I've replaced the MC and SC but still misbehaving) and a leaking rear main seal.
Anyway something someone mentioned to me was to use Silvo to clean up the piston surfaces and inside the bores of the caliper housings. Anyone tried that?
Craig.
Getting stuck into it!
Righto I've got over my fear of doing this and just done it today! I've got the left side caliper (the one that's sticking the most) off after pushing out the pistons with it still hooked to the brake line but not bolted to the hub. One of the four pistons came out easily.
The other three I had to carefully lever out with a screwdriver using the caliper body as a levering point, and now they're all out. There's a lot of muck inside the caliper bores (looks like a mix of rust and dirt) mixed with the brake fluid, and the pistons surfaces themselves have a fair bit of black stuff around them. None of the pistons have any corrosion on their internal surfaces which is good.
I'm going to get the remaining brake fluid out of the bores now, clean up the pistons with brake cleaner and silvo, and have a go at re-assembly. I'll use PBR rubber grease (Aussie-made!) where recommended and hopefully I'll have a nicely-working LHS front caliper after it's done.
Craig.
Righto I've got over my fear of doing this and just done it today! I've got the left side caliper (the one that's sticking the most) off after pushing out the pistons with it still hooked to the brake line but not bolted to the hub. One of the four pistons came out easily.
The other three I had to carefully lever out with a screwdriver using the caliper body as a levering point, and now they're all out. There's a lot of muck inside the caliper bores (looks like a mix of rust and dirt) mixed with the brake fluid, and the pistons surfaces themselves have a fair bit of black stuff around them. None of the pistons have any corrosion on their internal surfaces which is good.
I'm going to get the remaining brake fluid out of the bores now, clean up the pistons with brake cleaner and silvo, and have a go at re-assembly. I'll use PBR rubber grease (Aussie-made!) where recommended and hopefully I'll have a nicely-working LHS front caliper after it's done.
Craig.
serenity
SILVER Star
If you have access to a cabinet blaster and air compressor at all then use them, it's the best way to clean up the calipers. It might also be a good time to have your brake fluid replaced with fresh stuff.
I bled the brakes recently so I've put my Turtle Jaws brake/clutch hose pliers to use clamping the flexible hose.
I've got a compressor here but currently no air-blower unfortunately.
Craig.
One other observation worth mentioning...
The pistons themselves are quite clean and I used a new stanley knife blade to run around the outer surface of them to remove the bulk muck. One thing I found was that all four pistons have a very small area of corrosion at the back and I think it was the lowest point in each piston bore where some muck must have accumulated causing the piston metal to very slightly etch away.
I used a fine file to carefully work down the corrosion on each piston so it's smoother and less likely to catch inside the bore when they are re-inserted with freh seals, rubber grease, etc. I was careful to not mark the sliding surfaces at all (since that will make for leaks).
Seeing as I don't yet have any spare pistons, I'm re-using all the existing ones (at least for the LHS caliper I'm working on currently). The RHS one is still the original that was on the vehicle when I got it and going by the original LHS one (which is horrible and those pistons have LOTS of rust), I might new new pistons for the RHS one. LHS was sticking much worse though.
Craig.
The pistons themselves are quite clean and I used a new stanley knife blade to run around the outer surface of them to remove the bulk muck. One thing I found was that all four pistons have a very small area of corrosion at the back and I think it was the lowest point in each piston bore where some muck must have accumulated causing the piston metal to very slightly etch away.
I used a fine file to carefully work down the corrosion on each piston so it's smoother and less likely to catch inside the bore when they are re-inserted with freh seals, rubber grease, etc. I was careful to not mark the sliding surfaces at all (since that will make for leaks).
Seeing as I don't yet have any spare pistons, I'm re-using all the existing ones (at least for the LHS caliper I'm working on currently). The RHS one is still the original that was on the vehicle when I got it and going by the original LHS one (which is horrible and those pistons have LOTS of rust), I might new new pistons for the RHS one. LHS was sticking much worse though.
Craig.
