front caliper service

Jon Wildsmith

Super Moderator
Supporter
Guru
I am in england
Feb 24, 2010
6,721
143
63
Stourbridge, West Midlands, England
Garage
I nearly forgot I rebuilt some 80 series front brake calipers for someone a few weeks ago and then realised tonight I should have took pictures for the forum :? So what follows is a bit of a cheat because I took a boot / piston out of the finished job to take pictures of :roll:

The main thing that seems to go wrong is the rubber boots round the end of the pistons get torn either through age or abuse and then mud sits inside there and corrodes the end of the piston so it won't go back in any more. Even if your boots seem pretty much ok it would be good PM to do a rebuild to make sure corrosion can't get started and cost you 8 pistons :(

Before you take the caliper off the truck, take the pads out and use the brake pedal to force the pistons out a good way. Once the caliper is off, clean all the mud off BEFORE to take the boots off or the pistons out.

Yours will be a dirty version of this:

IMG_0902.JPG


They don't need to be spotless, just lose all the lose stuff for the bulk of the caliper and get them properly clean in the area of the pistons. Then pop the metal clips off and pull the boots off. Have another clean round the raised lip that the boot covered so the new boot has a clean surface to sit on. Now you can pull the pistons out and shouldn't get dirt inside the caliper.

This is one of the old pistons that really didn't want to come out even under braking pressure! You can see the marks from me putting the mole grips on very tight and slowly easing it out with a combination of tapping the grips with a hammer and rotating the piston.

IMG_0909.JPG


The fluid in these calipers was particularly dirty and I suspect had a lot of water in it so there was even some small corrosion inside the caliper:

IMG_0905.JPG


Here you can see the rubber main seal inside the caliper body. Just poke that out with a screwdriver. There will likely be some dirt in the recess that rubber sits in so give that a good clean as well - a rag pushed round with a small screwdriver works well. Then fit the new seal, it just pushes into place, and smear some of the special red grease that came in the rebuild kit on the seal so it's not dry. Then push the pistons into place, leaving quite a bit proud of the hole until the boot is fitted.

IMG_0904.JPG


Pop the new boot on and go all the way round stretching it out slightly and looking to make sure the lip is sitting flat and not twisted. It needs to sit flush or this is all a waste of time!

IMG_0903.JPG


Now push the piston all the way in, making sure you push it evenly and not too firmly. The pistons are a snug fit and only need to be slightly off square before they bind. If you're having too push hard then you may not be pushing it in as square as you think ;)

IMG_0907.JPG


Now the boot should easily stretch out over the outer lip. Make sure it's sitting evenly and flush. Then gently expand the metal ring till there's a small gap between the ends and put it over the outside of the boot. If the ring isn't sitting quite right, just expand it a little while pushing down gently where needed and it will go on easily. Make sure the ring is all the way on, flush against the rubber. It doesn't have to resist a great deal of force but you don't want it working it's way off. Avoid using anything sharp to adjust or poke the metal ring or you might puncture the boot - your fingers are best.

IMG_0910.JPG
 

Rob

Well-Known Member
Mar 1, 2010
3,019
16
38
Bristol
Garage
Thanks Jon, need to do this at some point. Now we need one for the rears :D :D
 
Don't like the adverts? Remove them by becoming a supporting member.   Click here

Julian Voelcker

Well-Known Member
Mar 5, 2010
313
4
38
Herefordshire, UK
Good write up.

A couple of things to add...

If you are really struggling to get the pistons out, try to get access to a MIG welder and run it around the inside of the piston a couple of times - the heat from this will break the seal and once cooled you should be able to ease them out quite easily.

Often the rust will have started on the inside of the calliper - if you undo the four bolts holding the two halves together, be careful not to loose the two rubber seals between the two halves and then you will have better access the the cilliper bores. Once we have hooked out the rubber 0 ring in the bore we use a bore deglazing tool in a drill to clean out the bore. It's also a good opportunity using a wire brush in a drill to clear any rust away from the lip of the bore where the seal goes.. we then treat it with a dinitrol rust treatment before re-assembly.

Finally, to help keep the moisture/rust at bay, it is worth buying a tub of red rubber grease from Frost and smother the top of the piston under the seal with the stuff.
 

Ecky Thump

Well-Known Member
Mar 4, 2010
1,422
3
36
Reigate, Surrey
Garage
Julian Voelcker said:
Finally, to help keep the moisture/rust at bay, it is worth buying a tub of red rubber grease from Frost and smother the top of the piston under the seal with the stuff.
Julian

Who is this Frost? When I did mine and Tommo's I couldn't find the red grease anywhere local to me. I used to use it years ago but thought it had disapeared from the market apart from the tiny bit Toyota supply with the seal kits.

I could do with some as it wont take long to peel back the new dust seals and put some more in.
 

Julian Voelcker

Well-Known Member
Mar 5, 2010
313
4
38
Herefordshire, UK
Jon Wildsmith said:
[quote="Graham Stirling":lz9bjujo]Jon,

Do you know what the pipe and fitting size is on an 80. I'm guessing 3/16 pipe and 10mm fittings?

Cheers, G
No I don't ,sorry, I only have the calipers not pipes. Anyone else know?[/quote:lz9bjujo]

If you are talking about the metal pipes, we had to make a stack of pipes up last week and I just picked up standard pipe and fittings from the local motor factors.

Graham, if you could let me know what exactly you want the dimensions for I can nip out to the workshop to check for you.
 

Graham Stirling

Active Member
Mar 8, 2010
74
0
16
Caputh, Perthshire
Julian Voelcker said:
[quote="Jon Wildsmith":393zy9ri][quote="Graham Stirling":393zy9ri]Jon,

Do you know what the pipe and fitting size is on an 80. I'm guessing 3/16 pipe and 10mm fittings?

Cheers, G
No I don't ,sorry, I only have the calipers not pipes. Anyone else know?[/quote:393zy9ri]

If you are talking about the metal pipes, we had to make a stack of pipes up last week and I just picked up standard pipe and fittings from the local motor factors.

Graham, if you could let me know what exactly you want the dimensions for I can nip out to the workshop to check for you.[/quote:393zy9ri]

Thanks Julian, much appreciated.

I have to make new pipes up to connect to the load proportioning valve. It's just the pipe size and fitting size i need so that i can order some from the motor factors. I've always bought full made up sets of pipes in the past but i was hoping to make my own up this time and i'm just not sure what i need to order.

The other thing i could really do with is a number or website for custom braided hoses as i need the flexi hose at the centre of the back axle but +150mm length. I stupidly bought new flexi hoses for the rear calipers direct from Toyota not realising what they cost until they turned up but i'll eventually swap them for braided hoses and keep the rubber ones as spares.
 

Andrew Prince

Well-Known Member
Feb 23, 2010
2,232
12
38
Joburg, sunny South Africa
Given that the weather looks just peachy for the Easter long weekend, I am thinking of finally getting round to refurbing my calipers.

Quick question, what is the best way of sealing the brake lines when the caliper is removed? I guess I could fold the open end back on itself and clamp it but that would weaken the hose quite a bit...

Cheers,
 

Rob

Well-Known Member
Mar 1, 2010
3,019
16
38
Bristol
Garage
I have seen pictures of mole grips used to clamp down on brake lines, sometimes i have seen 2 short metal pipes one on each jaw of the mole grip to protect the pipe.
 

Rob

Well-Known Member
Mar 1, 2010
3,019
16
38
Bristol
Garage
adrianr said:
Rob said:
I have seen pictures of mole grips used to clamp down on brake lines, sometimes i have seen 2 short metal pipes one on each jaw of the mole grip to protect the pipe.

Pipe - couple of long sockets from your socket set?
Thinking about it, they where deep sockets
 

Andrew Prince

Well-Known Member
Feb 23, 2010
2,232
12
38
Joburg, sunny South Africa
I like the pipe clamp option, I think. I want to do a minimum of bleeding until all 4 are done and then change the fluid altogether.
Dunno how much fluid drains out if you just leave the hose hanging?
 
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock    No Thanks