SpitfireS

Hi,
Here are some pics and some tips on how to rebuild the rear caliper.

These are the parts in the OEM rebuild kit.
(Thanks again HTG )
3 types of grease, orange for the sliding pins, pink for the dust boot and silicone for the other boots.
On the right the "piston" seal and the dust boot.
I say "piston" because the seal seats in the caliper.
In the middle from top to bottom: 2 alu washers for the banjo bolt (brake line), sliding pin boots, e-brake system seals.



This is a tool you must have to replace the e-brake seals.
The circlip that sits at the bottom of the caliper is hard to reach with any other tool.



This is a tool I made to make it a bit easier to turn the rear piston.


This is what it looks like after 9 years of rain & salt.
The e-brake cable bracket is allready removed.
Now is a good time to remove the e-brake spring.
It pops right off with a screwdriver.
No need to remove the nut (if you do: it has loctite on the thread)


Turn the piston out (anti clockwise).
Now it shows why it got stuck every now and then.


The piston is pitted and I was a bit worried it would not seal again but it did.
I guess I will replace it if it ever gets stuck again.
Or starts to leak.


The piston internals.
NO need to remove it if it is clean.
There is a strong spring in there.
I found the circlip to be partly out of its groove (must have been so from new) so I did remove it but I needed a "trick" to get it back in.


Here's that trick: find something in the right diameter (just a little smaller than the circlip) and press the circlip back in.
Now it sits allright (look at inserted picture)
The other piston was ok.


Rebuild Time!


If you're not doing the e-brake seals you HAVE TO COVER THIS UP before removing the rust.
I doubt a wash will get everything out if you don't.


E-brake parts top to bottom:
Circlip, some sort of cover, spindle with spring and bearing and small seal, piston with pins and o-ring, pushrod, e-brake actuator.


Now remove the actuator seal and you will see it's running in a needle bearing with a couple of needles missing - that is where the pushrod goes through.
I used alu-complex-based grease in there (is water proof).
I guess you could use the orange sliding pin grease there too.
Replace the actuator seal.


All cleaned up and ready to install.
Its clear the rust did some damage.


The pins on the piston need to go into the holes at the bottom of the caliper (duh)
I used the needle nose pliers to put it in and turn it a bit.
Don't forget to replace the o-ring and put the e-brake actuator (and spring) and pushrod back in first.


E-brake spindle.
From left to right: spindle with bearing, with thin washer, with spring, with cover.
On the bottom of the spindle is a seal to replace.
The picture showing how it goes is in a later post.


This is how I put the piston back in: first slide the boot in its groove then push it out towards the bottom of the piston, that will stretch it a bit to get the part of the boot (lip) that sits in the caliper lower than the piston.


Now wiggle that lip into its groove and pull gently to confirm its in.


The first time I pulled it out again to feel how tight it should be, to feel how much force it should be able to take when its properly in.


Now push the piston past the seal and onto the spindle.
Then turn the piston back in (clockwise) until it doesn't go any further.
The boot should nicely fold into place.
If there is some air stuck underneath you will need a small (not sharp!) screwdriver to let the air (or too much grease) out.


If you're doing the sliding pins as well: don't forget they are not the same.
One is not round but has flat spots on it.
Just do one at a time so you can't go wrong.

Have fun.



edit: typo and extra info.

cdelena

Great detail, thanks. These are pictures and tips not documented before so lets make sure we save this thread.

Olegator

cool stuff, but for the amount of effort, it looks like buying new ones would be easier.

SpitfireS

Some extra things I would like to add:
Random.

This is a picture I forgot I had taken.
It shows the way the e-beake spindle seal goes on.

When the caliper is still bolted to the hub, loosen the brake line banjo bolt.
Its hard to do when you have the caliper in your hands.

I applied some silicone grease to the thread of the bleeder.
Coat the thread (on the bleeder and in the caliper) with grease when its out and screw it in / out a couple of times.
That way you won't see small air bubbles when doing a gravity bleed.
They seem to seep past the thread when you loosen the bleeder and may make you bleed for eternity.
Gravity bleed is best but someome helping you pump the pedal makes filling the empty calipers a bit quicker.
Also, the silicone grease mentioned earlier may (only a bit) block the bleeder and gravity bleeding will take forever.
Finish with a gravity bleed though.
Maybe do it again after driving if the pedal feels soft.

The caliper/piston seal should only be lubed with clean brake fluid.
No grease.
Same for the piston.
IMO it doesn't hurt much if a little grease stays on it when you slide the boot from top to bottom.

I still don't fully understand how the e-brake system works.
I do know it doesn't work without fluid, as in: it doesn't pump the piston any further out, just the same stroke in and out.
You can re-use the clip that holds the e-brake cable, eventhough the manual says to replace it.

Feel free to add tips, tricks and comments.

Jano

THANKS! I will definitely use this DIY. Your piston tool is great, a socket extension always slips out when doing this.

negcamber

For those in the US, the tool below is available at most part stores and fits on a socket wrench:



Nice write up Spitty...it's been added to the DIY FAQ.

my2ks2k

hell of a write-up i wish this had been around when i powdercoated and rebuilt my calipers last spring. i just kind of tore them apart and learned as i went it's really not a big problem, other than that damn circlip at the bottom of the rear calipers. those things are a PITA!

i actually did a little drawing of the parts for a guy who had asked some questions at the time


for the hell of it, here's a few shots of my calipers along the way







if you're putting these on a track car, you don't want to powder coat as the powder insulates the heat in and keeps everything hotter longer, but on a street car it's not a problem.

i didn't notice when i took them apart that all the slider pins weren't the same, and i can't remember now how i decided to put them back the way i did.

it can be a real PITA to get the pistons back in with the new dust boots in place as well; my method was to install the boot into the caliper, then use a rubber-tipped air hose in the banjo-bolt hole to keep air blowing the seal out as i pressed the piston in. it works pretty well

again, hell of a write-up, and thanks again for the contribution. i know it will make a tough job a lot easier for people

PJCC

Great write-up.

terahertz

great write up!! now anybody gonna do the fronts?

my2ks2k

it's basically the same, except there's no e-brake section, and the piston just presses in instead of being threaded