S3 E-Type

Rebuilding these rear calipers is straightforward, the only complication is the need to be 110% confident that everything is right, as these brakes are so difficult to get to - you certainly don't wanna have to go back there again...

Here's a pic of my caliper on removal, some hint of oil leaking from the differential output seals and causing some contamination ( a common failure mode):



Apart from the general result of 35years use, it actually looks OK.




No need to take much care on disassembly as all new rubbers are needed.  Here you can see corrosion around the piston.


Sorry it's a little blurry....this piston is damaged.. the chrome plating is corroded where the seal will sit... using these parts again invites early failure (with new, thick, pads you'll be using this part of the piston).




One benefit on these rear calipers is that the fluid channel between the 2 sides is 'external', via that short brake pipe. That means you can split the caliper without worries: there's no fluid seals in there.

Given the state of these brake pistons I decided to get some new Stainless Steel ones made. That was quite straightforward at a local engineering shop, they are '304' Stainless, here's the drawing:

I cleaned the caliper halves using a wire brush in an angle grinder & decided (non-original) painting would be the best protection...  on eBay the only high-temp paint I could get was boy-racer-red ... but it's like wearing kinky underwear....who's gonna know...??

So, heres the parts - new seals & new pistons:



Fit the pressure seal into the groove in the caliper, lubricate the bore with brake fluid:



Slide the dust-cover over the piston:




Push it nearly all the way down the piston:



Until the caliper seal part is hanging off the end of the piston:



Lubricate the piston & inside edge of the seal with brake fluid. Then locate the outer seal in the caliper groove by manipulating the piston. Push very gently and the piston will slip down and locate the outer seal in the caliper... check carefully it's located... if you need to push with more than thumb pressure then something's wrong!



Now continue to push the piston down thru the pressure seal, this has more resistance...will need palm-pressure ... if it requires more then be careful - the piston could nip/cut the pressure seal.



When it's nearly all the way down, the dust cover should be properly located in the piston groove using a fingernail (& attached finger):



like this:



Once both halves are complete, bolt it back together:


Should be good for another 35 years...