Brake Caliper Refurbishment

[peteracs]

Good points Nigel also the screw mechanism is not fixed into the piston so it can rotate independently

Peter

[unclejam]

Chris,
Just to note that the rear discs and pads are thinner than the front,
10.1mm and 7mm respectively, new.

The piston on the rear does not fully retract like the front, it remains
at about 4mm protruding from the body of the caliper.

Thanks Nigel - I am fitting Green Stuff pads and I haven’t measured them but they seem thicker than 7mm.... Also, the piston is sticking out more than 4mm, more like 15mm in total - see pic below!

[Nigel]

Now that I see your photo I got the protrusion estimate wrong!

It should go in a bit more than that but not much more.
I'm not sure what that tool is you're using, but I use a flat-blade screwdriver
to wind in the piston.
As Peter said, make absolutely sure that the handbrake lever is fully back, and that
it moves freely.

One other item inside the piston is a spring that wraps around the self-adjust screw.
This spring, with a tag on it, acts to prevent the self-adjust mechanism from
unwinding itself by gripping the screw in one direction and allowing free movement in the other.
 The tag can break off causing the self-adjust to malfunction.
 This may be causing your issue, but I can't recall exactly its
relationship to the winding in screw.

Nigel

[unclejam]

Thanks Nigel - the other point which I haven't mentioned yet, is that the other side went together perfectly, with no issues whatsoever.  The piston on this side looks slightly different to the other side however, so I'm now wondering if a non-standard caliper has been fitted?  I guess I'll have to dismantle the other side again and compare the two.... 

[unclejam]

I'm not sure what that tool is you're using, but I use a flat-blade screwdriver

I have a square-section screwdriver shank which fits perfectly into the slot. The piston keeps rotating but doesn’t retract any further, which is why I’m wondering if the mechanism is broken / misaligned.
The other side became stiff and wouldn’t turn any more when it reached it’s most retracted point.

[Nigel]

Chris,
Another thought is that maybe the caliper has been reassembled incorrectly
in the past.

Below is from the Haynes manual and may help your checking. It gives you an idea
of where the piston should be when retracted. #3 is the spring I referred to
above.

[unclejam]

Thanks Nigel - I have the Haynes manual but the narrative (and the diagrams) aren’t that clear unfortunately!  .  After watching a very clear video of a virtually identical Delta rear brake strip, there really isn’t much that could be wrong. I wondered if the piston had been wound out too far and the retaining spring tab had popped out of its retaining slot / hole (I assume there is one?) meaning the piston was unable to return to its innermost position.
I might unscrew the piston until it comes off the screw and then try to re-thread it and try again.
Otherwise, it looks like its a strip down fault-finding job. So much for my “quick-brake-overhaul-and-back on-the-road” fantasy!

[Clifford]

So. Having been in a position where I was unable to bring my Spyder to the 50th celebration because I had a seriously binding rear offside caliper (wheel too hot to touch linda bad!) and left with no time to get it fixed I have now had the work done.
Thank you for your earlier post UncleJam for Brake Caliper Solutions in Barwell.
I took them to BCS Wednesday lunch time and collected them today at lunch time. Pistons, seals, boots and bleed nipples all replaced. Calipers, and carriers cleaned and painted. £184.80 all in including VAT and I am very happy with the end result and the personal service was excellent.
Run by Sarah with 20 plus years experience they solved the periphery I had expediently.
The price included extracting a bleed nipple which had sheared off and one which was stuck solid.
They also sell refurbishing components if you want to do it yourself and have refurbished Beta calipers before they did mine.
Based on my experience I would definitely use them again.
Friendly,  competitive and meeting Sarah gave me confidence in their work.

[mangocrazy]

Thanks for that, Cliifford.

I have a number of rear brake calipers that I've disassembled and got new parts for, but am dreading reassembling them. I think I'll give them a call and see if they'd be willing to reassemble them for me.

[Clifford]

I am sure they would be flexible and be able to help you out. Sarah was very positive and helpful.

[unclejam]

Sounds good Clifford, thanks for the info - that seems like a good price to me.  I struggled with my offside caliper off and on for the last few weeks and finally decided to bite the bullet and take it off the car for a full strip down.  No, I didn’t know what I was doing but after watching an Integrale caliper strip video, I have done it and it’s fiddly and messy but not too hard actually. The problem was indeed what I suspected - the rear spring mechanism has a small tang which locates in a hole in the caliper body and this had come out, effectively blocking the piston’s return.  I am waiting for a banjo bolt bleed nipple as mine is stuck fast and I don’t want to force it and snap it off.  Hopefully once reassembled, my braking issues will be behind me, otherwise BCS are beckoning!

[Clifford]

Just a point regarding the greenstuff pads. They may need the protective layer EBC put on them in production sanding off to get them in place if new discs are fitted. There certainly isn't much room.

[unclejam]

OK thanks - I've got the banjo bolt bleed nipple fitted now, so when I've (finally!) got the caliper reassembled, I'll see how tight everything is.
I'm pretty sure that by the time I have the car back together, the rain will have set in for good and I'll have to wait for a rare dry day to drive the car!