Audi 80 rear brake caliper (UK)

About to fit some new rear brake pads to an Audi 80 (1993). Can't find a manual for this car but doing a quick web search I see that you can't simply push the piston back into its bore as that will damage the
automatic handbrake mechanism, but instead you need a special tool that winds the piston back in. Does anyone know if Halfords or similar sell such a tool to do the job or am I looking at Audi main dealer prices? Cheers.
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Mark wrote:

Halfords or most larger motor factors including Partco can supply the tool, also from Machine Mart and other mail order suppliers.
Before trying to fit new pads make sure the handbrake cable is slackened off.
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So far I've just removed the caliper section from it's carrier. Both the bottom sliding pins on both calipers were really rusted and pitted, so I suspect the piston will also be in a bad way. I was thinking of rotating the piston in and pumping it back out a few times to losen it up before reasembing.
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If you think it's that bad, then you need to overhaul the caliper, which means you'll probably need the special tool. The basic design of the rear caliper is the same on all Audis of this vintage - the handbrake mechanism means the pistons on the rear calipers have to be screwed in when you retract the piston and screwed out when you dismantle the caliper. Some of the mid-80s cars had a hexagon in the end of the piston and you used an Allen key to twist the piston (be warned that the hexagon tended to rust out, leaving you gripping the end of the piston with a self-grip wrench - be very careful not to damage the piston if you have to do this). Some other cars had pistons with a slot right across the piston and yet others have just two slots on opposite sides on of the piston - the Sykes Pickavant tool available from Halfords (20) will cope with both of these last two types.
In any event you need a repair kit (main dealer stuff, but not expensive) comprising the seal and dust boot for each side, since you'll need to take the piston out to see if it's knackered. If it is, it will be obvious and you'll need an exchange caliper - try German and Swedish or similar. If not, just change the seal and boot and re-assemble.
The tool is well worth the money, BTW.
HTH
Jonathan
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Thanks for the advice, I will get the tool tomorrow and have a closer inspection. Will let you know how I get on. Cheers.
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wrote:

When you see it and the price, you may decide to just cut a piece of 3mm scrap sheet to do the job. Or drill two holes in a length of square bar to take pins that engage the slots. Or abuse a pair of needle nose pliers - though if it is sized this will be major abuse.
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wrote in

I did read about using long-nose pliers but with it been my first attempt I wasn't sure how much pressure to use at the same time of turning the piston, and knowing my luck I'd knacker the thing completely. My local Halfords didn't have the Sykes Pickavant tool (20) but a nearby motor factors had a similar tool (think it was called Laser) for 14.95 which I must say is a well worth investment and a good tool to have. Really made the job easy.
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If the piston moves back in with the tool then it's fine. New pin kits aren't particularly expensive &they're easy to fit. If they rotate easily you can screw the pistons back in with a bodged tool but trying to do it without tearing the dustseals is tricky, the tool makes the job dead easy.
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Job sorted and everything is working fine. The piston went back easy (which was a pleasent surprise) and the handbrake is also working good and holding evenly on both wheels on the 3rd notch of the lever. I gave everything a good going over with copper grease.
Having had the chance to inspect underneath, I notice a very small drip of brake fluid which seems to be trickling down from what I think is the rear load regulator valve (the thing that pivots on a spring attached to the rear axle). Looks like 4 brake pipes go into this but I can't yet tell if the leak is from one of the pipe joints or the main regulator assembly. Anyone know if these regulator things are prone to leaks?
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That's the rear load reg. I've never seen leak but that's cos I normally seem to have to change them because they've jammed. YMMV.
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Do you know roughly the price of a regulator and are they easy to replace? Does the whole brake system need bleeding afterwards? Cheers, Mark
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IIRC they're about 40. eurocarparts.com & gsfcarparts.com are normally a good place to look. & yes you'll want to bleed it all afterwards
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Cheers m8. Will check that out later.
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