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D3 - Axles, Brakes, Suspension and Steering Brakes, Springs, shocks, steering racks, steering columns, suspension arms, wheel hubs etc.

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  #31  
Old 23rd September 2019, 08:07 AM
stripester stripester is offline
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Bumping old thread...sorry..

The two additional connections are to a hall sensor in the motor assembly, they count the revolutions to "Sync" left and right callipers AND measure the pad thickness.

I have a failed one...its a pain in the Arse, it still works but the sides are out of sync....looking for a replacement motor as we speak!
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  #32  
Old 28th October 2019, 03:31 PM
snapdragon snapdragon is offline
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If anyone has a faulty caliper motor, they are about £46 delivered now...
https://www.aliexpress.com/item/32987565843.html?
Dust boot, piston seal and guide pin boot kits are about £15 on ebay.
Red rubber grease £3
There's very little else that can go wrong from wear and tear so this should bring down the cost of fixing up a dud rear caliper up to around £65.
The pistons can usually just be cleaned up with 1200-1500 wet and dry gently polished all over in a circular motion.

Attachment 22292

Last edited by snapdragon; 23rd April 2020 at 09:18 AM.
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  #33  
Old 29th October 2019, 09:08 AM
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Architex_mA8tey Architex_mA8tey is offline
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Quote:
Originally Posted by snapdragon View Post
If anyone has a faulty caliper motor, they are about £46 delivered now...
https://www.aliexpress.com/item/32987565843.html?
Dust boot, piston seal and guide pin boot kits are about £15 on ebay.
Red rubber grease £3
There's very little else that can go wrong from wear and tear so this should bring down the cost of fixing up a dud rear caliper up to around £65.
The pistons can usually just be cleaned up with 1200-1500 wet and dry gently polished all over in a circular motion.

Attachment 22292
Good work that man!
That's excellent news. . . .
Almost worth sending for a pair ahead of needing them and keeping them "in stock". . . I note you also get additional discount for ordering a pair
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Last edited by Architex_mA8tey; 29th October 2019 at 09:18 AM.
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  #34  
Old 23rd April 2020, 04:32 PM
ulfilias ulfilias is offline
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I was certainly looking at the various Audi EPBs with an idea of repair!

http://forum.a8parts.co.uk/showthread.php?t=13431

I've "repaired" my left EPB at least 3 or 4 times. Taking the back of the EPB, freeing up and cleaning up the crap from it, sealing as best i could and putting back on. Always the left one!!!

I hit the same issue again about a week back and bought one of the Chinese ones off ebay ( https://ebay.us/4OKGtN )as to be honest the plastic casing of the old one was knackered and crumbling. It came with the big O ring seal and a pair of hex screws that are too small and the odd circlip that fits on the piston part where the actuator fits in

I swapped it over. My pads were low so i swapped on a spare pair of those. All went pretty well and things were quieter and seemed to work ok. I still had a pad error but often that sorts itself out.

However on getting home, the car checked the brakes and it errored again.

Today I popped it back off and tried the adjust the brake to the mid point and tried again and actually I'm a bit stumped.


The motor turns, the actuator is the right size, it fits nicely and sounds better, but it seems to run too long and then error. The ampage appears a bit higher but nothing drastic the left is 0.5ish more than the right.

I did pop the old one open and the motor part is potted into the case or i'd have swapped bits over.

I'm a bit confused to be fair why it seems to run longer than the other side and thus error
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  #35  
Old 24th April 2020, 11:07 PM
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You need to use vagcom on the rear EPB to tell the brake module you are changing the pads for new and also re-enter the new pad thickness as measured. This is so that the brake module knows that the pad thickness has changed and where to start in assessing the remaining thickness
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  #36  
Old 27th April 2020, 12:18 PM
ulfilias ulfilias is offline
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Quote:
Originally Posted by Architex_mA8tey View Post
You need to use vagcom on the rear EPB to tell the brake module you are changing the pads for new and also re-enter the new pad thickness as measured. This is so that the brake module knows that the pad thickness has changed and where to start in assessing the remaining thickness
Yeah.....I've got vagcom/odb11 and i can play with the thickness, open/close the epb, do the test.

That's how i know the left is running way longer than expected.

I've tried various thicknesses of pad, but the error says left disc not reached which is curious as i know it does eventually get there.
I think i'm going to try and referb the old one again and swap that on and see what i get from it.
It feels like the two motors are out of sync or not recognising things.
My discs are on the thinner side (i'd swap but getting hold of a pair atm is probably tricky) and with new pads on that side they should easily compensate.
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  #37  
Old 27th April 2020, 02:55 PM
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Quote:
Originally Posted by ulfilias View Post
My discs are on the thinner side (i'd swap but getting hold of a pair atm is probably tricky) and with new pads on that side they should easily compensate.
Most motor factors are open and will deliver (ECP etc). If you want genuine Audi then only TPS will be open but they will only deliver to a registered business address.
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  #38  
Old 28th April 2020, 01:28 PM
ulfilias ulfilias is offline
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Quote:
Originally Posted by homer simpson View Post
Most motor factors are open and will deliver (ECP etc). If you want genuine Audi then only TPS will be open but they will only deliver to a registered business address.
I actually run a small manufacturing business so could get round that, but the Audi is more a workhorse than show car. I ended up furloughing myself and my two guys on Friday, because lack of work, struggling with supplies and all sorts. The Audi is safe on charge in my factory.

I tried the old EPB yesterday after a good clean out, taping and sealing and it made no difference. Super long run times on the left side still.

I've ordered a pair of Mintex discs to home which should turn up at some point this week and then I'll go in a fit to both sides, check the pads balance up and try again with the new EPB and see where I get to.

I've got the Jeep to run around in and it's not like I'm going far anyway
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Also :
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  #39  
Old 30th April 2020, 09:35 PM
ulfilias ulfilias is offline
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Had another go at this today. The discs turned up and I fitted them to both sides, checked the pads were even and balanced.

No joy. The left still runs and runs. I popped the left side off again and tried the old motor and same thing. I had a C clip in the new motor parts, but never bothered changing it. It goes on the piston side around the large star drive slot. I took the old one off, cleaned things, checked that things were freely moving with a star drive and, yes the internal (worm screw?) seems to work fine. I wound it in and checked the caliper and made sure that was moving reasonably and cleaned things a bit too.
I put it back together but left the wheel off and ran the test.....It seems like the motor isn't engaging and turning the internal drive....But i can't for the life of me figure out quite how / why!

Both the new and old motor have the wobble drive thing, which seems like some form of clutch and allows the Star drive to engage and disengage and it just doesn't seem to do it in practice.

It's all a bit odd and i'm not entirely sure quite what to do next....I guess there is the option of a whole new caliper perhaps....But it seems a lot of hassle and expense for something that in all essence appears to work, but just doesn't!
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Current :
2005 A8 Sport 4.2 V8 D3 - LPG working!

Previous :
1998 S8 PF 4.2 V8 D2 - Gearbox died ~120k
2002 S8 FL 4.2 40v V8 D2 Prins LPG - Engine valves met pistons ~230K

Also :
1996 Jeep Grand Cherokee 4.0l (Post Apocalyptic makeover)
2003 Brabus Smart FourTwo (should sell)
2003 Mazda Rx8 2.3 (might sell)
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  #40  
Old 4th May 2020, 02:27 PM
ulfilias ulfilias is offline
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I'm probably going to go back into work and do some more testing, probably try with the motor off and see if that resets some things.

I could try something interfacing between the star drive and the socket in piston. I was also wondering on using two circlips to maybe bring the interface back out a bit. I could always open the old motor back up and push the mechanism forwards, but I'm not sure how comfortable with these thoughts, particularly being in the brake area, despite rarely using the parking brake.

I guess the other option is replace the whole shebang:

Ebay gives a Chinese full copy at £143, but the delivery times atm probably scratch that and you always have the is the copy any good factor.

There's a second hand option from our sponsor, which is £150 and a couple of days delivery. No specific 4.2's and most are older 3l's but I believe that it's all the same actual model. A little worry in longevity perhaps, but once the old one is off and stripped down I can check it out a lot better and referb it pretty cheaply and I have 1-2 motors etc!

There's also re-manufactured ones for £150 and also a few days delivery. However there's the hassle of £100 deposit and then sending the old one back and IF mine qualifies etc too

I'd like to get my normal driver back and so i can easily carry on my Post Apocalyptic make-over on my Jeep
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Current :
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Previous :
1998 S8 PF 4.2 V8 D2 - Gearbox died ~120k
2002 S8 FL 4.2 40v V8 D2 Prins LPG - Engine valves met pistons ~230K

Also :
1996 Jeep Grand Cherokee 4.0l (Post Apocalyptic makeover)
2003 Brabus Smart FourTwo (should sell)
2003 Mazda Rx8 2.3 (might sell)
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