dvs_dave

So my left side parking brake motor has stopped working. Local specialist is quoting $700 to replace it. The part alone he says is $550. Online the part can be had for about $400 which is still very expensive for what it is.

Anyway, is the EPB motor used on the B6 VW Passat the same unit the D3 Audi A8 and A6 uses? They're made by TRW (along with the caliper and ECU). Only apparent difference from the parts diagrams being that the VW unit can be had for half the price online (parts.com).

Audi part:http://www.jimellisaudiparts.com/sho...ssembly=753491

VW part: http://www.jimellisvwparts.com/showA...ssembly=745607

Parts.com part: http://www.parts.com/parts/2007/VOLK...agramCallOut=7

Can anyone shed any more light on this?

Whilst researching this I came across these sites which are interesting in relation to this topic.
Motor description and dis-assembly:
https://sites.google.com/site/1810ma...ric-park-brake
System description:
http://pmmonline.co.uk/technical/how...-and-diagnosis
http://pmmonline.co.uk/technical/how...er-type-system
Manufacturer data sheet:
http://www.trw.com/sites/default/fil...g_EPB3_eng.pdf

mishar

Check here and here.

Audi part number: 4E0 998 281 B

VW part number: 3C0 998 281 A

Must be some small difference.

dvs_dave

Apart from the part number difference, is there any physical difference between the units though?

I know VAG price gouge across their various ranges for the same parts. For example the Audi R8/Lambo Gallardo have a lot of shared parts but they're priced hugely differently.

So I'm skeptical...

snapdragon

http://reviews.ebay.com/ebaymotors/V...00000012971486

The above explains how the part numbers are devised and suggest the parts may in fact be the same, but I can't be sure.

mishar

Audi:



VW:

volvopentaman

The motor can easilly be taken apart from the caliper, only the electrical connector and two screws keep it there.

I had to lubricate mine, as it had got stuck, has now worked a year after fixing it. Was like a 30minute job.

You should of course calibrate the brake again after taking out the motor, but if you put all the pieces exactly back as they were, it's not necessary.

dvs_dave

Bummer about the electrical connector differences.

Ok, so how did you lubricate the motor mechanism? Just take it off and squirt WD40 into it or something? Is it possible to dismantle and reassemble it without damaging it?

Would be good if that's all it needs, especially as the tool to remove the motor and wind the caliper in is included in the tool kit. Now why isn't that little nugget of info detailed in the handbook????

volvopentaman

Just took the motor away from the caliper, sprayed in wd40 or crc rust-lubricator and lubricated the moving parts with grease.

You don't need to dissasemble it too much, just take it apart from the caliper, and you see the motor and the problem.

Of course if it's rusted you have a bigger problem, and lubrication won't necessarily be enough. Mine was only slightly jammed.

I don't know about that tools to wind in the caliper would be included in the toolkit that sits in the bootlid... especially when you can't wind in the caliper with anything else than electronically, or removing the motor, and move it in by rotating the same machinery that the motor rotates.

But as i said, no need to wind in the caliper if you only remove the motor. Tough, a calibration would be good to do, because mine was erratic a while afterwards, tough the brake worked. The side that i had dismantled took longer to engage the brake than the other side. But this problem disapperared after a few uses of the brake.

mishar

Piston can't be winded in even electrically. Only hand brake pivot will wind in allowing piston to be pushed in. Same can be done by rotating piston. I did it on a friends Passat before VCDS and A8. Not the right way to do it but possible.

dvs_dave

Have a look at page 15 of this SSP
http://www.volkspage.net/technik/ssp/ssp/SSP_285_d2.pdf

Helps if you can read German but the pictures are enough. Now you know what that torx tool in the tool kit if is for!

Yes I know the actual hydraulic piston can't be wound back, but the threaded plunger inside it can which is the only thing that stops the piston from being pushed in manually in a conventional manner.

All VCDS does is wind this plunger back all the way electrically and then you recalibrate it, but that's only so that it can work out pad wear. Having thought about this I think you could get away with a rear pad change without needing VCDS.

All you need to do is make sure the parking brake is off, remove the motor and then manually wind the plunger back out so that the caliper can be opened and the piston fully retracted. Pop the new pads in, and then wind the plunger back in so that the pad faces are back to a similar relative position to the disc as before. Then put the motor back on. Work the parking brake on and off a few times to allow the ECU to recalibrate itself (it monitors the motor current and determines when to shut off from the current draw spike at it's travel extremes, much like electric windows), and then it's job done. The only thing I don't think it will do properly straight away is reset the pad wear measurement system. This is calculated by the ECU counting the number of motor turns between full off and full on. However it may eventually also figure that out itself once its done an auto re-calibration.