First job completed on the A3 with moderate success and a few tips for those who are up for the challenge.
I followed the procedure and method in this excellent post:
Post in thread 'Brake servo / booster replacement help please'
https://www.audi-sport.net/xf/threa...r-replacement-help-please.189525/post-1881886
However it took me 17 hours not 9 so I think the extra challenge was due to the DPF being in the way. I lowered the engine and gearbox as one unit but it gets to a point where the DPF sits on the OS drive shaft even with the lower wishbones and brackets all disconnected. It took about 2 hours to resolve and there is only just enough wiggle room to remove/install the servo unit without the MS attached. The way I did it was to push the activating rod from inside the cabin into the engine bay. This then allows the servo to be rotated so that the face where the MS attaches passes over the DPF. The activating rod gives you a bit more tolerance and remove the heat shield off the DPF.
I also made a tool to undo the clips on the brake pedal from a modified exhaust bracket, the Haynes manual suggests this and with a bit of trial and error it worked very well.
The other challenge was reassembling the lower suspension and brackets/subframe, this all a needs to be aligned as it effects the wheel alignment. It’s not that clear in the Haynes manual but anyone attempting this major repair should consider marking with paint the location of the brackets to the body/subframe etc before dismantle.
I said it was a moderate success as I now appear to have air trapped in the brake hydraulics and from reading other posts on bleeding brakes it sounds like it maybe trapped in the ABS unit. The pedal travels half way to the deck before the brakes bite but a second stroke brings them into sharp operation. Unfortunately I have also discovered I need to upgrade my VCDS to access the ABS purge option.
Planning on a third bleed of the system using the Gunsons pressure bleeder but I think I may have used too high a pressure previously. As back up I have it booked into my local VAG independent to sort the brakes (For what it’s worth they quoted 4 hours labour to swap the servo out, I can’t see how that was going to be possible!)
Next job, inoperative rear wiper...
I followed the procedure and method in this excellent post:
Post in thread 'Brake servo / booster replacement help please'
https://www.audi-sport.net/xf/threa...r-replacement-help-please.189525/post-1881886
However it took me 17 hours not 9 so I think the extra challenge was due to the DPF being in the way. I lowered the engine and gearbox as one unit but it gets to a point where the DPF sits on the OS drive shaft even with the lower wishbones and brackets all disconnected. It took about 2 hours to resolve and there is only just enough wiggle room to remove/install the servo unit without the MS attached. The way I did it was to push the activating rod from inside the cabin into the engine bay. This then allows the servo to be rotated so that the face where the MS attaches passes over the DPF. The activating rod gives you a bit more tolerance and remove the heat shield off the DPF.
I also made a tool to undo the clips on the brake pedal from a modified exhaust bracket, the Haynes manual suggests this and with a bit of trial and error it worked very well.
The other challenge was reassembling the lower suspension and brackets/subframe, this all a needs to be aligned as it effects the wheel alignment. It’s not that clear in the Haynes manual but anyone attempting this major repair should consider marking with paint the location of the brackets to the body/subframe etc before dismantle.
I said it was a moderate success as I now appear to have air trapped in the brake hydraulics and from reading other posts on bleeding brakes it sounds like it maybe trapped in the ABS unit. The pedal travels half way to the deck before the brakes bite but a second stroke brings them into sharp operation. Unfortunately I have also discovered I need to upgrade my VCDS to access the ABS purge option.
Planning on a third bleed of the system using the Gunsons pressure bleeder but I think I may have used too high a pressure previously. As back up I have it booked into my local VAG independent to sort the brakes (For what it’s worth they quoted 4 hours labour to swap the servo out, I can’t see how that was going to be possible!)
Next job, inoperative rear wiper...
