The key to changing rear discs- A4 B6

[pj123]

I've read many posts about people rounding the 8mm allen key bolt off whilst removing the caliper carrier and discussions around whether you can or can't put a new disc on without removing the carrier. What I didn't read about is there is a cutout on the back of the hub to fit the new disc on without removing the carrier. If you dont rotate the hub to the exact position then you cant get the new disc on. Hope this is of help, suggest a sticky thread...

(Was just about to buy bolt extractors/ plusgas/ easy outs before i discovered it can the be a very quick disc change!)

 

[quattrojames]

Nice one, I'll add it into the DIY guides sticky when I get 5.

 

[T0m]

Would of been good if you had a picture of you taking the old one off fella, I had to get mine in the garage a few months ago as I couldnt remove the Caliper carrier...

Only reason I ask is, it cannot be as simple of slotting the disc into the grooves on the carrier as didnt notice these when I took my caliper off to try and remove my discs...do all A4's have them?!

 

[pj123]

My whole point is that you dont have to remove the carrier. I can only comment for the single solid rear disc, S4 etc I guess has vented discs. The old disc comes off easier than the new one goes back on because it is missing 1mm or so of steel either side of the disc, the last photo shows the half way position between on and off.

 

[T0m]

My whole point is that you dont have to remove the carrier. I can only comment for the single solid rear disc, S4 etc I guess has vented discs. The old disc comes off easier than the new one goes back on because it is missing 1mm or so of steel either side of the disc, the last photo shows the half way position between on and off.

Appreciate your comment fella and I know what your saying about not having to remove the carrier just saying I must of missed this when I tried to remove my old rear discs which meant I sent it packing to the garage for them to do it....like I said in my other post I dont remember seeing those grooves on the carrier where you have the new disc positioned on your last pic....oh well nice to know for the future.....

Edit* Doh!!!! The groove I was on about is the part that the disc sits in, Ive just took a look at mine in the flesh, how thick of me!

 

[Turkster]

yep, you dont need to take off the calliper carrier as the disk will just slid in as to pj123 pics, I just change my rear pads the other day and serviced my callipers and cleaned the whole area down and treated the who area to a bit of black heat proof spray paint that have made the whole area look smart and tidy, will post a pic later for you.

 

[T0m]

yep, you dont need to take off the calliper carrier as the disk will just slid in as to pj123 pics, I just change my rear pads the other day and serviced my callipers and cleaned the whole area down and treated the who area to a bit of black heat proof spray paint that have made the whole area look smart and tidy, will post a pic later for you.

Cheers fella, Ive been to bed since yesterday and can see what cut out he is on about however it is only small and can miss it in his pic if your not looking properly, will atleast I know for the next time.....

 

[pj123]

To be clearer...

 

[SL11CKK]

If only i had known about this when i changed my disks. However i did end up cutting my hands deep because of that tight 8mm carrier bolt. Ended up in the end in need of the ramp though just to get a breaker bar in from the bottom and un-tight the bottom bolt.

 

[pj123]

Just replaced a friends rear discs on a 52 plate A4 130 diesel. It was actually different to mine and there was no cut out. I did still manage to fit the new disc in without removing the carrier. I did use a rubber mallet to tap the disc past the hub. Better than trying to remove the carrier bolts which wouldn't budge!

 

[scott b]

did mine last week, i just removed the lower carrier bolt and firced the carrier up out of the way, wasnt a bad job to do

 

[starnon]

Just to add my experience, I didn't have the slot as shown in the first image, but with a tug the discs came out without removing the carrier and the new ones just needed a shove to get back in.

On a side-note, for winding the caliper back, I saw on other forums people saying that only the most super-expensive-est tool would work (as forum folk often do) but on my 130 Avant, the cheap ebay one (£12.99 posted) worked fine.

 

[bencowp]

I've just changed my rear discs (and pads) and thought I would add my experience for anyone else, like me, who found this thread when looking for help.

It seems the above hub cutout is not a sure thing, mine did not have them (2004 PD130 Avant, 245mm rear discs). I was not comfortable forcing the new discs onto the hub with the carriers in place, as damaging the new discs (however unlikely) would defeat the point in changing them.

The carrier bolts are so tough because corrosion occurs at both ends of the bolt; the head end, and the tip end because it's exposed behind the disc (see above). To compound the problem, access is poor. You can get a 1/2" drive breaker bar with a 8mm hex socket bit on the top bolt (just), but not the lower. The lower shock mount is square in the way. If you had a 1/4" or maybe 3/8" drive breaker bar with the socket bit, you might have more success.

I tried WD40, Plug Gas and ATF/acetone at first. I only realised that the bolt tip corrodes after taking my disc all the way off. If you're reading this in the future; lift your old disc up/off as far as possible, and get your penetrating fluid up/down behind the disc onto the ends of the carrier bolts.

I managed to get the top bolts on both sides using a blow torch (make sure you get a small one with a long nozzle, it's tight in there and the top bolt is between the brake line and the ABS sensor...). Make sure you get a suitable sheet of metal to shield the brake line/anything you don't want to toast.

I never got the lower carrier bolts off. I tried heat with Plug Gas and ATF/acetone between heating sessions. I even tried a few choice swear words. I feel if you could get a breaker bar on it, you could crack it. But with an allen key (and ring spanner for leverage) it wasn't going anywhere.

Once you get either the lower or top bolt off a caliper carrier, you can simply hammer the carrier over, swivelling it on the bolt that has stayed in. This allows the discs to come out and new in. See above.

tl;dr: You only need to get one carrier bolt off, I would recommend the top one, and then swivel the carrier.