Rear S4 caliper bleeding..

[creechy]

Installed the calipers this afternoon, connected up the ezeebleed and watched the bubbles gradually subside.
After three attempts my brake pedal after the initial bite gradually sinks to the floor.
There doesn't seem to be any leaks so has the master cylinder given up after only seventeen years.

 

[Samuel c5 Q]

Did you bleed the whole system? Start rear right then proceed to rear left, front right, front left.

 

[aragorn]

Did the calipers come filled with fluid? theres a bench bleeding procedure if they are empty and even if you bench bleed them they can be a total **** to get the air out of.

I would suggest taking the car for a drive and trying again. The vibrations/movement etc will often shift the air out the area where its stuck.

With one of mine, i ended up using a vacuum bleeder, as i just couldnt get a pedal. That seemed to fix it. Took weeks though

 

[creechy]

I've noticed the bleed nipple is lower than the inlet on the S4 calipers so I lifted them off the disc and position the bleed nipple at the highest point. There was quite a bit more air in them despite bleeding them with the ezeebleed three times. The pedal is still spongy but much better, will have another go this weekend. Thanks for the advice.

 

[Samuel c5 Q]

Must be totally different from the standard 245 mm setup calipers. The front wheel drive ones are almost the same only the handbrake cable bracket is the other way up.

 

[creechy]

That explains alot, I've got them mounted the same as the original fwd calipers. Handbrake cables mounted with no problem and everything bolted on with just a change to M10 banjo's on braided lines. Not sure if I could mount them the same as the S4 but that's part of the fun in making things work.

 

[aragorn]

You've not got them on the wrong sides have you? Bleed nipples should be at the top?

 

[aragorn]

have you got some pics?

 

[Samuel c5 Q]

Yes on bleed nipples to the top. Quattro handbrake cable and brake fluid hose both come in from below. Front wheel drive handbrake comes in from above. I will need to check to be 100% sure what way the fluid pipe feeds in.

 

[aragorn]

I guess hes fitted them to the wrong sides to get the handbrake to line up?

I wonder if you can take the handbrake linkage off, and swap them side to side?

 

[Samuel c5 Q]

I'm not sure that it's possible but I may have a photo of Quattro and fwd calipers somewhere.

 

[creechy]

Yes, I,ve got them fitted so the handbrake lines up to the top as on the original setup. I don't think the brackets for the handbrake would swap side for side but if I cam get the air out of them I,ll just use them as they are. I might see if the handbrake cable can be mounted from below then I'd swap them but for now I just want to get my firm brake pedal back.

 

[aragorn]

yeh they're a pig to bleed anyway, but they certainly wont bleed on the car if they're upside down.taking them off and bleeding while holding them the right way up is your best bet!

 

[Samuel c5 Q]

Just remember to keep a disc and pads between the piston to stop it extending to far.

 

[Samuel c5 Q]

This isn't an s4 caliper, it's a Quattro one though.

If there is a threaded hole above the pivot point for the handbrake lever or if you can create one without compromising the integrity of the caliper then it should be possible to swap the handbrake cable bracket and lever assembly. The method for removing the handbrake lever eludes me though as I only had a quick look at mine, it was well seized on.

 

[creechy]

Bled the calipers again and now have a nice firm pedal. I think there's enough slack on the handbrake cables to mount the calipers the correct way up it the future. Just need to find some larger brake shields that I can adapt to fit as the ones on there are quite corroided and somewhat small compared to the disc's.

 

[aragorn]

good work!

Pics?

You done a full writeup of the bits you used? I know i roughly documented what was needed years ago but it'd be good to have it all written in one place.

 

[creechy]

Should of taken some pic's before I put the wheels on. Basically 100/A6 rear hubs with the disc mounting section reduced to 65mm to allow ttrs pagid rear discs to be used. RS4 rear carriers and S4 calipers (I found the S4 carriers had a stripped thread) and 2mm stainless washers had everything lined up. I was using some Mercedes rear discs and homemade brackets but it was difficult getting it all to line up correctly and with the Rs carriers is just seems a neater oem+ solution.
I haven't used the brakes in anger yet but it does seem nicely balanced especially compared to just the S4 B6 fronts and standard rears.
Just need to get my finger out and get the ko4 064 fitted and running.