Spongy Pedal After Fitting HP2s

[waveydavey]

Got my C4 A6 back yesterday from having S6 struts and HP2 brakes fitted. Although the new brakes work fine the pedal is quite spongy despite having been bled through four times. The pedal was fine with the old strut/brake combo. I had rebuilt the calipers with new pistons and seals so they were empty of fluid when fitted and I'm wondering if there is some special way of bleeding them that gets all the air out. Either that or is there a difference in bore of the master cylinder between the A6 and urS6 that means the A6 master cylinder can't shift enough fluid for the HP2s?

Any thoughts or BTDTs would be a great help

Cheers

David

[priba]

calipers purge valves should be on top so all the air from drained cylinder should normally escape during purging
I did the same upgrade years ago using A8 HP2 calipers and yes it felt spungy
next was tandem master cylinder replacement with one from S6 ... it's 25,4mm in diameter and it was better but still I wasn't happy
yesterday I finished booster/master cylinder upgrade to A8 D2 setup and now it is much better
it is soft but it really bytes at half the travel of the pedal

more info you can find in my topic http://www.s2forum.com/forum/showthr...317#post864317

cheers