Biba, I think your right on about the pistons retracting. I've fought this with my GTV and Spider. The dust boot wants to pull the pistons back in, and the spring that mounts under the pad retainer pins does much the same. I've has some success with removing the pad and installing an old worn out pad or piece of wood and letting the piston travel more to stretch out the dust seal. I've also removed the spring under the retaining pins. Both seem to help, but the pistons retract more than they need to. Years ago I had similar problems on my 66 Gulia Sprint GT, and solved it by installing a residual pressure valve that kept a few pounds of pressure on the system. Most modern systems have a similar valve built into the master cylinder. Here's a link http://www.wilwood.com/products/006-MasterCylinders/010-RPV/index.asp You will need on for the rear, and two for the front unless you rework the front calipers to work off one port of the master cylinder. Volkswagen used to have ones that mounted to the 3 outlet ports of the master cylinder that would make the installation very clean. Also, time does seem to help the problem, but I doubt your customer wants to hear that.
Good Luck, Dick Stachowiak 71 GTV 71 Spider On Nov 11, 2009, at Wednesday November 11 6:41:27 AM, alfa-digest wrote: > Date: Tue, 10 Nov 2009 19:36:58 -0800 > From: AlfaCyberSite <[email protected]> > Subject: [alfa] Stuck caliper brake piston vs bleeding brakes > > Jeff, anyone, what is really annoying is that before the rebuilds, the > pistons/brake pads were quite happy being right up close to the brake > discs. Now they're staying some distance from the discs. I have to > lock > the brake pedal down (almost to the floor) before the four wheels will > lock up. I remove my locking device (aka, stick) and all of the wheels > spin with none of the metallic sound of the pad being close to the > disc. > > Why would they retract so far back? I'm not talking a long way, but > none > of this self adjusting brake pad situation. True, I've not taken it > for > a run - mainly because it would be foolhardy at this point - but they > sure don't need the spinning of the discs to retract them just > enough so > they won't bind. > > I started bleeding the brakes late Sunday. The two quarts of brake > fluid > I had (almost all gone) had been sitting for a couple of weeks. I'll > buy > two more tomorrow and try not to jiggle them. Perhaps four more. > Maybe a > case. > > Biba > Irwindale, CA USA -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
