New calipers from rock auto ... for an 86 part A1 18-4238 and 18-4237... Pistons wont retract enough to have pads clear rotors... tried rotating , no success ... tried pressing , no success.... am i missing something huge?
Please help
Ryan

quote Originally posted by CheshireGrin: New calipers from rock auto ... for an 86 part A1 18-4238 and 18-4237... Pistons wont retract enough to have pads clear rotors... tried rotating , no success ... tried pressing , no success.... am i missing something huge? Please help Ryan

The piston should rotate in. Do not try pressing the piston in..

so which piston rotates which way because neither direction produced any appreciable results. Dad also thinks that that because the pads are shimmed they wont fit.. part WAG ZX262 from Rock auto.
Still stuck
Ryan

Edit to mention that method followed was that described in the cave.

[This message has been edited by CheshireGrin (edited 07-30-2012).]

just to make sure, do the pins on the back of the pad line up with the "slots" on the piston? I usually take the ebrake lever off, put the nut back on loosely and push the piston all the way back in. The shaft should spin as the piston is pushed back.I don't rotate the piston, unless it is misaligned (the pad pins don't line up). I never really had a problem with pads on the rear (or front).

quote Originally posted by CheshireGrin: so which piston rotates which way because neither direction produced any appreciable results. Dad also thinks that that because the pads are shimmed they wont fit.. part WAG ZX262 from Rock auto. Still stuck Ryan Edit to mention that method followed was that described in the cave.

I never managed to get the pistons to retract without a combination of rotating and pressing simultaneously, make sure you have the proper tool to do this since you are having trouble in the event that you don't (I never do). You may be able to rent it from a local parts store, that's the safest way to be sure there is, or is not a problem with the caliper.

The piston CAN rotate but it does not when retracting them. You push it straight in and the screw shaft that comes out the back rotates (remove nut and lever and put a socket over it so the clamp you are using to compress the piston is not on the screw).
There are locating studs or tangs on the pads that must go into the slots in the piston, similar for the non piston side. If you don't get things lined up and sitting where they should be, the pad will sit too high.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

Yes the pins on the pad must line up.

Rotation to retract the piston for 84-87 is not needed required or wanted.

Use the clamp once you remove park brake nut and level. Clamp doesn't need much force to retract. Force = something wrong or reach the bottom of bore.
See my cave, rear brake in brake section.

New rebuilt caliper means rebuilt piston and are often bad right out of box. Means won't retract then return to store ASAP!
Rebuilders will rebuild the piston but problem is that the Piston is not made for rebuild, made for one shot use then trash it.
These are for my rebuild ones... They blew out the piston's guts...

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

I had this problem and people told me to take off the ebrake lever and turn the ebrake screw. This allows the piston to retract. It worked. I bought a harmonic balancer puller and some hardened washers and 5-16ths nuts to attach it to the caliper via the pad holder holes. It was twenty bucks at Sears and works great.





The nut under the ebrake lever takes a 14mm socket if I remember correctly. Don't turn it a lot, less than a turn should do it. To allow the piston to retract you turn opposite the way the ebrake lever would turn the nut (that depends on which side you're on).

ok so here is what ended up working:
***** do not read this as the correct way , merely as what worked for me *****
Passenger side only needed the "caliper tool" and some finesse.( mounted the caliper to the work bench and turned with some pressure inward)
Drivers side required pulling off the ebrake lever, Maintaining inward pressure from here forward.. Turning the nut that the lever sits on into the caliper then turning the face the opposite direction pushing the nut back out but compressing .. this was repeated twice and then aligning the face of the piston so the pad pins would fit, (pressure still maintained) ebrake lever replaced and outer bolt tightened.

So it was a combination of turning and pressing... again please only repeat at your own risk as this was only what worked for me.
Thanks for all the help posts in the meantime though
Ryan