Brake Caliper seals question

[georgeramos]

I ordered the front & rear brake kits from Autoricambi and removed my front calipers today for a rebuild. I am a bit confused about the seals and O rings. One box of rubber parts has o rings that fit over the rim of the piston but leaves almost 1/16" of metal showing. in other words it would not touch the inside of the cylinder. the other box has o rings that are much larger so I am assuming that the rear pistons are larger than the fronts, is that correct?

So 2 questions-
1) should the o ring be shy, flush or proud of the edge of the piston?
2)are the rear pistons a larger diameter than the fronts?

Oh, also, I am having a hell of a time removing the bolts that retain the caliper/pad holders. Any tips? Id like to keep my knuckles if possible...

thanks

[vandor]

George,

The rear caliper pistons are smaller than the fronts.
Please send me pics, especially of the boxes the seals came it - so we can make sure you got the right parts.

I usually have no trouble removing the 17mm bolts with a long ratchet.

[georgeramos]

I sent you a couple of photos, thanks Csaba.

[4uall]

This video is awesome http://www.youtube.com/watch?v=QXcClOfFmlg

Here is what my fronts look like http://forum.fiatspider.com/f08/viewtop ... s&start=75

I too ordered from AR and the blue box was for the rear and the red box was for the front

[georgeramos]

awesome video, thank you. And thanks again to Csaba for straightening me out. My confusion was partially due to a PO "rebuilding" a caliper with a large round O ring seated at the lip of the piston instead of the proper dust cover. The other one appears to have the correct parts.

[spider2081]

As far as the video goes: I would not place my fingers between the caliper piston and the caliper housing as this video shows. If the piston is stuck when the air pressure pushes it out it comes out with a loud pop and a lot of force. I put the caliper in a vice and place a folded piece of old carpet between the piston and the caliper. Cover the caliper with a rag because the brake fluid could spray out all over the place when the piston comes out. If the piston comes out smoothly like in the video fine. If it comes out with a pop the carpet protects it and your hand is not going to get hurt.

[4uall]

I laughed so hard when I first watched it as I was actually expecting him to crush his finger I should have prefaced it as "here is a good guide to follow and be safe". I use cardboard myself and lower my pressure on my air compressor

[narfire]

If the piston is stuck when the air pressure pushes it out it comes out with a loud pop and a lot of force.

Took 6 months for my fingernail to grow back....

[georgeramos]

I made it past that part "safely"...my fingers were clear but I didnt use a rag so it sprayed brake fluid all over the place...luckily AWAY from my face.

[4uall]

two words......................safety glasses