On an early 914 4 cylinder front brake caliper, there are pins cast in tot eh caliper halfs for each piston. They are missing (ie broken off) on the caliper.

Any one know how they work? (the part in the piston that they "guide" is free floating).

Anyone experience running with them broken off?

I haven't see this type of cast in pin on other cars calipers.

Thanks

show a pic...I dont get what you are saying

contact Eric Shea, he's the master.

I seem to recall hearing something about someone running with a broken one and not having a problem. I know, I know... big help I can't image the piston getting cockeyed in the bore without the pin.

That is part of the retraction mechanism. When you put your foot down, you force the piston out against the pad and rotor. This moves the piston along the pin, and stretches the O-ring in the bore. When you remove your foot, the pressure is released and the spring in the piston pulls itself back on the pin, and the O-ring relaxes to normal shape. Both serve to restore the venting clearance between the rotor and pad on the front calipers. Without the venting clearance you get unnecessary drag and pad wear.

You can run without the pin, but you should expect a little more drag and pad wear. I would replace the calipers with good ones. They are cheap enough. I have never seen broken pins in my 25 years of rebuilding calipers. I think someone did it on purpose, and I can't think of a good purpose.

On purpose?, maybe, both front calipers were like that, hoever on one side the prior owner used different pistons on one side (pistons with no provision for the retractor pin, hence that side had to be broken off to fit the pistons, on the others side, they was broken, but stock pistons installed.

Ugh!!!!

So they either screwed up some pistons and used VW pistons instead or got a VW caliper. Doen't say much about their abilities.

Sumitotos had the same thing...we purposely broke them off so that lateral movement in the rotor would push the pad back a tad. To many times, in the race car, when the brakes got real hot the "retraction" mechanism would freeze the pads in the extended position.

So then on the race application with the pins broken off did brake pad wear nromally (ie even)?

thanks

QUOTE (dmenche914 @ Jan 19 2006, 11:32 AM)

So then on the race application with the pins broken off did brake pad wear nromally (ie even)? thanks

Yes they did...we never had a real problem until we ran Firebird and the brakes got so hot the piston seals got wiped out and the front brakes caught fire

Really upset the driver......

Ouch thats some braking! At least I feel beeter now about the pins beeing broken, I guess i will have these rebuilt.