As much as I hate to start a new thread, I have been searching for hours now... I figured it would have been covered before but I sure can't find it.

Car - 88 Fiero 2.5 Auto - 100% factory stock.
Problem - Leaking rear seal on brake master cylinder.

I purchased a reman from AZ (P/N - M2357)
A knowledgeable Fiero friend told me to watch for them selling me one with the wrong bore size.
So I am verifying... maybe...

From the little I was able to find here on PFF in threads about the differences between the Fiero and S-10 masters, the Fiero master has a 0.944" bore diameter. That equates to 24mm.

The spec sheet AZ printed out for me says that their master has a 1.414" bore. So right off the bat, I think I have the wrong master.

However, I went to Advance as well as O'Reilly's and any master they brought up said 24mm/36mm.

So I'm on a hunt for what the correct bore size should be.

I suspect that the chamber for the front brakes is 24mm and the rear is 36mm. Dose anyone have the no longer available shop manual? Perhaps it would say in there. I lost my downloaded version with my last hard drive failure.

Either way I figure I'll be taking the old one apart and comparing it to the new one. I just want to try to make sure I get the right part before I tear the car apart again.

[This message has been edited by 2002z28ssconv (edited 02-03-2014).]

I don't know the bore size offhand, but can send you the FSM when I get a chance.

Also, are you going to the CFF club meeting on Thursday? I'd like to chat about cyl heads, if possible.

I'll be there. Need a set of heads?
My gmail is chjesthe, if you want to email the FSM.

Thanks

Actually, I just need one cyl head. And if you want, I can put the FSM on a CD. That will save it from hard drive crashes.

For closure... I didn't get to take the new MC apart. Once I got a chance to work on the car I was in a hurry to get it in and bled. The new Dorman one is aluminum. The old one was iron. I have the same Dorman MC on my other 88 GT and it's brakes are good so I installed it.

But it seems to be working okay.