I just finished up replacing all the components to my 88 IROC'S brake system, with the exception of that ugly yellowed original Delco Master Cylinder, since it seemed to be the only part of the brake setup that actually worked.

I had our 3rd Gen's famous Ed Miller put me together a full brake kit, including Earl's stainless lines, the fix for the parking brake issue, slotted Raybestos rotors and Hawk pads to match my driving style. I flushed the entire system 3 times before installing the powder coated NEW calipers.

For the past two years since I bought this IROC the car would barely stop and the rear discs would barely tighten up.

Last week I put the last parts on and suddenly noticed a nail in one of the tires as I went out to break in and set the new pads. I tried several times to get the rear tyres to lock up, but to no avail.

Since I needed the tyre patched anyway, I drove over to a tire/brake shop and asked them to figure out what the heck was the problem. These guys actually autocross cars and sponsor a big monstor truck event a couple times a years; they're not a cheap oil change or Pep-Boy palace. Initially they discovered that I had installed the front directional rotors backwards, but then spent the next three days scratching their heads, mumbling about installing a proportioning valve as they also couldn't get the rear's to properly engage.

I can turn a wrench fairly addaptly, but a mechaninc I am not. However, I figured that it should'n't be taking 3 full days for a handful of brake/frontend specialists to figure this problem out. I did some computer research and found out that a proportioning valve was usually only used with rear drum setups and not with full 4-wheel discs. then I ran into some articles that state that some master cylinder's themselves are different between the two systems. So I called the shop and asked them to check to see if a previous owner might have installed an incorrect Master Cylinder. After having them ask me if I knew what the correct master cylinder part number was, I lost ALL Confidence in these guys. And then they stated that they were about to close for the weekend and couldn't get back to the car till Monday.

What I'm afraid of is that they're going to call me up in the morning and offer to replace the ugly Master unit I already have with another ugly rebuilt unit.

So (finally getting to the point) what I'm desperately looking for is some sort of bilet or polished new Master from the likes of Wilwood, Baer, Spahn, etc. Something that looks serious and can back up the hard core brake package that will eventually go in here when the drivetrain is buttoned up rock solid.

~SEARCH~ has been down all weekend and I havn't been able to focus or find a useful thread. I just want to sound informed when they call me in the morning...... Nitro

I'd also like a basic understanding of the actual differences in our 3rd gen brake systems should any of you actually have an understanding of what's really involved. Can You Help?????????????

 

http://www.partsamerica.com/ProductD...pe=230&PTSet=A

100% brand new

its a special order though

 

Neagen, my turn to help you.
Hope it is not to late, Keep your master cylinder, or a buy a new fancy unit if you wish for cosmetic reasons. buy the wilwood or summitbrand (which is wilwood, relabled) proportioning valve and run your master cylinder brake line directly into this new proportioning valve, and then plug your rear brake line into the outlet of the new proportioning valve. Probably want to plug your holes on your stock unit. the **** will let you adjust how much pressure the rear brakes get. the stock proportioning valve is very sad and lets very little pressure back their, but with the new peice you need to purchase, you can go anywhere from full pressure, and adjust it down accordingly to where it needs to be. usually a bit looser then the front, And by that I mean the rear brakes will lock up right after the fronts do.
Let me know if this helped you.

 

The rear disks will not lock up with the stock proportioning valve. Either modify the stock proportioning valve or get an adjustable one. I don't blame your mechanics because they are looking for something broken and it's working the way it was suppose to (i.e. crappy). I spent many weekends trying to figure it out. See:
https://www.thirdgen.org/forums/brak...od-better.html