Ok, before I start, please understand I tried to search this by putting in 9 bolt, "9 bolt" and 9 AND bolt. All got me over 14,000 hits, returning every post with a "9", and/or a "bolt" in it. If the simplest answer for my questions is instructions on how to correctly use the search feature, I'm OK with that. I know I've seen the answers to most of my questions before, I just cant find them now. Since this swap (and these questions) are so common, however, I wonder if it would make sense to put up a sticky with the answers?,

I have an '89 Formula WS6. The rear end is crapping out on me, so I got a 9 bolt out of an '89 Camaro with 12" rotors and aluminum calipers, so I assume they're PBRs. Swapping the rearend is step I of my brake upgrade; step II is an Ed Miller C5 front brake kit.

I've been sitting on this awhile, other things have come up, but now I'm getting ready to do the swap, and need to start gathering parts.

First, on a street-driven car, that only sees rare use at the autocross or the track (and then only on street tires), is there any benefit in upgrading the rear brakes? As I understand it, the PBR, 1LE, LS1 and C4 rear brakes are all essentially the same thing, and the front brakes do 70-80% of the stopping anyway, I'm thinking the cost/benefit of upgrading the rears isn't there. Am I correct? If I'm wrong, what upgrade would be best for my situation?

Second, assuming that upgrading is not in my best interest, exactly how do I address the parking brake issue. I seem to remember someone posting a source and part number for it. Better yet, If someone were to walk in a parts store, what year/model would they ask for the parking brake cable for? Also, are there any other parts necessary?

Third, what about the master cylinder? I seem to recall some posts saying no change is required, and others saying it is. Is it dependent upon the year? How does one know?

Fourth, how about the proportioning valve? Again, I'm pretty sure I've seen some posts saying you have to change it, and others saying you don't. Clearly, I'll have to change it when I go to phase II of the project, the C5 fronts, but, what about beforehand?

Fifth, what about calipers and rotors? Mine are in pretty bad shape, and will need to be replaced. I've looked on the NAPA and Autozone sites, and there are numerous part numbers listed for various years and models. Now, I'm pretty sure calipers and rotors for any F-body 9 bolt will fit any other disc brake 9 bolt. If that is correct, what year/model would I walk into a parts store and order to get the best for my 9 bolt?

Sixth, I seem to recall seeing a post about swapping the backing plates out for those from an LT1 Fourth Gen. Is that correct? What's the benefit?

And finally, seventh, I read in another post that the brake line sizes changed mid-year in 1989. if that is correct, what were the before and after sizes, what is the best way of determining what I have, and which are best?

 

I've swapped to 1LE's front and rear, so you may find much of the info you require in the following link:

https://www.thirdgen.org/forums/faq-...iscs-89-a.html

JamesC

 

Ok, I followed the link (thanks james) and got some info, and some more questions.

First, I gathered the differences between the rear brakes are: pre-89 (BAD!), and post 89 (GOOD!).

Now, my rearend was represented as coming out of an '89. It already has 12" rotors and aluminum calipers, so, it is either an '89 or later PBR rearend, or a pre-'89 ILE. Correct?

Looking on parts sites, however, I see different calipers and rotors listed for pre-89 ILEs and 89 and later PBRs. Are there differences, if so, which is better, and, if there are differences, are they interchangeable?

Second, Ed Miller (The Baron of Brakes) says the backing plates for 89-92 and 93-97 are the same, so, was I incorrect when I said I though someone said the 93-97 LT1 backing plates were better? I seem to remember the premise being that the LT1 backing plates were more rigid.

Third, Ed lists the e-brake cable number on NAPA as UBP P/N 94624. That part number sows up three times; as a "rear parking brake cable", as a "left-rear parking brake cable", and as a "right-rear parking brake cable".

I'm assuming they're all one and the same, and that you need two of them?

 

The 82-88 rear discs have the 10.5 rotors and iron calipers. The 89-92 have the more desirable 11.7 rotors and alum calipers (PBR's). The 1LE and LT1 calipers are pretty much the same regardless of year, 89-97. You'll need the perfomance package, 89-92, for the rotors. I'm unsure if the 93-97 rotors are interchangeable with the 89-92. The backing plates are interchangeable, 89-97, though the 93-97's may be a bit more beefy. Since you have a rear end already equipped with PBR's, you won't need to worry about the plates.

The e-brake cables I used are from CarQuest (P/N BRK 8788, 1st design, 1434 mm). You'll need two.

JamesC

 

I called to order a set of these cables for my car and was told that the part number has changed. Carquest part BRK 69369.

I was also told that these cables are on back order and we don't know when they will arrive. They have been on back-order for at least 2 months.


YUCK!

I just converted from a 9bolt to a 10bolt and I have no ebrake. I NEED to get these cables and get it working. Also, are the guides REQUIRED or only for stock exhaust avoidance? My race car has headers and straight pipes so there's not a conflict, just curious about the guides.

Brian

 

Avoidance.

JamesC