Hey, I know there's a ton of posts on rear drum to disk swaps, I can't seem to find what I need though. At a swap meet, I ran into a guy that had Camaro parts. For $60 I couldn't pass up two perfect condition grid tail lights, posi unit (Auburn I think, not worried about that yet,) and the brake stuff shown below. I can't remember, but I think he said the stuff came from a 89 or 90 Iroc-Z. I'm wondering what other parts I'll need to swap these into my 87 with drum brakes. Obviously I'll need rotors, which size are used with these? E-brake cable, proportioning valve. Do I need an adapter plate, if so which one? What else?

 

You'll have to modify the axle flanges on the drum rear or purchase one of Ed Miller's "No Hassle Kits." Most of the info you'll need is in the link below:

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

JamesC

 

So essentially, the only thing useful to me in the pic is the calipers? It's a pain to find info on this swap on the site, or I'm an idiot.
This link was pretty helpful too.
https://www.thirdgen.org/forums/brak...drum-rear.html

 

TTT

 

I thought the PBR's were decent calipers? Or are they just better than the 82-88 setup? I'm not too worried about the E-brake because my car is an automatic. I'd like to have rear disks, but it's not an "OMG! I need these right now!" upgrade y'know? I made my money back just selling the tail lights so if the PBR's are junk, not using them isn't that big of a deal.

 

They're certainly not junk. With the "free travel" set correctly, the parking brake works very well (though not as well as the LS1 set-up).

JamesC

 

Those are aluminum calipers. There is one part that is tough to find and you have to find it used since it is not made anymore, I think it is the cable for the ebrake housing... Someone else will chime in. The calipers can bring good money - meaning over $100 and I think close to $150 since they are aluminum and only made for 89.

 

...So the only issue is the e-brake setup/parts then? I can live with that if that's the case.

 

No, in 89 they used bigger disc too.... I cannot remember exactly what the part is since I have two 89 rear ends complete - it doesn't affect me but there is one part that is tough to find to convert the disc and calipers to work on other 9 bolts.... I don't know if they can even work on a 10 bolt. Search using term PBR rear caliper.

https://www.thirdgen.org/forums/sear...archid=5288831

 

Most of the info required for the swap is provided in the link in post #2. PBR's with their larger rotors were used on 9-bolts in 89, in 10-bolts 90-92 (in thirdgens). The single difference is that the backing plates have a different bolt pattern. Backing plates, cables and cable brackets are available from the following site:

http://www.flynbye.com/

JamesC

 

Sounds like a lot of "love them or hate them" opinions about them on this site! Thanks for the info. Regardless if I can do the swap or not, I'm not sure if my current rims will work with it. One of my neighbors has an 89 Iroc Z that he special ordered in 88. I think he got the 1LE package. Maybe I can see if he'll take it out of storage and let me see if my rims will fit on it. If not, the swap will have to wait until I can find an Iroc rim (I've got 3 out of 4 on my parts car.)

 

Frankly, I haven't heard much about hating them. Most members, I think, would agree that the upgrade is worthwhile--they are after all the brakes that the 1LE's were equipped with.

JamesC

 

Assuming you have a 10 bolt you will need to either make or buy a drum to disc adapter plate. Check the Flynbye website posted above. Rotors are readily available. May need to use to later 93-97 style rotors to fit over the ends of the axle. The emergency brake cable is available through flynbye also. some auto parts stores used to be able to order it also.
Will they fit your wheels is a good question. What size wheels are you using? These will fit in 16" wheels without a problem. Should fit most 15" wheels. Some needed to grind off a little from the fins to clear their 15" wheels.
I have the later style 93-97 PBR calipers which do not have the same fins and they clear the 15" wheels I am going to use. My calipers are essentially the same as those except for the fins.

 

Yes - 10 bolt. I plan on buying the adapter from flynbye, once I check rim fitment. The rims are an aftermarket 15"

 

TTT

 

You dont need a 1LE prop valve. Just get a late thirdgen prop valve. You can adjust how much pressure goes to the rear brakes with a $0.25 spring from a hardware store.

 

I've tried to follow the 'spring replacement' mod, but I've never really seen any data on the swap except 'seat of the pants' recommendations. Have I missed something important?

JamesC

 

...What's the difference between the 1LE prop valve and the late model disc prop valve?

 

Two valves for two different brake designs: one with 10.5" rotors and iron Delco-Moraine calipers vs. one with 11.7" rotors and alum PBR calipers.

JamesC

 

Oh ok. So, since I'm not upgrading the fronts in the near future, which will work correctly for now then? Or would I be better off getting an adjustable one?

 

Maybe this can help some https://www.thirdgen.org/forums/brak...m-o-e-j65.html

BTW if you do not plan to use the used disc backing plates in your pic, I would be glad to buy them from you. I have been loking for a set of 10 bolt backing plates for a while.

 

What makes you sure the parts in the pic are from a 9 bolt and not a 10 bolt axle?

 

How do you propose we empirically measure rear brake pressure? It's just not worth the trouble when seat of the pants tells you theres a difference.

Regardless, as you know, the prop valves in these cars really dont do very much. Fronts always get 100 percent of the pressure, and the spring just moderates what fraction of that pressure goes to the rears also.

 

Perhaps a brake pressure gauge used before and after the spring swap?

JamesC

 

I'll take $100-150 for my aluminum calipers. They came off a rear end I bought used.

They aren't hard to find. I found remanufactured in stock all day from Napa, Advance, Auto Zone, etc...

Good news is they help keep these in circulation by charging high core prices. I bought 2 reman. PBR's from NAPA for $85/ea. with an $85/ea. core charge.
Am I returning my old ones...heck yeah!

Maybe hard to find already on a car, but not hard to find replacement if yours go bad or to buy outright.