I know I've had a couple threads regarding this before but bear with me. Here's the deal:

I've got a 3.70 9-bolt BW Posi lined up. My plan is getting rear disc brakes off of an LT1 car.

#1- Should I get the Proportioning valve and E-brake cable included with the 9-bolt? Any other parts? I'll get 9-bolt backing plates from that website Ebmiller reccomended.

#2- What all will I need with the LT1 setup, Calipers, rotors, lines, what else?

#3- Will there be any "fabricating" or custom parts I'll need?

Thanks!

-Rippin

 

TTT, C'mon guys!

-Rippin

 

Sorry about the delay...my cable has been down for the last 4 days.


The prop vavle from the 9-bolt car is useless to you. The threads are different and it will be a lot of trouble to bolt up. Your stocker will work, but if you REALLY want a 4-wheel disc valve then find one to fit the year of your car. That way you won't have to change the master cylinder to make the threads match. It'd be easier to just get an adjustable prop valve from Summit and rent a flare tool so you can put it in the stock line. Also you'll be using the LT1 style E-brake cables, so you don't need the 9-bolt ones.

As for LT1 disc brake swap parts, you'll need the rotors, calipers, abutments (caliper carriers,) E-brake cables, and pads. I think that covers it, and I think with the plates it'll be a bolt-on install, but don't quote me on that because I haven't done it yet.

 

What's a flare tool?

When you say plates, you mean the backing plates from the 9-bolt?

-Rippin

 

My rear is a 90' model BW with 3.45 gears and everything looks exactly the same as my nieghbor's 95' LT1 brakes in the rear....IDENTICAL....same rotors, same caliper (besides having ABS sensors). Not positive, but they sure look the same!! Now, before I got my 3.45 rear, I had an 87' BW out of a formula 350 with 3.27 gears, and it had completely different disc brakes....smaller rotors, different calipers... Dont know if my rear could have come out of an 1LE car??? Paid $475 for the 3.45, but it had low miles and the LT1 style brakes already installed...Hope this helps.....

 

A flare tool is a tool that's used to flare the ends of a steel brake line. That's how you make custom lengths and splice fittings in and things like that. flare tool When I say plates I mean the conversion plate that Ed Miller sells.


Shane...you don't have a '90 BW 9-bolt. GM stopped using them in '89 so that's the newest it can possibly be unless you imported it from Australia. 1989 is also the year they started using the PBR rear disc brakes, which is the same thing they used on the LT1 cars. That's why your brakes look the same.....they are. It seems that you have the highly-sought-after '89 3.45 rear. It's the deepest ratio 9-bolt that can be had with the good brakes from the factory, and they only came in the '89 5-speed cars. The cast iron calipers on that '87 rear were the old Saginaw brakes that aren't work a crap.

 

I could have been mistaken. Bought the rear from a pretty big salvage yard here in Greenville, but they hard to get it on what they called "the wire", found it in Winston salem, N.C.... It said on the reciept that it was a 90' Iroc, but they could have been wrong. I know that it helps ALOT more than the brakes on the 3.27 87' model brakes... The later rear 89-90??? costed about $125.00 more than the 87' also!! Just my 2 cents!!! Good luck!!!

 

I picked up an 87 BW 3.27 disc rear for 100 bones, and I am going to swap the backing plates, and rear brakes off my 89 into that rear. the whole rear only has about 60K miles on it, less than half the mileage my stock 2.77 posi has. I hear 3.27's are pretty good gears for 350's, decent performance and still very daily driveable.

Will

 

All 90 IROCS were made before dec 31st 1989 so its out of a 90's IROC, but its the 89 PBR setup.