Will the rear disk brakes from an 84 Camaro work on an 89 IROC?

I have been lucky enough to find one in the bone yard with the complete system if it will work I am striping it asap.

Thanks
Phil

[This message has been edited by IROCRULZ (edited February 06, 2001).]

 

It depends. If your IROC already has rear disc brakes, then they'll fit but it's not worth swapping them in as that's a step backwards. If your IROC has drum brakes, then no they won't fit. The drum-brake rear has a different mounting flange than the disc-brake rear.

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Greg Westphal
'87 IROC 305TPI/A4

 

Ok, I have drums. Thanks for saving me time and money.

Phil

 

Although- you could swap the whole axle. What kind of '84 is it? Is the engine code "G"? It might just be the rare 3.73/locker/disc axle! And yeah, I said locker... in '84, GM had trouble getting Auburn Posi units, so they bought the Eaton Gov-Lock lockers for the f-bodies.

You would need a bunch of stuff though- click on "search" at the top right of this page, and look for rear disc- you should find swap information. In a quick nutshell, you'd need the rear axle, proportioning valve, master cylinder, and maybe even the front-to-rear hard steel brake line from the '84.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Hmmm, the entire brake package is there. I will have to go back and check on the codes to see if it is a "G" coded car. If so do you think that the rear disks would be better than the drums I have now. I have read that the pre-89 disks were not that great. I am planning on running the IROC in some autocross, the last thing I want is a headache for brakes.

Phil

 

For autocross, the brakes (especially the rears) aren't nearly as important and handling and a good set of tires. Unless it's a very-high-speed auto-x course (heh, it'd practically be a road-race course then), you'll be fine on stock or Perf. Friction brake pads up front.

I've even ran some open-track events on road-race courses with my rear drum brakes (both with stock and 1LE front brakes) and the drums worked fine, although they don't do much work anyways when stopping from 100-115 mph. It's really fun trying to slow your car down when the front brakes have faded and only the rears are doing the work.

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Greg Westphal
'87 IROC 305TPI/A4

 

Greg, Your reccomendation is to get a good set of shoes for the rears and pick up a set of vented rotors and performance pads for the front?

Phil

 

Sort-of. I still have the Midas shoes in back from a few years ago, so they work OK. For the fronts, something like the PF Street or Z pads will do fine, or the new A/C Delco Durastop pads. If your rotors aren't warped and haven't been turned down to where they're not usable, then I wouldn't bother replacing them since the stock rotors are also vented...

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Greg Westphal
'87 IROC 305TPI/A4

 

Greg, why couldn't you take the mounting bracket from the disc rear and bolt it to the drum rear--the axle flange bolt pattern should be the same on both rears.

TomP, I hate to be the bearer of bad news but the Eaton Gov-Lock is hardly a locker! In fact, imho, it is a useless POS and should be avoided at all cost. It has a set of internal gears along with a counter weight that tries to route power to the wheel with the most traction. The problem is the internal gears are TINY and when they break they can become wedged between your pinion and ring gear teeth thereby causing them to break.

[This message has been edited by JeffT (edited February 06, 2001).]

 

Thanks, for all the input. Looks like I am going to be staying with what I have for the time being. Unless I get lucky enough to come across an LE package.

Phil

 

JeffT, everything I've heard and read indicates that the disc- and drum-rear mounting flange bolt patterns are different. GM even has different part numbers for the disc and drum axle housings because of this.

I agree with what you said about the Eaton "lockers." Dan Burk had one in his rear before he rebuilt it and installed a HD Torsen with steeper gears and the newer-style disc brakes (his WS6 already had rear disc brakes). He didn't like it very much from what I can tell, and I've also heard of them failing more often than other posi units.

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Greg Westphal
'87 IROC 305TPI/A4

 

JeffT, don't worry, you're not bringing me any bad news. I never said it was the best thing out there, I was just saying that it's a locker, not a posi. The gov-lock in my swapped '84 axle is missing some teeth on the spider gears- luckily the ring & pinion are fine, good thing GM had a magnet in the rear cover. But thanks for covering those problems!

Oh and Greg, you're right. I've seen both axles side-by-side on my garage floor. The flange at the end of the drum axles is rectangular, with a hole in the flange to let the wheel cylinder's brake line through. The flange for the discs is smaller, and square.

"Possibly" the drum flange could be cut down and re-drilled for the discs. I never bothered to check dimensions, though...

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited February 07, 2001).]

 

That would be very good to find out as there are millions of third-genners wanting to swap disc brakes onto their drum-brake rears w/out having to pay Baer Racing $800 or swap whole rear ends out. If anything, I'd sure appreciate the dimensions and such...

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Greg Westphal
'87 IROC 305TPI/A4

 

Greg,

I'm going to be going the Baer rear disc conversion route. I think that even if there was a chance to convert the drum axle flange to accept stock rear discs, you'd end up spending more than $800 in parts for rear brakes. Rotors - $80 ea. Calipers - $150 ea. Pads - $60. Assorted brackets - $150. and then all the other BS you come across when you start tearing things apart. Unless you're lucky enough to find a functioning set in the junk yard and can swip em, resurface the rotors and swap some pads, but nobody's that lucky.

And after all that, you still have 11.65 x .81 rotors, when you could have the Baer 12 x .81 rotors with brand new calipers and pads for $100 or so more. I'm just trying to justify spending $800 on a Baer rear disc kit I think.

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-Jason M. 1991 Camaro Z28