Will a 1984 rear end fit in my 1989 IROC? Is there a difference in the disc brake sizes between the two? Thanks.

I just got a Camaro and know nothing about them

 

They should bolt right in and if you have complete rears just swap them over and connect the brake lines up. You can also install a 4th gen rear on the car but you will need to get a adjustable Panhard bar to center the rear up.

 

84 rear brakes are junk compared to the stock 89s,

 

And the shafts of the 84 are weaker and the ebrake lines are different and I think the fittings on the 84 are SAE where the 89 is metric.
In other words, an 84 axle is a poor swap choice for an 89 iroc.
What ratio gears are in the 84? Posi?
I think you would be much better off fixing the 89 rear.

 

While the 84's rear end will have 26 spline axles in place of the 89's 28 as long as it has disc brakes I say swap the rear end over. I just swapped a 10 bolt from an 83 pace car into my 89 Formula and couldn't be happier. The car will most likely never make more than 450 ftlbs of torque and the disc set up works better than my old drums did. The ebrake cables from the 84 will hook right up but you might have to re use the brake line fittings that run into the rubber line with the "Y" block. You'll also want to buy a the correct proportioning valve for the brakes. If you don't and you currently have drum brakes you'll notice the rear brakes will be a bit on the grabby side and might drag a little like mine did.

 

[QUOTE=Derek The Great;5375605]While the 84's rear end will have 26 spline axles in place of the 89's 28 as long as it has disc brakes I say swap the rear end over. [QUOTE]

We really need more info as to what rear is in his 89.
If its a performance 305 or a 350 car it will have a 11.65" rear disc with aluminum single piston calipers on a 9bolt with 3.27 gears.
If he has a drum rearend in his 89, I sure wouldn't want the 88 and older iron rear disc rearend. Id keep the drums and wait for a good rearend for it..

 

More info on his car is indeed necessary.. I'm not sure but I think those 11.65" brakes only came with the 1LE package otherwise yeah he should wait like I did until something better turned up. I prefer the 10bolt and I know I could always upgrade the brakes if I want. Right from the get go though I can tell the discs out perform my drums buy a significant margin.

 

Nope, not just 1LE cars. Fronts, yes(kinda) rears nope they were standard on 89-92s with performance options