hey everyone, long time viewer, first time poster here.. My buddy has an 89 RS 2.8 right now..

He wants an Iroc rear with discs and posi but, what will the gears do that are in the axle currently? I know theres gonna be a big change since the Irocs are V8s of course.. Also, whats needed for the posi rear to work on his RS? Any electronics needed FROM an Iroc to put into the RS or does it act as a spool or locker in a truck, no electronics needed?

Also, his speedometer doesnt work and his tachometer is WAYYY off (registers insanely higher than it should, as in outside red just normally driving) Is this any indication the guage cluster isnt the stock one? I have an inkling that the RS was originally a V8 but we have no way to be sure really.. We want to swap in a 140? MPH Iroc Cluster, think itll fix the tachometer issue, by any chance?? Last question is : his speedo wasnt accurate when he bought it but it then died (cable snapped I think) How and where does the cable hook up to the engine/tranny? How strenuous is replacing the cable too? We gotta do that for inspection time

Thanks!

 

The easiest way to change the rear to a disc-brake and posi rear is to totally remove the current one in the car, and bolt the new one back in. All rear ends from any thirdgen camaro or firebird bolt up exactly the same, and none of them have any wires or computer control to them, so it's a pretty straightforward swap. The only problem is that going from a drum rear to disc will require an adjustable proportioning valve, or the prop. valve off of a thirdgen with rear discs.

Will post later with more, have to leave now.

 

The rear disc swap from an Iroc would be pretty pointless on a couple levels. First, most rear disc systems on these cars don't work well. The drums work better. Second, most V8 differentials will have higher gears. Unless you find a donor with G92 you'll probably end up with 2.77 or 2.73's instead of the 3.23's or 3.42's you have now. To get a rear end with good gears and the PBR discs, you'll be spending a lot of money and it will still be a cosmetic upgrade.

It sounds like you've got a V8 cluster in a 6cyl car. The tachometers are different, and will not read correctly connected to the wrong engine. Get the correct tachometer and swap it out and it'd be fine.

Replacing the speedometer cable isn't too difficult, it screws onto the tailshaft, and has one anchor to the body at the frame rail. Even still, the cable won't cause the speedo to be off. The calibration is in the plastic gears inside the tailshaft.

 

cool cool.. I found a complete axle from an 87 Iroc locally for a good price, so we would Probably have just swapped that axle with his, yea but my biggest concern in that is the gear ratios.. Dont know what exactly they would do to the V6 drivetrain in terms of power and torque.

I actually now think the car WAS a V8 but the douches who sold it too him never told him that (the 2.8 in it does look mighty clean for the car, i think).. Anyway to tell by VIN number original engine size?

The speedometer before the cable broke wasnt too terribly off, i think those gears you mentioned just needed adjusting.. What troubles would we run into swapping in the 145 MPH Iroc cluster we found? I know some things need changed like the speedometer calibration and bigger things like oil pressure stuff(ORR, would that be fine since, apparantly the cluster he has is already a V8 cluster, and those guages work fine?)

Ill get a pic of his cluster and car in general, see what you all think about it (offer insight to what it was originally engine wise and all that fun stuff)

 

Vin code "S" is for the 2.8 V6.

You should just swap the brakes off of the Iroc rear and keep your rear axle. It's a little bit of work but you have everything you need if you have the complete donor rear end.

I think the master cylinder listed is different as well as the combination valve. There is a small check valve in the output of the master cylinder that goes to the drum brake line to maintain a certain amount of pressure (like a pre-load) to the drum brakes to keep them extended almost to the drum so that they do not lag when applied.

You don't need a picture to know if it's the wrong cluster. Look at the redline on the tach and the maximum number that it goes to. V8 cars are 6000 I think and show a redline of 4500. I can't remember exactly and my car is freezing it's tail fin off in Ohio while it waits for me to buy a garage. I think the V6 car shows a redline of 5000 or 5500.

I may be a little off but just let us know what the gauge reads...

 

i have a 4 wheel disk brake mastercyl and proportioning valve if u need it,and yeah if u can get a pic of the cluster that would help in determining which it is

 

Where would the S be in the VIN number? Which slot is for engine size? It has an "S" in the number towards the middle of it. Dont mind the bumper, shes under construction.. Repainted, new emblem and grill will be tossed back on soon.. Dont mind my sexy Geo in the background (i know it trys to steal the attention in pictures)

 

That's a 6cyl and always has been. The speedometer would drop right in and wouldn't need any recalibration. The only calibration is for the rear gearing, which is in the transmission. Unless the transmission has been changed or the rear end has been changed, it's not a concern.

Most Iroc's are equipped with a Borg Warner rear end. Nothing on that rear will interchange with the 10-bolt that's probably in the car now. The only reasonable way to make it work would be to swap the entire rear end. Unless the donor car has the same or better gears, you'll lose performance.

Edit: You're looking for the 8th digit of the VIN number for the engine designation. Also, since the car is a 5spd the gear issue is even more important. The T5 has higher gears then the 700R4, most 5spd cars came with better gears then the auto.

 

i guess it is and always was a V6 then /\

Only thing i saw that made me weary was that speedometer went up that high (a lot of these i see in junkyards are only up to 85 or so, thats why i was always curious if that thing was stock or not..

Ok, ive gathered the gearing is too low (right, too low?) in the Iroc axle he wants.. Now, can the gears in the diff of his Camaro be swapped into the Iroc axle to be posi rear then?

I know an entire axle swap and rebuilding of sorts is in order, we always assumed that.. I just wasnt sure if we could feasibly USE the Iroc axle (i guess we COULD but the gears are off unless we could swap his stock gears into the 10 bolt carrier)

Im coming over from Suzuki 4x4'ers here to help my buddy with the Camaro, feel free to school us in this stuff so we learn I dont have intricate understandings of everything in the Camaros yet, Im just goin off of things that I know about cars from over yonder working on my Geo's and Zuk's (On them, gears can be swapped in the diffs for others, regardless of axel really.. lol. Any Sidekick, Samurai or Tracker gears can interchange anyway if you set them up right)

For the Iroc 145 MPH guage cluster, itll swap right in then? If im reading correctly, it appears you said it would.