Hi everyone,

I have an 87' IROC Z-28. Swapping out the motor, and tranny, suspension, etc... doing a major overhaul. I'm looking to go with 4.11 gears for the rear posi.. Other than the gears, do i need to change the actual axle? What would I have to change exactly? It currently has the stock 3.27 Posi.

Thanks-

Lou

 

First off does it have a 10 bolt or 9 bolt? The gears between the two are not interchangeable at all.

Since you said 3.27 I'm guessing a 9 bolt, but count the bolts on the rear end cover to confirm.

That being said 3.27 should be series 3 carrier which should accept the 4.11s. If it's 10 bolt you can get it from just about any aftermarket supplier (Summit, Jegs, etc). If it's 9 bolt you're options are more limited. www.9bolt.com has spare gear sets look at spending $275 for the gear and pinion alone though. Strange has 3.70 gears. Randy's Ring and Pinion carries 3.70 gears. Australian suppliers will carry a variety of gear ratios if you want to pay for shipping.

Gear setups are not for the novice to do in my opinion. It takes special tools to do it correctly and it takes a little bit of know how else you're new $200-$400 gears will be scrap metal in a few miles if lash isn't set correctly.

You shouldn't have to change the axles at all. The axles get reused as you're not changing the splines on the housing or anything. You'd be looking at getting an install kit (that has the seals and new bearings) then the gear itself. Expect to pay $300 to $800 for Labor to have it done (local shop or dealership).

 

Plus changing speedo gears to compensate.

 

big lou, where are you located?