I know this topic is old, VERY OLD. But i want to make sure i have this right. Im gonna buy a 10 bolt out of a 4th gen and put it in my 89 iroc that has an lt1. Im gonna put the stock iroc rims on it to. Do i have to do any mod to the rear end to make it work or is it a direct bolt in? Thanks

Bobby

 

Direct bolt in, but your wheels will stick out 2" more on each side.
Some stock wheels look fine but others stick out too far.
My friend has a set of 16" 3rd gen aftermarket wheels on his 92 Firebird with a 4th gen rear and it stick out 1.5" past the fender.
Looks kinda ghetto but he likes it.
I'll see if I can snap a pic of his car tonight so you can see.

I have a 4th gen rear on my 86, but I am using 4th gen offset wheels on my car and they look awesome.

 

Yeah that is what i was worried about, i had a feeling my iroc rims would stick out. Oh well, ill see what i can come up with. Thanks for the help Zepher.

Bobby

 

No problem.

 

If I order a moser 12 bolt for a 4th gen car, and I run the 17x11 Zr-1s in the back, will it still rub and will I still need spacers?

 

Why don't you just get a moser 12 bolt rear for a third gen and save yourself a whole lot of hassle? Sounds a whole lot easier to me.

 

n/m

 

Yes, it will rub the inner fender well, but a hammer should take care of that.

Oh, and you will have to relocate your bumpstop.
I tried to put a set of 17x11 GS Wheels on my car a few months ago,




I stuck a 2.25" spacer on just so I could see how it sat since I didn't want to take off the bumpstop at the time,




My friends wheels stick out just like that on his 92 Firebird with the 4th gen rear and the 3rd gen wheels.

 

Well, the whole idea of running a 4th gen length rear is to eliminate having to use a spacer! The spacers are expensive and weaker than running the right size rear end.

What bump stop has to be removed? Any pics? Also instead of using a 2.25 in spacer, they recommend using a 1.25 - 1.5 spacer. With that size spacer, the wheel wouldn't stick that far out.

What size tire is on that GS wheel? 335 or 315?


Mike (1bad91Z)

 

To Zepher - wait a minute, you are running a 4th gen rear? If so, they should fit without a spacer, right?

 

What spacer are you talking about? I really don't know much about the technical detail of these rear ends.

 

The bump stop that is on the body right above the axle has to be moved. The top edge of the wheel hits it.
the tires on those wheels were 335/35/17, so they are slightly wider and taller than the stock size of 315/35/17.

I do have a 4th gen rear, but the bump stop kept the wheel from mounting and I didn't want to get all wet trying to remove the bump stop since it was raining when I was trying to fit the wheel.

 

ONLY if you're switching to 4th gen wheels. Bobs89IrocZ wants to keep his stock IROC wheels. The whole idea of changing rearends to him is to get rid of the weaker 3rd gen rearend.

If you're going to get a Moser rearend, get one set up for the wheels you have and they'll bolt up with correct offset.

 

what is the back spacing on the 4th gen wheels? i am in same situation as OP but i do not like the look of most 4th gen wheels. i dont mind going to an aftermarket wheel..just dont know what size to get. i want to go as wide as possible without it sticking out or rubbing.