Rear help please............

**LETHALxLS1** · 06-14-2007, 07:31 AM

I have a 1998 z28 camaro with the 4l60e transmission. I want to replace the rear gears and possibly the differential. Could you please tell me what differential the stock one is(auburn?etc.) and if the reAR is 7.5? Is it possible to make the rear in my car posi trac? I dont have traction control. Also I want to lower my gear ratio but still want to travel 70-75 on the interstate sometimes for trips. Would 3.42 gears be a better choice for me? I dont take my car to the track ever its a dd. I am lost. Thanks for any help.

Here is a site I was looking at for the parts-and I plan on getting the labor done somewhere because I have 0 experience. Also is it possible to tell what ratio gears I have now without taking the rear cover off?

http://www.ftpp.net/LS1main.htm

**vetteemt** · 06-14-2007, 08:44 AM

I thought all z28s had posi from the factory and the 98 SS had the Auburn I think not sure about the z's? Stock rear gears, if you don’t have the opt. 3.23 for your Z then I think it would be a good gear set to go with. If you went to the track more often then you might want to look at the 3.42 set. The 3.23 set is what my SS has and its seems to be a good mix of enough gear for performance, but high enough that I still drive it to work everyday 98% of the time on the highway. What set you have now std. was 2.73 the performace gear opt. was the 3.23 for the Z.

**LETHALxLS1** · 06-14-2007, 09:43 AM

thanks

**slims00ls1z28** · 06-15-2007, 12:12 PM

Look at your driveshaft if its rusted its got 2.73 gears if its aluminum and not rusted it will have 3.23's. 3.42's from a 2.73 will be a decent jump. 3.42's from a 3.23 is not worth the time or effort go 3.73 or higher numerically. All LS1's should have a posi in it already. It could be auburn or torsen they just kinda threw in whatever in different cars mine had the torsen.

**LETHALxLS1** · 06-15-2007, 12:34 PM

Thanks man thats a great way to tell without takin the cover off!! I really appreciate your help. The reason I am changing gears in because it howling/whining really badly+ I want a lower ratio so I figured now is the best time to do it. Do you have any idea what would make the car make a banging noise(not terrible but I can hear it) when changing into 3rd gear? It doesnt do it every time and 1/2 the time it doesnt do it. It seems to do it more often at low throttle. Seems to be coming from behind my seat under the car maybe back even further towards the rear -not sure. If I give it more gas it doesnt seem to make the banging noise while going into 3rd. I never abused the car but I am certain the shop I took it to did because it started this shit right after I took it to them for some other work. Do you think it could be the transmission or the rear? I am hoping its the rear cause the gears started whining about the same time the banging started. I know its hard to diagnose but any sugestions would be great. I am gonna get a new trans. mount put on hoping that may help as well.

**2001NBMZ28** · 06-15-2007, 01:10 PM

I'm thinking the '98 should be an Auburn whether 2.73 or 3.23. Before suspecting the trans I'd change the rear diff fluid if it hasn't been done already - and add the GM limited slip additive. Removing the cover to drain it will give you a chance to verify what diff and gears it has, and if there's any obvious damage. Replacing the fluid is easy. My car has GU2 on the door and a steel driveshaft - but put a complete 3.42 rear out of an M6 car in it a few years ago. People change gears all the time.