jons69

I am looking for a rear end to replace the worn out rear end in my 69 camaro. I think I would like to upgrade to posi, and go with lower gears"3.55 or3.73 or even 4.11's"; I really dont know what I need? Jon

Greed4Speed

More drive trian info would be needed. Also, how often will it be driven...especially how much highway time will it see?

CHPshown67

Do you want to swap out the entire rear-end or just components? The posi units run about $300-$350, and gears about $200. What tranny do you have and what size tires in the back(hieght)? 4.11's will be steep if you have a 3-speed and want to do freeway driving. I have 3.73's and top out at about 70-75 on the freeway with 14" rims in the back, 15's would help to lower the RPM's, but right now I sit at about 3200-3400 @ around 75mph.

angel71rs

If you are going to swap the diff, and you don't have a 12 bolt, consider an 8.5" diff out of an early 70's Nova. Same carrier as 70's Fbod, so parts availability is excellent (much better chance of finding a used posi diff) and it is stronger than the 8.2 diff.

As far as gear, I have 3.42's with a 26" tire and would consider that the deepest gear I would use if any freeway driving is planned. Or 3.73's with a 28" tire.

jons69

Okay, I have a 350ci motor, lt1 heads, weiand intake, and a 600cfm edelbrock performer carb, backed by a turbo350 tranny. Right now on the interstate I run around 3200 rpm's at 70mph.
I will see about 10 miles at the most of interstate miles a day, the rest are in town. Right now it is my daily driver, but I also have a truck that I could be driving. My rims are 14 inchers, and the tires are 24 inches tall.

jons69

Okay,heres the other problem, last month I had my car in the shop getting a rear axle leake fixed. The guy called me up and said that he had to put another bearing saver in there, becouse the old one crapped out. Bearing saver, what does that mean. Do I just need to replace everything or what. I'd really like to have posi, but the cheapest ones I could find were around $450. Thats a lot. So maybe posi isn't as important to me as it was before. I'd also like to step up to some bigger beafier tires.

Greed4Speed

Running that RPM at 75 I'm guessing you have decent gearing already, but running taller tires will decrease your effective gear ratio. What you want to do when picking a gear is to look at your power range and chose one that will keep you in that range with your tire size. A shop could help you out there. With 4.11's in my 12 bolt I used to run, 10" converter, and 275/60 15 tires my Camaro ran ~3000 RPM at 60 mph, but it was a beast off the line.

I picked up a 2nd gen 8.5" 10 bolt with disk breaks, posi, 3.08 gears for $250 used, but still fresh. Deals are out there, just have to find them. Talk to chevy guys, or any other gear head for that mater, in your area if you know any. Thats how I found mine.

I have no idea what he meant by bearing saver.

angel71rs

Bearing saver: Chevy axle bearings run directly on the axle. Can eat up axle on the spot where it rides. Bearing saver is offset so it rides in a different place. It's a crutch to keep from having to buy a new axle.


3200 @ 70 w/24" tire calculates to about a 3.23.

jons69

How did you calculate the gear ratio, just from the tire size and engine rpm. I took the numbers from axle tube, went online and found out that they are 3.08's. The guy I bought it off of said that they are the originals. Maybe he lied to me.