[406chevelle]

Can anyone tell me what 8.5” rear ends will bolt up to a 72 Chevelle??? (what cars, years etc.)

I have the 8.2” 2.73 gears and want to up grade to a 8.5” that I can put 3.55-3.73 gear and a posi unit in, but I am have very poor luck finding an 8.5” rear end for a 72 Chevelle.

I would love to have a 12 bolt but they are impossible to find.

406chevelle

[poncho62]

68-72 Chevelle, Lemans, Skylark and Cutlass rears are the same.

Earlier (64-67) rears will bolt in but are about 1" narrower, which might help if you want to run a bit wider tire.

[406chevelle]

Thanks for the info Poncho62.

If thats the only options I have then I will be making my 8.2" rear end work, I am having one heII of a time finding an 8.5".

Am I going to be able to put 3.73 gears into my 8.2" rear end housing????

406chevelle

[jimfulco]

http://emporium.markwilliams.com/pro...sp?prodid=3185

They have gears also.

[406chevelle]

Man I just can’t find anything good about my rear end I just found this original posted by OddRodder in another post,
G.M. made 2 series of differential for the 8.2 rear. Yours is designed for 3.00 and numerically lower gears, the other is designed for 3.08 and numerically higher gears! One note though, Mr. Gasket has a ring gear adapter for the later 8.5 rear, there may be one available for the 8.2 also!

Is this right!…..I can’t use gears numerically higher that 3.00 in my 8.2” 2.73 stock gear rear end??????……with out a ring gear adapter that might exist??????

Wow this gets more frustrating every time I try and figure out whats going to work for rear gear in my car…..can’t find a replacement rear…..can’t get low enough gears for the rear I have…..whats next.

Sorry…..just venting.

Thanks,

406chevelle

[EricTopless68 Camaro]

Down boy!

I have been asking around, and I still have not been able to confirm that an 8.5-inch rear from a 73 to 77 Chevelle will fit in a 72. I am sort of doubting it will, as it is probably wider.

Don't sweat what gears your existing carrier can handle, since I assume you want to go posi anyway. When you hear talk about the "differential", that is the center carrier that the ring gear bolts to and the axles slide into. The rear axle housing is the same size, no matter which carrier/diff you have. Some folks use "differential" to describe the entire rear, which is just wrong.

Just FYI, the reason the higher numerical gear ratios require a different carrier is because there are only so many teeth you can fit on a ring gear of a given diameter without weakening it too much. So, they decrease the number of teeth on the pinion (remember, gear ratio is number of teeth on the ring divided by the number of teeth on the pinion), which makes it a smaller diameter, so the ring gear needs to be closer to it, hence the need for the other carrier or a spacer (this is probably over simplified, but you get the idea). Some manufacturers like Richmond make thicker ring gears, instead of spacers, so your "2-series" carrier could be reused.

The above linked site, Mark Williams, has a really good price on the Eaton posi unit, about $100 less than Summit. I looked for the gears on that site, but it looks like they don't carry 3.73s for the 8.2. Richmond makes 3.73s for your rear, and they are around $200.

I'll keep checking on the swap of an 8.5, but your 8.2 is usable unless you're putting a whole lot of ponies in front of it and using wide, sticky tires.

Hope this helps!
Eric

[406chevelle]

Thanks Eric I appreciate your time and effort, I am going to change the gears and add a posi unit, it is helpful to know I can use the gears I want.

I am fairly sure that the 73-77 rear end won’t fit.

I may still have a slight problem with the 8.2, I would like to run slicks at the track and my motor is approx. 473 hp and 472lb torque, I think the 8.2 might not like that, and all I can find are a few more 8.2 rear ends no 8.5 or 12 bolts.

406chevelle

[jimfulco]

3.73's at MWE: http://emporium.markwilliams.com/pro...sp?prodid=3236

Someone at Southside Machine told me 73-77 housings have a different setup for mounting the trailing arms from a 68-72, so I'm assuming they won't interchange.

[OddRodder]

Sorry 406, didn't mean to worry ya'! If you are buying a posi unit anyway, you'll be able to put the gears that you want in your 8.2" rearend!

Hey 406, someone just posted that he has a 69 SS chevelle that he rolled, it should have a 12 bolt!!!

A good co. to deal with & fair prices is Randy's ring and pinion at www.ringpinion.com

[406chevelle]

No problem QddRodder, thank for the link.

I am sorry to hear that some one has rolled there car, but…who, what post, where that 12 bolt…LOL, I can’t find a post about rolling a Chevelle can you put up a link to it?

Jimfulco thanks for the link, they have some great prices and may be the way I need to go, just not sure the 8.2” will hold up to 470HP 470lbs Torque.

406chevelle

[OddRodder]

It's in body & exterior the thread is "Rolled Chevelle"!!