8.2 posi

buickman7076
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8.2 posi

Postby buickman7076 » Tue Jun 27, 2017 10:51 am

Hello all

I've recently been wanting to change my 70 Buick skylark from a peg leg to a posi unit. I have done a lot of research so I'm trying to narrow down the right fit for me. The engine is stock. Might do some mild upgrades in the future but nothing to wild. Has a TH350, but will probably change it to a 4 speed in the future. I want the car to act like a everyday driver and climb nice size hills when going on a road trip, but can still get off the line at a stop sign. So my question is do I stay with the BOP 8.2 rear that it has? Or go with a GM 8.5? I say the 8.5 because I was hoping to find a complete rear end in the junk yard with disc brakes already on it and some have said parts are more readily available. Any ideas if I could find that as well? Hope to hear from all of you. Thanks for all the help in advance.

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monzaz
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Re: 8.2 posi

Postby monzaz » Tue Jul 04, 2017 10:52 am

Ok, Well first off your not doing your self any better going from one USED rear to another. NO reliability there.

Next you really need to figure out what ratio is in your original rear - This reason is for knowing what you are driving around with that is NOT doing the job for you and where to go to the ratio that WILL do the job for you.

The only reason I agree with swapping the rear to another rear that the 68 69 70 Buick 10 bolt 8.25 rear is PARTS availability. Aftermarket gears are available only in 3.42 or 3.64 ratios and the cost of these gears is steep. (550.00 +)

NOW if you do have a ratio in the 8.25 Buick rear you LIKE...we can make it posi and all aftermarket disc brake kits will fit that rear also. Just buy the ones that fit the Chevelle rear 64-72 era.

10 bolt 8.5 rear swap you will need to shorten the drive shaft about 1 - 1.25"
10 bolt 8.5 rears in the era you are buying NEVER came with disc brakes so do not bother looking. IT DOES not exist.
10 bolt 8.5 WILL have a great selection of ratios for all your driving needs NEW and USED.
10 bolt 8.5 rear can be upgraded to 12 bolt strength with 30 spline aftermarket race axles and still be limited slip posi .

Hope some of this info was helpful and not deflating.

Jim Mitschke
J D RAce
J D Race

buickman7076
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Re: 8.2 posi

Postby buickman7076 » Wed Aug 09, 2017 1:24 pm

Thank you Jim for the response. I have been crunching my numbers and had a few more questions. You said the 8.25 gear ratios are limited to 3.42 and 3.64. If I put the 3.42 with a TH350 I already have how would the RPMs be at highway speeds? Do you think I could live with them. There is a possibility that in the future I'll be adding a 4 speed and I know the overdrive will help a lot. Let me know your thoughts. Thanks again.

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monzaz
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Re: 8.2 posi

Postby monzaz » Mon Aug 14, 2017 12:01 am

4 speed AUTO I am assuming and YES that will help a bunch for RPM driving.
3.42 you will be in the 2800-3000 range with stock size tires 26" with the 3 speed trans...Remember also torque converter slippage also...
As far as me thinking what you can deal with in the RPMs is not a good Idea...YOU have to deal with it. Best way is to run your 3 speed trans with 2.56 gears in 2nd gear and drive it around like that for a while. That might give you an idea how more gear will affect your life.

As long as your not traveling too far... you might be ok. I personal will never go back to a 3 speed trans and steep gears. When you go with over drive trannies you will not go back. :)

You have to evaluate what your doing with your car and what you want out of it. It is your car and if it all makes you happy and you can deal with it all...then you are good.
Different people have different tolerances to RPM ranges. The more RPM you drive around with the more noise you will have from your car. Vibrations shakes and resonating noise from the mufflers.

Jim
J D Race


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