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brandyv73's 1968 Firebird

2019 June
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Hey guys still working on my project, and I need a new rear end so I don’t smoke one tire and get them both to hook up.... do I have to change out the whole rear end or just the gears in the pumpkin ?( don’t know the real term for it). Again this is a hobby for me not a money maker so any help would be appreciated thank you

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Are you looking for a positraction rear end 82firebird? Most 10-bolts were limited slip which means one wheels gets the power and the other didn't. A positraction unit means power is sent to both wheels, thus allowing you to do a two-legged burn out.

Now assuming that you are happy with your present rear end gear ration, a differential carrier change to a positraction unit runs $370-550 from Summit Racing. I am sure you can probably shop around perhaps find a better deal but that gives you a ball park.

It will mean draining the diff fluid, removing the axles, and removing the center section of the rear end. So essentially you are rebuilding your rear end. Now would be the time to change your rear end gear ratio of you wanted to.

 

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7 hours ago, Frosty said:

Are you looking for a positraction rear end 82firebird? Most 10-bolts were limited slip which means one wheels gets the power and the other didn't. A positraction unit means power is sent to both wheels, thus allowing you to do a two-legged burn out.

Now assuming that you are happy with your present rear end gear ration, a differential carrier change to a positraction unit runs $370-550 from Summit Racing. I am sure you can probably shop around perhaps find a better deal but that gives you a ball park.

It will mean draining the diff fluid, removing the axles, and removing the center section of the rear end. So essentially you are rebuilding your rear end. Now would be the time to change your rear end gear ratio of you wanted to.

 

 

19 hours ago, 82firebird said:

Hey guys still working on my project, and I need a new rear end so I don’t smoke one tire and get them both to hook up.... do I have to change out the whole rear end or just the gears in the pumpkin ?( don’t know the real term for it). Again this is a hobby for me not a money maker so any help would be appreciated thank you

Well, I have to disagree a little, sorry! A positraction rear end and a limited slip are very close to the same animal for GM, with one difference. GM’s positraction sends almost all of its power to the wheel with out slippage. No slippage full power to both wheels. GM’s limited slip on the other hand only increases power to the better drive wheel in the case of slippage by a much smaller percentage. This has to do with cornering logic & how inside & outside wheel speeds come into play. In the end both will give you two black tire marks only if the suspension is setup relatively correct.

That said so will an open rear end! I’ve said this before! An open rear end will lay two black patches just as well as any, if the suspension is setup right! The purpose of positraction or limited slip is not for burnouts! In actuality that is the fastest way to break a posi or limited slip rear end! If you’re looking just for burnout performance!? Put the money into the suspension & a blueprinted open rear end!

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49 minutes ago, Last Indian said:

 

Well, I have to disagree a little, sorry! A positraction rear end and a limited slip are very close to the same animal for GM, with one difference. GM’s positraction sends almost all of its power to the wheel with out slippage. No slippage full power to both wheels. GM’s limited slip on the other hand only increases power to the better drive wheel in the case of slippage by a much smaller percentage. This has to do with cornering logic & how inside & outside wheel speeds come into play. In the end both will give you two black tire marks only if the suspension is setup relatively correct.

That said so will an open rear end! I’ve said this before! An open rear end will lay two black patches just as well as any, if the suspension is setup right! The purpose of positraction or limited slip is not for burnouts! In actuality that is the fastest way to break a posi or limited slip rear end! If you’re looking just for burnout performance!? Put the money into the suspension & a blueprinted open rear end!

Drumroll please.... LOL was waiting for you to chime in on this one.  Remember your words of wisdom to Joe in another thread.  Have to admit, I would like to read about your suspension tricks to accomplish duel patches from a single spinner.   BTW    Thank you for the awesome arrowhead that matches my turnsignal.  Has found a new home on my console in front of the shifter.  Frosty's JURY logo DEMANDED a ton of attention.  I'm sure I speak for him when I say we couldn't be prouder to display your artwork. :bowdown:

smiley-transport027.gif

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23 hours ago, JUSTA6 said:

Drumroll please.... LOL was waiting for you to chime in on this one.  Remember your words of wisdom to Joe in another thread.  Have to admit, I would like to read about your suspension tricks to accomplish duel patches from a single spinner.   BTW    Thank you for the awesome arrowhead that matches my turnsignal.  Has found a new home on my console in front of the shifter.  Frosty's JURY logo DEMANDED a ton of attention.  I'm sure I speak for him when I say we couldn't be prouder to display your artwork. :bowdown:

smiley-transport027.gif

Hey buddy! Pictures please!

Another one of my many projects over my 40 years with LZ was a live axle test for GM, Ford & Chrysler. This was were we built rear axles put them in a car and ran them to test limited slip or in the day positraction. In the beginning of the design there were some challenges to say the least.

Many things make using an open diff for the purpose of two wheel hookup challenging and rewarding. In general you need 300 hp or hookup may be hard to achieve. You need to know how and what to blueprint for the rear diff, I.E. balance the spider gears and shims as an example. You need to know how to limit axle housing rotation to effect hookup, while tying the axle to the body without limiting the rest of it movement. Leaf spring suspension lend better to this than coil, but both can be done. Also in this particular build drive shaft design will play a role in success. If you look through the internet you’ll find a few folks who have done it. Most people thought prefer to just keep replacing the carrier.

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Awesome advice guys thank you much. I’m going to have to do some research but you guys sent me in the right direction 

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Posted (edited)

That's the great thing about this forum. Not all of us know everything about every ride or every nut and bolt. We all chip in with collective knowledge and experiences.

Let us know what you end up deciding to do, oh, and pictures please!

Edited by Frosty
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12 hours ago, Frosty said:

That's the great thing about this forum. Not all of us know everything about every ride or every nut and bolt. We all chip in worth collective knowledge and experiences.

Let us know what you end up deciding to do, oh, and pictures please!

What Frosty said! And pictures please!

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On 6/12/2019 at 6:48 PM, indymanjoe said:

You guys and your fancy pics LOL NE Ohio isn't that far Last Indian Us Michiganders should plan a trip to visit. Or if ya want a place to stay visit us for the dream cruise and you can stay at our house. BTT

I am up for that.

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Posted (edited)
On 6/12/2019 at 6:48 PM, indymanjoe said:

You guys and your fancy pics LOL NE Ohio isn't that far Last Indian Us Michiganders should plan a trip to visit. Or if ya want a place to stay visit us for the dream cruise and you can stay at our house. BTT

 

On 6/14/2019 at 11:39 AM, Frosty said:

I am up for that.

Me too! As I’ve said before I really don’t do car shows, but one thought is the Nationals are in the beginning of August!?

Edited by Last Indian

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Here’s progress so far. 

547A61AA-B045-4140-B6C1-2B85359F7BDD.png

B0B57440-CA42-4B8F-8A96-B49A1BBF9A73.png

305 to 350

 

Original state of wiring and what I did 

52BEA9A3-E967-4AEA-92F2-88BCC2EB5CE6.jpeg

B9B7E39C-454F-45EC-993D-FDFD18F502ED.jpeg

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On 6/15/2019 at 8:07 PM, Last Indian said:

 

Me too! As I’ve said before I really don’t do car shows, but one thought is the Nationals are in the beginning of August!?

The Pontiac Nationals in Norwalk, Ohio? I would be up for that - except that is the weekend I am leaving for Hilton Head Island SC. Dang it!

http://www.pontiacnationals.com/

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On 6/17/2019 at 4:46 PM, Frosty said:

The Pontiac Nationals in Norwalk, Ohio? I would be up for that - except that is the weekend I am leaving for Hilton Head Island SC. Dang it!

http://www.pontiacnationals.com/

Yup! Those Nationals, but who wouldn’t prefer sun, surf, warm breezes, and the company of a fine lady! I’m sorry what were we speaking of 🤔!

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