How hard is it to add posi?

[JRC86GN]

Hi

I am looking at a 87Gn that does not have factory posi. How hard is it to add and what does it cost?

thanks
Jack

 

[kh440]

Two ways you can go: either a complete used posi rear (drum to drum) or replace the differential you have now with an Auburn or Eaton unit. Price tag in any case runs anywhere from 500-800, not counting any labor.

 

[RUQWKNF]

Here's a break down.

Carriers:
Auburn HP series posi unit part # 542018.
This is the entry level posi for our 8.5" 10 bolt rear ends with 28 spline axles. Typically good till you get into the 500 rear wheel hp range. However, I've seen cars with 450 rear wheel hp wear this unit out with frequent track visits with slicks. It's a good stock replacement carrier and your factory 3.42 gear set will bolt right up.

The best Auburn posi unit is their Pro Series part # 542050.
This unit is good for up to 750 rear wheel hp. (Even though some have pushed it well past this level) It has a beefier clutch pack and can take more abuse than the standard HP series unit. It is also for 28 spline axles and your factory gear will bolt up.

Anything more power wise, (800+) and I'd recommend either an Eaton unit. or a Detroit Locker.



Installation kit:

Raytech Deluxe kit # 3003K contains everything you would need to do the job right, including axle bearings, carrier bearings, shims, seals, everything.

]

Ratech 3003K - Ratech Deluxe Ring and Pinion Kits - summitracing.com


Rear differential cover options:

For far out factor, Trans Dapt has a clear diff cover part #8402.

However, I would recommend upgrading the rear diff cover with one of TA Performances' cast aluminum covers. Either part # TA_V1807, or part # 1807.

TA_V1807 with the Buick logo.

TA Performance Products Inc.


1807 with the carrier bearing cap, pre load torque screws.

TA Performance Products Inc.


With all of these parts in hand, a few bottles of diff fluid and posi additive, a competant shop should be able to get you setup and rolling quickly.
Hope this helps.

Patrick

 

[JRC86GN]

Thanks for the info. any Idea how much it costs to set the rear end up?

Thanks
Jack

 

[Project TNX]

Carriers:
Auburn HP series posi unit part # 542018.
This is the entry level posi for our 8.5" 10 bolt rear ends with 28 spline axles. Typically good till you get into the 500 rear wheel hp range. However, I've seen cars with 450 rear wheel hp wear this unit out with frequent track visits with slicks. It's a good stock replacement carrier and your factory 3.42 gear set will bolt right up.

The best Auburn posi unit is their Pro Series part # 542050.
This unit is good for up to 750 rear wheel hp. (Even though some have pushed it well past this level) It has a beefier clutch pack and can take more abuse than the standard HP series unit. It is also for 28 spline axles and your factory gear will bolt up.

Anything more power wise, (800+) and I'd recommend either an Eaton unit. or a Detroit Locker.



Installation kit:

Raytech Deluxe kit # 3003K contains everything you would need to do the job right, including axle bearings, carrier bearings, shims, seals, everything.

]

Ratech 3003K - Ratech Deluxe Ring and Pinion Kits - summitracing.com


Rear differential cover options:

For far out factor, Trans Dapt has a clear diff cover part #8402.

However, I would recommend upgrading the rear diff cover with one of TA Performances' cast aluminum covers. Either part # TA_V1807, or part # 1807.

TA_V1807 with the Buick logo.

TA Performance Products Inc.


1807 with the carrier bearing cap, pre load torque screws.

TA Performance Products Inc.


With all of these parts in hand, a few bottles of diff fluid and posi additive, a competant shop should be able to get you setup and rolling quickly.
Hope this helps.

Patrick

Great post, I'm going to have to bookmark it.

I'm saving the posi unit for my last mod before slapping TNX on the road, unfortunately it will be the only piece I farm out and have someone else do. There is a place near me that will do it while I wait, so I don't have to worry about it getting joyrode.

I have never done one, or never seen one done, so I'm not comfortable doing it since I know you have to do it with some weight on the rear end and what not.

 

[Silver Fox]

Thanks for the info. any Idea how much it costs to set the rear end up?

Thanks
Jack

I just had mine done in my none G80 Turbo T - I believe I have about $800 in an Eaton posi, deluxe installation kit, lube and install fee.

Rob

 

[JRC86GN]

I just had mine done in my none G80 Turbo T - I believe I have about $800 in an Eaton posi, deluxe installation kit, lube and install fee.

Rob

that's about what I was thinking

Thanks
Jack

 

[edfiero1]

Bumping an old thread. This has some great info for adding a posi to a non-posi car.
Though one question.... is a new Diff Cover/Girdle required, or is that just something that is suggest for guys with mods like a cam, alky, etc? My car is mostly stock, with no plans for big mods; I'm wondering if I can just re-use the stock, non-posi cover.

 

[2QUICK2B6]

Bumping an old thread. This has some great info for adding a posi to a non-posi car.
Though one question.... is a new Diff Cover/Girdle required, or is that just something that is suggest for guys with mods like a cam, alky, etc? My car is mostly stock, with no plans for big mods; I'm wondering if I can just re-use the stock, non-posi cover.

Yes stock non posi cover will work. I went with eaton

 

[WE4REAL]

My WE4 was non posi from the factory with aluminum brake drums. A local mechanic at the Buick dealership sold me a posi unit and installed it for $250. This was back in 1992. Still going strong. He did it in a couple of hours.

 

[2QUICK2B6]

I think mine stayed peg leg 1 week..

Put ta cover on mine

 

[Lockman]

Great post, I'm going to have to bookmark it.

I'm saving the posi unit for my last mod before slapping TNX on the road, unfortunately it will be the only piece I farm out and have someone else do. There is a place near me that will do it while I wait, so I don't have to worry about it getting joyrode.

I have never done one, or never seen one done, so I'm not comfortable doing it since I know you have to do it with some weight on the rear end and what not.

......Be prepared to 'Wait" about 4 Hours , minimum ?.
Just Say'n