8.5 3.73 open to posi swap

[gp02a0083]

Ritter, thanks for the clarification on the terminology.

Chevy2480, I appreciate the offer. I think i want to spend the money on a new unit so that i will not have to worry about servicing the rear anytime soon, however I may be interested in the clutch pack you have. We could meet sometime to look at the parts being i am off of exit 7A on the NJTP

 

[jrm81bu]

The Powertrax IS a locker, it's just not like a factory gov-lock, it's better but still a locker.

POWERTRAX makes 2 different units :idea: The "Lock-Right Locker" and the "No-Slip Traction System" :wink:

I was recommending the "No-Slip Traction System"

They are either engaged or not ergo locker. They just use their synchronizers to softly engage. But when engaged they are locked. Look at the specs as to carrier style.
http://www.summitracing.com/parts/PWT-92-0786-3005/

 

[TexasT]

Anyone here know of a reputable place that is reasonably priced for a stock style posi unit?

This place is pretty well know in the Buick community.

http://www.stage1automotive.com/contact.htm

 

[pontiacgp]

i have a 8.5 3.73 rear that came out of a 84 hurst olds that had around 30,000 miles on it, bad news is that it didn't get the G80 option. Anyone here know of a reputable place that is reasonably priced for a stock style posi unit? Im assuming i can re-use the gears as they do not even have any mesh wear marks, but after looking at G body parts they were mentioning about the diff bearings need to be replaced, how true is this?

it is not true you need to replace the bearings, you only replace them is they need to be. It's easy enough to check the bearings for heat markings and pits. If none found no need to replace them. I have a rear end from a 67 Chevelle and it has the original bearings as far as I can tell, they are fine so I'm reusing them. I rebuild and set up my own differentials and it would only cost me $80 for the bearings so if changing the bearing was needed I'd be doing it. All you have to do if the bearings are good is to get a new carrier and keep the backlash shims the same as they came out and it should be within specs...6-10 thousands, if not adjust as needed. Also remember the bolts for the crown gear are left handed thread.

 

[gp02a0083]

im really thinking of ordering the Eaton 8.5 posi R5185 from strange engineering. Everything looks fresh , the bearings have no markings on them. i should be set with this, a set of shims , plasti-gauge and thread lok?

 

[pontiacgp]

you don't need plastic gauge....you need a dial indicator to measure backlash, gear marking compound to check the gear footprint and a micrometer to measure the backlash shims

 

[V6UnderPressure]

I too was looking at the powertrax no-slip. I have a 19k mile open diff on a 442 with 3.73 gears. Is Powertrax 92-0785-2805 all I need to swap this from open to posi?

 

[85GPLef41]

i was thinking of doing this upgrade along with matching axles and girdle for my open 85 442 rear with 3.73's.. :http://www.moserengineering.com/differentials/detroit-trutrac/gm-10-bolt-8-5-rear.html

 

[ssn696]

I am looking at $600 in parts and $200 in labor to install an Auburn 30-spline 8.5 limited slip I found on Craigslist. Installation kit with axle bearings and seals, 3.73 gears, and 30-spline Moser axle shafts.

I currently have 3.42 OEM gears, open differential and 28-spline axles with 80K miles on them. For $340 and free labor (me) I could put in a Powertrax soft locker.

If I used the lunchbox locker for a few years, no racing, what do you think I could remarket it for on the Forum?

 

[L92 OLDS]

I am looking at $600 in parts and $200 in labor to install an Auburn 30-spline 8.5 limited slip I found on Craigslist.

Over the years I have installed 4 posi carriers in GM 8.5 rears myself with no issues. (3) of them have been Auburn pro carriers. The 1st one has been in my 1986 Olds 442 for over 20 years and it still works like it did when new. As noted above, the factory carriers are not available anymore but there are many good aftermarket units. I would encourage you to do it yourself if you are not changing the ring and pinion gears. If you follow the install procedure and use the correct tools (mag base with dial indicator available for cheap at Harbour Fright) you will be OK. I found that when swapping in the Auburn units the back lash was perfect with the factory shims. Easy Peasy....: )

The pic below shows an Auburn Pro carrier installed in my 1984 Hurst Olds