[Schoust]

Can a Factory 8.5 posi be modified to handle 450 Hp??If so what parts would I need to make these mods???Also the car is a stick...

[Schoust]

Can a Factory 8.5 posi be modified to handle 450 Hp??If so what parts would I need to make these mods???Also the car is a stick...

[75cancup]

I used 30 spline axles ,auburn posi bolt in axle set up and had a chassis shop weld the tubs to the center section.

[Skip Fix]

A Stick will definitely stress it more. Good U joints and driveshaft first. Weld on ends or C clip eliminator and good axles should probably cover your needs. The next upgrade would be an Eaton 4 spring posi. For a really strong one get the 30 spline posi and axles to match.Lots of guys like the aluminum covers that act as a brace for the bearing caps also.

I've seen stock ones run in the 10s and prepped ones deep in the 9s.

[Schoust]

I was talking to a guy that I want to have set it up and he told me the first thing would be to adress the spider gears,just how good is the factory posi?Would I be better off just putting an Eaton posi and axles in my stock 8.2???

[Jeff Walker]

The 8.5 is a pretty tough unit but the factory posi's weren't the greatest for good holding power. In other words they can let one wheel spin pretty easily. If you went to an Auburn or Eaton unit with a good pair of axles you should be ok.

[tikiklubracing]

spool----spool----spool--moser---moser---moser---C-clip eliminators.

[Skip Fix]

With a spool you can go 33 spline also for more strength.

[Schoust]

The car will be seeing some track time but I also want to use it on the street,I have been told that a spool on the street is NO fun,and a real hassel,just looking for a happy medium is all.Will the stock 8.2 with an Eaton posi and some good axles do the job? I would rather go that route if it will hold up and just sell the 8.5....

[russ467]

Stick with the 8.5! More parts available and stronger unit in stock form.

[johnta1]

I would also weld the tubes all around where it goes into the cast iron housing.

[sdbob]

Tom's Differentials in Calif. helped me alot. You will have to check it occasionily for problems. When running it.

[Schoust]

Just how much power and torque can a modified Saftey Track Handle with a new Eaton Posi.and Moser axles?????

['ol Pinion head]

Depends on how you are trying to load the differential... Def a difference between footbraked, & leaving on a transbrake at 5000 rpm.
To better answer your question concerning 8.5's... which Eaton carrier, 30 splines Moser axles am assuming, lh billet cap or performance type rear cover? If your question concerns upgrading an 8.2 Pontiac 10 bolt rear that is non nodular case piece, you're playing with fire.

Footbraked with progressive spray, know of quite a few 8.5 A-body rears with above pieces in 3600-3950 lb A-bodys all running low 10 sec 1/4's. These rearends were built to go that quick all motor. One is soon to dip into the 9's. Properly built, the 8.5 A-body is right up their with similiarly built 12 bolt. Stock, many 12 bolt posi A-body rears are weaker due to weak stock spider gears & weak axles.

In relatively stock 28 spline condition, Floyd's 8.5 A-body rear holds up in his '66 LeMans to consistent 11 sec times. Personally like the durability of the 30 spline Eaton carrier & it can be upgraded with thicker plates & springs. Going to buy new axles, might as well go 30 spline carrier, as well. Want to go real quick with 8.5 rear, skip the posi & go 33 spline spool & axles.

[FORSALE]

Not to steal thread but can 8.5 be used in 8.2 rear??

[Jeff Walker]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by FORSALE:
Not to steal thread but can 8.5 be used in 8.2 rear?? <HR></BLOCKQUOTE>

Nope.

[Skip Fix]

My 28 spline stock axles with an Eaton posi is high 10s,but its footbraked. Will probably get 30 spline posi and axles at some point soon and a toned down motor.

[Schoust]

Ok guy's decided on the 8.5,will have to move the perches because the diff is from a secound gen.car,is there anything else I should know?What e-brake cable do I use??Who's got the best pricing on an Eaton thirty spline posi.?????What axles do you recamend?Will I need a c-clip eliminator kit also??

[Skip Fix]

Tom's had the best price on the Eaton's when I got mine. He has axle ends or C clip eliminators as well.

[JSchmitz]

OPH, did all Chevy 8.5's have C-clips? I have an 8.5" "O" type with bolt in axles.