Posi info

by Dead Man Sun Jul 19, 2015 10:35 pm

well after looking for a local rear end to covert my 73 ss to posi, with no luck. im leaning toward just making my stock rear end posi. was needing some info on this kit. is this everything i need to convert mine over ? and im unsure on the spline count this one is a 30. any advice is appreciated

http://www.ebay.com/itm/Auburn-Posi-Package-10-Bolt-GM-8-5-3-42-Ratio-Gear-Set-Master-Bearing-Kit-Early-/251270534520?fits=Year%3A1973|Model%3AChevelle&hash=item3a80e41578&vxp=mtr

by alowerlevel Mon Jul 20, 2015 9:08 am

Ours cars have 28 spline axles.

But IMHO I would skip the auburn posi unit and buy a detroit/eaton truetrac instead.

by brownbomber77 Mon Jul 20, 2015 9:59 am

If you're going to spend the money....ya....Tru trac. No clutches to burn out

by Joe73 Mon Jul 20, 2015 10:14 am

Or, if you like your current gear ratio, just install a locker kit that goes right into your carrier. Then you dont have to mess around with gear contact pattern and bearing preload and such. Pretty simple installation and streetable.

by Dead Man Mon Jul 20, 2015 12:41 pm

thanks guys, so other then it saying 30 spline it seems correct. I will look into the others that was mentioned also. and I really hate my gear thats in it now, im really hoping there not 342 lol, if i had to guess the 2??

by Joe73 Mon Jul 20, 2015 1:30 pm

A guess would be 2.73 or maybe 2.56. I have factory 3.42 gears and it really isnt too much fun on the highway but manageable.
If your going to change gears and put in a posi, then you need the install kit and I'd also get outer wheel bearings and seals.
Doing the job yourself would require normal hand tools, torque wrench, INCH POUND TORQUE WRENCH.
Its not a hard job, just need to be meticulous.

by dynchel Tue Jul 21, 2015 8:17 am

Joe73 wrote:Or, if you like your current gear ratio, just install a locker kit that goes right into your carrier. Then you dont have to mess around with gear contact pattern and bearing preload and such. Pretty simple installation and streetable.

ive done this, easy install, but it wont do anything to correct a crappy gear ratio.

by thatfnthing Tue Jul 21, 2015 8:57 am

And then John will sell you a pair of his custom traction bars for the wheel hop. Smile

by dynchel Tue Jul 21, 2015 10:03 am

Naw, Lakewood & competition engineering both sell them.

by brian74montecarlo Fri Jul 31, 2015 12:50 am

im about to dig in to my rear axle as well - i managed to score a gm 8.6" posi unit from a buddy who owes me a favor so i got it for a hand shake

aparently our cars are a 10 bolt / 8.5" carrier / 28 splines axles of a factory leingth of 30.5" ish - saw mosier axles spec at 30.32x leingth tho

a posi unit from an 8.6 can swap on a 8.5 axle housing - but the carrier bearings for 8.6 and 8.5 are diffrent sizes from eachother. - they do make an adapter bearing to put an 8.6 carrier in to an 8.5 housing but not the other way around.

since im a street car just looking to do burnouts with both rear tires - i plan to keep the stock axles for now and hope the 8.6" posi will last a while - but before i got one for free i was searching hard at getting the detriot true track style unit - as no clutches to burn - but i wonder - how will it hold up to repeated long smokey burnouts... haha thats my goal is to be able to shread tires at will and during contest. since my 74 montecarlo is so heavy it must be good at something haha burnouts might as well be a croud pleaser vs 11 second time slips at the track ( wishes haha )

by Joe73 Fri Jul 31, 2015 6:55 am

Long, slow, smokey burnouts are especially easy with a line lock valve in the REAR brake line. You press the button with your foot OFF the brake. Then hold the brake and mash the gas. Then you just using you brake pedal to keep the car moving slowly forward while the rear wheels are smoking away. Seen guys do that for hundreds of feet or til the tires blow.

by alowerlevel Sat Aug 01, 2015 5:03 pm

brian74montecarlo wrote:im about to dig in to my rear axle as well - i managed to score a gm 8.6" posi unit from a buddy who owes me a favor so i got it for a hand shake

aparently our cars are a 10 bolt / 8.5" carrier / 28 splines axles of a factory leingth of 30.5" ish - saw mosier axles spec at 30.32x leingth tho

a posi unit from an 8.6 can swap on a 8.5 axle housing - but the carrier bearings for 8.6 and 8.5 are diffrent sizes from eachother. - they do make an adapter bearing to put an 8.6 carrier in to an 8.5 housing but not the other way around.

since im a street car just looking to do burnouts with both rear tires - i plan to keep the stock axles for now and hope the 8.6" posi will last a while - but before i got one for free i was searching hard at getting the detriot true track style unit - as no clutches to burn - but i wonder - how will it hold up to repeated long smokey burnouts... haha thats my goal is to be able to shread tires at will and during contest. since my 74 montecarlo is so heavy it must be good at something haha burnouts might as well be a croud pleaser vs 11 second time slips at the track ( wishes haha )

Going through all the trouble of swapping out the carrier, and having to get special bearings and change the axles sounds like alot of effort just to use a stock gm posi unit. I would rather take the money youd have spent on new axles and adapter bearings and just buy a new posi.

And the true trac will hold up to just about anything you can throw at it, my brother has one in his '70 with a 468bbc in it and he beats that car like a rented mule,
old vid but you get the idea----> Posi info Th_039

and yes hes doing that in his driveway, lol

by Limey SE Sat Aug 01, 2015 8:53 pm

Kinda Like me doing the Burnout in My Garage Right Lowerlevel LOL

by alowerlevel Sat Aug 01, 2015 10:42 pm

Lol yup. He does that too Laughing

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