# Limited slip or not?



## vev46 (Sep 29, 2015)

Just bought a restored '64 with a .030 over 455/tri-power. I was told that it has a non-posi rear, so I wanted to verify. I raised the rear tires and spun one of them to see what the other one did, and it did not turn at all. Same result when I spun the other tire. It took more effort than I thought to spin each wheel, & the drive shaft turned both times. My knowledge is that with an open rear, other tire should spin opposite, and with a posi rear it should spin the same direction. What may be going on here?

Thanks for any guidance.


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## PontiacJim (Dec 29, 2012)

vev46 said:


> Just bought a restored '64 with a .030 over 455/tri-power. I was told that it has a non-posi rear, so I wanted to verify. I raised the rear tires and spun one of them to see what the other one did, and it did not turn at all. Same result when I spun the other tire. It took more effort than I thought to spin each wheel, & the drive shaft turned both times. My knowledge is that with an open rear, other tire should spin opposite, and with a posi rear it should spin the same direction. What may be going on here?
> 
> Thanks for any guidance.


It's not a posi. Nothing going on.


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## younggto (Nov 22, 2013)

The driveshaft spinning is the question; was the transmission in gear (manual transmission) or park (automatic)?


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## vev46 (Sep 29, 2015)

4-speed muncie, in neutral


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## younggto (Nov 22, 2013)

The transmission needs to be in gear to check for posi vs open rear. 


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## ALKYGTO (Mar 29, 2010)

Uhh, no.


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## HP11 (Apr 11, 2009)

younggto said:


> The transmission needs to be in gear to check for posi vs open rear.


If you think about that statement you'll understand why it's wrong. With an automatic, it does nothing, with a stick you're turning the drive shaft, transmission, clutch and, therefore, the engine.......


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## Goat Roper (Oct 28, 2014)

I thought about swapping my pegleg out with a posi but the more I thought about it I decided to just keep it original.
I don't plan on drag racing the car and since I live in the mountains and drive these roads drifting or swapping ends isn't something I need to do.
Think about how you plan on driving the car before you spend the money to change it out.


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## Rukee (Feb 8, 2007)

One tire in the grass the other on the road, do a small burnout both tires will spin if it's a limited slip. If it's open just the one in the grass will spin. You could always do an Auburn posi unit, my limited slip one went out so I put one in mine years ago and never looked back.
http://www.auburngear.com/


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## Irishmic (Sep 24, 2013)

I have always liked 2 black lines ,myself.


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## geeteeohguy (Feb 2, 2008)

Goat Roper makes an EXCELLENT point. Open rear end cars with a dead 'anchor' wheel are _much_ safer to operate on slick roads or on off-camber surfaces. Depends on where you drive and how you drive. Limited slip is great for hard acceleration on dry pavement, though!


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## Pinion head (Jan 3, 2015)

Every performance Pontiac I've ever owned and driven in the elements has had a posi unit in it and I never thought anything of the posi being back there. Other than one LeMans I owned with a built 441, hard shifting T400, 3.90's and a Moroso Brute Strength unit...it was was halfway touchy on wet roads. As a college kid in my modded turbo car, 3 miles to OU, 450 ft lbs at 2000 rpm with the choke stuck on high with 255 60's spinning as was taking off at the stop sign on the ice and snow, no big deal. With those 255 60 Wingfoots and Eagle NCTs, drove them down to the wear markers and still drove very aggressive on rain slicked streets, never a problem.


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## Pinion head (Jan 3, 2015)

Smartest thing to do on any new purchase '64-69 GM with bolt in sealed bearing axles is get It up on a lift, or at least on jack stands. Pull the rear wheels/tires, the rear drums, and pull the axles. Get the darn things out and ck the archaic design sealed axle bearings. If the sides of the RW507 sealed bearing have a look of a green phenolic material, they are the original sealed bearings. Many didn't even make it 30,000 miless before seizing and chewing up an axle. They were designed for an age when abodys had skinny 7.75 tires, not 60 series tires, nor todays 17" or 18" hooptee specials. 

Next, press those sealed axle bearings off, ck the axle for wear at the area the bearing was pressed on. If axles are chewed, count yourself very very lucky the axle has not pulled through the retainer and exited the car. That usually happens during low speed cornering, but have provided parts and differential work for owners that it happened getting onto a freeway on ramp at speed. At same time axles are out, pull the rear cover, ck the carrier and numbers stamped on the outer edge of the ring gear. single track carriers, they are windowed, or "open", easy to spot the side gears and spider gears and the single pin through the spider gears. Safe-T-Track rears, aka posi's, are easy to spot, they are usually more closed in design, ESP for the 2 pinion and 4 pinion cone style units. Can't figure it out, post a good picture with the cover off, should be able to identify.


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