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How to tell if 1965 8-inch diff is posi

Hi all,

My '65 A-code 4-speed fastback has an 8-inch diff. If I decode the VIN and warranty plate, it comes back as an 8-inch open diff with 3.00:1 gearing. With a 42 year-old car, however, it`s anyone's guess as to what's really in there now. Presently, the engine and tranny are out of the car. The fellow who is doing the install had the car on the hoist this weekend and told me that by turning the wheels, you could tell if the car was posi or not. He says the things the diff in the car is a posi unit. Can anyone tell me how this works? By turning the wheels, can you tell if it is posi or not? If yes, what am I looking for?

Thanks in advance, Richard in Ottawa '65 A-code 4-speed Shelby clone '70 convertible

Reply to
lxixboss
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Do you leave one or two black marks if you spin the tires from a stop?

Reply to
Jason O

Ok. Turned by hand, tires go in same direction if trac-loc. Otherwise, it's an open diff.

Reply to
Jason O

lol...

Hard to say when the engine and tranny are out of the car.

:-)

Reply to
Jeff Mayner

Unless it's a Detroit locker, it's not much of a limited slip differential anyway........

Reply to
Kruse

The 8" uses the same clutches as the 9". What do you mean? A locking differential is "not much of a limited-slip" one? No, I guess not.

Reply to
Jason O

8" ford rear diff that is posi is a "limited slip" or "equa-loc" design. It uses a set of clutches preloaded by a bellville spring. Torque splitting is constant unlike the track lock which opens and closes depending on torque input. to test this rear lock both pinion and one tire into position, using a torque wrench try and rotate free wheel, you should at least get 50 foot pounds of resistance in turning wheel. Less than 50 lbs of resistance means that clutches need to be replaced or reshimmed. check the bolts holding the diff into the carrier look for a narrow metal tag under one of the nuts. It may be covered with 40 years of grime. the tag should give the ratio in terms of 3 25" or "3l25" the letter in the second position indicates locking rear the other number are the ratio
Reply to
walt peifer

The Ford Trac Loc uses clutches.

Reply to
Jason O

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