Got an 8.8 today, identify this.

[stevenf]

Pulled an 8.8 with 3.73 gears from a 93 explorer today. I noticed it had an electrical switch at the top of the diff. All I had to do was unplug it.
what is this? Is it for traction control or something?

 

[LBarr2002]

Abs

 

[boominXplorer]

ABS sensor

 

[stevenf]

Great thanks! Also, How can I find out if its a posi unit or not? When I turn the drive shaft, both axles spin forward. When I turn one axle, the other spins the same direction which wasnt the case with my old GM 12 bolt.

 

[XxxMonoxideChild]

either take a pic, or go back to the truck you pulled it from, open the driver side front door, and look at the axle code. if it has the 3.73's, and the factory lsd (which most of them did) i believe it would have the D4 code.

 

[68amc]

Yes look for the D4 code on the door if it is an LSD unit.

 

[IZwack]

Since you already have the axle, just pull the diff cover off --no need to make another trip to the junk yard . If you see the giant "S" spring in the middle of the spider gears, and the clutch discs sitting behind the lateral spider gears (with the notches on the carrier for the clutch discs to catch onto), then limited slip it is.

 

[robmurt04]

I believe if the axles spin the same direction it means its a posi unit

 

[Cobraguy]

I believe if the axles spin the same direction it means its a posi unit

That is correct. But just to be sure, have someone hold the pinion and try it. You should have to overcome their holding force. Of course, that's assuming the posi clutches are good...

 

[CDW6212R]

...When I turn one axle, the other spins the same direction ...

That is a non open rear for sure, no Ford diff will do that if it's open. All open diff's will make the other axle spin in the opposite direction.

There should still be a tag on the cover bolts, expect to find a "3L73" on that somewhere.

 

[IZwack]

That is a non open rear for sure, no Ford diff will do that if it's open. All open diff's will make the other axle spin in the opposite direction.

This is true for the most part, but not 100% dependable because rust will freeze the spider gears. In addition, any damage to the carrier's internals (which we've seen some on this forum like broken main shafts and/or damaged spider gears) will exhibit some locker/LSD characteristics. This is why when we look for an axle, we should always remove the diff cover and inspect the carrier's internals.

 

[CDW6212R]

This is true for the most part, but not 100% dependable because rust will freeze the spider gears. In addition, any damage to the carrier's internals (which we've seen some on this forum like broken main shafts and/or damaged spider gears) will exhibit some locker/LSD characteristics. This is why when we look for an axle, we should always remove the diff cover and inspect the carrier's internals.

Yes true I agree, but for an intact rear from an assumed working vehicle, the basic check is good. For any damaged rear or one exposed to the outside, yes definitely pull the cover. You are going to be pulling the cover anyway to change fluid and axle bearings/seals.

 

[gijoecam]

That is a non open rear for sure, no Ford diff will do that if it's open. All open diff's will make the other axle spin in the opposite direction.

There should still be a tag on the cover bolts, expect to find a "3L73" on that somewhere.

***assuming, of course, that the pinion is held in place when doing the test, yes.****

The tag is a good indicator too. But before using it, you'll want to pop the cover and change the fluid anyways, so that's the best way to know for sure what's inside.

-Joe