Identify rear end?

[MaSnaka]

How do I determine what rear end I have. What would be the tell tale signs between a ford 9", 8.8" and so on. Also how do I determine what gear ratio is in the rear end? I know there must be some obvious ways to identify the goods it's just that I'm clueless. Thanks for your help in advance.

John

[trctrdrvr]

pics would help, is there a tag on you're rear end, you can jack up the car and mark the tire and driveline, count the revs and that will get you close to you're ratio,the, only other way is to disasemble and count the teeth on the pinion and ring gear

[Woodz428]

Between the 2 you mentioned, it's easy. The 9" has a removable carrier so gear changes can be done on a bench. The 8.8 has an intregal carrier and the gears come out a cover on the back. There was also an 8" used in many 60's and 70s cars, it looks like a small 9" and has more ribbing (at least the later 8" ones do). Rotating the pinion and counting how may rotations occurs with the axle is the simplest way to check ratio, if it is open(non-posi) one flange will have to be held.

[Ibr8k4vetts]

the rear cover on a 8.8 is bolted on and on a 9" it is welded on.

[Fastblueoval]

Originally Posted by Woodz428

Between the 2 you mentioned, it's easy. The 9" has a removable carrier so gear changes can be done on a bench. The 8.8 has an intregal carrier and the gears come out a cover on the back. There was also an 8" used in many 60's and 70s cars, it looks like a small 9" and has more ribbing (at least the later 8" ones do). Rotating the pinion and counting how may rotations occurs with the axle is the simplest way to check ratio, if it is open(non-posi) one flange will have to be held.

On the 9" unit you will need a wrench to remove the bottom 2 nuts - On a 8" unit they can be removed with a socket - Divide the number of teeth on the ring gear by the number on the pinion will give you the ratio - ex - 39 ring gear and 10 pinion would be 3.90 ratio - Here is a link to a site which may be of some help

http://www.kevinstang.com/Ninecase.htm

Enjoy - Ed

[LMH]

Aren't Classic Roadsters set up for Ford 8.8"?
Thought I read that somewhere.
Larry

[MaSnaka]

Thanks for all the info guys. That website link is chock full of info...Thanks for that. I think I can figure it out now. I have one question that needs some clarification though, Woods428 you say if it's a non posi rear end to hold one wheel while rotating the other. Does holding the one wheel make a difference. I spun one wheel around one rotation, the opposing wheel spun in the opposite direction (I wasn't holding it still), and I counted just under 3.75 turns of the driveshaft while in neutral. Would holding that wheel still give me a different count on the driveshaft revolutions? If you know the answer can you reply, thanks.
John

[MaSnaka]

I crawled under my car to read some numbers from the differential. I have determined it is not a 9" rear end. Still not sure what it is...but I did find a tag held in place with one of the bolts and this is what it said, WDW U7GM (top row) and 4L11 8521B (bottom row). I do not fully understand all the numbers and letters. I am guessing the bottom row means it's a 411 with a equa-lock (posi), 8.5", manufactured Feb. 1971 week 2. Anybody know how to decifer all this? Please help. Thanks John

[LMH]

This may help: http://www.coloradok5.com/axleguide.shtml

As far as the numbers, I'd say it's a limited slip, 4:11 ratio. Beyond that, I'm not sure w/o looking at it.
Larry