Ford 8' vs 9" ... how to tell them apart?

Beoweolf · Oct 30, 2004

If you are new to Ford rear ends or can't "eyeball" things very well or can't find or are unsure if your find is an unmolested original rear end with the tag in place...how can you tell if you have an 8" or 9"? They are very much alike in appearance, it is easy to be confused.

The metal tag on an original rear end can be decoded and give you all you really need to know. Over the years many of them have been removed or the rear end has been replaced. Back in my "street days", I would put and keep a 2.79:1 tag on my rear end, just in case someone was sizing me up...trying to get an idea of how the car was set up. Just keeping up the "sleeper" image. Did I hear someone say "Sand bagger"? Not true, I was just trying to help the guy make a decision.

Anyway...see the below info, hope it helps.

This seems to be a decent source of information on Ford 8 and 9 in rear ends. Like anything on the net, there are possible ommissions, but I didn't see anything obviously wrong with the info.

http://www.ridgenet.net/~biesiade/Fordrears.html

The easiest way to tell is to try to put a socket on the lower bolts. On the 8", the socket goes on straight without hitting the case.

On the 9", the socket won't fit this position or the bolt on the other side of center, you'll need to use a wrench to remove those nuts. There is a pocket at the bolt location necessary because of the larger pinion support

Don't have the carrier?
If you look at the top and bottom most bolts that hold the carrier to the housing with the housing horizontal as it would be in the car, an 8" measures about 8 7/8" center to center of those two bolts, and a 9" rear measures about 10" on those bolts.

<font size=-1>[ This Message was edited by: Beoweolf on 10/30/04 11:31pm ]</font>

cord318 · Oct 30, 2004

"The easiest way to tell is to try to put a socket on the lower bolts. On the 8", the socket goes on straight without hitting the case. "
Cord

69fstbk · Oct 30, 2004

I read these all over the web and I have had 2 Galaxies a 63 & 65 both BB cars and both had 9" rears but never can find any info why is that?

Just Strokin · Oct 31, 2004

info such as?????

69fstbk · Oct 31, 2004

I would like to be able to reference axle size by year and spline, possible gear ratios etc. and can never find anything about them

mj70cj428 · Oct 31, 2004

I thought it was easy to identify an 8" rear because it is oval looking from the back and a 9" is more round in shape.

ckelly · Nov 1, 2004

Nope - you want to know the splines on a 9", pull the axle and count. The references to the "dimples" or "slot" ID is not 100% reliable. The door code or the tag on the rear should give you ratio info.

Another way to tell an 8" from a 9" is to latch onto the center section. You can hoist an 8" fairly easily. A 9" will send you to the chiropractor.

Ford 8' vs 9" ... how to tell them apart?

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