Emergency please read... 7 1/4 gearing in 8 1/4 housing?

[Wilnutt]

I went to cohper's and found a nice 8 1/4...or so i thought..i pull out the 8 1/4 housing..open it up and measure the gears..it's diameter is close to 7 1/4 inchs...does this mean that it's a 7 1/4? i'im confused..plus, i turned the brakes 2 times to try and find the gearing, it was about 2.25...is this correct?
mind you, the differential plate was an 8 1/4 plate??? PLEASE HELP ASAP!!!

 

[Wilnutt]

anyone have a good pic of the rear of a 1/4 and 8 1/4..just for reference, and not an illustration, but a real photo

 

[Wilnutt]

bump????

 

[jeeper]

http://www.moparts.com/Tech/Archive/axle/6.html

This should get you started.

One has ten bolts and the smaller has nine.

I hope that helps, ROB

 

[longarm]

go to the top of this page
click forums
go to tech archives and click
go down 1/2 half page
click o nmopar rearend id
a very good article by 7demon2

 

[memike]

Good job jeeper!!! That will get him fix'ed up.

I saved the info for myself :thumbup:

 

[FASTBACK340]

TRY HERE TOO:

http://www.autohobbydigest.com/a-rearend.htmlhttp://www.autohobbydigest.com/8_75.html

 

[Wilnutt]

i know the housing a 8 1/4...i'm sayin'...can 7 1/4 gears fit in a 8 1/4? could those be 7 1/4 gears..did i measure wrong maybe? i measured the diameter of the gears

 

[Ace]

Uh, no.

 

[Mrmopartech]

This is the chart you need,mrmopartech

 

[demon seed]

Wilnutt, If you've got the rear end cover off count the teeth on the ring gear and the teeth on the pinion gear. Divide the ring teeth by the pinion teeth and you've got your ratio. You may allready know this but it's more accurate that turning the pinion gear and counting the axle revolutions at the tire.

Terry

 

[Wilnutt]

THIS IS WEIRD!! It has 10 bolts, and looks like an 8 1/4..but is the size of a 7 1/3..bc i saw a d150 or d250 with what looked like an 8 1/4 right beside it, and it was much bigger.....the gear was barely over 7"...but not a 7 1/4...thinkin' maybe this isn't even a mopar rear?

 

[OldVart]

What did the rear end come out of? Post a picture and you'll get an answer quickly.

 

[Wilnutt]

didn't have a camera.. it was a 73 duster/dart sport.....

what has me guessing is... the rear was in almost perfect condition...the rest of the car was trashed and crap...i'm movin' on..there's somethin' up with this rear end..tryin' to think of how to configure a ford 9" or 8.8" rear...

 

[jeeper]

my guess is you saw a 9 1/4" in the trucks nearby, or maybe a Dana 60.

The 8 1/4" rear is the ten bolts and the cover is different.

The used the 8 1/4" in some trucks depending of GVW.

Another hint is to measure tube OD. If it is 2 1/2" it is likely a 7 1/4. If it is 3" it is an 8 1/4" and stronger rear.

I hope that helps, ROB

BTW- on the 8 1/4" rears that I have been in recently they were both stamped on the ring gear what the ratio is.

As an aside, one had an OEM tag that said 3.21:1. Guess what it had......a 3:55:1 inside.

 

[Ace]

It's a truck rear. D150-D250 are 80's early 90s truck models.

 

[jaws]

ratio should be stamped on the ring gear. You might have a set of 2.45s in there also. Dave