9inch diff axel worn

[Chocosmith]

Just to confirm:

Does a 9" axle fit into the 9 3/8 housing? The bearing o.d seems to indicate yes.
The 9" bearing housing is 3.15", a conversion on the 9 3/8" o.d bearing of 3 9/64 inches is 3.140 so I guess this is the same.



If so I might be best to order 2 new 9" 30" 31spline axles, which is a massive saving over the 9 3/8 bearings (60bucks vs 240each) almost pays for the axles

I can then plonk the 9 3/8 pumkin back in and upgrade later to 9" center with an eaton locker when the funds are available.

[ultraranger]

Just to confirm:

Does a 9" axle fit into the 9 3/8 housing? The bearing o.d seems to indicate yes.
The 9" bearing housing is 3.15", a conversion on the 9 3/8" o.d bearing of 3 9/64 inches is 3.140 so I guess this is the same.



If so I might be best to order 2 new 9" 30" 31spline axles, which is a massive saving over the 9 3/8 bearings (60bucks vs 240each) almost pays for the axles

I can then plonk the 9 3/8 pumkin back in and upgrade later to 9" center with an eaton locker when the funds are available.

A '68-'72 Ford 9-inch rear end is the same width as a '68-'72 Ford 9-3/8" rear end. The axle housing bearing bores on both rear ends are the same too.

The difference comes in the axle bearing I.D. If the 9-3/8" rear end has a factory Traction-Lok differential, the 9-3/8" 31-spline axle bearing will measure 3-9/64" O.D. x 1-5/8" I.D. If the 9-3/8" rear end has an open (single track) differential, the 31-spline axle bearings will measure 3-9/64" O.D by the smaller I.D. of 1-17/32".


9-3/8" 31-spline axles (3-9/64" x 1-17/32" axle bearings) and a Ford Daytona 9-inch N-case with a 31-spline Traction-Lok differential and 3.50 gears I put in my '69 F100 short bed Ranger's factory 9-inch rear end housing.

http://www.ford-trucks.com/forums/13395 ... st14974787

http://www.ford-trucks.com/forums/13395 ... st15010099

http://www.ford-trucks.com/forums/13395 ... st15023575

http://www.ford-trucks.com/forums/13395 ... st15054362

[Chocosmith]

Excellent thanks.

I've dropped it into a diff guy, he's dumping in a 9" centre with an Eaton truetrac and 3.7 gears and changing the axles to some 28 splines.

In order for me to get 31's they would need to be ordered from the states and set me back 4 weeks, this unfortunately is my main truck and was time I couldn't afford.

The 28's for that length he had in stock.

I know it's weird to "downgrade" to 28splines especially with the cost involved but I don't run slicks or dragrace this truck, and I can't see me working the engine to get to 450hp or more.


Two side notes:
1) the diff guy said the diff was warn at they bearings due to the axles being slightly bent, which I guess causes a slight wiggle on the inner race

2) the housing was also bent (he showed me on his jig, and it was by a fair chunk almost 1/2" on the worse side), he was able to straighten this (no idea how)
my offroading days are long behind me and my truck is now slightly lowered from stock so I can't see myself doing this again.


Many thanks all for the replies, especially ultraranger.