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Re: [oletrucks] rear end questions, F*rd 9"

To: Old Trucks List <oletrucks@autox.team.net>
Subject: Re: [oletrucks] rear end questions, F*rd 9"
From: J Forbes <jforbes@primenet.com>
Date: Thu, 05 Apr 2001 16:40:07 -0700
Brian--

See below for specific answers...this info is what
I've learned from working in a junkyard, building
hot rods, repairing cars, reading, etc over the past
20 years or so.

> Date: Wed, 04 Apr 2001 23:14:00 -0700
> From: "Brian _" <pkupman57@hotmail.com>
> Subject: [oletrucks] rear end questions, duh!?!
> 
> hi all,
> recently i got a ford 9" houseing from a mid 70's ford truck (thats what i 
> was told when i bought it) it already has the spring perches ground off and 
> is ready for new ones, it is the same width as the cadillac rear end thats 
> in my '57 now. i also got a carrier and gear set for free from my auto body 
> teacher, now, my questions are,.
> 
> is this a 31 or a 28 spline rear end?

The mid 70s Ford trucks generally had 31 splines. 
You can count the splines on the axles when you pull
them out (assuming you have axles!).  You can also
count the splines on the differential side gears in
a pumpkin that is removed from the housing.
 
> how can i tell if its a traction lock or a open differential?

If you can turn one axle and the other turns the
other way, then it's open...also, if you pull the
axles out, one will have wear from two different
parts at the splines if it's a trak loc.  If you
just have the pumpkin, look at the splines on the
side gears, the trak lok has a split in the middle
of the gear on one side, because it's actually two
pieces, the gear (which is narrower than a normal
gear) and a hub for the clutch plates.  The track
lok uses clutches on ONE side only! so it's a rather
weak design.  The differential case which houses the
track lok has a tendency to crack in half under
severe use, because it's real thin where the ring
gear fits onto it.  The diff apparently was designed
to not have posi, and when they put it in they
discovered that there wasn't really enough room for
it! so they have to machine the parts very thin to
fit it in.  This is mostly because of the pinion
pilot bearing, which makes the rearend very strong
because of the additional pinion support.

> 
> can i get an ARB air locker for this rear end?

Probably, if you really want one....
> 
> summit has some richmond gears, they only list 9", could i buy these and 
> will they work with an ARB locker?

They should work, the gears for 9" rears are
interchangeable.  That's one nice thing about them.

> how can i tell if its a 2.891" carrier bearing or a 3.062" bearing and if 
> its a 3.062", its it a normal bearing or a daytona pinion support?

Measure!  Usually the 28 spline use the small
bearing, and the 31 uses the big bearing, but not
always--I've seen early 28 spline rears with the big
bearings.  31 spline axles were introduced some time
in the 60s, while the 9" was introduced in 57, and
both big and small bearings were available back
then--I have a pair of 57 car rearends, one a wagon
with big bearings, the other a pass car with small
bearings.

The Daytona pinion support has two different size
pinion bearings, the normal pinion support has the
same size for both--the odds are 99% that you have
the non-Daytona support.

> i also need axles that will fit, with chevy 5 on 4 3/4" bolt pattern, where 
> can i get these?

Moser will make you a pair of new ones for a
reasonable price ($300ish), but you need to get
brakes that'll work first!  Brakes can be a pain.

> i dont know much about rear ends, and as far as i can tell without seeing 
> what i have, theres no numbers to reference off of. any help is GREATLY 
> appreciated.
> thanks in ADvance

There is not much to reference...if the rearend has
it's original tag, it'll be attatched to one of the
pumpkin nuts.  It will have a number that'll tell
you the year and model it was installed in (D6TE
would be:  D=1970s, 6=1976, T=Truck).  It will also
have the gear ratio, such as 3.25 or 3L50, the L
means it's a track lok (posi).  The tags often get
lost.

More info:  To tell if it's a 9" rearend, it'll have
a drop out third member (pumpkin), with no rear
cover bolts.  At the front the pinion bearing
retainer is held on with 5 bolts.  The nuts that
hold on the pumpkin require an end wrench to remove
the two bottom ones  (if you can use a socket, then
it's an 8" rear, NOT a 9").  The ribs on the front
of the pumpkin will be straight, if one is curved,
it's a Lincoln 9-3/8", and gears will NOT
interchange with the 9".  The 9" was introduced in
1957, used on all the big cars and trucks back then,
and on midsize cars with bigger engines thru the
early 70s.  They were last used about 1986 or 1987
in trucks and vans.

Jim F
59s in AZ

> Brian M
> Atwater, CA
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959

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