Well after reading all the threads about how easy it is to put a
9 inch rear in a F1 truck, I went to a junk yard and got one from
a 70 F100. Knowing that just the lower shock mounts and drive
shaft will need attention. I removed the stock rear and positioned
the 9 inch up to the spring pads. I understand that I will have to
check the pinion angle. I flipped the U bolts 180. The face of the
rear where studs are for center section is pointed up about 15 degrees.
To bring the face close to straight I have to shim pads 1/4 inch. This
doesn't seem right. Pads are on such an angle the pins are out of
locating holes. I guess I'm going to have to cut off pads and relocate.
It has Posie Super Slider springs. I don't think that should matter.
Sorry for such a long post but this easy job just got complicated.
John

 

Be sure to measure the angle with the weight of the truck on the springs, not with the axle hanging. I found my perches were almost 10 deg, so I cut'n'welded them too. Not that hard and I prefer that to shims.

I think you'll find there are bout a half-dozen more "little things" you need to change, it is not a bolt-in deal.

BTW you shouldn't re-use U-bolts.

 

Same here. Mine was at 12 degrees. Torched them off and welded a new set on at 3 degrees to match the engine angle.

 

You sure that's what the rear springs are? Or does it have the optional Flex-O-Matic spring suspension?

1968/72: TWO different 9" rear axles. One has 28 spline axleshafts, t'other has a 9 3/8" ring gear, 31 spline axleshafts and Traction Lok.

9 vs 9 3/8: Only 5 parts are the same: Housing gasket, pinion seal, pilot bearing retainer, one pinion bearing and cup. EVERYTHING else is different!

Flex-O-Matic =

 

Thanks for all for your replies.
Bill, I bought the springs form Posie suppose to
replacement for stock.
Ross,Dmack guess I'll get cutting and
checking.
Thanks to all.

 

Hey John,
Hang in there. Nothing is "plug & play" easy on these old trucks but I bet it still takes you less than 2 weekends to get it done. You'll be happy with
the new gearing, very happy. We also picked up an emergency brake
with our's - yeah! I drove our truck home from purchasing it after being told "sure it's drivable" - I had the brake pedal on the floor & the truck was still moving - looked for the ebrake - nope.

Looking good over there in PA.

Ben in Austin
1950 F1

 

I used my original Dana 44, rebuilt the brakes, replaced all the bearings, re geared it, converted it to a posi. Everything is available to rebuild the original there seems to be a misconception you cant regear them. I also went with Possies springs front and rear and am happy with the result.

Possies rear stock replacement spring seemed to lower it an inch, but I was OK with that. I used the 2 leaf Possie spring for the front, it lowered it about 3 inches, however I like the stance.

 

Hello Bill, is there any identifying marks on the housings that let you know if it is a 9 or 9 3/8". I have access to a truck in the 68/72 year v8, my understanding is that it should be the same track width of a 56.

 

I would like to be able to tell the differences too.
I have 2 9'' rear ends ,and both are 1971 f100.
Thanks.

Hi 56PANELFORD.....long time since I have had time to visit here. How is the panel coming along?

 

It's done but still waiting for my rims to arrive. Don't look like I'll be driving it this year but will be next spring for sure. Getting ready to start on my pickup this winter.

 

9 3/8: Notice the ribs on the carrier (4141). The large rib on its left (right in pic) side curves downwards.

 

Hey Bryanknie, please post dana 44 posi and gearing scource, part #'s etc. I am planning on using my stock '53 rear end and would like posi, perhaps graring change. Thanks, Gree.

 

The actual diff housings are the same, hence the gasket is interchangeable, so if you got the right width housing you can bolt a 9" pumpkin into it. Just saying so you don't get rid of something of value if you find out it is a 9 3/8", besides if it is 9 3/8" it still works great you just need to know when you go to get parts or change gears most things wont swap over.

 

Here you can see the upper rib of the 9 3/8" that curves down. The 9" is straight.

 

Yes my 70 f100 9 inch says 9 inch on spec.
sheet but tag on rear says 8.7 ??