Hey guys,

As you can see in the attached pics, the U joint I'm trying to install in my rear end yoke is not a perfectly snug fit. This rear end is from a 60's mustang I am told. There is just a hair of day light showing between the bearing and the inside of the yoke. How snug does this need to be? The U joints fit very snugly in the drive shaft tabs. I have to lightly hammer them into place. Am I good, or do I have the wrong U joint for the rear end? Thanks! Tyler

 

I think you have the wrong one, is the drive shaft the one that came with the diff? You can get U-joints with 2 different bearing diameters.

 

No the drive shaft came off the FMX tranny I pullled out of the truck. Replaced the tranny with a T5. I originally had the Dana 44 rear end, now this one form a 60s mustang or galaxy. Attached is a pic of the box the U joint came in. So wrong size you think? t

 

It looks like you have a 1310 size joint cap on the u-joint and the diff takes a 1330 size joint. You can get a conversion joint 1310x1330.

 

Great! I'll look into it. Thanks! Tyler

 

Measure across the yoke with the DS and u-bolts off, get the diameter of the cups. That looks to me like a 9" and also looks like the longer yoke, which is what I have. It uses a relatively unusual cup size.

To mate the stock DS to it here is what I used:
U-Joint: 2 cups are 1310's (1.062" dia x 3.219" wide), 2 cups are FORD 1330's (1.125" dia x 3.625 wide) / use NEAPCO 1-5349 u-joint

edit: Oops, I missed Dave's post

 

Well...unfortunately the 1310x1330 is *longer* not thicker. So it didn't help... Trying to find one with the same length both ways but fatter bearing... T

 

A "Ford 1330" is different than other 1330's

Go to a local driveline shop and tell them what you need, they can come up with it.

 

Tyler you are trying to use a standard size u-joint. You need a BC Joint or Big Cap, this is a joint Ford used the larger caps kept them from being crushed if the u bolts were over tightened. Her is a link to a chart so you can figure out the exact joint you need.
U-Joint series identification

 

According to my research the joint you have there has an outside width of 3.219" with bearing caps that are 1.063 in diameter.
I believe the joint you need is PN 1-4635, or 1-4635HD, which was used in 68-69 mustangs with the 289/302/351 engines at the rear of the driveshaft only. This joint has the same width as yours, 3.219", one set of bearing caps that are the same at 1.063 (fit into the driveshaft) and the other two bearing caps are slightly larger at 1.125" (axle end). i assume the joint you have fits the driveshaft fine which explains the different cap sizes.

 

Wow! OK thanks guys! I am gonna take this whole post to the parts store on Monday and go thru it with them to get this sorted out. Thanks for your help. I'll let you know what I find...

t

 

Ok, this U joint kicked my a$$ all weekend, but I *think* I have it right now. As you recommended, I got the 1-4635HD and it fits as well as I think it's gonna. The thing is, I can still see some daylight on the rear side of the bearing in the diff yoke. See the attached pic (the top of the pic is to the rear of the truck). I think the bearing sits on a tiny lip in the bottom of the differential yoke cup and that creates a smidge of a gap to the rear. Am I right about that, or am I making that up just so I feel better? There is no gap to the left or right side of the bearing. If the bearing were any wider, it would not fit in the left-to-right dimension of the yoke cup. Again, see the pic (the right side of the bearing is all that shows in this pic). Do I have this settled or am I off the mark still? Thanks! Tyler

 

Well with my limited knowledge of Ford ( I have a 9" in my 55 chevy that I have not looked under in years) I cant say if that is normal or not. Is the cap seating all the way into the yoke or is the cap hanging up on the outer edges keeping it from seating all the way? If the cap is firmly seated in the yoke and all the way in then I would leave it as is. If the cap is not seating all the way down then I would SLOWLY clean up the yoke with a carbide bit to let the cap seat all the way down.

**EDIT** looking at the pic again it looks like the cap is NOT fully seated unless it is an illusion, possibly the yoke is distorted somehow. I would clean it up with a carbide to get the cap fully seated into the yoke or test fit with another yoke. Looks like the yoke opening is not round like it should be.

 

That ain't right. Did you measure across the area where the cup sits? There are 1.062, 1.125, and 1.188 inch cups.

It is also completely possible since this rear end is out of a 60's Mustang that some teenager has beaten on the donor car, and spread the yoke. All it takes is a few neutral drops with loose u-bolts on the u-joint and you've got a "custom" size. Measure everything up and post it. But like Dave says, it doesn't look round. The cup's centerline should be flush with the face of the yoke when seated.

 

Had a mustang when you were a teenager did you Ross ?