Universal joints.....

[Fran Blacker]

In post #12 your measurement is 2.125".

 

[Fran Blacker]

Was there a typo in post #17? 246 7620 you typed . https://www.summitracing.com/parts/mog-246/make/dodge

 

[Fran Blacker]

Are the cups on the u-joint with red seals seated? If you put that in a vise and gently tighten it do the cups move in so clip to clip measure 2.125"?

 

[bobs63wagon]

Is it possible this needs some type of conversion u-joint? There are three types of them I think.

 

[Durandal25]

Is it possible this needs some type of conversion u-joint? There are three types of them I think.

No sir, the yolks are the same size. I might just have to take it to a drive shaft shop

 

[Durandal25]

So this is interesting. All the U joints that I have gotten that say they are 2.125 ...are not. I have yet to get a true 2.125 7620 joint. Anyone have one? I'm taking this part back to Summit, but I also want to confirm this with them in person so they can see it. Moog 246 U Joints are not true 2.125 out of the box.

 

[Durandal25]

Went to summit racing and there different u joints.....all were incorrect. Is there some magic u joint that came out for a 67 coronet?

 

[Durandal25]

I'm going to try these.

NEAPCO 1-6300

 

[Fran Blacker]

I'm going to try these.

NEAPCO 1-6300

That's a 7260 u-joint that comes on small blocks not sure about B or RBs I think?

 

[dvw]

That's a 7260 u-joint that comes on small blocks not about B or RBs.

There are only 3 Mopar factory joints. 7260, 7290, and 1330. If one of those doesn’t fit the installation process is incorrect or the inner width of the driveshaft has been bent slightly. I would get someone with real world U joint experience to help you. By the way. Buy a real dial caliper, they’re cheap.
Doug

 

[TN Mopar]

Make sure you get it right
not just okay or it will work

This is the result of U-joint failure
it happened while on the dyno
And it's going to cost me a bit

but I will never use anything but Spicer again
Also going with the largest size U-joint

 

[Durandal25]

That's a 7260 u-joint that comes on small blocks not about B or RBs I think?

Actually 7260 units were standard on big blocks too in 67.

 

[Durandal25]

New digital caliper

 

[JimCoronette]

I'm going through EXACTLY what you did with the u joints.

Everyone claims 2.125 (2 1/8") but is actually about a 1/4" (2 3/8") too wide.

I tried Spicer, Napa, Duralast, all claiming 2.125, but all too wide.

Can I press them in with my 25 ton press? Yes but they are too tight.

I was hoping to mix and match new and old, but the cap inner diameter is different.

I'm going to ask around for original Detroit ones.

 

[Durandal25]

Finally. It’s astounding that manufacturers can’t measure or advertise correctly.

 

[Durandal25]

I’ll let you know about the NEAPCO 1-6300

 

[Durandal25]

If you find the correct ones, grab me a set too..I’d appreciate it

 

[JimCoronette]

I'm going to send a note to Dr. Diff to see if he has heard any
thing.

I have an old original shaft from my 70 D200.

I'm going to measure everything before I take it apart.

I'm going to message all my buddies to dig up any original Detroit 7260s in their junkpiles.

 

[JimCoronette]

Talked to Dr. Diff.

He said after installing the u joint, give the yoke ears a whack with a dead blow hammer (hard plastic) to seat and relax the u joint.

I'm going to AZone to pick up a couple of u joints and give it a whirl.

 

[dvw]

I think you’ll find that the grease boots hold the cups apart. Squeeze the joint together in a vice and measure. It’s not uncommon to see the shaft dimension close up some either. Dr Diffs method will usually spring them back. Much better caliper.
Doug