New Driveshaft; which universal joints to use

[Joel Talka]

Hi;

I need to have a new driveshaft made for my 66 Coronet; small block, 4 speed, 8 3/4" rear. From what I have been reading/seeing Mopar basically has two choices for universal joints; the 1350 and the 7290. They look to be almost the same size... The question is what is the difference between the two, beyond the obvious measurements, and more importantly if I'm have this driveshaft build which should I use?

Thanks!

Joel

 

[steve340]

You probably need to consider what is compatible with the transmission yoke and the diff pinion yoke.
I think the Mopar yokes are 7260 or 7290.

 

[ruffcut]

Agree, my bet is the 7260 yoke is on the rear and the trans slip yoke presently.

 

[PurpleBeeper]

Going from memory….the two u-joints are about 3” across & about 4” across. Either works just fine. Use the size that your transmission yoke and rear end yoke already have. If you have a mis-match with the driveshaft (eg 3” driveshaft yoke & 4” rear end yoke), there are “adapter u-joints” that are 3” one direction and 4” the other direction

 

[Nirvana]

Id go 1350, you can get a billet slip yoke from Dr Diff for $100. He has 727/833 and 904.

This is in my 67 Barracuda

 

[Joel Talka]

Id go 1350, you can get a billet slip yoke from Dr Diff for $100. He has 727/833 and 904.

This is in my 67 Barracuda

View attachment 1692813

Very nice. I got my 3rd member from Dr. Diff and it came with the 7290 (7260?) differential yoke. Everything else is 1350. I'll order the correct one for the rear. I've seen the "conversion" universals out there on a few sites but I think I would rather use the same standard joints front and back...

 

[Nirvana]

Very nice. I got my 3rd member from Dr. Diff and it came with the 7290 (7260?) differential yoke. Everything else is 1350. I'll order the correct one for the rear. I've seen the "conversion" universals out there on a few sites but I think I would rather use the same standard joints front and back...

Might as well make it the same. I like overkill for my U joints. The driveshaft shop claimed the shaft/joints are good for 500 hp.

 

[Joel Talka]

Hi;

I need to have a new driveshaft made for my 66 Coronet; small block, 4 speed, 8 3/4" rear. From what I have been reading/seeing Mopar basically has two choices for universal joints; the 1350 and the 7290. They look to be almost the same size... The question is what is the difference between the two, beyond the obvious measurements, and more importantly if I'm have this driveshaft build which should I use?

Thanks!

Joel

I think I have this figured out finally. From what I have read, Mopars, at least vintage ones, use "inside locking" universals. These come in basically two flavors; the "Small Dodge" 7260 and the "Big Dodge" 7290. The 7290 was common in vintage big block 4 speed applications.

What I have going on is a 7260 transmission yoke, a drive shaft tube of unknown origin with a 7290 differential yoke. There is a "conversion" bearing at the differential end; 7260/7290. The shaft does not seem to be compatible with the bearings.

I'm going to have the new driveshaft built using 7290's only. I ordered a 29/30 spline 7290 transmission yoke from Dr. Diff yesterday. It was less than $100 including shipping. Nota a bad deal...

I also found a decent website which calls out this stuff which cleared it all up for me.... Driveshaft Specialist Home

Old cars.....the learning never stops!

Joel

 

[451Mopar]

the 7290 and 1350 are almost the same in size. Given the choice, the 1350 is way more common, and can be bought cross drilled or solid. I also like the way the diff yoke U-joint straps bolt through the 1350 style yoke. If you break a strap on the Mopar type yokes and the bolt head snaps off, it can be a chore to get the rest of the broken bolt out of the yoke.

 

[BSB67]

7290 and 1330 are the same size generally speaking- the cross is the same and interchangeable between the two with the correct caps and needle bearings.

1350 is larger and stronger than the 7290.

1330 is common on 67 big block cars with auto transmissions.

Unless you are making a bunch of power, you don’t need the 1350. If the 8 3/4 yoke is either the 7290, or 1330, I would just use that in both locations

 

[steve340]

I have a factory 340 4 speed car that has the 7290 universals fitted with the 8.75 rear end.
As posted earlier I agree - unless you are going to torture the hell out of it the 7290 will be more than adequate for the job.

 

[ruffcut]

Agree, my bet is the 7260 yoke is on the rear and the trans slip yoke presently.

 

[Joel Talka]

Hi, Yes, the front slip yoke is 7260 but the rear is 7290. When I bought the new 3rd member Dr. Diff supplied a "conversion" bearing.

 

[BSB67]

IMO, putting the 7290 on all four attaching points makes sense. But obviously, you’ll need to get a new slip yoke for the transmission.