Couple u joint questions

[pearljam724]

69 Coronet original small block car.
I’ve been chasing a driveline vibration for some time now and believe I finally found it. I replaced u joints several months ago and may have installed them incorrectly. I have the smaller 2-1/8” yoke that calls for a 7260 u joint. When I put car in neutral there is a millimeter or two of slope at the rear u joint. Just now for the first time I recognized the 7260 u joint is shorter across one section compared to the other cup to cup.
Does the shorter stretch attach to yoke or driveshaft at axle ?
Are inside or outside clips required for the rear with the u joint straps ?
How about inside or outside clips on the front and shorter cross section. Which end tranny yoke or driveshaft ?
It was several months ago when I changed them and pretty darn sure there were outside clips somewhere on the previous ones ?

 

[bm02tj]

Original was inside clips only

 

[Fran Blacker]

The outside dimensions are the same, cup to cup. You need to have clips on all 4 cups to center yoke in rear. You may have bent ears on driveshaft, did u-joint move smoothly after install?

 

[pearljam724]

The outside dimensions are the same, cup to cup. You need to have clips on all 4 cups to center yoke in rear. You may have bent ears on driveshaft, did u-joint move smoothly after install?

I didn’t bend the ears because I didn’t hammer anything and U joint is loose where it attaches to rear yoke. Therfore I never touched rear yoke as far as bending anything. I used a socket and vice to press everything in and out very carefully and mindful not to bend any ears.
The joints were very tight after initial install. I could barely turn them by hand. I put 2500 miles on them and now that grease is pushed out they have play in them. The inside clips don’t push up against the rear yoke from the inside.
I stopped at Napa today. They gave me another new 7260 u-joint that is shorter cup to cup in one direction compared to the other direction ?

 

[Fran Blacker]

I don't think there should be more than a few thousandths difference cup to cup, MO.

 

[493 Mike]

I didn’t bend the ears because I didn’t hammer anything and U joint is loose where it attaches to rear yoke. Therfore I never touched rear yoke as far as bending anything. I used a socket and vice to press everything in and out very carefully and mindful not to bend any ears.
The joints were very tight after initial install. I could barely turn them by hand. I put 2500 miles on them and now that grease is pushed out they have play in them.

After install and clips in drive shaft--Give the shaft yoke a smack with a hammer on both sides and all the clearance between the clip and yoke will be eliminated, thus loosening the cross.
I stopped at Napa today. They gave me a 7260 yoke that is shorter cup to cup in one direction compared to the other direction

This sounds like a 7290/7260 adapter joint.
Mike

 

[pearljam724]

I don't think there should be more than a few thousandths difference cup to cup, MO.

I’m not near the parts now. But, my memory’s says one measured across 3-5/8 “ and across the other direction it was 3-1/8” with the cups on. One direction is a lot longer than the other.
Napa says it’s the correct part for 2-1/8” yoke (inside width ear to ear ). I ll have to measure inside ears of driveshaft when I get a chance. Regardless, from my understanding. A 7260 u joint should work. It’s a 741 case and through that research that’s what it calls for, 7260.

 

[Fran Blacker]

I’m not near the parts now. But, my memory’s says one measured across 3-5/8 “ and across the other direction it was 3-1/8” with the cups on. One direction is a lot longer than the other.
Napa says it’s the correct part for 2-1/8” yoke (inside width ear to ear ). I ll have to measure inside ears of driveshaft when I get a chance. Regardless, from my understanding. A 7260 u joint should work. It’s a 741 case and through that research that’s what it calls for, 7260.

That's a combination u-joint 7260 and would need cup diameter to tell what the other part is, 3 5/8"side.

 

[pearljam724]

That's a combination u-joint 7260 and would need cup diameter to tell what the other part is, 3 5/8"side.

I think I understand what you’re referring to. A 7260 - 7290 combination ? The cups appeared the exact same diameter on this one I bought today. But, I ll double check. I don’t understand why Napa would give me a combo unless I specifically asked for it ? The other thing. The 2500 mile one that is on it now. Is definitely not a 7290 attached to yoke. Because the one attached now needs to be wider by 2-3 millimeters and that one is supposedly a 7260 also ? Thank you, I need help figuring this out. Makes no sense

 

[Fran Blacker]

Here's a chart, note the width measurements on 7260 and 7290 are snap ring to snap so measurements will be short. The picture is a 66/67 1330 u-joint yoke, note the small tabs below cable. Don't think yours is this. Those tabs center the u-joint in the yoke.

 

[pearljam724]

Here's a chart, note the width measurements on 7260 and 7290 are snap ring to snap so measurements will be short. The picture is a 66/67 1330 u-joint yoke, note the small tabs below cable. Don't think yours is this. Those tabs center the u-joint in the yoke.View attachment 873338 View attachment 873339

Thank you, Fran. You’re a good man. That’s a nice chart. I also asked Napa to look at 7290 for shits and giggles. As I thought it would be, entirely too large. What doesn’t make sense, I most definitely have a 741 case, with a 2-1/8” yoke. I measured the inside of rear yoke. That definitely calls for a 7260 u joint. U-joint inside yoke is a good 2-3 millimeters too small inside rear yoke. I removed it there a few times to verify clips being installed correctly.
I can slide the cups up against the inside of the yoke. Use the clamps to hold the cups there. Wiggle u-joint afterwards. And of course the u-joint still moves a couple millimeters because the u joint itself, is still too small.
At first, I thought maybe the ears of the rear yoke was warped outward a few millimeters. But, the way the rear yokes are formed. I think it’s very unlikely and the kicker is. It’s doing the same thing in the front of driveshaft, lol ?

 

[Fran Blacker]

Hate to say this but the odds are the d shaft ears are tweeked, it's not hard to do I've done it.. If you have a u-joint in the shaft check to see if clips are square against ears if there is a space on one side clip and none on the the ear is tweeked. The fact that you have a gap I can think of any other reason. I'd take it to a driveshaft and have them install joint explain your problem, should cost $30/$40. The rear end is something else.

 

[pearljam724]

Hate to say this but the odds are the d shaft ears are tweeked, it's not hard to do I've done it.. If you have a u-joint in the shaft check to see if clips are square against ears if there is a space on one side clip and none on the the ear is tweeked. The fact that you have a gap I can think of any other reason. I'd take it to a driveshaft and have them install joint explain your problem, should cost $30/$40. The rear end is something else.

The clips are tight against the ears on the driveshaft. Maybe you’re right about the rear yoke. Just seems unlikely the way the rear yoke is formed. It has a lot of density. The best thing to do now, is probably take every piece to a reputable driveshaft shop near me. Is there anything I need to know before removing rear yoke. Precautions, etc. I assume it’s a pretty straight forward affair ? Or do You suggest plunging for a new rear yoke ? Rather than having an old one tweaked tighter ?

 

[Fran Blacker]

Having a puller to remove yoke helps. Sometimes you can tap them forward using a brass hammer they just slide off. Just don't beat the crap out of it.

 

[BB BELLA]

sorry to get off topic here but, where do you find the ujoint charts with dimensions, I'm currently trying to cross [no pun intended} a mercruiser to moog! trying to save a friend couple hundred! mercruiser is $$$$!

 

[miller]

Enjoy...

http://driveshaftspecialist.com/HTML Measure/UJ ID Guide.html

 

[miller]

You start, by figuring out what 'yokes' you have, all four locations, before you can chose which u-joints you need.
Trans yoke, rear end yoke, and both on the driveshaft. Don't assume both on the driveshaft are the same, until you measure them.