Hi guys,
I’m chasing down a slight driveline vibration at cruise around 65, under accel or decel it’s not there, I can accelerate up to 65 and back the throttle off to just maintain 65 and there it is, enough to vibrate the rear view mirror. I’ve updated to a D60 with 3.74 gears and had a new driveshaft made by Spicer here locally, had it back to them to re-check balance. One thing I did notice is my new 1350 trans yoke was shorter then the original E body yoke, I can grab the driveshaft and feel the yoke has some movement in the trans so the bushing is possible a little worn. But I can’t help but think the shorter yoke may not be helping, sorry I can’t recall by how much it’s shorter but from memory it’s probably about an inch maybe???.

Question is, is there different length yokes??? Can I get a long yoke for my 727??

Just to follow up, the original yoke length is 6”, I’m now thinking the 1350 yoke I have is more like 4” to 4-1/2”

Yes. I had that same issue &I kept the yoke (904) with a slightly longer shaft & it took care of it (part time vibration at various speeds, mostly decel iirc).

I would put it up on 4 jack stands so the vehicle is level like it is driven on your roads and have someone run the throttle in gear and watch under the car what is vibrating
Let us know what you find, that will help others on here later, hopefully

Thanks Guys, yes Cab I’m still to do that, my dad has his car on my four post so as soon as it’s off I’m onto it, I thought I found the issue last weekend as I thought I’d take the wheels in to check the balance, both rears and one front were 45g out, the other front was 105g out, steering didn’t shake, put the wheels back on and could notice a difference.

Interesting for sure Rob

I wouldn't try it on a lift that lets the suspension hang down, you want the weight on the suspension just like it would have sitting on the tires on the road.
In other words have the weight loading the chassis with the rear wheels off the ground so you can simulate the tires and drive train spinning like you drive it without the front tires spinning eliminating those two from the trouble shooting chain. I hope that makes since

Cab, on the 4 post lift I can put the Diff on axle stands and run it under weight and at least get under the car to see what’s going on,

I think the runout on the yoke is .050 at the caps and this will tell you a lot on the fit of it to the output shaft.

Saved.

Clanton, are you saying that the spec and it shouldn’t be more than that?
Pretty sure I have more

Correct.That is not exact but maybe transman or dr.diff will chime in.The more ingagement on the spline with output and yoke the less it will be.I had 3.5" to 4" on mine spicer 1350

Clanton, yep finding a long barrel 1350, slip yoke is difficult, Sonnax make the longest I’ve found (thanks Cass) at 4.7” compared to the stock Mopar yoke at 6.1”, that said the bush in the trans is only like 2-1/2” long or similar, so it should be ok🤷‍♂️

Update, took my drive shaft into a different place to have it high speed balanced, this time I took some measurements of the trans to Diff, spoke to the guy, he measured things up and we agree’d my driveshaft was a bit over 3/4” shorter than it could be, that with the short slip yoke meant that it it’s length was possibly more important so I’m having a new shaft made, well we will see how this one goes. I had my suspicions it was on the short side

I moved my axle back 1" to make more room for a bigger tire by using a 1" spacer on the front leaf spring mount and I had to check the yoke movement.