8 3/4 Clunk/Yoke Tightening Advice...

[mrmolding]

I noticed that my 70 Road Runner had that typical clunk when slowing down or going into gear when I first got it. I have paperwork and pictures from both the engine rebuild and tranny rebuild so I assumed something in the rear end or u-joints vs mounts.
Yesterday I took out the driveshaft and the u-joints look ok and seem fairly new, but one side was really stuck to get out of the yoke.
After reading some posts, I tried to see if there was play in the yoke. There was none side to side, but I was able to push in the yoke just a little bit and back out to recreate the clunk sound -- maybe 1/8 to 1/4 of an inch. So, do I tighten the nut on the yoke or is it a more serious issue (or is this normal)?
Any help is welcome!!!

 

[1967coronet]

Is it a 8.75 or a dana?
The 8.75 drops out the front , dana has a rear cover plate.
Also if its a 8.75 need info on what one it is.
Casting # lower left will end in 741 , 742 , 489, some use shims , 489 i think will have a crush sleeve.

 

[1967coronet]

If someone has replaced the front bearing or seal and re installed the yoke with the old nut its possible it may have came loose.
Or they never had it set right.
Is it all cleaned up , nut , yoke ect.
Or leaking grease ?

 

[wagonman]

More than likely you have a 489 style case unless it was changed. The 489 use a crush collar to set pinion bearing preload. If is moving in and out that far you have some serious issues going on. even if it is a 741 or 742 case its still not good. If it was me i would pull the chunk and tear it down to see whats what. Is the pinion seal leaking? Got a picture of the case and yoke movement?

 

[steve340]

In and out free play is not normal. Something needs attention there.

 

[Cranky]

1/8" is a lot but 1/4" is....well, really not good. No other noises like howling or even a slight whine? On accel, the pinion tries to push forward and on decel it tries to pull back. If it's not 2881489 case, you might get away with making sure the nut isn't loose and if it is, tighten it up. If that works without anymore clunking and no gear whine, pull the nut back off, clean the treads and Loc-tite it! And yes, they take a lot of torque to tighten up.

 

[mrmolding]

Thanks so much for the responses everyone! It is an 8 3/4 and 3.23. Here are pics of the case and right before I dropped the driveshaft.

 

[mrmolding]

1/8" is a lot but 1/4" is....well, really not good. No other noises like howling or even a slight whine? On accel, the pinion tries to push forward and on decel it tries to pull back. If it's not 2881489 case, you might get away with making sure the nut isn't loose and if it is, tighten it up. If that works without anymore clunking and no gear whine, pull the nut back off, clean the treads and Loc-tite it! And yes, they take a lot of torque to tighten up.

No other noise than the clunk. Thanks!

 

[mrmolding]

Is it a 8.75 or a dana?
The 8.75 drops out the front , dana has a rear cover plate.
Also if its a 8.75 need info on what one it is.
Casting # lower left will end in 741 , 742 , 489, some use shims , 489 i think will have a crush sleeve.

8 3/4. Just posted pics of case. Thanks!

 

[mrmolding]

If someone has replaced the front bearing or seal and re installed the yoke with the old nut its possible it may have came loose.
Or they never had it set right.
Is it all cleaned up , nut , yoke ect.
Or leaking grease ?

Not leaking, replaced fluid a few months ago so I know it’s full.

 

[steve340]

The nut torque on a 489 is 175 foot pounds minimum.
However it is hard to check the bearing preload with the diff fully assembled.

 

[mrmolding]

The nut torque on a 489 is 175 foot pounds minimum.
However it is hard to check the bearing preload with the diff fully assembled.

Just got a large torque wrench and breaker bar to finish front end. Looks like I can use it here as well. Thanks!

 

[Cranky]

Thanks so much for the responses everyone! It is an 8 3/4 and 3.23. Here are pics of the case and right before I dropped the driveshaft.

View attachment 1267236 View attachment 1267237 View attachment 1267238

89 case and came with a crush sleeve in it from the factory. Whenever I build one that sleeve gets replaced with a solid spacer and then it sets up like a 41 or 42 case. I've seen the 89's with collapsed crush sleeves before. Best thing to do is pull it out and tighten the nut up some. If it locks it, it needs a new crush sleeve. You could also do that in the car with the axles pulled out but then you will need an impact wrench to 'sneak' up on the nut. Or, if the nut is loose, tighten it up with the axles in and wheels on the ground....then pull the axles out and see how many inch pounds it takes to turn it. Pain in the butt no matter what you do....and block the wheels if you do this in the car.

 

[mrmolding]

Oh wait, so based on what Cranky said I should probably pull the rear since it is a 2881489 case. Right?
Edit: Nevermind, just saw his response!

 

[Fran Blacker]

Got a feeling your going have a noisy rear after tightening, hope not. The stress to snap that 1/4x 28 bolt says something even for a small bolt.

 

[dadsbee]

 

[mrmolding]

View attachment 1267247
View attachment 1267246

I won’t have that kind of an angle. I’ve got it up on race ramps. Should be fun!!!

 

[Cranky]

Got a feeling your going have a noisy rear after tightening, hope not. The stress to snap that 1/4x 28 bolt says something even for a small bolt.

Is it snapped or was he already taking the driveshaft out and then took a pic? I looked at it pretty close but couldn't tell.

 

[dadsbee]

I won’t have that kind of an angle. I’ve got it up on race ramps. Should be fun!!!

Showing you how to hold the yolk ! ... so you don't "drive" the car off the ramps!

 

[Cranky]

I won’t have that kind of an angle. I’ve got it up on race ramps. Should be fun!!!

Make sure your front wheels are blocked good and the E-brake is on....