Have Rumble...Driveshaft Rotates 1/4 inch...normal? '89 Laredo

I have a rumble that seems like it’s coming from the rear of my '89 Laredo. It begins around 55 mph. All wheels have been balance recently.

I inspected the drive shaft and the rear u-joint was bone dry as I shot a ton of grease in it. But it doesn’t seem like there is any play. But that is only rotating by hand...under load could be a different story and I’ll replace both soon.

The front u-joint by the trans wasn’t dry but will replace...

The front has new axle u-joints and hubs. I haven’t inspected the front drive shaft yet and I know that can be the culprit for rumbles...but I don’t feel it in the steering wheel...I feel the rumble in my seat.

My question:

With the wheels on the ground and trans in neutral I rotated the driveshaft by the differential...it rotates a 1/4 inch – measured from the outer u-joint bracket. Is this play normal?

Thanks!

that's about what I get with mine. I've got a 231 T-case in my 87.
Have you popped the rear dif cover and taken a looksy?

I just got under mine. With the back wheels off the ground I have at least 1/4 inch, perhaps more. The slop is in the diff or axels. My ujoints seem tight, I was going to grease them while I was under there but no zerks!!

87manche said:

that's about what I get with mine. I've got a 231 T-case in my 87.
Have you popped the rear dif cover and taken a looksy?

Click to expand...

Not yet! I hope that's the last resort.

You don't have any problems with rumbling?

I've searched the forums and saved some posts and will try the trouble shooting methods described. I'm sure I'll have questions!

Rear wheel bearings. While youve got the rearend open, might as well pull the shafts and check the bearings. Only about $30 with seal to replace.

Thanks!

Do the bearings need to be pressed in?

with a 89 you have a non c clip rearend, im not sure how they work.I believe they are pressed on.

On a non-clip axle D35c axle, the rear bearings are pressed on. The Dana 35c bearing kit has the bearing, outer seal, retainer plate, and locking collar. Google for "83501451" and you'll get a number of hits and vendors. The kit does not include the inner seal, which is part number 83503010.

I did my bearings and seals last month while I had everything apart. The kit was $32 per side, and the inner seal $4.40 from Rustys Offroad.

You will need a slide hammer to remove old seals and axle bearings. You will need a bearing/seal installer to put them back in. You can get these on the loan-a-tool program at Autozone.

Have we already established the rumbling is from the rear axle bearings? Could the rumbling come from other components?

Last week I did a brake job and pushed and pulled on both rear axle flanges along their length. It moved back and forth about 1/64 of an inch or so. Is that acceptable?

I there another way to test the rear axle bearings?

Thanks!