Rear End Hopping after Replacing Slip Yoke / U-Joint

[YukonCrazy]

A while back my 2008 Yukon developed the GMC *CLUNK* after coming to a stop and taking your foot off the brake. I fixed that by ordering a new slip yoke, trans rear extension, and u-joints. I had a machine shop press the U-Joints onto the drive shaft and slip yoke.

That fixed the *CLUNK* noise. A few days layer, I also put on a set of new Bridgestone tires and took a trip to the mountains. On the freeway, it felt like the rear wheels were out of balance. I assumed Costco screwed up the balance when mounting the new tires. I had the balance checked somewhere else and they were all in balance.

So what is this thing that feels like the rear wheels are out of balance on the freeway? Kind of feels like the rear end is slightly hopping on the road at high speeds. Rear U-Joint not pressed on correctly? Can the drive shaft be balanced?

 

[992dr]

Could be bad shocks.

 

[08grey]

Yes you may need to balance the drive shaft. Contact a axle rebuild er and ask if they do it. If they don't they will likely know where to go. Pull out the shaft and take it there.

 

[YukonCrazy]

Well, I finally found a shop that does drive shaft balancing. He put it in a machine and spun it up and right away noticed a wobble. Took about an hour of straightening the shaft with a press and then balancing it.

I can now safely blame Napa machine shop. When they pressed in my new slip yoke and u-Joints, they must have warped the drive shaft. Not sure what those num nuts were doing at Napa, but I will not get work done there anymore.

 

[08grey]

Great news.

 

[osidesurfer365]

I'm experiencing something very similar right now. Did your rear tires almost feel like they were locking up after going from dead stop to moving?

 

[YukonCrazy]

Well almost 4 years later I still have a constant vibration at all speeds. Back in 2015, I replaced the slip yoke and u-joints on the drive shaft. Took the driveshaft to get balanced as well. I also replaced the transmission rear extension and transmission mount at that same time. Recently I put on brand new set of Michelin's that are perfectly balanced and yet I still have vibration at all speeds.

I guess at this point, the issue is either related to the following:

1. wrong slip yoke
2. wrong transmission rear extension
3. wrong transmission mount
   
4. bad driveshaft

So frustrated after this length of time without a solution to the vibration. Before I replaced the above items, there was no vibration so clearly it's one of these things. Any suggestions?

 

[swathdiver]

Well almost 4 years later I still have a constant vibration at all speeds. Back in 2015, I replaced the slip yoke and u-joints on the drive shaft. Took the driveshaft to get balanced as well. I also replaced the transmission rear extension and transmission mount at that same time. Recently I put on brand new set of Michelin's that are perfectly balanced and yet I still have vibration at all speeds.

I guess at this point, the issue is either related to the following:

1. wrong slip yoke
2. wrong transmission rear extension
3. wrong transmission mount
   
4. bad driveshaft

So frustrated after this length of time without a solution to the vibration. Before I replaced the above items, there was no vibration so clearly it's one of these things. Any suggestions?

Do you have a good friend with a Tahoe or Yukon of similar vintage? Swap driveshafts or pick one up at the salvage yard. Alternatively, just buy a new one from AAM or AC Delco or have that shop build you a new one.

https://parts-catalog.acdelco.com/catalog/catalog_search.php

Run your VIN through here and look in the drivetrain section, driveshaft and click through the pages until you see yours then google for prices.

How many miles and when were the shocks replaced last and with what? What kind of suspension is it equipped with?

 

[thompsoj22]

Well almost 4 years later I still have a constant vibration at all speeds. Back in 2015, I replaced the slip yoke and u-joints on the drive shaft. Took the driveshaft to get balanced as well. I also replaced the transmission rear extension and transmission mount at that same time. Recently I put on brand new set of Michelin's that are perfectly balanced and yet I still have vibration at all speeds.

I guess at this point, the issue is either related to the following:

1. wrong slip yoke
2. wrong transmission rear extension
3. wrong transmission mount
   
4. bad driveshaft

So frustrated after this length of time without a solution to the vibration. Before I replaced the above items, there was no vibration so clearly it's one of these things. Any suggestions?

The shop that balanced your driveshaft had to add/remove weight to get it right. are the weights still attached? IMO you will never get a thin wall tube to run true after it has been bent, replace the driveshaft/slip yoke combination.

 

[992dr]

I'd start with the driveshaft and agree with swath. If I were closer, I'd swap it out for a try.
I got a quote for a new aluminum driveshaft and it was relatively inexpensive, I think it was around 250. Its a 1 piece driveshaft.