Vibration after new gear install?

[Jeep~N~Jay]

Harmonic vibration after install a new gears? 

Jeep gladiator M220/M210 axles.
Jeep is brand new with only 800 miles and completely stock, started with 3.73 gears changed to 4.88. (Yukons). 31.5” tires stock.

I used to shop with one of the best reputations in the state, has done hundreds of sets of gears, comes highly recommended, I’ve known the shop for several years, and they have a stellar reputation.

The pattern looked good, the gears are quiet. When the owner took it out for the initial test drive and got it up to about 53 mph a vibration kicks in and goes away at around 59 mph.  he pulled the rear gears and put a different set in and a new install kit along with it, and it did the same thing. 

He said he could do one of two things throw another set in or give it back to me. Let me drive it a little bit and if it persists bring it back. 

Did a lot of reading looks like it could be several things, but I cannot help but think the gears are set up wrong as it didn’t do this prior and there been no other modifications to the truck yet.

In my research, I decided to pull the front driveshaft and take it for a drive to see if the vibration went away and it is still there without a front driveshaft.

Anyone seen this before or have ideas?

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[Jeep~N~Jay]

For anyone now or in the future I will keep this going until resolved.

I took the rear drive shaft and went for a drive. No more vibration. One thing I noticed was the rear drive shaft was a beast to remove. Very difficult to get it to separate from the pinion. I attached a ratchet strap then tapped on it with a dead blow until it popped loose. My JL I can free very easily with my hands.

I noticed the flange has screwdriver marks where the installer pried it loose. I am sure it didn’t come from the factory like that. Could he have bent the flange or ears just enough to cause the vibration? See pic. I am going to have the shop install a new flange and request a new gear set.

 

[jav_eee]

Well your driveshaft is spinning much faster now. Maybe it needs to be balanced.

 

[Jeep~N~Jay]

Well your driveshaft is spinning much faster now. Maybe it needs to be balanced.

i could see that if this Jeep wasn’t brand new? 800 miles never even been on a dirt road yet.

I’ve had the Jeep up to 90 prior to the gears and it never had vibration. Can’t imagine it’s the driveshaft at 52mph.

after reading up on it this weekend I suspect a bad gear set or something is off on the setup. According to Randy’s improper preload or backlash can cause driveline vibration.

 

[Brahmajoe]

Did you change the gearing in the pcm?

 

[Vtur]

Jack up the rear end and spin the wheel. See if the flange wobble. The pinion shouldn't have any in/out or up/down plays.

 

[Escape.idiocracy]

Did you change the gearing in the pcm?

Computer isn’t going to cause vibration…. Shift points are going to be off

Yukon gears… ? any chance you caught one from the batch with bad heat treated pinions??
Regardless whoever you went to for the gear install should make it right.

Im sure I read your post right? But if not correct me- you ran without the rear drive shaft (4wd, running it as front wheel) and no vibration? ?. So it is either the flange, the tail shaft bearing, or the driveshaft is tweaked…. When the shaft was out, any chance you stuck it on two pipes and rolled it to check if it was true? (Hard to describe via words- I’ll look for a photo…) maybe it was dropped when off, or they let it drop when disconnecting it?

If it’s the drive shaft, might look at it as a crappy time to pick up a Tom woods or something now- vs when you drag it over the rocks and tweak it later. ??‍

 

[Jeep~N~Jay]

Did you change the gearing in the pcm?

Yes, that was done. It wouldn't cause vibration anyhow.

 

[Jeep~N~Jay]

Computer isn’t going to cause vibration…. Shift points are going to be off

Yukon gears… ? any chance you caught one from the batch with bad heat treated pinions??
Regardless whoever you went to for the gear install should make it right.

Im sure I read your post right? But if not correct me- you ran without the rear drive shaft (4wd, running it as front wheel) and no vibration? ?. So it is either the flange, the tail shaft bearing, or the driveshaft is tweaked…. When the shaft was out, any chance you stuck it on two pipes and rolled it to check if it was true? (Hard to describe via words- I’ll look for a photo…) maybe it was dropped when off, or they let it drop when disconnecting it?

If it’s the drive shaft, might look at it as a crappy time to pick up a Tom woods or something now- vs when you drag it over the rocks and tweak it later. ??‍

My guess is a bad gear set. Will be talking to the shop today to make arrangements to take it back in. Yes I ran it in "front wheel drive" for this test, rear shaft completely removed. I did check and make sure all the factory weights were still there. I doubt the shop would have dropped the shaft as they only disconnect it from the pinon and then hang it to the side while working on it.

I would upgrade the shaft, but something tells me the vibration would still be there after dropping the 1k on a new one. One other thing I tried when reinstalling the shaft is clocking it in different position - 45 degrees, then 180 degrees but didn't change anything.

 

[whiteglad]

I would follow up on the difficulty of removing the driveshaft. Something, the shaft flange, or the flange on the diff, may be damaged and the two don't seat correctly.

 

[Pickle_Bill]

Same exact thing going on here. We replaced the gears and new bearings a second time, but the same exact thing. I also clocked the drive shaft several times and found a spot that is not as bad as other spots. It's not right, but it's tolerable. Lots of research has been done and found that some have this same harmonic right out of the dealership. The only thing I can come up with is after reading a PDF of drive shaft install instructions, they are very specific about not letting the carrier bearing joint be over angled at any time. I know my installer disconnected the shaft from the pinion and then let it hang off to the side. Apparently this is a no-no according to instructions. That being said, he also is a very seasoned mechanic that has done hundreds of installs, and aways done it this way. At this point I am just driving it. I did order new bolts for the drive shaft seeing as they are suppose be single use, and mine have been in and out many times. I may go get the shaft balanced, may just keep driving it.

 

[Jeep~N~Jay]

Same exact thing going on here. We replaced the gears and new bearings a second time, but the same exact thing. I also clocked the drive shaft several times and found a spot that is not as bad as other spots. It's not right, but it's tolerable. Lots of research has been done and found that some have this same harmonic right out of the dealership. The only thing I can come up with is after reading a PDF of drive shaft install instructions, they are very specific about not letting the carrier bearing joint be over angled at any time. I know my installer disconnected the shaft from the pinion and then let it hang off to the side. Apparently this is a no-no according to instructions. That being said, he also is a very seasoned mechanic that has done hundreds of installs, and aways done it this way. At this point I am just driving it. I did order new bolts for the drive shaft seeing as they are suppose be single use, and mine have been in and out many times. I may go get the shaft balanced, may just keep driving it.

this gives me hope in some weird way lol. My shop is putting a new set if gears in two weeks from now. If I still have the issue I will attempt a driveline balance, then after that I may have him install an aftermarket.

 

[Pickle_Bill]

Please report back here after. Hope you find a solution.

 

[Gazingwa]

this gives me hope in some weird way lol. My shop is putting a new set if gears in two weeks from now. If I still have the issue I will attempt a driveline balance, then after that I may have him install an aftermarket.

Any resolution to this??

 

[Jeep~N~Jay]

Any resolution to this??

i had a different set of Yukons installed. The vibration went away about 95%. They were still somewhat noisy. Pattern looked good after a couple thousand miles. I ended up selling this jeep after all that. I believe Yukons are just not good nowadays. I would stick with Dana spicer in the future.

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