Jeep Driveline Vibration/Noise

[Nick1994]

Well my brother's 1991 Jeep Cherokee is back on the road after 1.5 years. Was off the road due to car accident but it was a sideswipe that blew out some windows and crinkled the doors. In the meantime he has lifted it a little higher, somewhere around 6.5", has a custom rear driveshaft for the slip yoke eliminator and lengthened. He put in a Ford 8.8 rear axle and re-geared the front stock Dana 30 to match the Ford 8.8's gear ratio of 4.10. The jeep drove fine after the accident, I know the problem isn't accident related.

The problem is a vibration type noise (hard to explain) from 15-20 mph. It smooths out when sped up but the noise comes back when slowing back down. He's only driven it around the block a couple times, doesn't want to do high speeds yet. The vibration issue goes away when put into 4x4, but comes right back when put into 2 wheel drive.

My ideas: Tires haven't been touched since it has been sitting. They might have flat spots, we have inflated them. It sat on jack stands a lot of the time.
Another thought was the gearing in the front axle, maybe he didn't get the gears lined up. Front diff cover felt pretty warm after driving maybe a total of a mile in the neighborhood.
For reference, I then got in my grandfather's 1996 Cherokee and drove the same distance and the diff cover was still pretty cold.

Anybody have any ideas? Thanks

 

[Bluestream]

U-joint

 

[Rand]

gears are hard to setup right.. is he a pro?

 

[AZjeff]

He did the SYE for the rear, what about the front driveshaft? 6.5 lift causes some steep angles. T-case drop? Vibes in Cherokees are real common with bigger lifts. Money well spent to have someone set up the diffs properly when re-gearing.

Flat spotted tires are bump-bump-bump not vibes.

 

[Nick1994]

Originally Posted By: Rand
gears are hard to setup right.. is he a pro?
Not a pro, just checked the pattern. Not sure, he did it not me.

 

[ram_man]

There's so much done to it that it could be a lot of things first things first pin point which point of the vehicle it is coming from.

 

[Nick1994]

Originally Posted By: AZjeff
He did the SYE for the rear, what about the front driveshaft? 6.5 lift causes some steep angles. T-case drop? Vibes in Cherokees are real common with bigger lifts. Money well spent to have someone set up the diffs properly when re-gearing.

Flat spotted tires are bump-bump-bump not vibes.
It had about a 4.5" lift before for years and he used to have a transfer case-drop. Took the transfer case drop out when he installed the SYE.

 

[Nick1994]

Originally Posted By: Bluestream
U-joint
Rear driveshaft is custom made by a pro-driveline shop. They extended it, installed a new cardone joint, new u joints, and spin balanced it.

Front driveshaft has new u joints and a new cardone joint.

 

[Lyman]

Drop the front drive shaft and test drive it.

 

[AZjeff]

Originally Posted By: Blkstanger
Drop the front drive shaft and test drive it.


This.

So he went 2" more lift and raised the t-case back up. Angles.

Maybe go to naxja.org where they know Cherokees? All guessing here.

 

[Kuato]

Something going on in the front differential...shouldn't be hot after 1 mile!

 

[Nitronoise]

Make sure tire diameter between front and back are the same or REAL close , I blew a front differential as these are full time FWD and tire diameter is a key, as I replaced the fronts and not the rear tires and I took it out on the hiway /tollway and was rolling along at 70 mph when the front differential gernaded , and lit on fire , I still have the burn scars from saving my sons jeep and a $200 tow bill to have my buddy laugh at me saying got to replace all 4 tires at the same time

Just food for thought my son's jeep is a 1994 with a 4 inch lift

 

[SwampSurvivor]

With a sye there needs to be ZERO angle on the rear joint; the yoke needs to be pointed at the transfer case. The double cardan does all the work.

A 91 cherokee with the 231 can run all day with different size tires in 2hi

 

[Kuato]

Any update?

 

[Nick1994]

Originally Posted By: Kuato
Any update?
Still making the noise, nothing is obvious yet. He might take off the front driveshaft and drive it and see if the noise goes away.

 

[Nick1994]

UPDATE: Rotated tires to see if that was the issue. Negative.

Removed front driveshaft and went for a drive, smooth as silk. Going to take it to get it balanced first.

 

[Lyman]

Very common problem on Jeeps. Lots of different routes you can go too. Look up Tom Woods custom drive shafts. Lots of good info on the website. Also Carolina Driveline. I was lucky as when I bought my Jeep it had a new front drive shaft that had just been installed. Might just need new U-joints if he is lucky.

 

[Nick1994]

Originally Posted By: Blkstanger
Very common problem on Jeeps. Lots of different routes you can go too. Look up Tom Woods custom drive shafts. Lots of good info on the website. Also Carolina Driveline. I was lucky as when I bought my Jeep it had a new front drive shaft that had just been installed. Might just need new U-joints if he is lucky.
Yeah he already has new U Joints and a Cardone joint in it, probably just isn't balanced. Axle shop here in town balances for $60

 

[Lyman]

Originally Posted By: Nick1994
Originally Posted By: Blkstanger
Very common problem on Jeeps. Lots of different routes you can go too. Look up Tom Woods custom drive shafts. Lots of good info on the website. Also Carolina Driveline. I was lucky as when I bought my Jeep it had a new front drive shaft that had just been installed. Might just need new U-joints if he is lucky.
Yeah he already has new U Joints and a Cardone joint in it, probably just isn't balanced. Axle shop here in town balances for $60
Check driveline angles too.

 

[Nick1994]

Originally Posted By: Blkstanger
Originally Posted By: Nick1994
Originally Posted By: Blkstanger
Very common problem on Jeeps. Lots of different routes you can go too. Look up Tom Woods custom drive shafts. Lots of good info on the website. Also Carolina Driveline. I was lucky as when I bought my Jeep it had a new front drive shaft that had just been installed. Might just need new U-joints if he is lucky.
Yeah he already has new U Joints and a Cardone joint in it, probably just isn't balanced. Axle shop here in town balances for $60
Check driveline angles too.
Thanks, will do. Driveshaft likely needs to be balanced regardless so we're gonna see what happens.