I have a drive line vibration after 2.5" lift kit installation. what can I do to eliminate this problem?

Robin Banks

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I have a driveline vibration after a 2.5" lift kit installation. If I shift into neutral while driving vibration goes away completely. what is the fix for this problem? I appreciate all comments. This is my first Jeep and am learning some hard lessons. 1991 YJ 4.0 4 WD. Thanks.
 

Flyer58

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I have not lifted my YJ but you're right up against the limit of the driveshaft U-Joint angle. Accelerating puts more stress on the joints so the vibration will be more noticeable than coasting.

Others here will give several solutions. Let us know what you do.
Cheers.
 
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machoheadgames

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What lift? If it’s rough country those have improper shims on the springs that are not proper for a stock driveshaft. The shims they provide are only perfect if you’re changing the driveshaft and transfer case tailshaft to the slip yoke eliminator setup.

Best cheap move for a 2.5” lift is a moderate transfer case drop like the one from old man emu and then some 2° shims on the springs to complement the change.
 
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Stoopid Jeep

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When I installed my 2½" lift, I built a t-case drop, made out of 6 longer than stock bolts, and ¾" worth of oversized nuts (for spacers). It cost about 8 bucks.
I added a set of Rubicon express axle shims (4° if I remember correctly). That setup basically eliminated my driveline vibrations. Had a tiny buzz around 30mph.
 

Bucky

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On my 89 I installed a 2.5” Rough Country spring lift. It came with a transfer case drop and springs. No shims. It’s been going for 20+ years without any driveline issues or modifications.
 
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machoheadgames

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On my 89 I installed a 2.5” Rough Country spring lift. It came with a transfer case drop and springs. No shims. It’s been going for 20+ years without any driveline issues or modifications.
They’ve changed since then. They haven’t come with a tcase drop for at least 10 years and every single one I’ve seen has 6° shims on the rears. I had the 2.5 kit for a few years and the vibes were horrible until I finally realized that the way they shipped them was not ideal for an otherwise stock Jeep.
 
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Robin Banks

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I have not lifted my YJ but you're right up against the limit of the driveshaft U-Joint angle. Accelerating puts more stress on the joints so the vibration will be more noticeable than coasting.

Others here will give several solutions. Let us know what you do.
Cheers.
Thanks. I will post what happens.
 
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Robin Banks

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What lift? If it’s rough country those have improper shims on the springs that are not proper for a stock driveshaft. The shims they provide are only perfect if you’re changing the driveshaft and transfer case tailshaft to the slip yoke eliminator setup.

Best cheap move for a 2.5” lift is a moderate transfer case drop like the one from old man emu and then some 2° shims on the springs to complement the change.
It is a Rough Country kit. Thanks. I will try to locate Old Man Emu. It is a new unknown source for me. Rough Country/Extreme Terrain only lists transfer case drop for 6" lifts so I was at a loss for sources. My YJ had Boomerang shackles and the person I bought the Jeep from said it was a 3" lift. Leaf springs were flat. I thought a new 2.5" would lower it a bit but actually raised it. I think because the leafs were shot. Thanks again.
 
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Robin Banks

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They’ve changed since then. They haven’t come with a tcase drop for at least 10 years and every single one I’ve seen has 6° shims on the rears. I had the 2.5 kit for a few years and the vibes were horrible until I finally realized that the way they shipped them was not ideal for an otherwise stock Jeep.
Yeah. Sure would have been nice if in the kit description it would have listed that information. Thanks for the feed back. I can use all the help and info I can get.
 

machoheadgames

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Yeah. Sure would have been nice if in the kit description it would have listed that information. Thanks for the feed back. I can use all the help and info I can get.
get the OME tcase drop. I have some shims I can send you from OME that I didn’t need. They are what come on the rear OME springs. For the cost of shipping you can have them. That will fix you up properly. The OME shims match the OME transfer case drop perfectly. I haven’t had a stock driveshaft or transfer case output in many years now so none of this stuff is any use for me.
 
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Robin Banks

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get the OME tcase drop. I have some shims I can send you from OME that I didn’t need. They are what come on the rear OME springs. For the cost of shipping you can have them. That will fix you up properly. The OME shims match the OME transfer case drop perfectly. I haven’t had a stock driveshaft or transfer case output in many years now so none of this stuff is any use for me.
Hey, that would be great to get the correct shims. If you want to box them up and send them I can PayPal you what you need for $ if that works for you. I looked up Old Man Emu for a TC drop kit. The nearest dealer to me is Billings MT. I e-mailed them asking if they had a correct Transfer Case Spacer Kit but today is Sunday so I don't know when or what I will hear from them. Do you have any suggestions on where to go for an OEM Transfer Case drop kit? I can send you my address for shipping the shims and let me know how you want to get compensated. Thanks, I really appreciate the help.
 

machoheadgames

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Hey, that would be great to get the correct shims. If you want to box them up and send them I can PayPal you what you need for $ if that works for you. I looked up Old Man Emu for a TC drop kit. The nearest dealer to me is Billings MT. I e-mailed them asking if they had a correct Transfer Case Spacer Kit but today is Sunday so I don't know when or what I will hear from them. Do you have any suggestions on where to go for an OEM Transfer Case drop kit? I can send you my address for shipping the shims and let me know how you want to get compensated. Thanks, I really appreciate the help.
Quadratec has the kit in stock. I doubt you’ll be able to get it super fast but probably by Thursday or Friday. It’s about $100.

Send me a message with the address info and we’ll work that out.
 
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Robin Banks

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Quadratec has the kit in stock. I doubt you’ll be able to get it super fast but probably by Thursday or Friday. It’s about $100.

Send me a message with the address info and we’ll work that out.
Thanks. I will check out Quadratec. My particulars are: Robert Adams, 2340 East Ave. Apt C 25, Sturgis S.D. 57785. Your help is enough to make me think I should become a supporting member. Thanks.
 
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Robin Banks

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machoheadgames; I ordered the TC drop kit from Quadratec, $103. with tax. Great web site and was easy to order. Site said it was made for 2-2.5" lift kits. Thanks a bunch for that good info. During the rally in Sturgis a lot of delivery companies refuse to come into town because of the chaos. Can't say I blame them.
 
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Robin Banks

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MHG: Got your info on the drop kit bolts etc. How did you do that? Anyway, that sounds good, I will snap a picture and attach when they arrive. Now a new problem for me, I had a couple local guys with Air Power to install my lift kit. Might not have been the best idea I have ever had but I am too old to tackle some of this stuff. They left the rear Track Bar off. They said because it is an inch too short now that the Jeep is lifted. So along with that I noticed that when looking at the back end of the Jeep the Right side is 3/4" higher than the left side. I imagine this is because the Track Bar is not installed so the body in the back is not attached to the axle. Is this normal? If not, how does one solve that conundrum if you don't mind me asking. Thanks for your help, I am lost in the fog.
 

machoheadgames

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MHG: Got your info on the drop kit bolts etc. How did you do that? Anyway, that sounds good, I will snap a picture and attach when they arrive. Now a new problem for me, I had a couple local guys with Air Power to install my lift kit. Might not have been the best idea I have ever had but I am too old to tackle some of this stuff. They left the rear Track Bar off. They said because it is an inch too short now that the Jeep is lifted. So along with that I noticed that when looking at the back end of the Jeep the Right side is 3/4" higher than the left side. I imagine this is because the Track Bar is not installed so the body in the back is not attached to the axle. Is this normal? If not, how does one solve that conundrum if you don't mind me asking. Thanks for your help, I am lost in the fog.
Look up at the top of the screen and you’ll see the envelope. Private messages are there. To start messages with someone click on their name and click “start a conversation”, that’s what I did.

Rear track bar is totally unnecessary. Not sure why you’re sitting uneven but the track bar will usually pull the axle over and make it not centered under the vehicle. You’re better off without the rear track bar.

Maybe you have defective springs causing the lean. Not really sure. I didn’t have that problem on my RC 2.5. I did reinstall the track bars and they fit terribly. Removed them soon after. Didn’t like the steering slop without the front track bar so a year or two ago I added the front track bar back.
 
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Robin Banks

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Look up at the top of the screen and you’ll see the envelope. Private messages are there. To start messages with someone click on their name and click “start a conversation”, that’s what I did.

Rear track bar is totally unnecessary. Not sure why you’re sitting uneven but the track bar will usually pull the axle over and make it not centered under the vehicle. You’re better off without the rear track bar.

Maybe you have defective springs causing the lean. Not really sure. I didn’t have that problem on my RC 2.5. I did reinstall the track bars and they fit terribly. Removed them soon after. Didn’t like the steering slop without the front track bar so a year or two ago I added the front track bar back.
Thanks again. Saying that a lot to you. I will send pictures of the TC drop kit as soon as I receive it. And then we can do the other stuff we talked about if you still want to do that. Cheers for now.
 

FreeBird

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get the OME tcase drop. I have some shims I can send you from OME that I didn’t need. They are what come on the rear OME springs. For the cost of shipping you can have them. That will fix you up properly. The OME shims match the OME transfer case drop perfectly. I haven’t had a stock driveshaft or transfer case output in many years now so none of this stuff is any use for me.
Way cool members helping members !
 

Gilaguy23

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I don't recall you mention any aftermarket shackles or not. That being the case if you do have them and the guys who installed the kit got a little to happy with the air tools, they likely overtightened the shackle bolts. Doing this will squeeze or actually distort the ends or sideplates of the shackle which will cause binding and things to not settle freely. IIRC the factory ones are stepped on the shaft and smaller at the threaded ends so no worries provided the correct bushings were used. If they look to be aftermarket, big side plates, welded in center section kinda thing you might try taking a correct sized wrench and see if you can spin the bolt head somewhat easily. If there so tight you need to use lots of force Id back off the nylock nuts a tad to where,and im guessin here, 25 lbs of torque on a torque wrench will spin the bolts.