3'' rear lift/2''front BAD VIBRATIONS! - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Cherokee & Comanche Forums > XJ Cherokee Technical Forum > 3'' rear lift/2''front BAD VIBRATIONS!

Premium LED Lighting by VISION X, Proudly sold at ROCKRIDGBds fox ipf 2.0 racing series shocks now available at rockEngo winches available at www.rockridge4wd.com! Free shipp

Reply
Unread 11-30-2013, 10:22 AM   #1
Jeepnewb38
Registered User
1998 XJ Cherokee 
 
Join Date: Aug 2013
Location: smithville, Ontario
Posts: 8
3'' rear lift/2''front BAD VIBRATIONS!

So i just lifted my 98 cherokee sport (4.0L i-6) and betweeen 50-60km/hr i have a vibration. any speed <50 and >60 is fine.

The rear i lifted using a bastard pack of leaf springs, and the front i lifted using coil over spacers. Did i miss a step?

I've always thought to just do a transfer case drop but after doing alot of research apparently thats a bad idea because it actually basically angles everything back.. putting a worse angle on my front drive shaft, stress on my motor mounts etc.

the vibration isn't extreme but is noticeable.. i assume this is going to do damage to my u-joints?

is a SYE the only way to go? those are quite pricey and i wouldn't mind a cheaper route.

i hope i didnt go in over my head with lifting my jeep

what can i do?

Jeepnewb38 is offline   Reply With Quote
Unread 11-30-2013, 10:27 AM   #2
kgmkgm
Registered User
1999 XJ Cherokee 
 
Join Date: May 2013
Location: denver, co
Posts: 11
Yes, this usually requires a replacement rear driveshaft to work. SYE install & a front XJ driveshaft (or new custom) w/ Double cardan joint can solve this. I found a driveshaft company that makes rear double cardans for the XJ but retains the slip yoke alignment so it's just plug & play install. I am going this route, but I will see how it works. If that sucks, I guess I'll have it remade w/ a fixed yoke end.
kgmkgm is offline   Reply With Quote
Unread 11-30-2013, 11:39 AM   #3
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,277
I would start with new u-joints for the rear driveshaft. You can try a T-Case drop of up to 1 inch. It may or may not help, and if you didn't break any bolts, it is easily returned to stock.

IMO at about 3" of lift, you should start a savings fund to purchase an SYE.
__________________
.

According to the National Shooting Sports Foundation, AR-15 sporting rifles account for nearly 20% of all U.S. firearms sales.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problem; Government is the problem.
CJ7-Tim is offline   Reply With Quote
Unread 12-01-2013, 05:41 PM   #4
sAe23
Registered User
1995 XJ Cherokee 
 
Join Date: Apr 2009
Location: Los Angeles / SFV, California
Posts: 2,316
Quote:
Originally Posted by Jeepnewb38 View Post
So i just lifted my 98 cherokee sport (4.0L i-6) and between 50-60km/hr i have a vibration. any speed <50 and >60 is fine.

The rear i lifted using a bastard pack of leaf springs, and the front i lifted using coil over spacers. Did i miss a step?

I've always thought to just do a transfer case drop but after doing alot of research apparently thats a bad idea because it actually basically angles everything back.. putting a worse angle on my front drive shaft, stress on my motor mounts etc.

the vibration isn't extreme but is noticeable.. i assume this is going to do damage to my u-joints?

is a SYE the only way to go? those are quite pricey and i wouldn't mind a cheaper route.

i hope i didnt go in over my head with lifting my jeep

what can i do?
I ran a T-case drop for over a year and had no problems.
Someone on Ebay sells a drive shaft with a double cardan joint and the standard slip joint end (doesn't require a SYE kit).
Otherwise do the full SYE kit plus dbl cardan shaft...

If you don't do SOMETHING your U-joints will wear out prematurely.

Also, pay attention to your Caster and front pinion angles. At 2" you probably aren't too bad, but it's better to check and adjust as needed.
You'll want to set a proper pinion angle at the expense of your caster...
sAe23 is offline   Reply With Quote
Unread 12-01-2013, 07:21 PM   #5
Jeepnewb38
Registered User
1998 XJ Cherokee 
 
Join Date: Aug 2013
Location: smithville, Ontario
Posts: 8
thank you for the responses.. this is very comforting
what is Caster and pinion angle? do you know what it should be and how do i check it?

and just for clarification.. if i get a drive shaft with a double cardan joint and standard slip joint end..this will give me a good angle in the rear?
Jeepnewb38 is offline   Reply With Quote
Unread 12-01-2013, 07:40 PM   #6
rugsucka
Registered User
2000 XJ Cherokee 
 
Join Date: Oct 2008
Location: Sumware Inn, Ontario
Posts: 2,545
Consider getting a shim for the rear axle.

I ran a 4 degree shim with my 2" BB and had very minimal vibes with only a couple washers between the frame and the crossmember.
__________________
'00 XJ - Somewhat modified
'01 Venture - high mileage, paid for, shut it
rugsucka is offline   Reply With Quote
Unread 12-01-2013, 09:21 PM   #7
sAe23
Registered User
1995 XJ Cherokee 
 
Join Date: Apr 2009
Location: Los Angeles / SFV, California
Posts: 2,316
Quote:
Originally Posted by Jeepnewb38 View Post
thank you for the responses.. this is very comforting
what is Caster and pinion angle? do you know what it should be and how do i check it?

and just for clarification.. if i get a drive shaft with a double cardan joint and standard slip joint end..this will give me a good angle in the rear?
You use shims under the leaf springs to set the pinion to an appropriate angle.
A double cardan joint can operate through a greater angle than a single U-joint, so you line up the pinion with the driveshaft so the U-joint at that end doesn't have to work though an excessive angle, leaving the double cardan end to do all the ...flexing... (for lack of the proper term)
Here are a couple of site to read up on this stuff:
http://www.4crawler.com/4x4/CheapTri...l#Introduction
http://www.4xshaft.com/techinfo.html (read angles vs slopes, and geometry 101)
People usually modify the T-case with a SYE kit and a double cardan drive shaft.
One reason to do this is that after installing some kits, the T-case is shorter (which makes any drive shaft angles less). Another is that on older T-cases, driving with the rear drive shaft out will cause fluids to leak out. The T-case on your 1998 won't do this, so, you may be able to use a drive shaft that slips on the T-case output like a stock shaft but has a double cardan joint at one end (whereas the SYE changes the output shaft and requires a drive shaft with the slip in to the middle). (whew...)

As for CASTER, just google "caster angle" and it should be fairly clear.
Just take note that the relationship between the caster angle and the front pinion angle is FIXED (unless you pay loads of money to have the axle modified).
As you lift the vehicle, the pinion angle increases, which requires less caster angle to compensate. But again, at 2" you may be OK.

Clear as mud, eh?
sAe23 is offline   Reply With Quote
Unread 12-02-2013, 05:35 AM   #8
Kevin108
Registered User
2000 XJ Cherokee 
 
Join Date: Aug 2009
Location: Portsmouth, VA
Posts: 3,777
Iron Rock Offroad Hack & Tap Slip Yoke Eliminator and a set of 4 shims. Don't forget the YJ rear brake line. You're looking at about $150 for those pieces.
__________________
My build thread has pics again. http://www.jeepforum.com/forum/f177/kevin108s-2000-xj-build-867428/
Kevin108 is offline   Reply With Quote
Unread 12-02-2013, 11:07 AM   #9
Jeepnewb38
Registered User
1998 XJ Cherokee 
 
Join Date: Aug 2013
Location: smithville, Ontario
Posts: 8
wow thank you.
So first and foremost.. I need to measure some angles and see where I sit. That will be the tell tale of where my vibrations are coming from
Jeepnewb38 is offline   Reply With Quote
Unread 12-02-2013, 05:34 PM   #10
sAe23
Registered User
1995 XJ Cherokee 
 
Join Date: Apr 2009
Location: Los Angeles / SFV, California
Posts: 2,316
You got it.
If those web sites didn't make it easy enough, here are some pointers.
If your transmission pan is not dented, you can use it as the surface to get the T-case angle.
For the pinions (front and rear) there are two circles on either side of the differential cover that you can use.
Lastly, measure the drive shafts themselves.
For the front (which already has a double cardan shaft) the pinion and drive shaft ideally should be at the same angle.
For the rear, while running a standard drive shaft, the pinion and the T-case need to be at the same angle.

HTH
sAe23 is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.