Lifted with that *^% vibration! - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 01-07-2011, 08:45 PM   #1
Jeeper
 
mlt503's Avatar
 
Join Date: Jul 2009
Posts: 26
Thumbs up Lifted with that *^% vibration!

Finally I have a chance to give back to this great Forum with a tip about our raised Jeeps developing vibration!


'97 Sahara, 4.0L, 5sp, 35x12.50, NP231, 2" BL, 3" TeraFlex suspension lift:
Issue was extreme vibration. 1) put lift kit on, then 35" tires (on/off road tread) 2) vibration began 1 or 2 mo.s after 3) changed clutch (NAPA Perfection) which removed a lot of vibration but not all 4) changed motor mounts 5) rotated and balanced tires 6) SYE / short shaft installed.

All the above helped but did not remove this darned vibration. I should say along with the lift kit ( a yr ago) the shop added 2" aluminum spacers to lower the trans cross-member. When the SYE was put on, they romoved them. The vibration associated with taking off from a red light and going in reverse was better but now I feel a different vibration: the jeep feels like a truck....you can feel the drive train telegraphing its energy thru the steering column, the SEAT, thru the floor. I know I sound like a tourist but I believe Jeeps don't have to drive like this just because they are lifted and have bigger tires!
I had a thought: put back the alum spacers to do 2 things: help straighten the geometry a little more betw the trans and the aft rear and the alum would help absorb the vibration.
Not hoping for too much I put them back on took it out for a test drive and couldn't believe how much better it drove!
It almost feels as smooth driving as a factory Jeep.
Well, that's my little tip, email me at: mlt503@cox.net (Mesa, AZ) if you'd like more details.
My Sahara and me have the power again:

__________________

'97 Sahara TJ 4.0L 5spd
2"BL, 3"Teraflex Lift
35x12.50x15 Goodrich KM2
mlt503 is offline   Quote Quick Reply
Old 01-07-2011, 08:53 PM   #2
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 32,745
Images: 2
You're putting band-aids (the aluminum spacers) on to fix a problem that has a specific fix which is to simply correct your rear axle's pinion angle. With your SYE kit and CV driveshaft, the rear pinion angle has to be raised so it is the same angle as your new CV driveshaft. If the pinion angle is lower or above that of the CV driveshaft, vibrations will result.

The below illustration is exactly how your rear pinion angle must look... your rear axle's pinion shaft should be pointing directly at the output shaft of the transfer case. This is done by installing adjustable length upper rear control arms and lengthening them to raise the pinion angle as shown below. The rear axle's pinion angle can be 1-2 degrees under that of the driveshaft or equal to the driveshaft angle. But the pinion angle cannot be even 1 degree above that of the driveshaft.

So not only should those aluminum spacers not be there once you have a SYE and CV driveshaft installed, they have also reduced your ground clearance which removes 2/3 of the benefit of your 3" suspension lift.
Attached Thumbnails
Click image for larger version

Name:	cv_angle.jpg
Views:	154
Size:	29.1 KB
ID:	34256  

__________________
When you have a choice, buy American.

Jerry Bransford is offline   Quote Quick Reply
Old 01-08-2011, 02:29 AM   #3
Jeeper
 
mlt503's Avatar
 
Join Date: Jul 2009
Posts: 26
Thanks Jerry for the advice...ya know I was wondering if the pinion could possibly be clocked?
But unfortunately times are tough and after putting in $1148 on the SYE install more mods are out of the question.
The geometry as it stands now and the spacers may be a "fix" but it straightened out the line betw the tc and the rear AND got rid of the vibration.
PLus it still is mounted above the waterline of the front and rear pumpkins so ground clearance is not an issue.
I've read your posts/replys many times and you always give good advice but I'm told every Jeep is different and this is not my first one...it still drives smooth and quiet...I don't think the spacers are hurting anything so I think they'll stay.
Thanks dude!!!
__________________

'97 Sahara TJ 4.0L 5spd
2"BL, 3"Teraflex Lift
35x12.50x15 Goodrich KM2
mlt503 is offline   Quote Quick Reply
Old 01-08-2011, 03:48 AM   #4
Jeeper

WF Supporting Member
 
jeepjones's Avatar
 
Join Date: Jul 2010
Location: Canada, Eh?
Posts: 1,892
Using the t case drop completely defeats the purpose of spending the cash on an SYE and custom driveshaft. Now you have the DS, SYE and still don't have any more clearance than you did before just because of a small amount of vibes.
__________________
jeepjones is offline   Quote Quick Reply
Old 01-08-2011, 09:53 AM   #5
Jeeper
 
Join Date: Apr 2008
Location: Mississippi Gulf Coast
Posts: 339
Send a message via AIM to CapnDean
$1148 on the SYE? WOW: SYE kit from Adams driveshaft $400 shipping included. Only had to purchase 2 quarts of transmission fluid and some rtv. Let's say $415.....ope nope.... You're right...it was definitely $425 I had to buy a 12 pack of Miller lite to encourage my assistant.

Jerry is dead nuts on with the pinion angle. Having just gone through the same deal. You can do it anyway you want - - but if the line from your pinion to your TC is not straight you are gonna eat stuff up just give it time. I tried to do mine by reading this site and following other folks angles (some said 1 or 2 degrees, some said 5 to 7, one guy is running 15 degress) I am living proof that aint the way to do it. MEASURE MEASURE MEASURE. My pinion angle is dead on at 10 degrees.... no vibes and the measurements are identical from the top and the bottom of the shaft. Your needed angle will be based on YOUR particular setup. FIND it, SET it, LIVE it.

Jerry's diagram says it all..... just with less words.

I am no expert, this was my first 8.8 install. But - - having aligned many a engine and shaft in working boats the same principle holds true.
__________________


1999 TJ Sport 4.0L I6 5 spd Warn 8000
4" susp 1" body 35" AT's
4.88 Gears in Ford 8.8
Adv Adapter SYE
Adam's Driveshaft
CapnDean is offline   Quote Quick Reply
Old 01-08-2011, 12:14 PM   #6
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 32,745
Images: 2
Quote:
Originally Posted by mlt503 View Post
... but I'm told every Jeep is different and this is not my first one...it still drives smooth and quiet...I don't think the spacers are hurting anything so I think they'll stay.
In this case of the pinion angle requirement for a CV driveshaft, no not every Jeep is different. I think your decision to not correct the angle issue properly is a big mistake but that of course is your decision.
__________________
When you have a choice, buy American.

Jerry Bransford is offline   Quote Quick Reply
Old 01-16-2011, 05:46 PM   #7
Jeeper
 
mlt503's Avatar
 
Join Date: Jul 2009
Posts: 26
Jerry, re-read my last post; the geometry is fine and after 2 wks my Jeep is still running smooth. The added spacers produced an almost perfect line to the rear with just a few degrees off on the SYE!
Note: the SYE didn't cost $1148, it was installed. I've built engines but transmissions are still black magic to me
__________________

'97 Sahara TJ 4.0L 5spd
2"BL, 3"Teraflex Lift
35x12.50x15 Goodrich KM2
mlt503 is offline   Quote Quick Reply
Old 01-16-2011, 06:01 PM   #8
Founder, ThumbJeeps

WF Supporting Member
 
sevenservices's Avatar
 
Join Date: Sep 2009
Location: Mid-Michigan/Thumb
Posts: 3,951
may or may not be related but I've heard of lift accesories being put on and tighted down without the weight of the jeep on them. This throws everything out of whack...

If there is a chance of this, loosen the bolts while jacked up, set it down and tighten everything back up. Be sure your allignment is good as well.
__________________
-Chris
Founder, ThumbJeeps


1994 Wrangler YJ I6 4.0 H/O Auto 3 spd. 4" RC (33x12.5) (15x8) 3:54 Gears
sevenservices is offline   Quote Quick Reply
Old 01-16-2011, 08:29 PM   #9
Jeeper
 
Join Date: Jan 2009
Posts: 237
mlt503,
I was in the exact same position,Jerry and others are right as rain.Putting your spacers back in and having the vibes go away tells me right off your rear pinion is not pointed up high enough towards the transfer output .If you have adjustable upper rear control arms ,all you need to do is adjust them to point the rear pinion higher and your good to go? just sayin....
willysmb is offline   Quote Quick Reply
Old 01-17-2011, 12:44 AM   #10
Jeeper
 
Join Date: Apr 2008
Location: Mississippi Gulf Coast
Posts: 339
Send a message via AIM to CapnDean
I am missing the confusion or confusing myself again. Jerry's posted artwork shows a properly adjusted pinion angle. That's whatcha got to do to eliminate vibes. Get that pinion angle right. You can do it by shortening lower control arms, lengthening upper control arms or lowering your transfer case. The preferred method is lengthen upper CA's. The least preferred method is lowering the TC (because it negates part of the reason you lift to begin with). That said - get it right anyway you choose. I am with Jerry on this one. Adjustable upper rear control arms are the answer. I have both...only bad thing is my lowers can be adjusted without unhooking one end...makes that the easy even if less preferred option.

And YES adjust that angle with the wheels on the ground (Duh.... learned that one the hard way!)

__________________


1999 TJ Sport 4.0L I6 5 spd Warn 8000
4" susp 1" body 35" AT's
4.88 Gears in Ford 8.8
Adv Adapter SYE
Adam's Driveshaft
CapnDean is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Weird vibration Mikeys91 General Jeep Discussion 9 09-22-2010 10:13 AM
front driveline vibration theroks JK General Discussion Forum 3 08-08-2010 08:53 PM
Order in which to tackle vibration problem CubbieBlue TJ Tech Forum 7 06-30-2010 08:28 PM
Bad Vibration at or above 45 mph, not driveline. chiro2736 TJ Tech Forum 14 01-19-2010 12:10 PM
vibration that goes away in 4 wheel drive... barnum TJ Tech Forum 1 10-06-2008 02:49 AM



Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 05:36 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC