Rear End Thud! - 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 CJ Forum > Rear End Thud!

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitTHE NEW! VANCO DUAL MODE 15/16″ Big Brake Kit w/BlaFS: Wranger BRIGHT License Plate LED! Just $3! Great value

Reply
Unread 03-11-2010, 12:51 PM   #1
ckritcoad
Registered User
1986 CJ7 
 
Join Date: Jul 2006
Location: Oregon
Posts: 101
Rear End Thud!

I just put a 9" rear end in the CJ. Everything went fine, but when I put it in drive or reverse the pinion jolts pretty violently and makes a pretty bad noise. Is this a back lash problem...would the pinion bolt not being torqued enough cause this?

Thanks for your help!

ckritcoad is offline   Reply With Quote
Unread 03-11-2010, 01:35 PM   #2
78treehugger
Registered User
1980 CJ7 
 
Join Date: May 2008
Location: , IN
Posts: 1,606
Looks like you have an auto. Is the axle rotating causing the pinion to load an unload? Are your perches good? Did you rebuild the axle before installing it? If not did you check the bearings?
__________________
1980 CJ 7--3" Black Diamond, 1" body, locked both ends, 4.56, 35x12.50x15 SS LTB, "family" cage

It's easier to get forgiveness than permision.
Salad is what food eats!!!
http://emptypocketsoffroad.org/
78treehugger is offline   Reply With Quote
Unread 03-11-2010, 02:41 PM   #3
ckritcoad
Registered User
1986 CJ7 
 
Join Date: Jul 2006
Location: Oregon
Posts: 101
I got the center section and supposedly it was just built and run for 400 miles with no problems. I changed the yoke to the correct size and installed new axles. The spring perches are good and solid. It does feel like it is loading and uloading when I put it in drive or reverse...yes it is an auto.
FYI it is a LSD. The bearings looked good and I didn't feel any slop or movement.

Thanks for your help!
ckritcoad is offline   Reply With Quote
Unread 03-11-2010, 03:58 PM   #4
UPJ Wheeler
Registered User
 
Join Date: Sep 2006
Location: Johnstown, PA
Posts: 107
Make sure your U bolts are tight for the springs. Mine tend to loosn up over time, and then the axle will rotate about 20 degrees or so and make loud banging noises when getting on or off the gas. Simple Fix
__________________
'79 CJ7, rebuilt 258, HEI, T5 World Class, D300 Low max 4:1, Flat Belly, Narrowed D44 w/ true trac & diff gaurd, Widetrack AMC20 w/ superior shafts, Detroit locker & crane diff cover, 4" skyjacker lift, 2" BL, TJ flares, 35" tires, York OBA, YJ tub conversion, 6 pt. cage, F250 front shock towers

4.0 Head and TBI on the way
UPJ Wheeler is offline   Reply With Quote
Unread 03-11-2010, 04:07 PM   #5
ckritcoad
Registered User
1986 CJ7 
 
Join Date: Jul 2006
Location: Oregon
Posts: 101
Quote:
Originally Posted by UPJ Wheeler View Post
Make sure your U bolts are tight for the springs. Mine tend to loosn up over time, and then the axle will rotate about 20 degrees or so and make loud banging noises when getting on or off the gas. Simple Fix
They are good and torqued down...I will try them again though.
ckritcoad is offline   Reply With Quote
Unread 03-12-2010, 08:24 AM   #6
CSP
Registered User
 
Join Date: Aug 2002
Location: Colorado
Posts: 11,813
It's either backlash or bad ujoints.
CSP is offline   Reply With Quote
Unread 03-13-2010, 05:13 PM   #7
ckritcoad
Registered User
1986 CJ7 
 
Join Date: Jul 2006
Location: Oregon
Posts: 101
Quote:
Originally Posted by UPJ Wheeler View Post
Make sure your U bolts are tight for the springs. Mine tend to loosn up over time, and then the axle will rotate about 20 degrees or so and make loud banging noises when getting on or off the gas. Simple Fix
Amazingly enough it was my U bolts. Apparently my compressor and gun are extremely week. I figured I had torqued them down too much, but when I had it at work in our shop and checked them with a digital torque wrench they were only torqued down between 35 and 45 ft/#'s. I torqued them to 100 and they problem completely went away. Thanks for the suggestion!
ckritcoad is offline   Reply With Quote
Unread 03-14-2010, 07:31 AM   #8
UPJ Wheeler
Registered User
 
Join Date: Sep 2006
Location: Johnstown, PA
Posts: 107
no problem....
__________________
'79 CJ7, rebuilt 258, HEI, T5 World Class, D300 Low max 4:1, Flat Belly, Narrowed D44 w/ true trac & diff gaurd, Widetrack AMC20 w/ superior shafts, Detroit locker & crane diff cover, 4" skyjacker lift, 2" BL, TJ flares, 35" tires, York OBA, YJ tub conversion, 6 pt. cage, F250 front shock towers

4.0 Head and TBI on the way
UPJ Wheeler is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





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.