YJ noise over bumps in the back - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 10-11-2002, 07:57 AM
**DONOTDELETE**
Guest
 
Posts: n/a
YJ noise over bumps in the back

1st let me say a big HELLO to all of you. I'm a new member here. I was convinced to come here by NHCJ7 . (THANX!)

So, here's the prb...
Every bump I cross on the street, I hear this "thump" noise. Sounds like something metal & heavy gets to rub against something metal & heavy. Immagine having a rear axle that is not tightened enough with U-bolts to the leafs, so when you hit the bump, the axle jumps up, hits something, then comes down again hitting again. It is not that, it just kinda describes the sound. Plus, when it happens, I feel a light vibration coming from somewhere under the rear bench. Kinda like from the right-side back.

Now, I was suggested (by NHCJ7 - thx again) that it could be the rear driveshaft U-joint going bad. I checked the driveshaft, and it seems OK - not a minimal movement is possible, except rotating it (the way it does rotate itself when driving). Also, wheels aren't hitting anything in the wheelwell, because the movement needed to produce the "thump" sound is small - like passing down the dislevel of an inch. Front wheels-nothing. Back wheels - the sound.

It's my 1st Jeep, so I can't describe the problem much better than this. Sorry.

I had a "normal" (read: ugly, not worth mentioning) car before, and it used to make somewhat similar sound when it had it's shocks completely empty: driving a bit faster, it'd hit the bump, making the wheels loose the ground (cause of the speed) and since they were going down, they'd extend to the maximum & over, making similar sound. Kinda like lifting a car, holding the wheel compressed up with the hand and then letting it go suddenly - it'd extend and you'd probabyl hear the "thump" noise with a little vibration caused by the "pull" factor of extending shock.

If it helps, I have a stock '93 YJ (sob!), there are no driveline vibrations of any kind, the shocks are "almost perfect" (mechanic's words - checked them 15 days ago).

Any suggestions?
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 10-11-2002, 08:17 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: YJ noise over bumps in the back

Just to add a question here...
I came across a discussion on the "bottoming out" syndrom. I too tried to step on the (rear) bumper and jump up'n down, but I couldn't reproduce the sound. Anyway, I wanted to add this question: on a stock '93 YJ, how many leafs should there be in front and in the back? I'm asking 'cause I saw that those little brackets that hold the leafs together (not bolts, but that U shaped piece going around leafs) is wider than leafs. Actually, the part where it is open (facing towards the body) is not close to the top leaf, but has some space, a bit less than 1/2". Maybe previous owner removed a leaf here?
Also, the bump stoppers for the rear - where are they located? I found that I have only one in the front (the right one, closer to the pumpkin) that is a piece of rubber and is some 4-5 inches high, and is not more than 1" away from the axle. The right one is missing. How & where are they in the rear?

post #3 of (permalink) Old 10-12-2002, 05:40 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: YJ noise over bumps in the back

Hello back at you Blue Devil, I,m a new member too and this is my very first post of anything. I had the same problem on my 89 YJ. It ended up being the panhard bar was coming loose on one end. It sounded like the rearend was coming out of the thing. Check that and maybe it will help.
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 10-12-2002, 05:49 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: YJ noise over bumps in the back

You might wanna check everything on your rearend. From shocks to the axle. If there is one problem it can cause other. I had a broken leaf spring and it caused my axle to make noise. So check everything.
post #5 of (permalink) Old 10-12-2002, 10:05 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: YJ noise over bumps in the back

I'll second the panhard/track bar as the first place to look. The YJ doesn't flex much and these bars realy get in the way and limit the flex more. It doesn't take much to break the mount. Look at the rear axle. On the drivers side about 5 inches in from the wheel there is a mount with a single bolt and a bar attached that goes up to the frame on the passenger side. This is the panhard/track bar. Make sure both ends are tight. If one end is loose, there is your noise and just remove the other end. Other that very slight flex gains, it doesn't realy make a difference in handling on a stock Jeep.
post #6 of (permalink) Old 10-13-2002, 11:46 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: YJ noise over bumps in the back

To Stranger :

what "bar"? [img]images/graemlins/confused.gif[/img] I'm affraid I didn't hear that term yet. Is that the track bar? Or some other bar?

Thanx!
post #7 of (permalink) Old 10-14-2002, 12:27 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: YJ noise over bumps in the back

Sorry for the previous post...didn't see that nice explanation (still not familiar with the BBS).
I'll check the trackbar today (if I manage to find a 55 torx - you wouldn't belive how hard is it to find those, as they call them here, "american" screwdrivers. Not to mention that I'm ordering a lift kit, and that I'll probably have to go and purchase a set of inch-wrenches (here's all metric).

Thanx again!
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups 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:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not 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 On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome