Reverse Turn Clunk
 

Now that I've been driving my '98 Jimmy regularly I'm getting to know how the vehicle works and what some of its quirks are. The most recent one I've noticed is that when I'm backing up and I'm turning with the steering wheel cranked all the way to the right there's a clunk and hop from the front end. The noise and feeling continues as long as I'm backing up and turning fully. It has never happened going forward and at anything less than full lock on the steering.

The hop feels almost like tires binding on pavement in 4WD. It feels so much like the 4WD binding that the first time it happened I stopped the truck and left it running while I checked the front drive shaft which turned freely.

Just about a month ago I put in all new upper and lower ball joints, outer tie rod ends and and idler arm. At that time I took a good look at the CV boots and I didn't see any rips or tears and there was no grease coming out of the boots.

Any idea what's going on and how I should check out the truck?

Did you get a wheel alignment after changing steering components? It's pretty easy to be off after replacing tie rod ends. A 1/16th off at the tie rod can put you out, which might explain your problem. The other thing to take a look at is your upper control arm bolts and bushings. It's possible they're slipping slightly when your turning, which would cause the noise and hoping. These bolts are used to adjust the alignment too. They have eccentric washers used to move the arm in or out to adjust angles. If you didn't have your alignment done by a good shop that's the first thing I'd recommend you have checked out.

The first thing I did after I tightened everything down was to take it to Rick at Graham Automotive for an alignment. The toe had been set incorrectly before I tore everything apart which was probably due to someone getting an alignment with the lower ball joints being extremely worn out. Rick did a very thorough inspection of the front end and never said anything about the upper control arms. It makes a lot of sense and it's something I hadn't thought of.

How do I check the upper control arm bolts and bushings? Do I just look for gaps or is there a procedure for testing them?

Did you recently have it in 4wd? I get the same thing some times when it's cold and I switch from 4wd to 2wd. It feels like it's still in 4wd until I throw it in reverse. Then it makes a 'clunk' sound that you can feel in the steering wheel/front end. After the clunk, it feels like it's in 2wd. Mine only does it once after using 4wd, so I figure the 4wd isn't completely disengaging. It hasn't bothered me enough to troubleshoot, but with winter coming up, I'm going to throw it on the lift and make sure everything is ready.

To check the UCA bushings just look at them with a flashlight, and look for any serious cracking. If it's really bad you'll see it. If the bushings look fine, check around the bolts and washers for any signs of movement (dust worn off or shiny). You could put a wrench on both sides and make sure the nut is tight. Be careful you don't turn the bolt though cause that will change the allignment!. I had one of the nuts loosen off on me recently and it was making a thumping noise when the UCA would shift the bolt when I was turning at full lock. That was the only time I heard it though. If you find one of them are loose, you'll probably need another allignment. On an upside, if it's a good shop they should warranty the work, since it is something they would likely have worked on or adjusted those bolts when they did the allignment.

It's definitely not a 4x4 disengagement clunk. This truck is silent and smooth going into and out of 4WD. My old '93 Jimmy has a slight clunk when disengaging and this isn't like that. When I get time this weekend I'm going to pull the front tires and check the UCAs.

Meanwhile I think the alternator is going out so I'm going to pull that tonight and take it to the parts store in the morning for testing.

For the record if it is control arm bushings they are a biatch.Your almost better ording new control arms from rock auto.They have the new bushings and ball joint already installed.I have a set I need to put on my truck one of these days.:icon_bubbles:

I've heard the control arm bushings are bad. I'll take a look at the bushings this weekend. I also need to install a new heater core in my '93 Sonoma pickup so I've got plenty to keep me busy this weekend.

Sounds to me like your hubs are bad. They aren't too difficult to change and I would almost guarantee thats the problem.

Question do the Jimmys have the wheel bearing built into a inclosed hub?