What did I break? ---I need a new front driveshaft---

bighause · **Posted:** Thu Dec 01, 2005 12:38 am

Took the Libby out today wheeling for a few hours and I tore something up. It did great and nothing felt wrong till I got back on the pavement and got it up to 35 mph. Something is vibrating pretty bad and changes with vehicle speed. Enging speed and drivetrain load have nothing to do with it though. The only thing I see wrong it some gouges on the pinion where the driveshaft bolts to it. I know that doesn't help much, but anyone had similiar problems?

jpzkj · **Posted:** Thu Dec 01, 2005 1:13 am

Did you wheel in mud ? If so....there may be enough mud on the inside lip of the wheels (where the brakes are) to make the wheels unballanced . I had this happen after getting stuck in the mud and WOW what a difference that made on the highway the KJ was shaking down the road !

Let us know....

bighause · **Posted:** Thu Dec 01, 2005 1:27 am

No mud, just lots of steep rocky hills and a couple of creek crossings that were about 1 foot deep is all. It is very dry around here

crdawg · **Joined:** Mon Sep 12, 2005 10:55 pm **Posts:** 98

check your u joints for any slop or play

2003KJ · **Posted:** Thu Dec 01, 2005 5:26 pm

if you can maybe post some pics of these gouges, that might help us a little more.

krazz1e · **Posted:** Thu Dec 01, 2005 5:38 pm

maybe a tire wieght fell off (by scraping on a rock) and now you have a tire out of aligment?

Tokyojoe · **Posted:** Thu Dec 01, 2005 9:00 pm

look for branches or metal objects under (or is it on top of) any skids you have.

bighause · **Posted:** Fri Dec 02, 2005 12:39 am

After some crawling around under the jeep I think I fiqured it out. When you rock the steering wheel back and forth the rack and pinion moves and makes a noise as if it were loose, but the bolts are tight. The rubber bushing on one side looks really bad also.

Anyone else run into this problem? Hopefully I can get new bushings for it? It looks like the front axle has to drop down and maybe drop the lower control arms to get the thing out to replace the bushings.

It is way too cold in the mornings(30 degrees) to be riding the motorcycle to work while the jeep sits in the garage in peices. Hopefully it wont rain!

JediJeeper · **Posted:** Fri Dec 02, 2005 1:30 pm

If there are some serious "marks" on the pinion area of the diff, you may want to examine the drive shaft very closely, it could be slightly bent, which (like mud) produces a constant vibration that is coupled to the vehicle's speed.

Same thing goes for the U-Joint, as was mentioned, U-joint damage will manifest in the same way (at least until the joint breaks :-)

-Adam

FreedomKJ · **Posted:** Fri Dec 02, 2005 11:47 pm

JediJeeper wrote:

If there are some serious "marks" on the pinion area of the diff, you may want to examine the drive shaft very closely, it could be slightly bent, which (like mud) produces a constant vibration that is coupled to the vehicle's speed.

Same thing goes for the U-Joint, as was mentioned, U-joint damage will manifest in the same way (at least until the joint breaks :-)

-Adam

If you do find u-joint damage or bad driveshaft damage, don't drive your KJ at all until you get it fixed. Don't even try to drive it to the garage. It's not pretty when either of those fail.

ManicMechanicJoe · **Posted:** Sat Dec 03, 2005 4:23 am

I saw a guy at the drag strip tear the floor of his camaro out with his driveshaft when a U-join broke. I would definetly look at the U-joints for any play or slop before driving it. Also, take an angle gauge and measure various parts of each driveshaft to make sure everything is inline. It's amazing at how a slight bend in the driveshaft will shake all the nuts and bolts right off your Jeep.

JacksJeep · **Posted:** Sat Dec 03, 2005 5:32 am

I have had a similar experience twice. Both times I got a loud vibrating noise that I thought was the drivetrain. Both times it was that the engine skid got bent just enough that the exhaust pipe would touch it when it vibrated. If you have an engine skid (Skid Row, RRO), take a look and see if that is it. If it looks close to touching, loosen the front bolts so the skid drops a bit and try it. If the noise is gone, you found the problem.

(I am not saying the problem is not in the drivetrain. Just suggesting a less likely possibility to consider.)

bighause · **Posted:** Sat Dec 03, 2005 10:09 am

Thanks for all the help guys!

I checked all the U joints front and rear and they are still very tight. I am pretty sure the problem is the 2 bushings on the rack and pinion system. I got them out last night and one of them is really torn up. I could see grooves where it looks like it had been shaking back and forth on the frame where it mounts. Should have the new ones in tonight so we will see if that fixes it.

Hopefully you guys don't ever have to replace these, they are a pain in the butt to get to. I had to remove both lower control arms, drop the front axle down 2 inches and remove several other small pieces to have enough room to get the bushings out. So far it has taken me about 5 hours and 8 beers and I am only half way done! Guess that's the price you have to pay to play hard offroad.

bighause · **Posted:** Sat Dec 03, 2005 11:15 pm

Good news - I now know how to completely dissasemble the front suspension/axle assembly and I'm very familiar with how everything works now.

Bad news - The vibration is still there, but not as bad.

I am going to double check everything you guys recommended and then I guess I will take it in for repair. I would rather fix it myself if I just knew what it was :evil:

Thanks again for the help, anyone have any other ideas?

bootsers · **Posted:** Mon Dec 12, 2005 8:59 pm

Did you figure out what was wrong with your jeep? Mine is doing the same thing and heading to the dealer tomorrow.
Thanks
Vicki

bighause · **Posted:** Wed Dec 14, 2005 10:43 am

Not yet, at first they thought the wheels just needed to be rebalanced and rotated (I figured that wasn't the problem) but it didn't help at all. I have been on vacation the last 5 days so I am taking it back in today.

bootsers · **Posted:** Wed Dec 14, 2005 7:53 pm

When I arrived home this evening there was a message from the dealer saying the new rack they ordered will be in tomorrow. I am guessing they are replacing the rack and pinion? He didn't say anything about it not being covered under warranty so we will see what happens when I pick it up tomorrow.

bighause · **Posted:** Fri Dec 16, 2005 9:54 am

They replaced the rear u-joints since one of them had a hard impact mark on it, but it still vibrates. Decided to take off the front driveshaft and drive it and no more vibrations, it is as smooth as ever. The dealership said it is bent and needs to be replaced ($600 w/ labor), and way to tell if it is just out of balance? I can't imagine I bent the thing

Anyone thats done a SFA swap still have their front driveshaft they don't need anymore? :wink:

tniverth · **Posted:** Fri Dec 16, 2005 10:53 am

Does the drive shaft have a balancing weight? can you see any place that looks as if there was a weight and it got knocked off while wheeling?

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

bighause wrote:

They replaced the rear u-joints since one of them had a hard impact mark on it, but it still vibrates. Decided to take off the front driveshaft and drive it and no more vibrations, it is as smooth as ever. The dealership said it is bent and needs to be replaced ($600 w/ labor), and way to tell if it is just out of balance? I can't imagine I bent the thing

Anyone thats done a SFA swap still have their front driveshaft they don't need anymore? :wink:

Try Car-Part.com for some used late model takeoffs. Probably cheaper than 600 and you can do it yourself.

What did I break? ---I need a new front driveshaft---

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