Need Help

[jimbosz07]

Ready for a story? Here goes… Over the summer I yanked my front axle and took it down to Rear End Specialties in Santa Clara to have it regeared. I brought them all the parts (Motive gears, a 3.73 and up carrier, and a master install kit with Timken bearing and National seals, all of it brand new). After the install, I brought it home and threw it back under my Jeep. Everything was perfectly fine until about 300 miles later. My axle seals started leaking out the sides. I drove it back down to them and they replaced the seals (they charged me too). When I went to drive away from their shop, I noticed a steady thunking noise coming from what I thought was the front end. I pulled back up and they said it was a burr in the ring gear, cracked it back open, and ground any possible burrs smooth. Nothing changed so they told me to just drive it and it would either rub something until it got polished and I’d notice it, or clearance itself (great advice!)

I just went back down there last week because I was sick of it. They jacked it up and ran it in 4 wheel drive, but were unable to replicate the noise. They told me my transfer case was shot and that was causing the noise. When I asked them to take responsibility and pay for a replacement they told me to go fly a kite. I was infuriated, but went out and found another transfer case and swapped it in over the weekend. Now I have a newer transfer case that is all fine and dandy but nothing changed.

Here’s the problem: while driving at slower speeds (under 30) you can hear/feel a steady thunk, thunk, thunk varying with tire speed. Above 30 mph and road noise (exhaust, tire howl, etc) makes it impossible to hear. It makes the noise with or without a front driveshaft in and it is definitely easier to hear when the windows are up. The noise happens on both drive and coast. Yesterday I jacked up the rear and ran it in the air in RWD only. I was unable to replicate the noise. Using a broom handle as a stethoscope, I listened to my transmission, transfer case, and axle, and they all sounded fine.

I’m kinda stumped here guys. Any ideas?

 

[Letterman]

Sounds like your front axle has an issue, you could pull your axles and see if it is your unit bearings breaks etc. or your diff.

 

[crazymoose1990]

Dude that sucks customer service just is not what it use to be. I feel most of the time that I would rather learn how to do whatever needs to be done myself. Is it a disco axle or non. Everyone will want to know

 

[jeepme]

how are the u joints on the front axle??

 

[Alex E]

Nothing should clearance its self, I say check axle shafts and the unihubs. It could be possible the pinion depth is incorrect also. By any chance when you got the gears did you happen to look and see if they were a matched set? Even bran new gears have numbers on both of them indicating they are "a set". I know its more the installers job to check but you cant rely on anyone. Ive known lots of people who have had gears successfully installed there but I've also heard some pretty lame things about that place. They shouldnt have made you pay for the seals twice unless they notified you on the original install that the axle shafts had burrs and could cause the seals to go out, or something of the sort. I've done a lot of gear installs and they should never make noise. Is it an open carrier or something else? If its open did they reuse your old spider gears? Also the noise never started until they did the seals a second time correct?

 

[Alex E]

Now that I think of it, check the pattern. I bet when they pulled your carrier to replace the seals they just put everything back and assumed the pattern wouldnt change and it probably did. I bet they didnt recheck it.

 

[jimbosz07]

Ok so I know it is not my brakes, and I replaced the driver side unit bearing a few months ago because it went out. Definitely a different noise this time. The u joints are old but feel fine. I will be replacing them in a few days anyway though. I did not check to see if the gears were a matched set but they didn't have any problems before they redid the seals. I mentioned the pinion depth to them when i brought it in a second time and they either checked it or did a good job pretending to with me standing next to them... They checked the pattern and it was fine. It is an open carrier and they did reuse my old spider gears.

And to clarify, yes the noise started only after they redid the seals (second time they worked on it)

 

[Bryan C.]

Check for your breather tube rubbing on your front driveshaft.

 

[jimbosz07]

Nope breather tube is nowhere near the shaft. It's more of a solid metal on metal type of thunking also. And it happens with and without a front driveshaft in

Oh and it's the stock non-disco from 1996

 

[knucklehead 61]

try pulling one axle shaft at a time out & running around the block to help isolate the noise. possibly you killed a u joint. if both axles are out & it still makes noise then the problem is in the unit bearings or brakes, not the carrier.

 

[Alex E]

Does it sound like it comes from a particular side or not really? If you raise the front end and turn the yoke does it feel smooth and consistant? Just for grins did you try rotating the tires front to back just to eliminate the basics? Common sense would say its the axle or something if they touched it and now its got problems. hmm...it would be interesting to hear the noise.

 

[jimbosz07]

That is an amazing idea. I never thought of that. Thanks Tim

It kinda sounds like it is coming from the driver side but I can't be sure since I never really ride in the passenger seat. Haven't rotated the tires (don't really see how that could change anything), but I have had them off. Either tomorrow or Friday I will test the feeling of the yoke when it spins and try driving it without the shafts. Thanks for all your ideas guys

 

[knucklehead 61]

if the axle u joints are toast i have a spare set of axles for you.

 

[jimbosz07]

My friend works at Kragen's and is actually gonna grab me a pair of 5-760x joints but thanks anyway. That way even if they aren't shot I'll have new, beefier joints

 

[XJensen]

try pulling one axle shaft at a time out & running around the block to help isolate the noise. possibly you killed a u joint. if both axles are out & it still makes noise then the problem is in the unit bearings or brakes, not the carrier.

Is it safe to say the unit bearings will be fine just around the block without at least the stub shaft in? It was my understanding that they would die quickly without the support of the stub.

Just curious if there is a rule of thumb to follow.

Thanks
Josh

 

[jimbosz07]

That's actually a really good question. I know that if you don't torque those hub bolts properly the wheels bearings end up not having the correct pressure on them and prematurely fail. Without the shaft or any torque on them might do some damage

 

[knucklehead 61]

don't go wheelin' without the axles, just run around the block to listen for the noise issue.

 

[Bryan C.]

Is it safe to say the unit bearings will be fine just around the block without at least the stub shaft in? It was my understanding that they would die quickly without the support of the stub.

Just curious if there is a rule of thumb to follow.

Thanks
Josh

don't go wheelin' without the axles, just run around the block to listen for the noise issue.

I wouldn't bet on that. The bearings are lightly pressed together, the press fit is not strong enough to hold them together for very long at all. I wouldn't do it.

 

[jimbosz07]

I think what I'll do just to be one the safe side is do this when I change my u-joints. I'll run it with just the short outer shafts on the vehicle so the bearings will be fine, but the carrier won't spin

 

[knucklehead 61]

do 2 wd front axles use a different unit bearing? i kinda figured it was the same one & okey dokey to run without a shaft. i really have no clue.