grinding noise

just put my lift on (RE 3.5 on a 99 sport) and havent done a t case drop or sye yet. when i let off the gas there is a sort of grinding noise, sounds like itscoming from driver's side axel area just below my feet.

I had something like that on my old '86. Soon after I added 3" to it, I got a noise under my feet, followed by the eventual lose of drive to the front axle. Ended up being the splines on the front drive shaft. The splines wore down and were slipping, causing the noise.

so how much will that be to get fixed?

Can't remember what a new one was. I know it was enough to make me buy a used one though!! I got one off our local jeep forum from someone who was parting out an XJ.

so you are pretty sure thats what it is? nothing an sye or driveshaft would fix? it only happens right when i let off the gas at about 40+ mph.

Crawl undernieth and give it a few good twists by hand. Maybe it's just a worn U-joint. Take a few minutes to look things over real good. Feel for slop in the CV part too.

alright thanks man, im on a budget as it is!

How's your front pinion angle?
I ask, because I just finished a 4.5" lift, and the "recommended" LCA angle was junk- I've had to adjust a few more times, just to get the front angle right. In the meantime, I trashed my front u-joint, because it rotates even thought I'm not in 4wd. I have the non-vaccuum axle.

If you have major noises, then I'd be prone to suspect that your front angle is fubar- try removing the front DS for a little while. Go and buy a new u-joint and put things back together carefully. I have adjustable LCA's, so I had to use a pipe-wrench and a floor jack to keep the front driveshaft from shifting when I was adjusting the front LCA's, but after a few "pull-in's", I finally found the happy medium between correct castor and pinion angle. Big Suprise, it didn't even closely match what the manufacturer recommended...

Rule of thumb I learned here, Pinion angle takes precedence over castor angle- which means that you're shooting for 6-7* of angle on castor. If that doesn't meet your needs in mating to your lift and pinion angle, then adjust to meet the "best possible" pinion angle, otherwise you'll be replacing U-Joints every other weekend, when the front end is in "use".

A cheap dregee scale, and a WHOLE LOT of patience is required. DO NOT get frustrated, and don't ignore the important noises- the truck is telling you what it wants, regardless of what others tell you- if you hear noises, then something is not right, and requires more study on YOUR part. Things get (or ARE) loose, and require your attention before more troubleshooting takes place.

The pinion should be pointed TOWARD the driveshaft, and that is the "perfect match" there. The rear is a different story, and requires it's OWN adjustment procedures- please look deeply into the "search" function, and weigh each opinion for what the writer is trying to tell you. I learned a lot there, but I don't nessesarily agree with EVERYTHING I read there.

No 2 Jeeps are the same- even from the very same make, model, and production line run list. My best friend and I have "identical" models, only 300 units different, but our lifts have required vastly different adjustments to make the very same modifications work.

Read, and experiment. Sorry if that sounds like a lame statement, but there's LOTS to learn here. Keep searching, and reading. I know it sounds lame, but I've read WAY too many posts of people who lifted like I did, and had "No issues, whatsoever".

As IF...

so how long am i talking i can drive on it like this? i completely understand it needs to be fixed, but im pretty limited as to what i can do and i dont want to screw everything up with the driveline and all. am i looking to buy anything, or just get it lined up correctly

Don't take chances- pull that front DL as soon as you can. If you lose the "noise", then you know where your problem is... and unless you desperately NEED the 4WD (like for winter use) then you have time to fix the issue at hand.

Do you have NEW lower and/or upper control arms? If so, then go BACK to those, and re-torque those bolts! Once a lift is installed, you might be able to drive 200 or so miles, before you need to RE-TORQUE those bolts. It's just he nature of the animal, sir. I had horrible "groaning" noises, before I went back this week, and "breaker-barred" EVERY single nut and bolt attachment point.

No more moaning or grunting from the springs, front or back, since I went back and muscled those bolts down!

I can't even begin to over-emphesize the checking of the front pinion angle- it's just SO EASY to screw up! The angle has to be AS GOOD AS POSSIBLE, in relation to your other front-end additions and adjustments!

My 2 cents.

anyone have a how to write up on all of this? i dont want to get myself over my head.!

Great timing, I just came here to ask what appears to be the same question. An intermittent grinding/growling noise that almost sounds like the tires rubbing the fenders, or running over rumble strips/warning holes on the side of some highways (whatever they are called). I get it most when I'm coasting at 40 to 50. I haven't been on the highway yet, I've only driving about 15 total miles since getting it back.

I just had a lift installed, RE 4.5" coils in front, 3.5" RE full leafs + shackle in rear, 1.25" TC drop, new lower control arms, etc. In searching for the source the shop found the front U joints were bad and replaced them, which didn't solve the issue.

If I grab and twist the front drive shaft should I be able to rotate it at all? The rear DS is solid, can't move it, but if I twist the front DS I can get it to wiggle a bit.

(not trying to hijack the thread, just providing more info and asking questions for what appears to be the same issue).

easy way to figure out if its coming from your front driveshaft. Take it off and drive without it on. Good excuse to change u joints anyways. I'm going to get it's your rear shaft and you need a T-case drop or SYE. Basically it's doing exactly what mine (and many others) did.

skeptic_always said:

Great timing, I just came here to ask what appears to be the same question. An intermittent grinding/growling noise that almost sounds like the tires rubbing the fenders, or running over rumble strips/warning holes on the side of some highways (whatever they are called). I get it most when I'm coasting at 40 to 50. I haven't been on the highway yet, I've only driving about 15 total miles since getting it back.

I just had a lift installed, RE 4.5" coils in front, 3.5" RE full leafs + shackle in rear, 1.5" TC drop, new lower control arms, etc. In searching for the source the shop found the front U joints were bad and replaced them, which didn't solve the issue.

If I grab and twist the front drive shaft should I be able to rotate it at all? The rear DS is solid, can't move it, but if I twist the front DS I can get it to wiggle a bit.

(not trying to hijack the thread, just providing more info and asking questions for what appears to be the same issue).

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It will have some play when not in 4WD. Put it in 4wd then see if it has any play, it should be as solid as the rear. Look at your u-joints though. If you pull the joints and twist the caps and find drag OR move them and find play then that may be one problem.

GirlScout1 said:

It will have some play when not in 4WD. Put it in 4wd then see if it has any play, it should be as solid as the rear. Look at your u-joints though. If you pull the joints and twist the caps and find drag OR move them and find play then that may be one problem.

Click to expand...

The shop replaced the u-joints today. I threw it in 4WD, backed out of the garage and pulled back in and the front DS is tight and wiggle free. It also doesn't seem to make a difference if I'm driving in 2WD or full-time 4, the growling noise is the same.

The sound is definately coming from the front drivers side, I can't imagine it being the rear DS.

sounds like you have the same problem as i have, so would a new tom ds work

It may sound like its coming from one area but be coming from a different. To me it sounds like it is the T-case and that you are going to need a SYE and shims. Also don't if you have adjustable UCA's theat can fix the front.

its just a 3.5 in lift. Im going to get the pinion angle checked and see if that it the problem, also going to be getting a tom woods and sye asap.

jeepinxj99 said:

its just a 3.5 in lift. Im going to get the pinion angle checked and see if that it the problem, also going to be getting a tom woods and sye asap.

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"it's just a 3.5" lift"...actually it's most likely more around 4.5" since it is still new and hasn't setteled yet. Not that it matters. It doesn't take much to change the angles to wear it's unnatural and starts causing the vibes. The rear DS was/is not designed to do that. The front one is a different story since it has a CV in it which allows for a little more. However even that needs to be set right (pinion pointing at the TC output). Also on the rear it is a slip on shaft-normally called the slip yoke- that gets alot of stress put on it when it is lifted. Anyways, i'm willing to bet thats where your noises are coming from. Mine did the exact same thing. Didn't feel it going around the block but the more above 35 mph I went the more you could tell.

I don't know how much you know about Jeeps and honestly it doesn't matter. If you are doing all your own work (not having a shop do it) thats great. Boards like this are great for learning but practical experience is the key. Two years ago I struggled to put on a BB, since then I have done EVERYTHING myself from axles to hubs to SYE and cutting the hell out of the body. AT least it let me justify getting alot of tools!

i just dont understand how the grinding noise under my feet could be from the rear...