Looking for blind feedback on a rumble I'm experiencing before I get it checked out:

The silver piglet has 100K on her now, and I've experienced just about every front end issue aside from killing the front diff. Blown CV's. shafts, carrier bearings, hub/bearings, control arms, ball joints, etc.

First, I have brand new front CV/halfshafts, and a new Frankenlift installed (I figure I'm keeping her till she dies so it was time). I have Al's arms, and all new upper and lower Moogs. The rumble I'm describing occured before they were installed. I also just had a 100K tune-up/inspection by my old trusted mechanic and he found no anomolies (but I didn't have him look into this - I forgot).

2WD hard acceleration turning right (typical right turn entering traffic). (Edit - it does it straight ahead too) I feel a knocking from up front. Feels a little like the CV's, but it's a far deeper and bigger feeling. Otherwise things are smooth as burlap (she hasn't been silky for years).

4WD low, again hard acceleration but straight ahead (while on pavement for demonstration). The ship shudders and the knocking is loud and crazy. No me gusta.

I'm not an wiz at all when it comes to internal mechanics. My guesses are:

1. Engine mounts? Looked at the engine while in drive/reverse and on the brakes. You can see the engine torque over in each direction about the same amount. I have no reference to what should be a normal movement though. I experience no vibes, etc. in normal driving though, high or low speed.

2. Worn teeth on the front gears? Since everything spins even in 2WD, I figure this was possible.

3. Shot carrier bearings at the front diff housing? I had this before and it was evident at highway speeds. I'm not getting this now.

4. Prop shaft? Again it spins in 2WD. I've traced an annoying rattle to the prop shaft, but seems unlikely as the culprit. I'm going to pull it though, to see if I still feel it rumble in 2WD.

No issues with the tranny or transfer case to speak of.

Any thoughts?

Thanks,

Todd

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95 YJ 2.5" RE lift and 32's, Posi-Lock, 4.10's with a Tru-Trac up front, M8000 winch, CB, gear and what have you...
RIP: 02 KJ LE

No replies last time - maybe this time...

Well I had a new custom prop shaft installed and that solved #4.

I still have the same rumbles though. I think knocking is a better term to describe them. Anyway now I occasionally feel and hear it on engine start. This has me leaning more towards engine mounts. Would you agree?

Now that I'm used to it, the knocking occurs even while coasting through a right hand turn - completely off the gas. It doesn't do it on left hand turns at all. Nearly any straight ahead acceleration other than a crawl from a stop causes it as mentioned before. Also, I feel it when I go over a bumps while accelerating from a stop.

The suspension feels tight - I just had everything re-torqued. So I'm still convinced it's drivetrain related.

Any thoughts???

Thanks,

Todd

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95 YJ 2.5" RE lift and 32's, Posi-Lock, 4.10's with a Tru-Trac up front, M8000 winch, CB, gear and what have you...
RIP: 02 KJ LE

Todd,

It seems like the 4 low makes the knocking worse. This might be a big clue. Is the distribution of torque from the transfer case different in 4h vs 4 lo, I wonder? Is the very low speed of 4 low making the knocking sound from, say the transfer case, more noticable.

The right hand turn under no load means the left wheel is turning faster than the right, so it is the one spinning the front diff gears. Maybe this is another clue.

Difficult mystery !

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06 CRD LTD - Suncoast TC- Shift Kit - Spicer UJ - FRKNLIFT - F37 - Magnaflow - 22.0 City - 24@65MPH - Fumoto F-102 - AUX T Cooler - Tank Lift Pump

How often do you do 4LO testing on pavement? That may be your problem

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Have fun out there.

2003 Cactus Green Renegade w/ NP231 & NV3550
Al's 4th Gen UCAs
Custom 3.5" Lift
Rear DTT
Spidertraxed 245/75/16 Maxxis Bighorns

Do you have any side to side play in the half shafts?

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02 Liberty Limited
Silver Outside & Taupe Inside
Heated Seats, Sunroof & Infinity speakers
USA Spec I-Pod adaptor, Mopar Sub, Garmin GPS
Tow Package, Select-Trac
Rock Rails, Tow Hooks

Beepbeep, it was humorous: I was in the lot and put it in 4lo to test things. Sure enough I forgot where I was for a second and started to turn. After quickly stopping I smacked my self in the head and got out of 4 wheel drive. Even that slightest of a turn and I could feel things getting 'grindy' Don't try this at home kids!

Sleeve, I'll check for play - but I think I'm going to pull both CV/half shafts, then drive it to see if that generates some clues.

_________________
95 YJ 2.5" RE lift and 32's, Posi-Lock, 4.10's with a Tru-Trac up front, M8000 winch, CB, gear and what have you...
RIP: 02 KJ LE

Let us know what happends when you pull your half shafts.
I have reolaced front DS, rear DS both cv's and rear diff's. every thing was ok but now I am getting something like you are saying.

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2003 KJ Sport JEEPZILLA Edition
American Flag flying high
Frankenlift removed =(
Moabs and plenty of pin striping
Flexable people don't get bent out of shape!
Current MPG 6" to a gallon
L.O.S.T. # BL065211
www.ItAtYourHome.com

Update: Well in the end it turned out to just be a busted transmission mount. I had it replaced, so it's now nice and smooth and time to 'wheel. Yippee!

_________________
95 YJ 2.5" RE lift and 32's, Posi-Lock, 4.10's with a Tru-Trac up front, M8000 winch, CB, gear and what have you...
RIP: 02 KJ LE