So the strangest thing - just bought a 99 Wrangler with a 4.5 Rubicon longbar system and some big 35s on it. Me and my 2 son's first Jeep experience. the TJ Wasnt running when we bought it, so we R&Red the engine and the clutch and now we can drive it. Issue is, when i take off in first gear, a low groaning sound is comes from the back end of the Jeep. It goes away as you accelerate, and I know for sure I need to replace the shocks and lower control arm lower bushings... could that be where the sound is coming from? it only occurs upon acceleration or backing up.
So I looked at the rear dif - and there is some blue gasket sealer all around the cover - in addition to the gasket... so I know nothing about rear diferentials - how will i know if there is an issue in the event i pull the cover off?
If it has a lilmited slip differential, it could need the friction modifier added. Mine made some funny noises before I changed the fliud, and now it is quiet.
It only happened when I would start to move, and more so if I was turning a liitle.
easier than pulling the cover... jack up the rear end so both rear tires are off the ground. (with the front ones blocked so it doesnt roll) and spin the tire by hand. W/a posi rear end they will turn together. W/a semi slip rear dif. one will spin forward while the other spins backward. Regardless of which way they spin you should able to feel the gears splining together if there is any trouble in there.
It should spin easy and smooth and not feel like its growling in there. If you spin the tire slowly and you DO feel the gears meshing together like (bump bump bump bump bump) then they might need to be looked at or they could be dry from a rear dif. leak. In that case, pull the cover and check it out (with a pan under it, hehe...)
If you do not feel any resistance at all and the gears seem to be meshing together just fine then I would look elseware like clutch, throwout bearing, mis-alligned tires, etc...
Oh, that reminds me... you know how the front tires in 4 wheel drive will growl and jump on corners right, in my jeep I have a full locked posi rear end and it causes my back tires to growl around corners. Because of that I have to keep up on my tire rotations so I don't chew 'em up faster. If this happens to be your issue, it would only make the sounds on a corner and not while taking off straight.
So, not sure what it means, but I had my wife drive while I stood beside and listened and looked. She started out in reverse slowly turning towards the drivers right hand side. I heard the "sound" I was looking for-- the right rear wheel and tire were making a small but distinct jerking noise as she slowly moved the Jeep backwards. Taking off forward in first gear slowly- I heard and saw the same thing again. not really sure what it means- sounds similar to what Shoe was saying. am about to try what Sevenservices said about raising the rear end and spinning the tires.
So I did what you saif to do Seven - spinning the right tire (passenger rear) forward and backward the action was pretty smooth - no strage noises or anything, and drivers side tire rotates in opposite direction of passenger tire. Spinning driver side tire forward and backward is not so smooth - not really rough, but a noticible difference between the two sides. Also, when turning the wheel, the passenger side tire doesnt turn at all. Advice?
For $20 you can change the diff oil to synthetic with the friction modifier added. That would be the cheapest and easiest place to start.
Mine sounded a lot like you describe, like a rubber on rubber sound.
i have a similar issue every now n then when i am starting out while making a slight left turn. i went under and saw that my rear sway bar link bushing was not there anymore so that was some movement. i still dont think that should be making any type of noise but it might be something to check out. also, does it make the noise the constantly or just under initial acceleration?
I know a lot of things, most of them are only correct in my own head...
Better to be judged by twelve then carried by six. I'm sure this is going to get me in trouble down the line
not constantly - when i get up to speed it goes away. happens when i am starting out in first gear - usually from the right hand side of the jeep. both going forward and backward. Its more prominent when i am making a slight turn-- moving forward or backward...