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-   -   TJ groans upon acceleration (http://www.wranglerforum.com/f282/tj-groans-upon-acceleration-114223.html)

Awood9000 09-22-2011 10:41 PM

TJ groans upon acceleration
 
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.

MikalCarbine 09-23-2011 12:26 AM

Could be the gears in the rear differential?

TLATEOTW 09-23-2011 02:42 AM

i had that, it was a bearing in the clutch

Awood9000 09-23-2011 03:41 PM

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?

Shoe 09-23-2011 03:49 PM

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.

sevenservices 09-23-2011 03:54 PM

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.

Awood9000 09-24-2011 07:09 PM

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.

Awood9000 09-24-2011 07:13 PM

Just for clarification the sound is similar to a binding up kind of a noise-- d-d-d-D-D-DUT- DUT-DUT-DUT.... That about as close as I cancget to what it sounds like. Lol

Awood9000 09-24-2011 09:25 PM

Performed SevenServices test...
 
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? :confused:

Shoe 09-24-2011 11:28 PM

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.

Awood9000 09-25-2011 03:01 PM

Thanks Shoe - I'll give that a try first and see of that takes care of the issue...

00tj2 09-25-2011 05:41 PM

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?

Awood9000 09-25-2011 10:08 PM

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...

00tj2 09-26-2011 10:24 AM

Same thing as mine. But it only happens when no one else is in with me to hear it... Haha. Let us know what you find. I will be taking apart my rear drums to check everything out too.

Awood9000 10-02-2011 10:42 PM

So opened up the rear end and low and behold - teath are missing off the spider gears. So had it all cleaned out andnew gears put in, and all is well now...

On to replacing the lower bushings on the Rubicon long arm system....

Jeepzjlover 11-14-2011 12:13 AM

You solved your problem and I haven't taken mine apart but I'm having the same one. Did tempature make a difference with yours? Mine gets worse the more it gets driven like highway and stuff


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