post #1 of Old 12-17-2014, 03:35 PM Thread Starter
bigwave
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New (used) trany in now rear vibration at take-off

Ok, I just put in a new transmission in my 1998 jeep grand Cherokee, all stock, and now when I try to quickly accelerate from a dead stop the rear end vibrates, all most like wheel hop, but more in the drive train. If rolling or moving slowly and punching it, it does not do it, or very little. It's like the vibration you get from a misaligned rear drive shaft on a lifted jeep. But this one is not lifted and all stock. What do you all think?
Rear bushings, rear shocks, U-Joints ?? Anyone??
Thanks

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post #2 of Old 12-17-2014, 04:47 PM
Technohead
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The only thing that changed was the transmission?
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post #3 of Old 12-17-2014, 05:01 PM
jorhay
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I had the same symptoms in my zj a couple years ago. Took it to a trans shop and ended up with a rebuild on it.
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post #4 of Old 12-17-2014, 06:19 PM
Taz360ZJ
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bad trans mount?

'93 ZJ SE/Base Model/Sport/5.9 LTD clone.
Both built 5.9's have been sold & now rolled.
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post #5 of Old 12-17-2014, 10:30 PM
monte350
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did you mark the driveshafts in relation to the yokes on the front and rear ends? something I was always told to do by my mechanic uncles and teachers or you could end up with a vibration.

1995 Cherokee(XJ)-Rolled it
1998 Grand Cherokee(ZJ)-Sold it
1997 Grand Cherokee(ZJ)-DD
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post #6 of Old 12-17-2014, 11:35 PM Thread Starter
bigwave
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Darn it, anyway, any more ideas

Well, heck, I put new rear shocks, changed most of the rear bushings on sway bar, pulled the rear drive shaft back off cleaned up the joint and put it back on. U-Joint feels good and solid. No go, still doing same thing. I had a fellow with allot of experience ride with me and we did several "tests" and he thinks it's something in the rear. It does it if shifted to low1 or in drive, I can brake torque it and it will spin the rear tires with no vibrations or problems. I can put in reverse and punch it and no vibrations. Drove it 100 miles today on highway and interstate ran great and no problems at any speed. Just from a dead stop if I punch it, it almost jumps in the rear but tires are not spinning but it reminds me of wheel hop you get from a sports car or something similar. Anymore ideas??
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post #7 of Old 12-18-2014, 05:47 PM
Taz360ZJ
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wheel out of balance or out of round?

'93 ZJ SE/Base Model/Sport/5.9 LTD clone.
Both built 5.9's have been sold & now rolled.
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post #8 of Old 12-19-2014, 07:27 AM Thread Starter
bigwave
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Almost can't be a "balance thing" because it does not do it at any speed. Only at take off from dead stop. I can see the rear end vibrating at take off, I can see the rear control arms moving up and down, I replaced one sides bushings last night and it did not help. I thought for sure it was the control arm bushings by the way it looked.
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post #9 of Old 12-19-2014, 08:40 PM
Taz360ZJ
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bell housing bolts tight? flex plate bolts tight? you sure it's not the trans mount? motor mounts?

FWIW I had a bone stock 1999 XJ Classic with the 4.0, AW4, 231, as stated....no mods..bone stock. under hard acceleration from a dead stop, no wheel spin, it had this drive line vibration, only under HARD acceleration. that turned in to drive line vibes when I lifted it. eventually went SYE and that cured everything.

'93 ZJ SE/Base Model/Sport/5.9 LTD clone.
Both built 5.9's have been sold & now rolled.
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post #10 of Old 12-22-2014, 07:19 AM Thread Starter
bigwave
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Still looking Darnit,

OK, for those following I have removed the rear drive shaft to finally prove yes or no on the rear end. It's a big NO, it does the same strange vibes in 4-wd and no rear axel even attached. I just put in 4wd and went forward and backward on my driveway 50' but that was enough. Once again the whole transmission transfercase, drive shaft(s) just jump up and down. I'm now wondering maybe transmission mount on cross bar frame mount?? Darn this stinks, it was not doing this before swapping out tranny. And still only from a dead stop and hard acceleration. Transmission shifts and acts wonderfully going down the road. Only kind of strange thing is it seems to take a second longer than before to go into drive when you shift the shifter, I wonder if that could be an adjustment. Because when first in the jeep would not start in park due to shifter adjustment. But, I'm not even worried about that one yet.
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post #11 of Old 12-22-2014, 10:07 AM
Marcos
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What about trying it with no front driveshaft instead?
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post #12 of Old 12-22-2014, 10:30 AM Thread Starter
bigwave
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Haven't tried that one yet.

Quote:
Originally Posted by Marcos View Post
What about trying it with no front driveshaft instead?
I haven't tried that one yet. I think my next move is going to be to throw the floor jack under the tranny / Transfer case area and gently move it up and down and look for possible movement, perhaps that will tell me if a mount is bad.
Next step after that may be, sledge hammer, and TNT. Just the song, the other stuff is not legal.
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