Vibration / rattle at 20 & 40 mph

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SaharaNewbie

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Jun 6, 2021
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New at home mechanic here..I’ve done a few things to my 97 Sahara and am getting vibrations specifically around 20 & 40 mph.

I’ve so far done
-2” lift
-Replaced shocks & coils
-had transmission rebuilt
-replaced motor & transmission mount with polyurethane

any guesses off the bat for this vibrations? Thank you!
 
Yeah the polyurethane isn’t helping at all. But if the vibrations showed up after the 2” lift, it’s most likely the driveshaft. If not driveline, then tires.
 
A 2" suspension lift can cause vibrations due to it steepening the drivetrain angle. A 1" motor mount lift with rubber bushings or a 1" tcase drop can cure them by reducing the angle.

Polyurethane engine or transmission mounts will cause more vibrations since they are much stiffer and pass vibrations fare more readily than the factory rubber mounts do.
 
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Jerry Bransford said:
A 2" suspension lift can cause vibrations due to it steepening the drivetrain angle. A 1" motor mount lift with rubber bushings or a 1" tcase drop can cure them by reducing the angle.

Polyurethane engine or transmission mounts will cause more vibrations since they are much stiffer and pass vibrations fare more readily than the factory rubber mounts do.
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I’m guessing it’s the lift since the vibrations showed up before I changed the transmission/motor mounts and after the lift. But surely the polyurethane didn’t help lol. I’ll have to give a 1” motor mount a try. Thank you!
 
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SaharaNewbie said:
I’m guessing it’s the lift since the vibrations showed up before I changed the transmission/motor mounts and after the lift. But surely the polyurethane didn’t help lol. I’ll have to give a 1” motor mount a try. Thank you!
Click to expand...
I'd go for M.O.R.E. "Bombproof" 1" MML with rubber bushings kit, it's far better quality MML than Brown Dog's is. At the same time, since you're replacing the poly motor mounts I'd switch the transmission mounts back to rubber. Mixing poly and rubber motor and transmission mounts is not a good idea.
 
I have the same vibrations at 20-30 mph with 2 inch lift due to rear driveshaft. Mml lift and BL were installed before and didn't solve the issue. Ur gonna have to get the Sye and longer ds to fix the issue or drop the tcase
 
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