Author Topic: a knocking noise only when gear is engaged...  (Read 5758 times)

Red02TJ

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a knocking noise only when gear is engaged...
« on: June 12, 2011, 12:35:11 am »
my jeep is a 2002 tj, 4.0l, 5 speed, 4" lift, 33" tires, d30 spartan locker. last week, i was going through a round-a-bout in 3rd gear and heard a clunking/knocking noise coming from underneath around the tranny area. i placed it in neutral (noise went away) and i slowed down. i then downshifted to 2nd and released the clutch and the noise came back. so i pulled off the road and stopped. when i shifted to 1st and released the clutch, the noise returned. so i had aaa tow it back to my house.


when i got home, i drove down my street. 1st gear with clutch engaged and noise was there. i shifted to 2nd, noise went away during the shift but returned once in gear. the noise frequency is based on vehicle speed, not engine speed. so i tried starting in 4th, and the noise was still there. throughout this troubleshooting, with the clutch depressed i noticed the noise was a 2-3 on a scale of 10. when in gear and clutch released, the noise was a 8-9.


the driveshaft u-joints look okay and so do the axle u-joints. i'm leaning towards u-joints or axle bearings in the front. i plan on changing the clutch since it's still the original one with 87k miles, so that will give me a chance to checkout the tranny and t-case. any help is greatly appreciated. thanks.
Larry Padre

hillbilly

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Re: a knocking noise only when gear is engaged...
« Reply #1 on: June 12, 2011, 01:15:26 pm »
if its clutch related it could be a pilot or throwout bearing or a ujoint.
build it, beat it, break it, fix it, repeat
A member of the church requests to be buried in his jeep because "It ain't never been in a hole it couldn't get out of."
   91 xj 8.5" lift -33" x 12.50 and my own additions
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(Tattoo) Jack

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Re: a knocking noise only when gear is engaged...
« Reply #2 on: June 12, 2011, 04:26:42 pm »
    Just my opinion, but front transmission gears/input shaft turn congruent with engine speed, and related rear gears sets/output shaft (including DS, axle shafts, etc.) turn in relationship to road speed.

    Translation: I’ll go with DS U-Joints. Front Axle U-Joints usually only clunk when you turn the wheel sharp and/or when under power, i.e., 4 wheel drive.

 
   Of course, this is only MY opinion and it is subject to change or correction…   :P


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Red02TJ

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Re: a knocking noise only when gear is engaged...
« Reply #3 on: June 12, 2011, 05:12:48 pm »
thanks, jack and hillbilly!!!
Larry Padre