88 xj - 4 wheel drive clunk and jerk at 35 mph and over
02-03-2017, 11:57 PM
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88 xj - 4 wheel drive clunk and jerk at 35 mph and over
hey,
88 xj drives fine in 2 wheel drive (no hum) but when in 4 wheel drive going 30 mph or slower hearing a humming noise (i cant locate where its coming from since i only hear it while driving). once i speed up over 30 mph and reach 35 there is a sudden jerk and a clunk coming from underneath the jeep.
4.0 i6 np231 dana 30 and dana 35c both 3:55 ratio (fluid has been flushed and changed on all of these)
tires: 3: 225/75/15 and 1: 235/75/15 (i know its not matching but its just width my opinion that shouldnt matter, 2 rear tires are 225 and front left is 225 and front right is 235) am i wrong on this, might this be the issue ?
i read some about the humming noise usually its a bearing going bad but i dont know for sure. were in alaska and driving on icey roads, at this time i cant do a whole lot until winter has passed but just curious what to look for.. any idea ?
thanks, marc
88 xj drives fine in 2 wheel drive (no hum) but when in 4 wheel drive going 30 mph or slower hearing a humming noise (i cant locate where its coming from since i only hear it while driving). once i speed up over 30 mph and reach 35 there is a sudden jerk and a clunk coming from underneath the jeep.
4.0 i6 np231 dana 30 and dana 35c both 3:55 ratio (fluid has been flushed and changed on all of these)
tires: 3: 225/75/15 and 1: 235/75/15 (i know its not matching but its just width my opinion that shouldnt matter, 2 rear tires are 225 and front left is 225 and front right is 235) am i wrong on this, might this be the issue ?
i read some about the humming noise usually its a bearing going bad but i dont know for sure. were in alaska and driving on icey roads, at this time i cant do a whole lot until winter has passed but just curious what to look for.. any idea ?
thanks, marc
02-04-2017, 07:45 AM
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hey,
88 xj drives fine in 2 wheel drive (no hum) but when in 4 wheel drive going 30 mph or slower hearing a humming noise (i cant locate where its coming from since i only hear it while driving). once i speed up over 30 mph and reach 35 there is a sudden jerk and a clunk coming from underneath the jeep.
4.0 i6 np231 dana 30 and dana 35c both 3:55 ratio (fluid has been flushed and changed on all of these)
tires: 3: 225/75/15 and 1: 235/75/15 (i know its not matching but its just width my opinion that shouldnt matter, 2 rear tires are 225 and front left is 225 and front right is 235) am i wrong on this, might this be the issue ?
i read some about the humming noise usually its a bearing going bad but i dont know for sure. were in alaska and driving on icey roads, at this time i cant do a whole lot until winter has passed but just curious what to look for.. any idea ?
thanks, marc
88 xj drives fine in 2 wheel drive (no hum) but when in 4 wheel drive going 30 mph or slower hearing a humming noise (i cant locate where its coming from since i only hear it while driving). once i speed up over 30 mph and reach 35 there is a sudden jerk and a clunk coming from underneath the jeep.
4.0 i6 np231 dana 30 and dana 35c both 3:55 ratio (fluid has been flushed and changed on all of these)
tires: 3: 225/75/15 and 1: 235/75/15 (i know its not matching but its just width my opinion that shouldnt matter, 2 rear tires are 225 and front left is 225 and front right is 235) am i wrong on this, might this be the issue ?
i read some about the humming noise usually its a bearing going bad but i dont know for sure. were in alaska and driving on icey roads, at this time i cant do a whole lot until winter has passed but just curious what to look for.. any idea ?
thanks, marc
Front AXLE U joints binding?
To me an NP231 is noisier in 4WD mode than 2WD....Kinda whiney sounding.
02-04-2017, 12:10 PM
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Hi LadyKenai, Awesome to here from AK. My son lives just south of Fairbanks. While I can't say for sure the tires are the issue they certainly could be. Tire sizes are a ratio. The easiest way to think of them is to consider them percentages. For example 225/75/15 If the tread width is 225 units wide then the second number is the ratio of the sidewall in proportion to the width. So the sidewall is 75% as tall as the tread is wide. Now compare that to the 235/75/15. You are starting with a tread width that is wider to begin with. Therefore the sidewall will be taller at the end of the ratio calculation. I.E. the tire is taller making the distance it travels during one revolution a longer distance then the shorter tire. What you end with is one tire spinning faster than the other. Above 35 mph that could be an issue causing the front axle to jam up and skip until the tires reach the same spinning speed again.
Man that's confusing. But I think you have answered your own question. Good luck.
Man that's confusing. But I think you have answered your own question. Good luck.
02-05-2017, 07:55 PM
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thank you for the replies,
engine mounts and transmission mount have been replaced last summer, transmission and transfer case have new fresh ATF aswell. U-joints are two summers old im pretty sure they are good and thanks for confirming the np231 is a bit noisy (the hum/whiney noise doesnt sounds too bad)
the tire size i thought that was a fixed meassure didnt realize it is in percantage of the width, you explained it good all makes sense. my spare is a 225 but not a matching rim i will put that one on and see if there will be any change.
marc
engine mounts and transmission mount have been replaced last summer, transmission and transfer case have new fresh ATF aswell. U-joints are two summers old im pretty sure they are good and thanks for confirming the np231 is a bit noisy (the hum/whiney noise doesnt sounds too bad)
the tire size i thought that was a fixed meassure didnt realize it is in percantage of the width, you explained it good all makes sense. my spare is a 225 but not a matching rim i will put that one on and see if there will be any change.
marc
Last edited by LadyKenai; 02-05-2017 at 07:59 PM.
02-20-2017, 11:24 PM
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ok i managed to put the spare on with all matching tires now 225/75/15 but didnt take it up to 40 or 45 yet will let you know how that goes. of course something else broke while trying to fix one thing
https://www.cherokeeforum.com/f2/88-...-broke-233499/
https://www.cherokeeforum.com/f2/88-...-broke-233499/