Nick1994
$100 site donor 2024
Prepare for a long one!
This is on my grandfather's 1996 Jeep Cherokee 4.0L 4x4 136k miles with the trac-lock limited slip rear-end (Dana 35). The noise is a roaring, droning type of noise. It sort of had a pulse to it. The pulse of the roaring noise fades in and out and each pulse has about 3-4 seconds in between. It's also a vibration that doesn't shake the Jeep but it sounds just like there's a subwoofer in the back just playing pure bass. The noise starts at about 60 mph and stays throughout any speed faster than that. I'm not sure where the direction of the noise is coming from but it sounds louder when in the back seat. It has brand new U-joints for the rear driveshaft (originally thought that was the problem). I changed the front differential oil to Mobil 1 75w90 and the rear to Mobil 1 75w140 (incase the Jeep tows, I found it recommended online). Both oils have the limited slip additive. At the same time the transfercase and transmission were drained and filled with MaxLife ATF. I changed all of these oils 1 month ago. The noise started probably 1 1/2 years ago and it seems to be getting louder, the new fluids made no difference. The noise seems to get louder after driving a long distance on the highway, Saturday we drove it about 110 miles out to the desert and when leaving at the gas station I did a u-turn and there was a howling noise in the rear although it is possible it could be the drum brakes in the rear are over-adjusted and rubbing on the turn(my brothers jeep did this). I will adjust them tomorrow to be less.
I'm thinking it is the rear axle, Perhaps some bearings are worn or something. When replacing the diff-fluid, it didn't look too out of the ordinary, it was quite dirty in the rear but it didn't seem silver to me. The front was pretty clean.
Another thing I need to add is that when doing U-turns it seems like the rear end locks up both wheels and activates the limited slip. I'm also wondering if it is stuck or activates on the limited slip while driving straight down the highway, thus creating the noise.
Tomorrow (Monday) I will get out the jack stands and jack and do some tests. I will check for play in the front wheels to check for wheel bearing play and will adjust the rear brakes to not be so tight (not sure how to word that lol). I'm also going to put the rear on jack stands and put it in drive to see if a tire is wobbling.
I want to make sure it is reliable and safe as when driven on the interstate out of town every 2 months or so it is at 80 mph for 200 miles round trip on the interstate.
This Jeep was owned from new to 100,000 miles by the Arizona Department of Transportation, not sure what they did with it but it has a faded circle on the roof and screws to where a round orange siren was. I assume it was maintained fairly well. My grandfather has owned it since April 2007 and the last 36k miles and has had it's oil changed every 3,000-3,500 miles and maintained well. It does go offroad on some rough dirt roads and does some 4-wheeling. It has always had matching sets of tires since he has owned it, and it currently has a set of 1 year old BFGoodrich All Terrains with about 4,000 miles on them in 235/75-15 size. I have had them rotated and balanced and it made no difference.
Any help is greatly appreciated.
This is on my grandfather's 1996 Jeep Cherokee 4.0L 4x4 136k miles with the trac-lock limited slip rear-end (Dana 35). The noise is a roaring, droning type of noise. It sort of had a pulse to it. The pulse of the roaring noise fades in and out and each pulse has about 3-4 seconds in between. It's also a vibration that doesn't shake the Jeep but it sounds just like there's a subwoofer in the back just playing pure bass. The noise starts at about 60 mph and stays throughout any speed faster than that. I'm not sure where the direction of the noise is coming from but it sounds louder when in the back seat. It has brand new U-joints for the rear driveshaft (originally thought that was the problem). I changed the front differential oil to Mobil 1 75w90 and the rear to Mobil 1 75w140 (incase the Jeep tows, I found it recommended online). Both oils have the limited slip additive. At the same time the transfercase and transmission were drained and filled with MaxLife ATF. I changed all of these oils 1 month ago. The noise started probably 1 1/2 years ago and it seems to be getting louder, the new fluids made no difference. The noise seems to get louder after driving a long distance on the highway, Saturday we drove it about 110 miles out to the desert and when leaving at the gas station I did a u-turn and there was a howling noise in the rear although it is possible it could be the drum brakes in the rear are over-adjusted and rubbing on the turn(my brothers jeep did this). I will adjust them tomorrow to be less.
I'm thinking it is the rear axle, Perhaps some bearings are worn or something. When replacing the diff-fluid, it didn't look too out of the ordinary, it was quite dirty in the rear but it didn't seem silver to me. The front was pretty clean.
Another thing I need to add is that when doing U-turns it seems like the rear end locks up both wheels and activates the limited slip. I'm also wondering if it is stuck or activates on the limited slip while driving straight down the highway, thus creating the noise.
Tomorrow (Monday) I will get out the jack stands and jack and do some tests. I will check for play in the front wheels to check for wheel bearing play and will adjust the rear brakes to not be so tight (not sure how to word that lol). I'm also going to put the rear on jack stands and put it in drive to see if a tire is wobbling.
I want to make sure it is reliable and safe as when driven on the interstate out of town every 2 months or so it is at 80 mph for 200 miles round trip on the interstate.
This Jeep was owned from new to 100,000 miles by the Arizona Department of Transportation, not sure what they did with it but it has a faded circle on the roof and screws to where a round orange siren was. I assume it was maintained fairly well. My grandfather has owned it since April 2007 and the last 36k miles and has had it's oil changed every 3,000-3,500 miles and maintained well. It does go offroad on some rough dirt roads and does some 4-wheeling. It has always had matching sets of tires since he has owned it, and it currently has a set of 1 year old BFGoodrich All Terrains with about 4,000 miles on them in 235/75-15 size. I have had them rotated and balanced and it made no difference.
Any help is greatly appreciated.