project_renix

And it's not a normal jeep sound! It's not tire howl, it's not wind whistling around my dents. It happens above 30 miles per hour, and gets louder the faster you go.

The setup is an 87 cherocar
4.0
Aw4
Select-trac t-case
Dana 35
Dana 30
CAD is bypassed. I removed the broken fork and slid the collar over to lock the axle together.

Checked the wheel bearings and there is no play on either side.

Rear diff fluid is clean, front diff fluid is so so. Needs to be changed soon.

I haven't checked the t-case fluid yet, but it doesn't leak.

This howl is bugging me and quite frankly, it makes me nervous to drive it. Any help is appreciated! Please help, I mis driving my jeep!

Gauge

I had the same issue. Mine was actually pointing towards the left wheel hub assembly; I replaced it. Still had the howl. I replaced the right one and the howl went away. Mind you, both assemblies appeared fine when I checked them. They spun as they should, No play when checking to see if bearing were worn. And mine did the same... 30mph and above it would start to howl, the fast I went the louder it got.

Larry's XJ

Can you tell where the noise is coming from? Front, back, center?

project_renix

Its really hard to pinpoint cuz the jeep just echoes like a tin can, but from what I can hear, it sounds more like the middle.

RubberSideUp

If you have access to a GoPro or similar, you can single out the cause of the noise by moving to different locations. Where the sound is loudest, check the possible problem areas. Really helps with troubleshooting.

Larry's XJ

LOL @ "normal noise" and "tin can" Chasing a noise and vib myself.
Check TC fluid level, slop in out-put shafts, and drive shafts. Might be u-joint dried out and going bad. jmo

Turbo X_J

Pinion bearings.

project_renix

Which end of the jeep? Im assuming the rear... as it a d35...

XJ Sam

X2.... Or the carrier bearings on the diff case. Common on D35.

Pull the rear diff cover and let the fluid drain. If its getting louder and louder the faster you go, don't be surprised if you find some rollers from the bearing laying in the bottom of the diff housing.

If you do find rollers in the bottom of the housing, make sure you pull the entire diff unit out before ordering new parts. You might need a new open diff case as well if the carrier bearings have started dropping rollers.

project_renix

But wouldn't pinion bearings be noisy at all speeds?

XJ Sam

They will be to some degree, but not what you think.

Once a bearing has lost a few rollers, a low speed can sometimes still keep the bearing balanced to an extent. As you increase speed, the centrifugal force of the rotation will push the remaining rollers in the bearing together which will make it unbalanced. Once the bearing is unbalanced and you continue to add speed, you noise is going to get louder and louder as you have an unbalanced load on the bearing.

Think of having a hula hoop with a 1LB weight attached to it. As you rotate, its not going to rotate in a balanced motion because of the lopsided weight. Now think of your bearing losing a few rollers and the weight of the rest of the rollers coming together due to the force being applied. That's what eventually is happening when you hit a certain speed.

project_renix

Well, I've decided that it's time to scrap the 35. Now in search of a d2 code 8.8

XJ Sam

I would at least pull the diff pan and change the fluid. You will be able to tell if it is in fact the rear diff. We are all just posting on experience and what we have learned. We don't have the vehicle in front of us to properly diagnose. Its always best to verify yourself to figure out where the noise is coming from. We are here to provide suggestions and starting points.

There is always a possibility that it's not the rear diff. Anything is still possible at this point until it is verified. It would suck to swap in an 8.8 and still have the same noise you have now, only to find out it was something else other than the rear end. Start with the small cheap things first then work your way up. Fluid is inexpensive as well as a gasket.

If it turns out to be the rear end, I would definitely swap the axle if you can. I've rebuilt several D35's only to have them wear out again. Save the cash of rebuilding it if takes abuse and at least swap in the 8.25.

8.8 for my Jeep would be a waste of funds. I don't get into anything really crazy in my area where I need a bullet proof axle build. The 8.25 handles all of the abuse I can dish out at this point.

project_renix

I forgot to let everyone know that I did pull the differential cover yesterday evening, and did find that there were rollers in the diff. Where they shouldn't be.