Chevy & GMC Vans

I have recently noticed a low frequency sound which I can best describe as a rumble as there really is not noticable vibration with it, happening about 60MPH (100KPH) It disappears when the van slows down and at city speeds I hear nothing. The rear brakes have been grabbing lately as well, although I can't say if the sound has started concurrent with the rear brakes grabbing. I am wondering is anyone has any ideas of what I can check and how to find the cause of this. On the positive side, it keeps me driving 55 most of the time even though it is not very loud, it is loud enough to annoy me though.

check tire inflation. Also look for cupping on the tires or uneven or funny wear patterns. Also check the back brakes and make sure they are not rubbing. At 60mph they would be making some heat and warming up the rims. Take it for a burn down the highway for a mile or 2 then stop and feel the rims if they are cool life is good if they are warm then you are dragging a brake.

Rear brakes grabbing is usually a symptom of rearend lube leaking past the seals. The rumbling could be an axle bearing in self destruct mode which could be the cause of the seal failure.

That is one of the things I was concerned about. I don't think I would be up to doing the rear bearings. Axle seals were done a couple of years back and did not leak, but I will have to check if they are leaking or not. While there, how do I check the rear bearings, and what do I need to change them?

When you remove the drums move the axle fore and aft and up and down. There should be no play. Also rotate the axle. It should feel smooth. To replace the bearings you'll need to remove the rear cover, remove the pinion shaft, push the axle in toward the center and remove the 'C' clip. Then you just pull it out of the housing. To pull the bearings out you will need a puller of some sort. I use a slide hammer with a three arm puller attached to it. They usually come out in pieces. To install the new bearings use a socket close to the same OD and tap them in.

That doesn't sound so bad. I will have to check them. Hopefully if it the bearings the axle shafts are not damaged or worn. I don't have a slide hammer, so I will have to see if the loan a tool program at Canadian Tire has anything I can borrow.

If you drive on a failed rear wheel bearing very long, you will most likely need to either replace the shaft, or get one of the Timken "Axle Saver" offset bearing/seal deals.
I would opt for the new shaft over the offset bearing, they don't seem to last real long. I don't know if there is a speedy sleeve for the axle or not.

I have a nifty slide hammer and a set of attachments that go into the axle housing and turn 90 degrees and when you pull it out (with the slide hammer) it brings the bearing with it. I got it at Auto Zone, rented it without ever taking it back. The Manager said that was OK, just to let them know so they could get another one.

I always replace the little bolt that holds the shaft in the carrier, and loctite it when installing. You need a 6 point 8mm ot 5/16" wrench to remove the bolt. I pack the rear wheel bearing with grease and grease the seal for break-in reasons. Prolly not needed, but makes me feel good. I grease the splines on the axle also. This also helps on reinstalling the C clips.

My opinions and experiences, others may feel different, I'm cool with that.

Rileysowner wrote: I don't have a slide hammer

i happened to pick up a slide hammer kit for that exact job along with some other tools for it your welcome to borrow them if you don't mind me watching the job lol it'll make the attack on my rear easier if i see someone else's

The thing is I have no idea how long I have driven on it with the bearings going. I don't usually drive much over the limit which around here is less than where the rumble shows up. The rear brakes started grabbing when I started a trip to Harrisburg and back, so if they were starting to go before that, they have been driven a bunch of miles.

Where does one get the pinion locking bolt? None of the parts places around here carry them. Are they dealership only?

Before you go an plan for a rear end rebuild, how about start with rotating/checking tires and then clean out the rear drums. If you have a rear brake grabbing you either have a lot of wet brake dust from humidity or rain, you have a leaking axle seal or you have a wheel cylinder leaking. After these don't resolve the problem, then remove the rear diff cover and check fluid for contamination/metal flakes/etc. and look to either the pinion bearings going or an axle bearing bad. My money would be on the pinion bearings before the axle bearings.

I had a low rumble at about the same speed. Mine turned out to be the U-joint!

Lifted, thanks for the check list. It is things like that which are why I post when I have no idea what is causing something. I haven't had time to check things, but when I do I will check those as well. I am due for a rotation of the tires anyway, but a quick visual inspection seems to have them looking good, but I know unless I take them off, or have the van up on a hoist (only happens if I visit my BIL) there can be tire problems that can't easily be seen.

I can't imagine doing a rear end rebuild. If I had someone closer who 1) Had the tools and 2) Had the experience I would be interested in doing it. As far as I know I don't :(

I was out in the van today and in the morning I heard it. In the evening coming home I didn't. This is just weird. I will have to try what Lifted suggested, but when I have the tires off I will check for play in the rear hubs.

I started to look into this today, I took off the drivers side wheel, pulled off the brake drum and tried moving the axle up and down right and left and rotating it. It was very difficult to rotate so I thought I would check the other side. I removed the lug nuts, but could not get the wheel off. When rotated there is noise but is sounds like it is in the drum, but try as I might I cannot get the wheel off. Then I noticed that when rotating that tire, it was rotating the hub on the other side. I have a fully open diff, and I don't know if that is normal or not, but it seemed strange to me. Seeing as no matter how hard I kicked, whacked with a rubber mallet or pulled, that wheel would not budge. I may just have to take it in and have someone else look at it.

try bouncing a 12lbs sledge hammer off the rubber a few times. My 89 and 90 vans the rims would stick to the front disks so hard it took me over an hour of hitting the tire to get it to come loose one day.