Noisy rear axle...

Now that I have the motor sort of sorted out, and have the doghouse lid gasketed and insulated, I can hear all the more readily the noise that's coming from the rear of the drivetrain.

At least that seems to be where it's coming from. It is sort of a low pitched whirring sound. To me it sounds like bearing noise, which it could be. Could also be pinion gear in the differential, I gather. I got under there last night to check out the U-joints. The rear one has a little slop (it shouldn't have any) so I'm planning on replacing both tonight. But from what I've read online, the U-joints would cause vibration or clunking, but not the type of noise I'm hearing. It doesn't seem to vibrate much. The noise is there regardless of acceleration/deceleration, and is there if I just put the tranny into neutral and coast. Mostly it becomes noticible at speeds over 30 mph. Doesn't change if I turn the vehicle left or right, either. So I'm guessing rear wheel bearings.

After cleaning off 1/4" of oily road grime from the differential exterior, I noticed some blue silicone sealer around the cover and bolts. So I'm thinking it's been serviced once before, at least. Perhaps just to drain the oil, although I did find an oil filler plug, and it should be easy enough to stick a tube in there and suction out the old oil for a change. I doubt that the factory used blue silicone back in '67.

I'm wondering how hard it is to find a complete rear end (junked) for one of these vans. I understand this van was loosely based on the ChevyII. Would a ChevyII or Nova rear end of the same vintage bolt right on?

I also gather that this van (G10/20) has a semi-floating rear axle which appears to be relatively easy to replace the rear wheel bearings on (as compared to the full floating rear axle). Anybody tackled that job?

And if the axle is groovy, then what? New axle? Does GM still sell them?

PS-What a dumb design ;-)

Thanks! I understand that Autozone carries this product (or can order it). I gather that the kit includes the seal.

I replaced the front and rear U-joints after work today. The old rear one had some slop. The front one felt ok, but when I saw that it was missing its zerk fitting (there was just the open threaded hole where it was supposed to go) I decided to replace that as well. No sign of U joint failure but I suppose it can be hard to tell sometimes. At least the driveshaft is cleaned up now.

It seems to me the ride is a bit quieter as a result, but still noisier than I think it should be. I figure the rear axle bearings need to be replaced/ugraded with the Timkin repair kit. $25 a pop but probably worth it. Will have to find another differential cover gasket as well.

I found a pdf document on the Timken site that explains what the repair kit does:

http://autoam.timken.com/techseries/needle_pages/RepairBearing.pdf

Well, I'll probably pick up a couple of the repair bearings before the weekend, anyway. If I don't need them, I can always return them. But I suspect they will be needed.

Rebuilding the differential would be another matter - I could probably do it, it's just one of those complex assemblies I've avoided until now. If the wheel bearings have worn away the axle a bit, and replacing them with the repair bearings doesn't resolve the noise, then I'll look at what's involved with fixing the differential - or swapping in a good used one.

I don't imagine one can use a standard seal with the repair bearings, instead of or in addition to the one that's built into them.

I thought the replacement bearing/seal was supposed to seat flush with the end of the carrier.... 1/8" is a lot of excess.... wonder if a different part is needed for that axle...

My '64 Valiant blew out a differential on the freeway one morning a few decades back .... it had been making noise for about a year. Finally there was this loud BANG! and lots of grinding/vibration. Big hole in the cover. I was actually able to limp the car to the side of the road, but I think I called a tow. Got a replacement rear end from a wrecking yard for about $50, as I recall. Surprisingly simple to swap in. The mopar rear end has better wheel bearings - they are big honkers with real inner races... or at least they were in '64...

OIC now... I didn't take a real close look at the diagram in the PDF file. Now I understand... the repair bearing is supposed to stick out... and there is supposed to be enough room on the axle to allow for that. Is the problem that the weld bead between the axle and the flange is too big? If you grind that I guess you'll need to be careful that the surface is good for a sealing. I wonder if turning and then grinding would work (turning being a bit faster).

The more things change, the more they stay the same.

First, the good news:

The old bearings were stock bearings. I was able to get the Timken repair bearings in without any major problem. The one on the driver's side was a bit tight, but a few whacks with a deadblow hammer on the end of the axle gave more than enough room for the C clip to attach.

Previous mechanic to work on the rear axle (probably just a fluid change) didn't use a new gasket - just blue RTV. Took some time to scrape/brush all that gunk off (or enough so it didn't show and didn't make a difference) and put a proper gasket on. Filled up the gearbox with 80w90 and took her for a test drive.

Nice. The whirring sound is completely gone. There is mostly just road noise - tire noise. Some tranny whine in 1st/second gears. Nothing to write home about. A fluid change for the tranny is on the to do list.

Now for the bad news: As I was tooling along about 60 mph on the local highway, heard two "pops!" from the right side of the vehicle (window slightly open). As I braked for the next exit, heard a lot of grinding coming from that side as well. Got worse on right hand turns. Limped home on local streets. Pretty sure it was brakes, but not sure if it was front or rear.

Turns out the right front brake backing plate suffered a catastrophic failure at the upper shoe pivot mounting point. The metal simply cracked and fractured. I found a piece of the backing plate inside the drum. Surprisingly, the metal rubbed against the non-braking surface of the drum, and the drum and the shoes appear to be just fine. But I will have to either repair or replace the backing plate - it's toast.

Pictures to follow.

Oh, yeah, I checked the rear end. Wheels spin freely, no noise, no brake binding, no fluid leaks. I think my rear axle work was acceptable. It's just that on a vehicle of this age and partially unknown history, odd things will fail. Previous owner said he'd had a scare with the brakes on the freeway and had them completely rebuilt. Unfortunately perhaps whoever did the rebuild didn't catch the stress crack in the backing plate. Fortunately caught it before it flipped the vehicle on its top.

Yikes!

Other axle looks about the same...

Well, it looks like these backing plates are a salvage item. Can't find any "new" or aftermarket parts for it.

Checked the other front wheel - that backing plates shows a slight crack in the same place where the other one failed. So I'll be replacing both, or converting the front end over to disc brakes.

There is a heavy metal oval spacer between the backing plate and the pivot. In the plate that has not yet failed, I notice that it looks like it's in backwards. It has a definite curvature to it and I would think it would work better with the concave side towards the plate. The one on the plate that failed is too bent up to tell if it's in backwards or not, but it does seem to have the same concave away from plate installation.

I'll check the service manual to see if there is any mention of the correct positioning of this spacer.

These are 9-1/2" four bolt backing plates. I did find an internet source for 9-1/2" backing plates, but they are supposed to be for rear wheels of cars like Camaros and such. They do look very similar to what's on this vehicle, so I'm wondering if Chevy simply used these plates on the rear of cars of that era and on the front of this light delivery van. The 9-1/2" drum brakes were apparently an upgrade to the standard front drum brakes, as various brake shoe replacement listing specify a standard replacement and another specifically for 9-1/2" drums.

Visited one salvage yard but he didn't have much in the way of Chevy. Would like to get this all sorted out before the rains this weekend, but considering the limited availability of repair parts that may not happen.

Anybody ever converted the drum brakes on an early chevy van over to disc brakes?