TheSamba.com :: View topic - Loose outer race in Rear wheel bearing housing.

Tue Mar 17, 2015 1:09 pm

My 1970 bus was making some noise in the R/R driving down the freeway. I've been refreshing the mechanicals on this bus for the past serveral months. Ironically, the last remaining tasks where to inspect the rear brakes and pack the rear wheel bearings. Today while driving it on the freeway, I noticed the noise changed if I swerved a bit left to right. My thought was a loose rear wheel axle nut as it didn't sound like a bearing. I had not taken the rear drums off since purchasing the bus. Note to self- do this next time the first week of ownership.

So, I found the axle nut loose with only the cotter pin holding it on.

The drum has some wear from the loose axle nut. I'm not sure how bad this is? If I remember right, I had this same issue on a bug a few decades ago and the axle nut kept loosing up due to the drum wear like in this picture. I think I ended up buying a new drum to fix it.

The bearings felt fine spinning them by hand. No pits or roughness on either. They hadn't been repacked in a LONG time by how nasty the grease was and the amount of crud and hard dirt on the outside of the seals. The outter bearing race was German and the inner bearing was made in Hungry by MSMradax.

The bad news.. The outter bearing race was spinning in the hub. You can spin it with your fingers. You can see the marks on the outside of the race.

Here's the inside of the hub. Now, I've seen Colin's thread where he repacked his rear wheel bearings and had the same spinning outter race. His soluction since he was out in the middle of no where doing it was to use (red) locktight to hold the race in place.

What I'm wondering if there is any other solutions to this besides sourcing a good, used bearing housing. I know back in the day, folks would stake the hub with chisel marks to provide a means to hold the race in place. I'm not sure that's a good solution here.

Thoughts?

Tue Mar 17, 2015 2:24 pm

Start with a mic to see if the bearing OD is within spec.
Dimpling will tighten it up but its not a cure, its a fix but a decent fix as long as you followup by checking it periodically.

Im not sold on the Loctite idea.

I think you might find the brg out of spec

Tue Mar 17, 2015 3:02 pm

The outer race is designed to spin slowly within the bore. If the race can not turn then all the wear will happen in the same part of the race greatly shortening its life. So long as the looseness if the race isn't causing excessive play in axle shaft/brake/wheel assembly you should be good to go. You will need a new drum and should check the splines on your axle shaft carefully for signs of wear.

Tue Mar 17, 2015 3:38 pm

Thanks for the replies guys-

Macleod- I just mic'd both bearings outters and came up with a strong 72MM which is the spec. Good suggestion to double check though.

Wildthngs- I'd never heard that the outter race was suppose to spin? I can't see any OBVIOUS wear in the hub either..

On the drum, just for my awareness, why can't the drum be run? Will it not torque correctly or is it going to be short and too close to the drum when tightened down? The spacers don't show any wear on them.

Tue Mar 17, 2015 4:28 pm

wcfvw69 wrote:
Wildthngs- I'd never heard that the outter race was suppose to spin? I can't see any OBVIOUS wear in the hub either..

On the drum, just for my awareness, why can't the drum be run? Will it not torque correctly or is it going to be short and too close to the drum when tightened down? The spacers don't show any wear on them.

The "non" spinning race is designed to turn ever so slowly in many applications. On front wheel bearings it is the cones which do the slow turn as they are not tight on the axle shaft.

I can't really see all that well from your picture, but if the nut has worked loose then there is probably an unacceptable level of wear to the splines.

Tue Mar 17, 2015 6:13 pm

Wildthings wrote: The outer race is designed to spin slowly within the bore. If the race can not turn then all the wear will happen in the same part of the race greatly shortening its life. .

unless I am crazy or misread what you wrote that bearing is a press fit, and should not spin in the bore.

mic it out, and with a new bearing, you may be ok, but if it's a little loose (you be the judge) use green Loctite bearing and sleeve retainer.

I also believe you will need new a new stub axle if the splines are worn out

Tue Mar 17, 2015 6:45 pm

X3 on the bearing fit, it has to be tight in the bore.
A bearing can not spin in the bore ever, the bore is not the wear replaceable part, the bearing is. Now if the bore had a pressed in hardened sleeve it would be a different story but that's not how the VW rear bearing housing is designed and I've never seen anything where it was designed to spin on purpose, the bearing "bears" the load and takes the wear and is replaced when the wear exceeds limits, the load is spread over a large surface and with proper care and lubrication it's good for far more than the expected design life of the vehicle. If you wanted to get anal you could mark the outer race and reinstall it in a different position every 30-50K miles to spread the wear pattern out, sounds like work to me.
I apprenticed on big 50's Sikorski's (helicopters), they are essentially 10000 bearings flying in formation, if a bearing didn't fit the bore and an oversize wasn't available the part was scrapped, even if the replacement was $8K+, no exceptions and no gluing.
On a bus where a failure wouldn't be quite as critical the Locktite may be an option, or if it was the last one on earth machine the bore oversize and shrink in a sleeve to bring it back to spec.

Now the bigger question is how did that hole get worn?, is the axle bent a little making it rock in the bore?, or was a previous replacement bearing slightly undersize allowing it to move?

And X2 on the stub axle, if the splines are worn or the bearing doesn't fit on it tightly you'll need a better one.

Tue Mar 17, 2015 6:59 pm

Thanks for the impute Skils and BD. I have to say, I was taken aback by the suggestion that it was ok for the race to spin in the bore. As I mentioned, I had read Colin's thread where he was using the locktight to try and hold the race in place. That was my thought as well, that it should be a press fit but crazier things have been learned.

The bearing OD new is 72MM. The race measures a fat 72mm OD as does the inner bearing, so it would appear that the bearing retainer is wollowed out a bit where the race sits. I could spin the race in the hub though I did have to punch it out.

The bearings check out fine. The outter is a German DWB, possibly the original.
If the housing is junk, what's everyone's thoughts on using a chisel and staking around where the race sits and use the locktite that SKills suggested for a short term solution? I'll start sourcing a good used hub assembly.

Tue Mar 17, 2015 7:06 pm

Myself I'd explore the Locktite option before staking, staking only provides tiny contact areas where the punch marks are and not all the way to the bottom of the bore either (push on something heavy with the palm of your hand and then try it with your fingertip, concentrated loads with no surrounding support don't do it). There's some fairly well engineered chemicals designed for the same job you are doing but on heavy equipment like scoopers and bulldozers, if whatever you put in there sets up hard and stays in place the load is carried over the entire surface and likely will last for years (unless the shaft is bent and it rocks with each turn).

Tue Mar 17, 2015 7:23 pm

I looked at the axle closer and rolled it on flat bench. It's not bent. I also slid the axle in the drum and it only had barely and perceivable side to side play. I've seen worn shafts and especially worn out splines in he drum. These don't appear to be bad. The drum does have some wear where it rides against the spacer. Ironically, it's about as deep as a generator shim. :D I'm going to steal Colin's idea and shim it out with the generator shim until I get a new drum.

What's you thoughts about the axle and drum splines?

Tue Mar 17, 2015 7:36 pm

wcfvw69 wrote: What's you thoughts about the axle and drum splines?

Clean up the drum and the axle and stick it in there, does it go clank clank when you try to turn the axle in the drum?, or nice and solid?

Tue Mar 17, 2015 7:37 pm

You guys need to read up on bearing design a bit. An auto or light truck isn't a military helicopter and no one wants to be replacing bearings because one side has heavy wear while the other side has none. Yes the bearing bore in the housing may well wear over time because of the slow rotation of the race, visit the Vanagon forum and search rear wheel bearing housings and you will see that it can be a problem.

From: http://www.ntnamericas.com/en/product-support-and-training/shaft-and-housing-fits

The type of fit required varies on a number of factors such as load, operating temperature, bearing type, and shaft or housing material. A good rule of thumb for most applications is to use a press fit on the rotating component.

That is, a shaft or inner ring rotating application like an electric motor (or Bay rear axle) will use a press fit on the shaft and a loose fit on the housing. A housing or outer ring rotating application like a wheel hub (Bay front wheel bearing) will employ the reverse: a loose fit on the shaft and a press fit on the housing. This will greatly reduce the chances of creep or a loosened fit during operation.

I agree, either Skills is crazy or he can't read.

Tue Mar 17, 2015 7:46 pm

busdaddy wrote: wcfvw69 wrote: What's you thoughts about the axle and drum splines?

Clean up the drum and the axle and stick it in there, does it go clank clank when you try to turn the axle in the drum?, or nice and solid?

No clank, clank. It's pretty snug with just a very slight amount of side to side play.

Ok.. I'm going to secure the race in the housing with locktite and run the parts after a good cleaning and re-packing of the bearings.

Thanks for the 2nd opinion gentleman.

Tue Mar 17, 2015 8:10 pm

Wildthings wrote:
The "non" spinning race is designed to turn ever so slowly in many applications. On front wheel bearings it is the cones which do the slow turn as they are not tight on the axle shaft.

You know I had to look this one up. In all my years I have never heard of this. Never gave it much thought.

A bearing has a Rotating race and a Stationary race.

The Rotating race must be a press fit.
The Stationary race can be fit by hand.

The Rotating race in this case is the Inner race, which is pressed onto the stub axle. Note the stub axle is rotating.
The Non-Rotating race in this case is the Outer race which is slipped into the hub.

So what keeps the Outer race from spinning. The load on the bearing causes friction between the Outer bearing race and the Hub.

I can see when the load is static the Inner race would be allowed to Walk. With no load on the race there would be no appreciable wear.
It would be like sitting there spinning the race on a front spindle with your fingers. How long would it take to have any notable wear.

Not the best article but the physics makes sense.
http://mgaguru.com/mgtech/universal/ut106.htm

Any thoughts
Tcash

wcfvw69
Loctite 620

Tue Mar 17, 2015 8:15 pm

wcfvw69 wrote:
Ok.. I'm going to secure the race in the housing with loctite.
Be sure to let the Loctite fully cure before you set it back on the ground.
Tcash

Tue Mar 17, 2015 8:33 pm

Tcash wrote:
The Rotating race in this case is the outer race, which is pressed into the wheel hub.
The stationary race in this case is the Inner race which slid onto the Spindle.

This would be backwards from the design of a Bay rear axle assembly. :cry:

On the rear of a Bay the axle rotates within the hub so the axle is the rotating member. While the bearings are not a press fit on the axle they are locked to the axle by the compression from tightening the axle nut. The outer races in the hub are the non rotating member and thus need to be a bit loose as far as fit. There are engineering charts that show you how loose of a fit you need, taking into account, bearing size, load, thermal expansion, etc.

It has been a long time since I have dealt with this but as a guess I would say that you want one turn of the "stationary race" for every 100,000-1,000,000 revolutions of the rotating member. If I have my numbers right this would mean a revolution or two over a full day of highway cruising.

Let your bearings get dry or run them too tight and the rate of rotation of the "stationary" bearing races will go up and the wear to the bearing bore will greatly increase, while if you lock the bearing into the bore the bearing wear will increase.

Tue Mar 17, 2015 10:05 pm

This would be backwards from the design of a Bay rear axle assembly. Crying or Very sad
No need to be sad. I was using your example of the front wheel bearings. Which the hub is the rotating race and the spindle is the Stationary race.

For those out there. It is opposite on the rear as Wildthings pointed out.
The Stub Axle is the rotating race.
The Housing is the Stationary race.

Thanks Wildthings
Tcash

Note: I edited original post to reflect this.

Tue Mar 17, 2015 11:51 pm

I used to work in a motor repair shop. With the bearings that are supposed to be a interference fit and they are not, we would either Knurl the housing or use red Locktite. Loose bearings in motors was pretty common, because the housings were aluminum.

Wed Mar 18, 2015 8:18 am

I have not disassembled my red loctited rear wheel bearings, and cannot provide an update until the next 30,000 mile repack. The good news for you is that will be right about at the end of this itinerary.

If there is very very slow rotation of the outer race in the hub, I do not think I am going to worry about it. I will have to disagree with Wildthings that it is an intended design aspect. There is no reason not to make the bearing rollers/balls do all the work, and there is no long term good that come of an outer race wallowing out the wheel bearing housing bore in the rear or an inner race wearing down the steering knuckle up front.
Colin

Wed Mar 18, 2015 9:43 am

Thanks Colin for your impute too.

I tore down the drivers side rear wheel bearings today and found the outter race as snug as a bug. No movement what so ever.

After reading everyone's thoughts and opinions, I'm going to use the locktight and secure the race into the hub. I do want to prevent the harder race from spinning in the hub adding additional wear to it.

Again, thanks to everyone who shared their thoughts.

Bill