Stub axle bush spinning inside stub axle?

[Rob]

Striped my front axle and found that the bush had been spinning inside the stub axle picked up on the inner face of the stub axle, completely messing up the bore. Anyone had this problem before? On the other side the wheel bearing inner race spun up and has worn away at the outer face. So that is 2 new stub axles for me.

 

[Jon Wildsmith]

I've seen wheel bearings wearing the spindle before and it's not all that unusual for the bush to be loose enough to turn but not seen one damage the spindle before. Any time you see wear on the inside face of the thrust washer you know the bearing has been spinning on the spindle, a lot and after a while the spindle will be junk.

 

[Rob]

Seems like I need to brush up on my bearing tightening skills, although this would of only saved one stub axle. The bore on the other one measured in at 39.85 and the new bearings are 40.00mm, far too tight a press fit for a bearing of that size. The other stub axle bore measured in at around 39.99mm, so much better. Can't rely too much on these values as I only used callipers, not a mic and bore mic but its accurate enough to come to the conclusion that the press fit was far too tight to even try pressing the new bearings in.

 

[frank rabbets]

Hi Rob

Do you mean that the new bush is larger than the worn hole?!! They should be looser shouldn't they? Or does the workshop manual say a press fit? I was thinking that loctite could solve both your problems. The manufacturers will tell you how much clearance the loctite will take up.

Frank

 

[Rob]

Yes the new needle roller bearing and bush is larger than the hole by quite a bit. The bore surface has been damaged and the steel has picked up creating considerable burrs and the surface is generally very rough. As the replace for the bush is a needle roller bearing I would prefer not to use loctite in case it contaminates the open bearing (if the bore was larger). Pressing a needle roller bearing into a bore with 0.25 ish mm interference would cause it to bind. I could put it up on the lathe re machine the stub axle bores but I don't really have time to mess around with that so I just got complete new ones. Will take a pic later today of the 2 bores.

 

[Andrew Prince]

Any time you see wear on the inside face of the thrust washer you know the bearing has been spinning on the spindle, a lot and after a while the spindle will be junk.

What sort of wear are you talking about, Jon? Is this the ring that gets worn into the thrust washer? I've stripped down the hubs of a few different 80s now and they've all had thrust washers with rings worn in (even where the washers are fairly new) - so it looks like normal wear to me. But you've now got me thinking that my 80 is busy wearing down its spindles at rapid rate of knots

 

[Chris]

Rob, I have certainly had loose bronze bushes in the stub axle before. I replaced both my fronts with the new needle roller assembly but didn't have any issues installing them at all. The rollers pushed in very nicely and the bronze faces were a very snug fit. Andrew, I am with you, I have had quite a few forays into 80 axles in a very short time and have always seen wear marks on the inside of the thrust washer. However, not noticed any significant wear patterns on the stub axle itself. But the inner bearing races are not a 'tight' fit as such on the stub, are they. They just slot on, so the thought that they might spin is not unusual. I don't think they'll spin (as in slip) all the time, mostly they'll just sit still with the stub, but with extreme side loading or some such maybe they get dragged round - especially if your preload if off.

Incidentally the replacement stub axles at Miler are genuine boxed Toyota ones.

Chris

 

[Jon Wildsmith]

What sort of wear are you talking about, Jon? Is this the ring that gets worn into the thrust washer?

Yes, that's what I'm talking about, where the inner race rests against it, what else would cause that kind of wear as I'm open to other explanations.

 

[Rob]

Incidentally the replacement stub axles at Miler are genuine boxed Toyota ones.

Should be delivered today

 

[Jon Wildsmith]

But the inner bearing races are not a 'tight' fit as such on the stub, are they.

A new bearing on a new OEM stub axle is a tight fit or at least that's been my experience, they only loosen up over time.

 

[Chris]

From memory - and it is from memory, if you put the TW onto an empty stub axle, it will only go so far up the sleeve won't it? So eventually as your bearings wear in the races and retreat up the sleeve toward the hub, there comes a point where the thrust washer can no longer exert sufficient pressure on the bearing - hence you fail on the pre load. If (as I suspect) mine is getting very close to that stage as I am at the bottom end of pre load) certain flexing and movement may well allow the bearing to slip under load. It's not that the bearing is necessarily worn out, just to a point where the TW can't reach it anymore. You can bounce on the nut with a long bar until you are blue in the face but the pre load won't go any higher. This is why I think that measuring the pre load with a set of scales on the hub is better than measuring the torque on the nut. Could be wrong on the details of the stub axle - going to go and have a look at a spare in a minute.

Chris

Sorry Jon are you saying that you'd have to knock a hub on? I have only ever had to line it up and give it a push to get the hub onto the stub. Never needed a mallet for eg.

 

[Jon Wildsmith]

Sorry Jon are you saying that you'd have to knock a hub on? I have only ever had to line it up and give it a push to get the hub onto the stub. Never needed a mallet for eg.

Yes, a hub with new bearings going onto a new OEM stub axle can need a tap to get it all the way on and even on older ones I find a tap round once the 1st nut is getting tight creates more play suggesting the bearings still need help getting fully seated.

 

[Chris]

OK, well that was informative. Clearly you can see that the TW will only go so far down the outer sleeve of the SA. However, this is way more than the minimum depth of the bearing unless somehow your stub axle bearing seats were worn away. The bearing sits much higher in the hub than it does in my picture of it alone on the stub axle. Therefore the travel of the TW is unlikely to be the limit of the pre load on the bearing as I suggested.



Causes of loss of pre load are therefore I guess, wear in the bearing, incorrect seating of the outer race leading to movement or incorrect pre load on the TW that allows the inner race to move causing wear in the TW - which of course gets worse as it wears. I use Milner TWs and I wonder of OEM are perhaps harder?

Incidentally there was clear wear on my spare stub here. It looked like erosion more than wear. They do have a hard life sitting in water etc. I put a brand new bearing on the stub and it needed only a slight push to seat it. It was quite possible to turn it on the shaft.

Good having spare stuff lying around! I still have to marvel at just what load most be carried by that short tube.

Chris

 

[Rob]

Right, now that I have 2 shiny new Toyota stub axles from Milner I have noticed that the reason for the interference fit being so tight on one axle is that it is not genuine. So the roller bearing mod may not work if you have non genuine stub axles. On closer inspection the inner bore has been damaged slightly but not the cause of the small bore. Odd thing is that the original bush on the factory fitted stub seems fine but the aftermarket one is completely worn. As I am on my work laptop it's a bit of a faff to get photos uploaded to the net without getting into trouble so no photos today.