1971 HLS30-14938 "Lily" build

[Patcon]

So I mic'd the second "B" piece @ 2.068" . The seat to seat dimension I got was 2.087" & 2.080" I measured in the scallops using the "B" piece as a surface to work from. Didn't have a sacrificial set of calipers

So do the bearings have 0.020" freeplay?

@Captain Obvious

If I can't sort the other hub and have to disassemble it I will measure those parts too

[Zed Head]

9 minutes ago, Patcon said:

So I mic'd the second "B" piece @ 2.068" . The seat to seat dimension I got was 2.087" & 2.080" I measured in the scallops using the "B" piece as a surface to work from. Didn't have a sacrificial set of calipers

So do the bearings have 0.020" freeplay?

Your hub doesn't measure out as a B hub.  Actually looks like it's out of spec.  The race guys say that the hubs can get wallowed out over time.  Or wallered out if you're in the south.

[Patcon]

8 minutes ago, Zed Head said:

Or wallered out if you're in the south.

My hub specs out at larger than even an A hub! So it can't have been wallered? out. The dimensions would be smaller in that case. Confusing...

Now it is possible my measuring is suspect. I would only have to be off by 0.010" to be a B hub, at least on the one side

[Zed Head]

If  I had the parts in front of me I'd put the spacer in to the hub  by itself, with a solid flat piece on one end to set the surfaces.  Then feel or eyeball the other side, just to see what's what.  Might tell you something.

I got my measurements backward, you're right, your hub is measuring too big.  That's an odd one.

[Captain Obvious]

8 hours ago, Patcon said:

So do the bearings have 0.020" freeplay?

Absolutely not. The bearings have nowhere near .020 free play. If your measurements are correct and the distance between the bearing seating surfaces is .020 longer than the distance piece, then it won't work. The bearing will certainly bind when you tighten the nut to even a modest (50 ft-lb). Your balls will be pushed together so tight, you'll feel like... Well, like your balls are in a vice.

I'm hoping it's just a measurement error.  So what do you mean by "scallop"? Can you take a pic of how you're making your measurements?

Want me to send you my newly made custom hub-checking calipers? They have been calibrated to a NIST traceable standard and everything. You can use them to make a direct measurement and then give them back to me at Zcon? Be happy to.

And the amount of torque really doesn't matter. In theory, all of the pieces down the center have been crushed together taking up all available play. Once all the play has been taken up, there is very little axial movement even as the torque increases. I'm no bearing expert, but IMHO, there should be no discernible difference in bearing preload between say 50 ft-lb and 200 ft-lb.

We torqued Matthews bearings to maybe 50 ft-lb at my shop and he was going to do the final torque at home. He bought a torque wrench that goes high enough.

On my own car? I  tightened them with a 1/2 inch breaker bar and some black iron plumbing pipe until my eyes bugged out just a little. I don't condone or suggest that level of cavalier behavior, but... I didn't measure it, but it was "a lot".

[Patcon]

13 hours ago, Captain Obvious said:

Absolutely not. The bearings have nowhere near .020 free play.

Yeah, I was a little incredulous at this thought

13 hours ago, Captain Obvious said:

Can you take a pic of how you're making your measurements?

I might be able to later. all these parts are masked up in the paint booth currently.

13 hours ago, Captain Obvious said:

Want me to send you my newly made custom hub-checking calipers? They have been calibrated to a NIST traceable standard and everything. You can use them to make a direct measurement and then give them back to me at Zcon? Be happy to.

That would be great! It would remove one of my variables

13 hours ago, Captain Obvious said:

And the amount of torque really doesn't matter. In theory, all of the pieces down the center have been crushed together taking up all available play. Once all the play has been taken up, there is very little axial movement even as the torque increases. I'm no bearing expert, but IMHO, there should be no discernible difference in bearing preload between say 50 ft-lb and 200 ft-lb.

I agree this is what I thought was going on. I was pretty careful when I set the bearings to make sure they were down on the seats. I wonder how thick that little washer is? Maybe I lost it when I pressed it apart...

[Captain Obvious]

That bronze washer has nothing to do with the bearing preload. It's outside the races. You could get the exact same effect by adding metal to the inside face of the yoke and making it that much longer. Doesn't fall into the geometry at all. Doesn't matter. Honestly I'm not even sure what Datsun was trying to do by putting it in there at all. Doesn't make much sense to me.

So, here's to hoping it was simply a measurement area. I'll get those calipers out to you tomorrow and you should have them Wednesday or Thurs. I just can't believe your hubs would be out of spec like that.

[jwtaylor]

I seem to recall at some point seeing that a washer (copper or bronze) was added to help reduce noise? or ???  Maybe that was in the differential though - memory not what it used to be.

[Captain Obvious]

Your memory is fine. It was added to try to quiet something down back there. But the thing is... I don't understand how it could possible do anything like that. The geometry just doesn't make sense.

It's like they got a couple complaints back at the factory and they lit a fire under some engineers butt who quickly threw a half-baked poorly thought out fix at it. Then after a couple years, they took that same fix back out. Probably because they realized it cost money and didn't do anything. 

[240260280]

Maybe it was to protect the bearing from over torque, i.e. the copper would compress if the torque or a force exceeded the max torque spec. Sort of a sacrificial  "bumper".

Edited June 4, 2018 by 240260280

[Captain Obvious]

That's about the only thing I could come up with as well. Since that bronze is softer than the steel, it will ooze out a little if the torque is high enough. Although, I'm not sure the normal expected torque is anywhere near "high enough".

Nissan said it was to reduce noise. We talked about it a bunch in this thread:
https://www.classiczcars.com/forums/topic/58935-lost-rear-bearing-shim-washers/

They put it in at the beginning of 72 and took it back out the middle of 73:

 

I still think the whole thing was a fire under some engineers butt and that was his knee-jerk bandaid. As long as the marketing guys were convinced, then it was a success.     

[Captain Obvious]

Oh, and I forgot...  @Patcon The custom hub-fitting caliper is on it's way. You should see it soon. Weds or Thurs.