1971 HLS30-14938 "Lily" build

[Patcon]

4 hours ago, Captain Obvious said:

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

Fabulous. I hope you are mulling a solution for me if my measurements prove correct...there's beer in it...

[Captain Obvious]

Crap... I knew it was just a matter of time before someone asked that question.

I don't really have a good answer. I just can't explain how that could possibly be the case, and therefore I don't really have a good solution, other than to make special custom distance pieces to accommodate the situation. Or get "normal" strut bodies that aren't screwy.

I haven't looked closely at the sizes involved, but it is also conceivable that one could place appropriately thick hardened washers "in series" with the distance piece to bring it's overall effective length up to what it needs to be to work in a hub that is .020 too wide. McMaster carries some very thin hardened washers.

Haha! But I simply refuse to seriously entertain anything like that until someone can prove to me that you have a hub that far out of spec.

PS - There was another guy looking for replacement distance pieces because he needed "B" and what he had in his possession was "M". I've never heard of "M" and was curious about what was going on there. I didn't look into it at the time, and now I can't even find the thread... I thought it was on this forum?

[Captain Obvious]

Oh... Here it is:
https://www.classiczcars.com/forums/topic/60007-78-280-re-assembly/

Maybe the "M" spacers are .020 longer than "B"? 

[Zed Head]

I still like my idea for a quick check.  You can feel .020" with your finger.  1/2 mm.  Use a washer.

Sometimes we get too caught up in having a number.  The tables show the parts are supposed to be about the same dimension.  The tables are actually kind of nonsensical when you really look at them.  The ranges overlap.

 

p.s.  funny also that they have a huge error that they even converted to inches.

[Patcon]

8 hours ago, Captain Obvious said:

I haven't looked closely at the sizes involved, but it is also conceivable that one could place appropriately thick hardened washers "in series" with the distance piece to bring it's overall effective length up to what it needs to be to work in a hub that is .020 too wide. McMaster carries some very thin hardened washers.

I thought this would be my first choice. After I verify I can measure with the CO specialty tool...

[Captain Obvious]

I'm still holding out 95% hope that it was a measurement error.

Make sure the bores where the bearings go is clean and there are no burrs kicked up anywhere. I use an eye loupe for magnification of all the surfaces involved.

[Patcon]

Ok. So I received a package today and headed down to the shop.

The bearings seats all look good except for a little overspray

Initially I measured in the scalloped areas. That allowed me to back up against two points and set the heel of the caliper against both sides of the opposing scallop

Distance piece

@Captain Obvious

I have another question, how firmly do you hold the caliper? I can easily move the needle 0.005" with finger pressure. I have also found you have to swing the caliper back and forth looking for the smallest dimension to be sure you are square to the bore...

Off of these dimensions, it would appear the bearings are being crushed by roughly 0.007" That seems like a lot of the bearings don't have any slop...?

 

[Zed Head]

Looks like you need an "A" distance piece.  Can't remember if you found a mark on the hub or not.  .007" is much better than .020".

[Patcon]

30 minutes ago, Zed Head said:

Looks like you need an "A" distance piece.  Can't remember if you found a mark on the hub or not.  .007" is much better than .020".

You are correct the dimensions are much better. Some of that may be because I can use some pressure when measuring as opposed to the way I was measuring. The distance piece is stamped "B". I am assuming it is original. The distance piece from the first side was also a "B" piece. I don't know what these pieces are made out of but they are very hard and dense and tend not to rust.

[Zed Head]

The hub casting itself should have a stamp on the outside.  A, B, or C.

[Patcon]

10 hours ago, Zed Head said:

The hub casting itself should have a stamp on the outside.  A, B, or C.

Interesting! I will look

[Captain Obvious]

Yes, you have to wiggle the calipers around a little and look for the minimum dimension. This is because you are looking for the shortest distance between two points and unless you have the calipers perfectly square to the faces which you are measuring, you will be seeing the hypotenuse of a triangle instead of the shorter side.

Problem is, in an application like this, down in a hole trying to register on small surfaces, it's difficult. If you have larger flat surfaces and better access, you could use the wider, flat part of the jaws to make the measurement (like you are doing on the distance piece). But down in that hole on those small surfaces, you are unfortunately limited to using the narrow ground tips portion of the jaws.  So you have to "finagle it".

And yes, the more pressure you apply, the lower the reading. And that phenomenon becomes more pronounced the longer the piece you are checking because you are actually bending springy things a little and the farther apart the jaws, the easier it is to bend the beam between the two of them. So you have to "just get a feel for it".

But on the good side, look at it this way. You have already reduced your hub measurements by at least twelve thousandths. Only a couple more to go!

Try doing things like this... First, the bore where the bearing sits does not have a perfectly square corner at the outside. There is a little rounded fillet down there at the bottom of the holes. Make sure you stay away from that as it will increase your measurement.

Second, wiggle the caliper around while applying a small amount of pressure until you get the absolute minimum you can find. Let the jaws slip around a little on the hub until you get the smallest distance. That should help position the jaws directly opposite eachother and reduce the hypotenuse effect.

Third, move your thumb off the dial, and use the little wheel below the dial to hold the caliper in place, And try to apply the same amount of force every time you take a measurement. See where my thumb is when I'm taking that internal measurement:

I'm completely confident in the external measurement you are making on the distance piece. Try to use the "same amount" of force when making the internal measurement on the hub faces? All of this stuff is where "the knack" comes into play.

From what I see above, my opinion is that last couple thousandths is "the knack" and you have the correct parts.

13 hours ago, Zed Head said:

The hub casting itself should have a stamp on the outside.  A, B, or C.

Zed, Where on the casting is that mark? I've never looked for that mark. Is it in some rusty, crusty spot that is probably undecipherable at this time?