Bearing Tolerance

[bob58o]

Steering Bearings.
41mm OD, 12mm height
If I need to put a tube on a lathe to accept these bearings, what type of tolerance / interference is suggested?

I don’t have a press. I think 0.002” is enough to slip in. Maybe -0.002” requires a press?
What should I shoot for?

0.000” ?
0.001”
-0.001” ?

41.025mm? For a 41mm OD bearing?
1.6152” for a for a 1.6142” od bearing?

 

[Master Hack]

It depends on the application also.
002 might be a bit much.
"generally speaking" 0005 to 001. If there is high temp involved things are different.
Thrust loads change things again.
if the fit is too tight is changes the internal clearance of the bearing bu compressing the OD the reverse can happen on the ID.
Sorry ya asked yet?
90% of the time looser is mo bedder.
Locktite is your friend!

 

[bob58o]

I also asked on Reddit and was also told I should try for .0005” to .001”smaller pocket than the race.

So if 1.6142” od of race, the pocket should be 1.6132” to 1.6137”. I guess asking for 1.6135” seems reasonable. Still need to figure out the depth I need for the bearing cups.

Cut twice then measure then cut again.
Until I start putting pieces together, it’s hard for me to visualize what I need where. Planning on using this 1.5/1.75” tube as welded on collars for bearing pockets on this 1.25/1.5” tube.

I think the bearings are 12mm thick with outer race 9mm thick.

 

[Master Hack]

Why are you using tapered rollers? Nothing wrong with that, plenty heavy duty.
how much does this thing weigh?
Get yerself some mechanical (seamless) tubing with a thicker wall.
That gives ya more to work with. Ya won't need a snap ring at the bottom of the pocket.

Nevermind....
l figgered out thats the steering head, your bearing choice is appropriate.
l don't think .065 wall thickness is...

 

[bob58o]

Weight? No clue. Need momentum to break down walls. lol

I figured we will be heavy and have more rake than the original configuration this Honda Z50 front end. I assumed the tapered roller bearings would be better because of the weight and rake angle. Maybe this is incorrect?

 

[bob58o]

So it should be thicker?
Like this 2”OD / 1.5”ID (1/4” wall thickness) would be better?
0.193” wall thickness after machining ID to 1.6135”

 

[bob58o]

And what’s the deal with DOM Seamless?
I thought DOM was welded? Is eBay lying?

 

[Master Hack]

Yeah that would be mo beddar. Bore it out and ya have a nice shoulder at the bottom of the pocket. The bearing be happy in there. Go for a fit closer to .001.
put the steering head in the oven @350 for an hour (or until tender)
put the cups in the freezer overnight. No press needed.

DOM = drawn over mandrel.
l use a lot of tubing like that. Its available in a million sizes and thickness.
visit yer local welding shop or steel supply. Ask to look at the rems.

 

[Rat]

Why are you using tapered rollers? Nothing wrong with that, plenty heavy duty.
how much does this thing weigh?
Get yerself some mechanical (seamless) tubing with a thicker wall.
That gives ya more to work with. Ya won't need a snap ring at the bottom of the pocket.

Nevermind....
l figgered out thats the steering head, your bearing choice is appropriate.
l don't think .065 wall thickness is...

Tapered rollers handle odd angles and side loading better than traditional "Cup and Cone" loose ball steering setups on 2wheelers.

Think maybe I was the first one to suggest them for Bob's project... idk doesn't matter

 

[Master Hack]

. I assumed the tapered roller bearings would be better because of the weight and rake angle. Maybe this is incorrect

No, absolutley correct. I was a bit slow figgering what ya were doin.

 

[Rat]

And what’s the deal with DOM Seamless?
I thought DOM was welded? Is eBay lying?

Since Hack didn't OFFICIALLY answer your question...

All pipe/tubes are formed and welded, Excluding ONLY those marked "extruded" and obviously cast

DOM does mean drawn over mandrel, but what this means structurally (at least in a quality piece) is
1. That the weld is essentially invisible. Minor discoloration might be noticeable but you can't feel a flat spot where the weld is, or measure a different diameter across it like you can with something basic EMT conduit.

2. The strength (if done properly) is the equivalent of having been forged round instead of simply being formed and welded

There is a caveat; cold rolled and hot rolled are not equal.

Hot rolled is generally softer, easier to form, and doesn't have secret stress risers than make it warp when welded. It also tends to have a slightly blued and blemished surface

Cold rolled is exactly the opposite, it tends to he more rigid, a bit harder to mill, has stress risers every which way and is very prone to warping when welded, but it's surface is clean, and uniform.

 

[Rat]

I recomend instead of turning half the wall or more out, just match the ID to the OD, mock up an drill it for the frame unions, drill a row of 2 or 3 holes down each side to weld the two pieces together through... and then send it.

Sometimes the simplest solution doesn't seems the safest, I've done many refits this way... and many old motorcycles were done that way in manufacturing some still are I think.

Also those tapers seats are thick enough at the bottom edge due to taper, could easily be welded on... many are anyway

 

[Master Hack]

Also those tapers seats are thick enough at the bottom edge due to taper, could easily be welded on... many are anyway

welding a hardened, chrome steel race is a really bad idea.

 

[Rat]

welding a hardened, chrome steel race is a really bad idea.

I missed that fact

 

[bob58o]

TOP Steering Stem Bearing

So after looking at how things go together, it seems like the red goes directly on the green. The black dust cap seems to have ID of 1.9”, so it might be issue with 2” OD bearing pockets. Perhaps an ID and OD cut would be nice. I guess 1-7/8” OD 3/16” wall would have been better? Think that leaves over 1/8” wall thickness.

But what I was concerned about was bearing pocket depth. The race seems to be about 9.25 mm deep. The whole bearing seems about 12-13mm deep.

The green surface must protrude from the head tube right? The bearing pocket depth should be greater than 9.25mm but needs to be less than the 12mm?

A 10mm deep pocket should work for the top?

 

[bob58o]

And If If have a 10mm deep picket cut in the 1” long 2”OD x 1.5”ID tube, then weld on the other end of the 1” tube, will I have wished I welded first before cutting the pockets? Is the sleeve beefy enough to prevent warping during welding?

 

[Master Hack]

The bearing pocket only needs to be .005-.010 less than the thickness of the bearing assembly, which appears to be 12-13 mm.
The key word here is "needs". It can be more, or as in this case lesser. The bearing needs to protrude at least, 5-10, enough to be able to tighten the device that holds it all together, and have a little preload. More is ok just lets more dirt in, if the bearings are just hanging out there bare a$$ nekkid.
You can put the bearing flush or countersunk even, if ya put a "preload nut" under the hardware the actually holds the steering device on. Look at a bicycle.
As for the wall thickness, I can't advise you cuz we have not established a weight. So look at it this way, ya got two bearings in a tube with a 24 inch prybar attached, and a gorilla on the other end trying to bend sumpthin.
Substitute Gorilla for a chimp, if the weight warrants it.
What could go wrong? Don't over think it, it ain't rocket surgery.

 

[bob58o]

Frank and Beans

 

[Rat]

Frank and Beans

 

[Denny]

I have no tolerance!