Using Timken bearings instead of the old assembly on BT Springers

[firstripholdmybeer]

The 1" timken bearing I've been banging on isn't giving, even a smidge. I've but them on my wide glides before without issue and I know they need a good amount of patience sometimes. the bottom taper measures 1.03125. Is there a specific timken made for springers I should be aware of?

thank for any help

[farmall]

Some old springers have a 1-1/8 nominal diameter fork stem. No way a 1" nominal race is gonna tap onto a 1.031 shaft.

https://www.jockeyjournal.com/threads/vl-springer-on-a-49-panhead-frame.157146/

Study interference fits so you won't get unpleasant surprises like that. Thirty one thou is spark plug gap territory.

Drag or JB should be able to recommend a good supplier for the correct part number or can advise if a stem swap is preferable.

[TriNortchopz]

The 1" timken bearing I've been banging on isn't giving, even a smidge.

You are trying to bang the bearing onto the neck stem? or banging the old bearing off?

Did you measure the machined parts of the neck post where the bearings sit? if so, what are those measurements?
Did you measure the Inside Diameter (ID) of the bearings?

Share those measurements, and add photos

the bottom taper measures 1.03125

What do you mean, "bottom taper"? on the stem where the lower bearing sits? Is it the original lower bearing race, #48345-36 (or #48350-49) used for the original ball bearings? need a pic of that to make it clear.



Typically, the lower bearing is a 0.001" (one thou) interference fit (I.E; 1.000" bearing ID, and a 1.001" lower neck measurement), while the upper bearing is a size-on-size sliding fit.

Do you have the numbers from the bearings you are using?

That JJ link farmall shared; a guy also says the VL springer stem is 1.125"

[1-Set] Cone: 15590, Cup: 15520 Tapered Roller Bearing 1.125" x 2.25" x 0.687" (ID x OD x W)

https://www.amazon.com/1-Set-Cone-Tapered-Transfer-Bearings/dp/B01N1FB0XT

They make conversion kits to fit the VL springer on other year HDs:

VL I-beam springer conversion neck cups 1" to 1-1/8" big twin front end

Converts big twin frames to fit the 1930-36 VL i-beam springer front end with 1 1/8" steering stem. No welding or machining work required...

Fits 36-84 Big twin Knucklehead, Big Flathead, Panhead and Shovelhead. Softail 1984/1988 and most Big Twin style custom frames that are designed for traditional press in neck cups.
Note: Original lower race will need to be removed and some clean up on your stem at the base may be required to fit lower bearing, we suggest using some emery cloth sand paper. This is only one piece of the puzzle and stem hardware will still be needed to complete the install.

https://old-stf.com/products/old-stf-vl-i-beam-springer-conversion-neck-cups-1-to-1-1-8-big-twin-front-end-raw

[firstripholdmybeer]

Thanks for all the suggestions here. after reading around a little more I discovered a timken bearing designed for those thicker bottom stems. It's the same bearing that comes in one of the W&W cycles 1" Timken bearing conversion kits that they offer. The bottom has a bevel and is supposed to lay on the "lower bearing guard" (OEM #48361-38) which looks like a cone style washer essentially. similar to how the original bearing races layed on top of it, I'm guessing its the same design just on a timken.

I'll try to remember to update this with info on how it goes, I have the bearing just waiting on the bearing guard.

Timken bearing link: https://www.amazon.com/dp/B000X3EPWS...7E1YZ3YPST39HJ

[TriNortchopz]

you said:

the bottom taper measures 1.03125

farmal shared a link to that JJ thread, which I expanded on; the VL springer neck is 1.125"


From that amazon.com link above:

Timken SET4 L44649/L44610 Tapered Roller Bearing Cone and Cup Set, Steel, Inch,
1.0625" Bearing (cone) ID,
1.9800" Race (cup) OD,
0.560" Cup Width


The L44610 cup is a common HD cup (race) at 1.980" O.D., typically paired with the L44643 bearing (cone), at 1.000" ID.

now I am confused...hhhmmm...
How is a 1.0625 (1-1/16") ID bearing fit a neck post which is at 1.125" (if original VL springer neck)...or maybe 1.03125?

I didn't find that W&W Cycles 1" Timken conversion kit for the early springer... got a link?

Flatland has that lower bearing guard listed;
48361-38
Lower Self Centering Guide
1938-1948 Big Twin
Spring Fork Bearing Guard or Also Called Lower Self Centering Guide


inner Diameter: 1.028" for Big Twin 1" Springer Fork Stems

- FITS:

1938 - 1948 Big Twin

- Note: Original 1936--61" & 1937 Big Twin Lower Bearing Race Was Not Self Centering & Did Not Use this Piece. this Can be Converted to 1938 Style.

https://flatlandmotorcyclecompany.com/harley-48361-38-lower-self-centering-guide-1938-1948-big-twin.html

W&W Cycles has that part listed as #18-655:
fits Big Twin 1936-1948
with Ø 1” at lower end of fork stem
steel
tolerance class: ABEC 1
ID x OD: 25.4 x 36.7 mm (1.000" x 1.445")
replaces OEM HD 48361-38


V-Twin
VT No: 49-2000
OEM No: 48361-38
Spring Fork Bearing guard
Fits:
UL 1937-1948
EL 1936-1940
FL 1941-1948
Country of Origin: Imported

Measurements
Inner Diameter: 1.028"

https://vtwin.parts/supplier/v-twin/classic-pre-1984/front-fork/neck-cup/hardware/harley-davidson-indian-motorcycle-v-twin-bearing-guard-49-2000

[DustyDave]

I think for 30 thousandths I would grab my roll of 80 grit emery and start polishing. Divide the shaft with 4 marks on the quarters, Get a nice long piece of emery so you can take long strokes. Tear the emery length wise so its the same width as the bearing mount. I usually count 20 strokes then move to the next mark Once the paper gets dull go the other way on the marks with fresh paper. For a fork that will be straight enough and only take about an hour and a half, way quicker than getting the stem out and machining. OBW the bearing mentioned above that is 30 thousandths loose will drive you nuts shifting every time you brake or hit a bump! Don't ask how I know.
Dusty