How to Reduce the Diameter of a Splined Hole?

W

wpiruss

Plastic

Joined

Dec 1, 2011

Location

Massachusetts, USA

• Jan 25, 2018

• #1

Hello,

I'm looking for ideas on how to reduce the diameter of the splined hole in motorcycle kickstart lever. The aftermarket exhaust that is installed on the bike interferes with the stock lever. I have found a replacement that will solve the interference issue but the splined hole is about 1mm too big in diameter. Even with the lock screw tightened completely the new lever is loose on the shaft. The shaft is 13.5mm in diameter. The replacement lever has a minimum diameter of 14.5mm

It seems one way to approach this is to remove more material from the gap that allows the spline hole to contract around the shaft when the lock screw is tightened but I'm concerned that the screw itself will no longer line up correctly and end up cross threaded.

Another approach would be to somehow add material to reduce the size of the opening- maybe a shim or worse case welding the hole closed and then re-machining/broaching the splines.

The bike in question is a classic '72 Honda. I cannot buy another stock kickstart lever to modify. I do not wish to cut up, bend or modify the original.

Your thoughts are welcome, thanks!

 

H

HuFlungDung

Diamond

Joined

Jan 19, 2005

Location

Canada

• Jan 25, 2018

• #2

What are the tooth numbers? I can't see it working because no spline has that much tolerance built in for a clamp effect collar.

 

J

Jim Williams

Stainless

Joined

Oct 3, 2002

Location

Grant, Florida

• Jan 25, 2018

• #3

Try to find an original at a motorcycle breaker. Then you can modify it and save your original.

 

sfriedberg

Diamond

Joined

Oct 14, 2010

Location

Oregon, USA

• Jan 25, 2018

• #4

This might actually be a reasonable place to use JB Weld or other stiff epoxy putty. You want it to adhere to the lever, not the shaft. So clean the splined hole on the lever well, and thoroughly grease (vaseline or your preferred epoxy release agent) the splined end of the shaft. Pack some mixed putty in the splined hole (just enough to fill in the unwanted gaps, not the entire hole) and arrange to hold shaft and lever in the correct position until the putty sets up.

 

wheels17

Stainless

Joined

May 10, 2012

Location

Pittsford, NY

• Jan 25, 2018

• #5

Major hack, but how a little bit of properly sized wire in the gaps at the end of the splines radially, then tighten.

 

N

no704

Aluminum

Joined

Sep 14, 2017

Location

Tempe, AZ

• Jan 25, 2018

• #6

Wedge it on with a wrap of shim stock.

 

C

converterking

Stainless

Joined

Apr 17, 2004

Location

Kolding Denmark

• Jan 25, 2018

• #7

Wouldn't it be easier to modify the exhaust?

 

steve45

Stainless

Joined

Jan 16, 2012

Location

Midland, Texas

• Jan 25, 2018

• #8

I like the shim stock idea, but it might be hard to get stainless shim stock to form to fit. Try a beer can.

 

D

dian

Titanium

Joined

Feb 22, 2010

Location

ch

• Jan 26, 2018

• #9

put metal shavings (bandsaw) in the epoxy.

 

cyanidekid

Titanium

Joined

Jun 4, 2016

Location

Brooklyn NYC

• Jan 26, 2018

• #10

Wow, I really think epoxy or just jamming random metal in there are terrible ideas. You will end up with the splines on the shaft buggered with round rod in particular.
If it’s a Honda, there are probably tens of thousands of bike parts out there with the same splines. Find a part and modify!

 

M

magneticanomaly

Titanium

Joined

Mar 22, 2007

Location

On Elk Mountain, West Virginia, USA

• Jan 26, 2018

• #11

If I absolutely had to do this, I would hacksaw the donor lever with the too-big hole in pieces radially around the hole....three pieces would be nice if the spline # is a multiple of 3. File the cut faces if needed to get the pieces to fit snugly on the shaft. Bevel the pieces, clamp them on the shaft with wire, tack-weld, remove (so you don't draw the temper from the shaft), and weld back together.

But a junkyard replacement to modify would be my preference.

 

C

Cmsmoke

Aluminum

Joined

Apr 3, 2016

Location

Johnstown

• Jan 27, 2018

• #12

I don't understand why you do not want to cut or modify the stock lever, but you are willing to take the chance of ruining the shaft (and you will) by rigging something that doesn't fit properly. I would modify the stock lever or combine it with the aftermarket. If you are dead set on saving the original lever, find another one to work with. In the end, it will be the best route. Another way to do this would be to open up the splined hole in the aftermarket lever, weld or permanently fix a bushing in and get splines cut to properly match. You could also use the original clamp and make your own custom lever to fit.

 

S

steve-l

Titanium

Joined

Mar 2, 2012

Location

Geilenkirchen, Germany

• Jan 27, 2018

• #13

This is a machinist forum. Mickey mouse shit is not what you usually find here. The correct solution is to make a lever that is what you want. Then make a broach that cuts the Honda spine pattern. Then broach the hole correctly in the new part.

 

J

jrmach

Titanium

Joined

Jun 9, 2012

Location

Boise,Idaho USA

• Jan 27, 2018

• #14

A friend of mine years ago had a shifter that the splines were stripped and the pinch bolt would no hold in place.
He asked me to WELD it on,,,no shit,,,,so I did
I often wondered what the fck he did when he had to take off the primary cover for maintenance,,,,lol

 

S

SteveBausch

Stainless

Joined

Jan 11, 2010

Location

Indianapolis

• Jan 27, 2018

• #15

Modify the exhaust.

How bout some pics?

Specify the bike, and perhaps one can be found.


Here in Indy, there are two bike salvage businesses, relatives that may still speak to each other.

Cycle Re-Cycle are in the business names.

Part I
and
Part II

Call them up and ASK for a suggestion or two.


Find a truly expert TIG welder that (using a magnifier) can add to the splines lengths.

Or have it metal-sprayed


Find one that fits too tight, and use jewelers files and magnification to open it up a bit


You can always remove metal. Putting it back on is a bit tricky.