Conversion of Belt Drive, Bronze Bushing to Oilite Bushing

[Deleted Member 4613]

This is an easy conversion for a 15mm shaft motor. It requiries three new parts and about 30-45 minutes.

The clutch works as follows: The bushing bronze or oilite is bolted against the bottom
washer and locked to the motor shaft. The clutch bell rotates around the od of the
bushing. For this to happen, the bushing must be slightly longer than the clutch bell
housing. Spacers are necessary to prevent the clutch bell from moving outward.
Just enough space is required for the bell to rotate freely.
Grease is important applied to the od of the bronze bushing. The oilite
bushing holds about 18-20% oil, which migrates to the od surface of the bushing
when under load. It is self lubricating.

PARTS REQUIRED FOR CONVERSION
1. oil-embedded Oilite Bushing 841, 15mm id x 20mm od x 25mm length, Part Number 6658K178, McMaster-Carr, $3.44
2. Two spacer washers, known as fender washers, 1.25mm thick, 22.5mm id, from Ace Hardware
3. one 15mm id washer intended for an M14 bolt, from Ace Hardware.

All that is necessary is to remove a small amount of material from the clutch bell housing, using a brake cylinder
hone, Lisle, Number 10500 from O'Reilly's. The hone is inserted into a variable speed drill and slow hone the
housing with the use of brake fluid as a cutting oil, applied to the hone or housing. I used the Oilite bushing to measure the
honing progress. Hone the housing in repeated steps until the bushing just slips into the housing. It may
feel a bit rough when inserting the bushing, but when the housing is spun around the bushing, oil is
released and the feel is very good. This is a slow process as the hone removes very little material at a
time. Finish off with fine sandpaper for a polished look. Buy two Oilite bushings, one for fitting
while honing, and one for the final assembly. Put the bushing in the housing, then onto the shaft,
against the original bottom washer, then place two spacer washers over the shaft, place the 15mm washer
onto the plug containing the bolt and screw snug tight. DO NOT OVERTIGHTEN AS YOU ARE TIGHTENING
DOWN DIRECTLY AGAINST THE BUSHING. Use a small amount of blue locktight on the end of the bolt, not much.
Check that the bell moves freely around the bushing. That's it, hope I didn't miss anything.

 

[Wrench]

I wonder how much friction and wear will be caused by the spacers and 15mm washer.

One reason, Sealed Bearings would be better. If set up correctly there will be no friction

 

[Deleted Member 4613]

The spacers move freely and a drop of oil on them would be sufficient. Doubt
this would be a problem. When six sealed bearings are used, there is also some protrusion
above the housing and some minor contact, and there too a drop of oil is
helpful. I don't expect any problem, but testing is always a good procedure.

 

[Wrench]

The spacers move freely and a drop of oil on them would be sufficient. Doubt
this would be a problem.

The kinda friction I have seen before. Is that the clutch always want's to move outward on the shaft This puts pressure on the 15mm steel washer
and the washer eats into the face of the clutch.
If you have this problem of the 15mm washer eating into the clutch face, you can use a sacrificial 15mm bronze washer instead of the 15mm washer.
The bronze washer will last awhile but replace it when it gets worn.
IDK maybe you can get an Oilite 15mm washer (bushing)

When six sealed bearings are used, there is also some protrusion
above the housing and some minor contact, and there too a drop of oil is
helpful. I don't expect any problem, but testing is always a good procedure.

There should be no slop or minor contact when using a sealed bearing. The inner race has to be supported from both sides.
The clutch drum will have no back and forth play like the clutch drum with bushing
Use spacers the same size as the bearing ID race

Make your own spacers just cut open a bearing and take the ID race. Shave the height if needed for clearance issues

This is what I meant by setting it up correctly.

 

[Deleted Member 4613]

I could make my own spacers and match the id of the spacer to the od
of the bushing if I thought this was going to be a problem. Even the
original greased bronze bushing has contact under the flange where
I found the manufacturer applied ample grease. I want to see how this
design works out before making changes. At this point, I'm not worried about
some incidental contact with the spacers and bell or top washer unless I
see it is a real issue after testing. There must be some free space for the bell to
move. It should be minimal, but it must be there. You could, of course, if you're
interested, make any change you wish to improve the design. I prefer to go in
steps and see the results of testing first. First testing, then changes. First
an oilite approach, then a sealed bearing solution if necessary. The 15mm
washer can't eat into the face of the clutch bell. It doesn't contact the
clutch bell. The spacers separate the top 15mm washer from the clutch bell.
If there is any contact, it will be the spacers against the top washer or top face
of the housing, just like the original bronze bushing. Like I said, there is always
going to be some incidental contact when using a bushing, and also sealed bearings when
six are used and press fit into the housing. The contact will be between the
press-fit bearing in the housing that protrudes from the housing and the top washer.
The designer of the sealed bearing mod recommends a drop of oil under the top washer
to deal with this contact, and I believe he is correct. Some oil, a small amount on the
spacers, could be helpful but I don't see this as a problem because they move freely. Also
remember, there are two thin spacers that will slide over each other. With some oil,
it's hard to imagine the spacers locking up together and acting with any great force
against the top washer or the housing face. These are freely moving spacers.

 

[Wrench]

The Sealed Bearing Mod can be improved

The Sealed bearings will get rid of the friction from the bushing
Now ya gotta get rid of the friction from the spacers by supporting the bearings inner race from both sides.
The clutch drum shouldn't make contact to anything except the clutch shoes.

I'm sure your clutch will work fine as it is now. But less friction means less drag

 

[Will'smotobikes19]

Someone needs to put together a kit with no junky clutch. Something with japanese sealed bearings and no steel rings on the 100 tooth pulley, it wears through the aluminum and falls off. Also a fastener upgrade like 8mm side adjustment bolts. I had one of the 6mm ones break off so I drilled and tapped for 5/16.

 

[Wrench]

Someone needs to put together a kit with no junky clutch. Something with japanese sealed bearings and no steel rings on the 100 tooth pulley, it wears through the aluminum and falls off. Also a fastener upgrade like 8mm side adjustment bolts. I had one of the 6mm ones break off so I drilled and tapped for 5/16.

Yea OK, but maybe you should start another thread about your clutch it's different

 

[Will'smotobikes19]

Actually just started one about the fuel mix screw but yeah the ebay clutches on the 49cc are almost like the 2 stroke motors they work for a while and break. It's how China gets more American cash.

 

[Deleted Member 4613]

I'll think about sealed bearings after I test the Oilite solution. I think it
might be an easier solution for most users who may be hesitant about
removing material from the motor shaft, and more from the clutch
housing. It's complicated. FYI, the bronze flanged bushing that comes
with the kit makes contact with the clutch bell under the flange. But my
concentration now is testing what I designed. Right now, I'm not open to
any changes. I have to explore my concept with with testing.