Ultimate Bearing Solution for 4-Stroke Belt Tranny

  • Thread starter Deleted Member 4613
  • Start date
No, a dremel is useless. Only use a hone. I used a brake cylinder
hone from O'Riellys. It's perfect for the job.
 
Of course, the Grubee belt drive is the best - agreed. He uses
bearings and left bushings long ago. His stuff is more expensive,
but he's been at it forever, and started the hobby by himself
long ago.
 
There's maybe one more point about press fitting
which I don't have the answer to. The heat
generated from the motor may or may not
loosen the press fit. I don't know.
If it is done correctly, a press fit will hold. Ever wonder why the bearings on the crank don't walk out? They are a true inference fit. Heating will do nothing to get them out. They need pressed in, and beat or properly pressed out. What happens a lot of time is the bearings go, and the outer race is still stuck, because of the interference fit. If you can tap or pop out the bearings, they aren't correctly interference fit.
 
Links to Amazon may include affiliate code. If you click on an Amazon link and make a purchase, this forum may earn a small commission.
Heat from the clutch shoes and centrifugal forces will loosen the press fit
If it is done correctly, it will not. Why do you think the bearings in our cases stay where they are? There's a lot of heat going into them, and they stay right there, and have to be beaten, or properly pressed out. There are no clips or anything but a pressed fit holding them in a CG. If they walked, the crank would destroy them in short order.

If they are getting hot enough to walk after a proper interference fit, the bearing and the engine is dead and needs to be rebuilt or replaced. lol
 
If somebody has a expanding reamer set, you could use expanding reamer inserted in clutch bell the width of the bearing, then on the other side of expanding reamer make sure you use the centering collet on opposite side you are reaming to size. Then flip expanding reamer to other side of clutch bell & repeat the procedure. Then you would have a step on each side of clutch bell for the bearings to seat.
 
While your making a good interference fit for the bearing, just make it at the end of the boar
Now you accomplished a slight ledge for the bearing to rest on.

Centrifugal forces force the drum outward While the clutch shoes force the drum to spin slightly untrue.
This centrifugal outward force and untrue effect along with the shoes generating heat causing thermal expansion of the boar will loosen the (interference) press fit of the bearings. Then the bearing distorts the ID of the boar, becoming even worse.

All of this don't happen the first time ya ride your bike it slowly develops over time and the clutch gets sloppier and sloppier
When there is a ledge machined in the boar for the bearing to rest on this ledge is what keeps the bearing square in the boar
The boar can't walk on the bearings, it's impossible
It will not come out with a proper interference fit. The crank is applying a totally unequal force on the bearings. Try to pop those out. You can't without beating them, unless you bought garbage.

The bearings are designed for such forces. If you are getting wear, you have not done it properly. My motorcycle is a buzz machine, they have a counter shaft, but guess what, roller bearings. If it did not work, this sucker would have died a long time ago. I'm pumping 43-44hp though it.

If the material in the housing/bell can't hold shape, you shouldn't buy it. It's going to go bad no matter what you do. The reason behind the interference fit, so the holes don't go oblong or wear, causing the bearing to slip, eating the housing or shaft.

Only a racer will have a slide fit, for more power, they are also replacing parts a lot, they wear way faster with a slide fit, vs an interference fit, but allow slightly more power by reduced friction. Again the whole reason an interference fit is used is to prevent wear and if you are getting slide from an interference fit, it's not done properly.

If heat is causing it to loosen, you either have inferior garbage you shouldn't have bought in the first place, or the interference fit was not done properly. The engine my motorcycle uses, I have seen over 150k miles on them, same original interference fit bearings. If the bearings go, you have to cut the race out, or press it off.

Heat will not cause an interference fit to loosen, unless over heated drastically, again the reason behind using it is it prevent wear, by not allowing the races to slide on the shaft or housing keping the shafts and housing running true.
 
Back
Top