Left end Crank Bearing Support/Self Starting

[rosco15]

We had a discussion about this on the left end crank damage thread. Thought I would share what I came up with. The idea is to use a bearing to support the left end of the crankshaft. This was done to help keep the left end from breaking off. We left enough threads on there so I could still pull it off. This is on a self starting dragbike with a total loss ignition. They make these for the outboard starting guys, but not for the guys that want to self start.

I should say Mark came up with the idea and also thanks to TDM Machine for the work. So far they can make anything I can dream up.

[rosco15]

[rapidray]

VERY cool Ryan! How much to get the bearing & holder from you? Thanks & Merry Christmas! Ray.

[rosco15]

From me way more than it's worth. Probably alot cheaper cutting me/the middle man out of the equation. I could PM you the machine shop I use. He has all the specs on some scrap paper with my drawing on the bottom.

I got the bearing from Mcmaster-carr. Bearing#6906 Part#5972K247 ID30mm OD47mm.

I will call you about that head info eventually. I'm trying to get everything else out of the way first.

[rosco15]

So far 1 vote from off the list that the bearing is too small and that the cover will eventually fatigue and break.

[rapidray]

Whoever said that doesn't know of what they speak!!! Ray.

[Tarbash 27]

Is that bearing going to tolerate the rpms? What about the grease and oil mixing?

[Billy Ricks]

Is that bearing going to tolerate the rpms? What about the grease and oil mixing?

Very little oil make its way into the stator cover and since it's a total loss system there won't be much of anything to churn that oil up. Ryan stated they are already in use on outboard starter bikes so it seems to be a tested design with some tweaks.

[rosco15]

Bearing Specs, I was tempted to use a sealed bearing, but went with the open design.

Ball Bearing Style Open - General Purpose
For Shaft Diameter 30 mm, Outside Diameter47 mm, Width 9 mm
ABEC Precision Bearing Rating ABEC-1 ABEC-1 Precision Rating Regular
Dynamic Radial Load Capacity, lbs. 1,628
Dynamic Radial Load Capacity Range, lbs. 1,501 to 3,000 lbs.
Maximum rpm 17,000
Maximum rpm Range 15,001 to 30,000
Temperature Range -4° to +248° F
Bearing Material Steel

[doctorgonzo]

I am going to seriously consider this. Very cool.

[NoBars]

Mill or grind the rivet heads off and drive them out with a punch, then the remains of the magnet will come off. Less weight to spin up, and is also balanced better.

Really nice design, I am impressed. IMO all the bearing has to do is prevent it from wobbling off center at high RPM, I feel that is what breaks left ends. Yoy are probably good to go without the magnet but this provides some exra insurance

Anthony