Subject: Re: bearing damage?
Author: Patrick Hayes
Date: Apr 21, 2005, 5:58 PM
Post ID: 1718742294
Greg Bender wrote:
| With the clutch engaged, you simply want to be sure that the throw-out bearing isn't turning. The easiest way to check is to put the bike on the centerstand, start it up with it in neutral, and look at the rear of the transmission. If the plunger under the lever arm on the back of the transmission is turning, then your bearing is turning, too. |
The exposed portion of the throwout plunger shoult NOT turn under any
circumstances. That's why we have a bearing inside. If the exposed
outer body does spin, it is a HUGE indicator that the bearing is toast.
The crankshaft, flywheel and clutch are all spinning. You pull in on
the hand lever and a long rod from the back of the transmission gets
pushed against the center portion of the spinning clutch. This throw
out rod makes contact and immediately begins to spin in synch with the
clutch. At the back end of this rod is a bearing. Older 4-speeds had a
caged roller affair. Newer 5-speeds have a radial needle affair. The
bearing is there to allow the throwout rod to spin while the back
portion or outer body is stationary. The outer body is pushed by the
transmission lever and it should not spin. Something has to give in the
middle and that is what the bearing is for.
When the bearing fails, it now prevents the long rod from spinning.
Since the clutch is still spinning, the stationary rod begins to act
like a very blunt drill bit. It either overheats and welds itself to
the clutch. Or it overheats and shortens its length so that it fails to
function. Or, in rare case, it literally drills a hole through the
center of the clutch.
Patrick Hayes
Fremont CA