Noisy final reduction input shaft bearing

[blaudp79]

Hi All,

People GT 200i, 30k miles

I had a noisy final reduction input shaft bearing. It produced an alternating whining sound at high speed.
The OEM bearing was a 6205 made by TPI and it had a "ON" mark on it, which probably refers to C0 (standard) clearance.
I did spin it while it was still mounted onto the shaft and into the gearbox cover plate and it didn't spin smooth, so I decided to replace it.
The new one was no different, so I decided to try a C3 (larger internal clearance) bearing, but even that one felt a bit rough after installing it.
Both the C0 and C3 were spinning smoothly as is on my finger. After pressing them onto shaft and into the aluminum cover they shrank that much that the bearing didn't spin smooth.
I made sure I press it onto the shaft through the inner race and into the cover via the outer race, so the bearing race did not get damaged.
I tried later a bearing with C4 clearance (even larger) and this one was spinning smooth. However, now I get a typical high pitched continuous bearing noise at max speed.

Specs of the bearings I tried:

1st - NTN 6205 C0 with rubber seals, loaded with grease (I removed the seals and washed the grease out before install)
2nd - NTN 6205 C3 with rubber seals, loaded with grease (I removed the seals and washed the grease out before install)
3rd - NTN 6205 C4 open

I'm thinking to try a higher quality open C3 bearing, like an NSK or SKF to rule out the the possibility of contamination during grease removal and bearing quality issues.

Has anyone had similar issues?
 
Thanks.

[Ruffus]

Welcome here!
Pls have a look at links below

https://www.kymcoforum.com/index.php?topic=34962.msg243189#msg243189

https://www.kymcoforum.com/index.php?topic=31780.msg222806#msg222806

A CO rating for our bearings is right in general. C3/C4 might have too much tolerance. One reason for this noise again could be the bearing not deep enough in its seat, because then sprockets don't align properly and cause a whirring sound.

A little resistance after pressing in is normal. Just feelable, not blocking.

Both shanks (driveshafts) should go WITHOUT pressure in its seats, clutch- and wheeldrive. Only by hand, no press neccessary!

Pic below from a neglected sound.

[blaudp79]

Thanks for the quick reply!
The input shaft (#23411 below) sits in two bearings. The end of the shaft sits in the bearing that is in the gearbox housing. I can push the shaft end into the bearing easily by hand.
The middle of the shaft sits in the bearing that is in the cover plate (21301 below). This bearing needs to be pressed onto the shaft by a hydraulic press and it is very tight.

[Ruffus]

Once again...
Both shanks (driveshafts) should go WITHOUT pressure in its seats, clutch- and wheeldrive. Only by hand, no press neccessary!

I used heat/ freeze method for all bearings, without hydraulic press.
Restored about ten gears within last six years, all of them without press.