[NMPete]

Hi - I am in the process of removing the engine from my Sei 900 because the transmission is extremely noisy. The "gear noise" of the trans is louder than the exhaust! This is probably why the previous owner put it in a barn for 30 years. The shame is, the bike has only 9000 miles and the engine (pistons, etc) look like new.

Anyone have experience with this type problem?

Anything to watch out for on trans dis-assembly?

Thanks

 

[R Powell]

Not had this problem on either of my 900 seis both with over 30000 miles on each. It sounds like somebody may have run the bike low on oil and damaged a gearbox bearing!. You can access the gearbox by turning the engine upside down and removing the sump and lower casing. The gears should stay in position. Take plenty of photos as you disassemble and I found the Benelli SEI parts manual had better pictures than the manual. Good luck getting it sorted!

 

[Tornadoboy]

Hi,
The primary chain on the 6s can be a bit nosey but not louder than an exhaust. One of the gearbox shafts, I think it is the output shaft has inadequate hardening and wears at the needle bearing. The solution is to have it sleeved. Selwyn Motorcycles do this on an exchange basis. Let us know what you find!

Chris

 

[NMPete]

Hi - Thanks for the great responses! I hope to have it apart next week, so I'll let you know what I find.

Thanks again.

Pete

 

[NMPete]

Howling Transmission

Hi,
The primary chain on the 6s can be a bit nosey but not louder than an exhaust. One of the gearbox shafts, I think it is the output shaft has inadequate hardening and wears at the needle bearing. The solution is to have it sleeved. Selwyn Motorcycles do this on an exchange basis. Let us know what you find!

Chris

Hi - Got it apart and all parts look like new. Only problem I found is the main input shaft has lines (parallel to the shaft and same spacing as needle bearing rollers) on the needle bearing surfaces of the shaft and the inside of the starter gear. The lines are actually indentations in the bearing surface. I am guessing this is a result of rust (bike sat for about 30 years). It makes a loud rattling noise when I spin the starter gear. Needle bearing looks O.K.

Any suggestions as to how to repair this?

Thanks

Pete

 

[edgefinder]

Hi Pete, How many miles did you ride it and did you rev the motor up enough to tell for sure the noise is engine speed related, another question is was noise the same in all gears and neutral? The needle indentions on the input shaft, I'm guessing the ends ride in ball bearings and the indentions are where a gear freewheels when not selected. That shouldn't cause much if any noise and the bearing doesn't carry a load when selected, a sliding gear splined to the shaft slides into it locking engagement dogs on the sides to stop it spinning when selected. The starter gear, is it an idle gear that spins while the motor runs? That could be it.

 

[NMPete]

Hi Pete, How many miles did you ride it and did you rev the motor up enough to tell for sure the noise is engine speed related, another question is was noise the same in all gears and neutral? The needle indentions on the input shaft, I'm guessing the ends ride in ball bearings and the indentions are where a gear freewheels when not selected. That shouldn't cause much if any noise and the bearing doesn't carry a load when selected, a sliding gear splined to the shaft slides into it locking engagement dogs on the sides to stop it spinning when selected. The starter gear, is it an idle gear that spins while the motor runs? That could be it.

Hi - I did ride it about 50 miles and under load it is the nosiest (pull in the clutch and rev the motor: no noise). It is the starter gear on the primary input shaft (no speed gears on this one) - rides on a needle bearing. All ball bearings are like new.

Pete

 

[edgefinder]

Starter gear is before transmission so that shouldn't be it. Have you tried spinning each tranny shaft laying in the case by itself, the input without the clutch on it? A small amount of end play? No blue burn marks on the ends of any parts like a shim missing allowing things to rub? Bauer has good diagrams to point out different parts

09 Clutch - Benelli-Bauer.com

 

[NMPete]

Starter gear is before transmission so that shouldn't be it. Have you tried spinning each tranny shaft laying in the case by itself, the input without the clutch on it? A small amount of end play? No blue burn marks on the ends of any parts like a shim missing allowing things to rub? Bauer has good diagrams to point out different parts

09 Clutch - Benelli-Bauer.com

Hi - Thanks for the tips. I tried what you suggested - spun the 5 speed gears without the clutch gears and basically no noise. There is some slight rubbing noise from the selector forks contacting the gears with dogs, but no appreciable wear. No significant end-play Gear teeth look excellent (had a Norton guru inspect the gears and he said they look fine).
Since I am "in there", I am replacing the needle bearings and the bushings. Roller bearings are fine. Ordered the parts form Benelli-Bauer.

Thanks

Pete

 

[NMPete]

Howling Transmission

Starter gear is before transmission so that shouldn't be it. Have you tried spinning each tranny shaft laying in the case by itself, the input without the clutch on it? A small amount of end play? No blue burn marks on the ends of any parts like a shim missing allowing things to rub? Bauer has good diagrams to point out different parts

09 Clutch - Benelli-Bauer.com

Hi - I did find that the thrust bearing washer at the high gear on the middle spline next to the needle bearing cage has about .015" of clearance when the dog teeth are set into the top gear. The shop manual lists additional thicknesses in the thrust washer but no recommended clearance. The clearance on the other shaft thrust washer next to first gear is smaller (about .010") and both thrust washers look good and show little wear.

Do you know what clearance is recommended?

Thanks

Pete