noisey diff/gearbox ?

[upnorthbiker]

Hi,
Does anyone notice a whining noise when the throttle is closed quickly, and maximum engine braking takes over.
I have noticed this high pitched noise, especialy on hard engine braking.
If the throttle is closed slowly and there is minimum engine braking, there is no noise.
I cannot pinpoint the noise to either the shaft or the gearbox.
Its present in all gears, and slowing from varying speeds.
There is no noise on acceleration.
Anyone throw any ideas as to what it might be before I go to the mechanic.
Thanks in advance.
Jeff.

[M5'er]

From other posts here some say it is the shaft, some attribute it to tires on quick enging breaking. I think it is the shaft, my bike does it exactly how you describe. I am pretty sure it is normal and not a problem. If you want piece of mind you could have the dealer check it out.

[outlaw]

mine does it as well as most other ppls here in the forum. i think it has to do with the way the torque is applied to the shaft and then all at once it is unloaded and applied in the opposite direction as drag. i wouldn't worry about it.

[Rickster]

I use to have that same noise, but after I put the Vance & Hines cruzers exhaust on it, I can no longer hear it.
What do you suppose could be in that stock exhaust that could make the gears sound like that?












Seriously though, I wouldn't worry about it, seems like everyone is reporting that noise.

[outlaw]

could be the back pressure then. the bike needs all that air and your delivering it and then, hey, i don't need it anymore.

[upnorthbiker]

Thanks for the replies , im not worried about it as the bike rides great.
I will ask the dealer to take a look while its in warranty tho.
Jeff.

[djump]

I think it is completly normal and every bike (and some cars) I've ever had does this.

Its a combination of extra engine revs, everything being loaded on the opposite wearing face than normal, exhaust noise and tyres

[Kingby]

Its from the shaft/differential and its normal. The gears are cut to perform quietly while torque is applied to move the bike in a forward direction. The gear is cut in a such way to reduce that whirrr noise or the rider would be driven to insanity.

However, when the engine is braking, the torque is being applied in the opposite direction on the gears and the whirring noise becomes evident. Since you can't have the gears cut to reduce noise in both directions (you can only get one or the other) you can hear that whirring noise on engine braking.

Same reason as when you hear a those compact front wheel drive cars in reverse. They have that whirring noise.

[djump]

Cheers

[hammersfan]

You might want to try using Lucas synthetic gear oil , I have some but haven't put it in yet. It is supposed to help get rid of the whining noise. Also it is not very expensive either.