vibration when using rear brake at idle?

bimbom · Post by **bimbom** » Mon Sep 24, 2012 6:34 pm

Just took Buddy out for lunch and noticed something. This might be completely normal though:

When at a red light, if I press the left (rear) brake, I noticed the bike vibrates heavily. Not really any rattling or anything alarming, but it has a deep rumble to it that I can feel through the seat.

When I release the left brake, it goes away. Anything to be worried about?

2000 miles on the bike and about to do 2nd oil change.

stASH · Post by **stASH** » Mon Sep 24, 2012 7:04 pm

I've noticed the same thing and just figured that without the rear brake on, some of that engine vibration is absorbed by the suspension, when you hold the brake, it kinda solidifies things and you feel it.

bimbom · Post by **bimbom** » Mon Sep 24, 2012 7:16 pm

stASH wrote:I've noticed the same thing and just figured that without the rear brake on, some of that engine vibration is absorbed by the suspension, when you hold the brake, it kinda solidifies things and you feel it.

makes sense.. thanks!

cdwise · Post by **cdwise** » Mon Sep 24, 2012 7:51 pm

Same here and on the Vespa GTS as well. It seems to just be something scooters do.

ravenlore · Post by **ravenlore** » Mon Sep 24, 2012 8:02 pm

cdwise wrote:Same here and on the Vespa GTS as well. It seems to just be something scooters do.

Yep, my GTS does it too. (I'm so glad I'm not the only one)

Syd · Post by **Syd** » Mon Sep 24, 2012 8:44 pm

Same on the Fiddle and on the HD200. Plus, if I pulled on the front brake it would settle down too.

Post by **ericalm** » Thu Sep 27, 2012 11:19 pm

From the ModernVespa Wiki:

This falls into the category of "they all do that".

While idling, the engine noise (and associated vibration) changes when the rear brake is applied because the rear wheel is being clamped to the engine via the brake calipers. This allows vibration to travel through the frame via different paths, and also provides additional dampening that otherwise doesn't occur very efficiently through the axle alone.

The change in engine noise and vibration is not because of additional load being put on the engine. Stopped is stopped, and the centrifugal clutch is disengaged regardless.