Call it a "drift" then

saturnphive · Post by **saturnphive** » Wed Nov 20, 2013 8:29 pm

Ever since I fixed the damn rear tire I can't shake the feeling that my rear end is "Drifty".

I would call it "wobbly" but its not, it doesnt' go back and forth quicky or jarringly. it just seems to catch the urge now and then to pull a little left, pull a little right. It almost feels like understeer or oversteer in a car when I corner. It feels like it comes from the rear tire.

I can't remember if this is how it always felt or if I'm paranoid. The Axle nut WAS loose, but now it definitely is not. I tightened the shit out of that thing and then double checked two days later, I couldn't even turn the nut thanks to the locktite that's on there. So the nut is on strong, the wheel is properly inflated, the cotter pin is brand new, the tire is the same as I was using before. Shaking the wheel while off the ground produces maybe, MAYBE 1-2mm of shake between what I would call the surrounding drum and the interior hub.

This feeling/movement is slight (its never strong, just sort of a suggestion - "hey, we're gonna move a foot or two over in this lane...") and it just feels kind of soft back there.

Anyone have any idea what's going on or experienced anything like it after a blowout?

az_slynch · Post by **az_slynch** » Thu Nov 21, 2013 5:24 am

The vintage Vespa and Stella chassis have rubber bushings in the swing arm, lower rear shock mount and a rubber block on top of the shock. If either of these parts are decayed or torn they will be extra flexible in corners, making the rear end feel loose. Some places sell spacers to resist the lateral flexing of the swing arm bushings, and other places offer urethane swing arm bushings to firm things up a bit.

Try riding another Stella or vintage Vespa and see if it feels loose like yours, so you can have an idea if your suspension is "normal" or if it really has an issue.

One other, less significant item could be the tire's load index. Manufacturers offer 3.50x10 tires in 51J and 59J load/speed indexes. I recommend 59J tires as they're a bit firmer and the sidewalls don't flex as much.

saturnphive · Post by **saturnphive** » Thu Nov 21, 2013 3:35 pm

Thanks AZ - that's encouraging. I did a search on "swing arm bushings" and found this thread which seems to describe my problem and similar fix. Is this what you're talking about?

Like I noted in a different thread, while changing the rear tire I dropped the raw hub (with bike attached). I wonder if the shock deformed one of the pieces of rubber you refer to or affected the bushings.

Definitely good to hear its not life threatening. Looks like I've found my off-season project!

BuddyRaton · Post by **BuddyRaton** » Thu Nov 21, 2013 8:10 pm

Good advice from Az...az always! I would also suggest keeping a good eye on tire pressure.

It depends on how much and what kind of riding you do but it seems too early for the bushings to be worn out to me.

I used the Clause Studio mounts and for me it stiffened things up way too much. The handling was incredible...so was the vibration!

I think Az is headed in the right direction. The upper rubber shock mount is held on by one bolt. The rubber could be worn or the bolt could be loose. I would also check the bolt that goes through the swingarm bushings and also the lower shock mount. It could also be that you need a new rear shock.

As said these motors are always a bit "sloppy" and move around on their mounts. Clause stopped making the reinforced top mounts because they were too stiff.