Modern Vespa

Ride on my new GTS was crap. Took me a day or two to figure out suspension was bottoming out. Up one click on the rear preload adjusters and all was well at the rear but what about the front?

Factory rears have preload adjusters. All the aftermarket shocks have preload adjustment. Why Piaggio none on the front?

Took the shock off and took it apart, top just screws off, no spring compressor needed. At first i thought I could simply use fender washers as spacers on top of the spring, but turns out they need to be a precise size to accurately locate the spring top mount, nothing close enough at the hardware store.

Fabbed up a couple spacers from 1/8" ABS, ID has to match shaft diameter and OD needs to fit tightly in upper spring mount.

Reassembled with 1/4" total spacer. 1/4" looked to match one click at the rear. Success, no more bottoming front or rear. Will eventually go aftermarket but wanted to give the factory parts a shot.

No pics, but if you attempt this when you get it apart it's pretty obvious what needs to be done. Will take some pics when I go back in to swap out the bushings for urethane.

Downside obviously is shock needs to come off and apart to do this, it's not a simple adjustment. But wanted to put it out there that it is doable.

Not as simple as I originally thought.

Took it back apart to do the urethane bushings and take pics. Good thing, the way I had done the spacers I had no suspension travel. Verdict, this is not doable with simple spacers.

Bit of a rethink and a trip to the hardware store and I came up with Rev. B, repurposed a ABS plumbing fitting. Doable, but spacer has to be only at the outside diameter and located by the top cap.

Good initiative.

Have you thought about making a spring swap? What do you weigh if I may ask? Do you ride solo or 2 up?

Jerry

Issue with spring swap is what is stock spring rate? And it's progressive. Also by the time you source a spring you're probably over half way to a cheap aftermarket shock.

The fact that 1/4 inch of preload made a difference, means stock rate is close enough for my 205 lb rider weight.

In a similar situation to you bluecloud, a GTS300 HPE now with 20k klm on the clock. Front suspension feels like it sits at 50% or more thru its travel (at rest). Before i go and purchase an adjustable Bitubo or similar, thought i should try your solution of a spacer

As i have a 3D printer, i am considering to print a spacer from TPU (thermoplastic urethane) to exactly fit the dimensions.

My question (without yet dismantling the shock for a close look) is: did it look feasible to put the spacer at the lower end of the spring, rather than the top? I wonder if this would provide a bigger surface are to spread the load between the spring and the urethane spacer. I would appreciate any insights....

Yes, absolutely.

I didn't do it at the bottom because you will see it. With the printer can probably make something that doesn't look like a hack job.

With that said, the factory shock is crap, I've got about 3k on mine now and am researching aftermarket options.

I went ahead and made a 15mm spacer to suit the bottom of the spring. Does it look like a hack job? Maybe. Was it way cheaper than a new shock? Definitely.

When i took the spring and shock apart, i tested the damping and it seemed to be working properly. Is it the correct damping? Who knows.

After a quick ride around the neighbourhood i could definitely feel a difference - for the better. Time will tell if 15mm was the right guess.
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Looks fine, better than mine.