Chassis material

[GalacticFattPatt]

What is our chassis made out of? Steel? or some other alloy? Question is in reference to the Vespa having a steel chassis and therefore being more stable than the Buddy.
Also, I have read of the stability issues at high speeds on the buddy. This had kept me away from the higher speeds for some time, but now that I have experienced the higher speeds and never felt a wobble, I am not sure what the big deal is. It also make be think that the wobble is from over inflated tires, or properly inflated tires. Once, I filled my tires up to pressure and I could tell that the scooter was less stable. Makes sense since there is not as much tire contact with the rode.
Any thoughts?
GFP OUT

[Corsair]

I don't know what it's made from but I do know I've taken the Buddy to around 60mph and it's handled fine for me (I haven't been full out yet though)

[codemonkey]

I think the guy at the scooter shop said it was steel. I could be remembering wrong though. Don't listen to me.

[rablack]

The "chassis" is the set of exterior panels attached to the frame. The chassis of a Vespa, like that of a car, is made of steel. The Buddy has a tubular steel frame with plastic panels. So the answer is plastic.

Plastic is lighter and cheaper to repair (or rather replace) than the steel. A steel chassis gives a scoot more overall mass so it feels more stable at speed.

[codemonkey]

Der, I knew the panels were plastic. I'm not smart in the ways of mechanical stuff.

[ericalm]

Actually, your scoot will handle better with the tires inflated a couple psi over recommended amount. It also improves speed and gas mileage.

Riding on underinflated soft tires isn't good for anything and will not improve stability.

[San Francisco]

The "chassis" is the set of exterior panels attached to the frame. The chassis of a Vespa, like that of a car, is made of steel. The Buddy has a tubular steel frame with plastic panels. So the answer is plastic.

Plastic is lighter and cheaper to repair (or rather replace) than the steel. A steel chassis gives a scoot more overall mass so it feels more stable at speed.

As authoritive as your words sound, I'm not too sure about your definition.

In any event, I believe the member was asking in the context of what
everyone understands the the chassis to be, which is the framework to
which the bodywork is attached.

I did not know chassis was defined differently for scooters. . To be sure, if someone said the
Vespa or Buddy had a plastic chassis, I'd be freaking out. Is
there something out there from Vespa where they calling the bodywork
the "chassis?"

Here's Wikipedia's definition of chassis:

In the case of vehicles, the term chassis means the frame plus the "running gear" like engine, transmission, driveshaft, differential, and suspension. A body (sometimes referred to as "coachwork"), which is usually not necessary for integrity of the structure, is built on the chassis to complete the vehicle. Commercial vehicle manufacturers may have “chassis only”, “cowl and chassis”, as well as "cab and chassis" versions that can be outfitted with specialized bodies. These include motor homes, fire engines, ambulances, box trucks, etc.
In an airplane, the chassis consists only of the landing gear or undercarriage, not the airframe itself.

[illnoise]

Vespas have a monocoque chassis (the body IS the frame). It's been a big selling point all the way back to their introduction in 1946. there are good and bad things about a monocoque. Back in the day, it was lighter and arguably stronger than a tube frame with steel panels bolted on (like a Lambretta), it's simpler and more elegant, design-wise, and it reduces steps in painting and assembly. The cons: it's expensive to manufacture, heavier than a tube frame with plastic bodywork, and if you dent or scratch it, you can't pull off a small section to replace or repair it.

Both have merits, but Vespa's hyping their roots as a metal-body scooter, and it really is the only modern scooter with an predominantly metal body (though over the years, there's been more and more plastic trim).

In the 80s, Vespa of Chicago's ad tagline was "THE SCOOTER OF STEEL" which was targeted at Honda's tupperware which was taking over the scooter market at the time.

[San Francisco]

Excellent post and explanation of the Vespa "chassis."

I have had a few monocoque cars. The thought of expensive repairs
always concerned me, so too the insurance company as indicated by their
higher rates to insure those cars.

While I don't like the thought that an alternative name for my Buddy's
body parts could be Tupperware, for the moment I am enjoying knowing
the plastic fender, for example, might cost a whopping $25 to replace.

In great coincidence, and bad timing, on the subject of this thread, the
shop just called and said the frame on one of my Ducs is cracked [by the
head tube] . On the good side, it can be welded, which is way better
than saying I needed a new frame [or chassis].

[Bryce-O-Rama]

illinoise is spot on. The P/PX (and their derivatives) are primarily steel. About 40% of the bodywork on an automatic Vespa is plastic. It's nice plastic, but Vespa does exaggerate the similarity of the current and earlier products.

There are ups and downs to either method of production, but I think steel made more sense on the manual shift Vespas than it does on the automatics. They were using sheets of steel and leg shields, cowls, etc. could be replaced on many models. On the current ones, the monocoque frame is not at all easy to repair.

The Buddy and other plastic bodied scooters have steel tube frames with plastic bodywork hanging off them as the skin. The "chassis" is steel, just in a different form than the pressed steel that Vespa uses. Plastic bodied scoots are easy and (typically) less expensive to cosmetically repair as long as parts are available.

[Roose Hurro]

Yes... "as long as parts are available".

*explains why old vespas are still on the road...*


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[Bryce-O-Rama]

Yes... "as long as parts are available".

*explains why old vespas are still on the road...*

Well, there are parts that are near impossible to find for some old Vespas. If you want anything GS160, you have to be well connected. If you've got a P series, darn near everything is available.

One of the things I really like about plastic bodied scooters is that much of the bodywork on them could be replicated in fiberglass. Potentially even in one's own back yard. It's not without challenge, but it is feasible.

[Roose Hurro]

Yes... "as long as parts are available".

*explains why old vespas are still on the road...*

Well, there are parts that are near impossible to find for some old Vespas. If you want anything GS160, you have to be well connected. If you've got a P series, darn near everything is available.

That's what I meant, though you have a point in reguards to some rare items for certain old Vespas.

One of the things I really like about plastic bodied scooters is that much of the bodywork on them could be replicated in fiberglass. Potentially even in one's own back yard. It's not without challenge, but it is feasible.

Yes, you could make your own panels, but then, you could also have unavailable Vespa parts custom made, as well. Or make them yourself, if you have the skills and tools (aka - machine shop) to do so. The question is, will plastic bodied scoots... any plastic bodied scoot... have body panels available in twenty, thirty, fourty years? Baring rust, steel can live for hundred... if not thousands... of years, without molecular decay. Can the same be said for plastic? I'm presently waiting for my tax returns... since near half has to cover the deductable for my recent fender-bender, the rest with be used to aquire my first needed piece of gear (a helmet), and what's left after that will be used to purchase a Savage 1907 Pocket Pistol... made 97 years ago, still in excellent shape, with most of its original finish, and just as functional as the day it was made... somewhere early in 1910 (I've been looking for one of these for the last 25+ years, and I finally found The One for my collection). Tell me, if they'd made P-bodied scoots back then, would any still be around, sporting their original bodywork? Make it a point to visit an auto/bike museum in your area, some time, so you can take a gander at decades old steel, rubber, aluminum, brass and glass. Yeah, there are Ford Model T's (and Model A's) still out there, still running. With their original steel bodywork.


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[BlueMark]

Baring rust, steel can live for hundred... if not thousands... of years, without molecular decay. Can the same be said for plastic?

Yep.

Plastic takes hundreds of years to break down on its own, which is why it is such tragedy that our landfills are full of plastic.

Modern plastics with built in UV protection should easily last a century in good condition if left alone. Indeed it will last far longer than steel in conditions where moisture and oxidation are an issue. Plastic is as good as steel for a museum piece.

But of course plastic wears much more easily than steel, so in the real world scooter plastic in use will eventually wear to the point that it needs to be replaced.

[Roose Hurro]

Well, as you said, in "our landfills". Yes, if you never ride your plastic scoot, the body panels could indeed last for some time. But heat, use, wear and tear take their toll. And again, the question is, "will these plastic bits be available decades from now, when they do wear out and/or break due to service. Anyway, it's fun to speculate on all this stuff. Me, I don't care if it's steel or plastic, so long as it runs and serves me for as long as I need it... what more could any of us ask of a scoot?

And, rather than fiberglass, I kinda thought it would be neat to learn to pound out/bend up some aluminum sheet. Oh, and "plastic" for the chassis would be great if it was a carbon/kevlar/aluminum/stainless composite. Far lighter and stronger than steel, though it would make for an expensive scoot!


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[BlueMark]

Oh, and "plastic" for the chassis would be great if it was a carbon/kevlar/aluminum/stainless composite. Far lighter and stronger than steel, though it would make for an expensive scoot! Cool

As a bicycling enthusiast for 35 years, I can tell you that the hottest frame materials for strength and light weight are Titanium (not counting Berylium, AKA unaffordium) and some exotic 'carbon fiber' composites that include aramid fibers (Kevlar) and Boron. I'm not sure you need such strength/lightness characteristics for body panels.

-Mark

[Roose Hurro]

No, not for body panels... but for the chassis it would be great. Though you are right about titanium, if you want to do a tube frame with plastic. I was thinking more of a Vespa chassis replica, a monocoque made of composite materials, with metal at mechanical attachment points. I used to work in aerospace, so I know how light and strong such structures can be. I also like titanium, though my own bike (2002 Bianchi Milano) has an aluminum frame... I've heard titanium is excellent at damping vibrations, whereas aluminum is "harsh". Of course, steel has its own qualities... and boron alloys can match the strength of cro-mo at about half the weight (I think). Beryllium? Whew, that's indeed exotic! I know its been used in the firearms industry, alloyed with copper, but the process is illegal in the US, due to its toxic nature. Even those manufactures that use it (like CZ, on their M-85 Combat), use it only as a thin coating... a surface treatment, to smooth the interaction of moving parts, like the trigger and sear, and to provide greater wear-strength. Very small quantities.

Indeed, "Unaffordium", if you intend to make an entire frame out of it!

Edit: Just did a little internet poke, and found out the Saturn 5's exhaust nozzles were made entirely of pure beryllium! No wonder the blasted thing cost so much.... In 2001, beryllium cost $338 per pound ($745 per kilogram).


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[BlueMark]

Indeed, "Unaffordium", if you intend to make an entire frame out of it! Shocked

AFAIK the Beryllium Bike was a one off creation made by American Bicycle Manufacturing from cross rolled beryllium sheet and welded into tubes (extruded beryllium has an elongation coefficient too low to be useful as a bicycle frame - what ever that means!). the tubes were glued to aluminum lugs. Cost was $26k. The frame weighed 2.5 pounds. Of that, the Beryllium tubing was one pound (including one ounce chain stays), 1.25 pounds of aluminum lugs and 4 ounces of adhesive.

Interesting reading HERE about bicycle frame materials. Ought to have some application for lightweight scooters too.

Thing is ... weight gives vehicles stability. By putting their engines very low scooters have a low center of gravity that makes them more stable than a more conventional motorcycle design of the same weight. But as you keep reducing the weight you will lose more of the stability and good handling that scooters excel at. Just like bicycles the heaviest component becomes the rider, sitting way up high. The lighter the scooter, the more unstable the rider makes the scooter/rider combination by raising the center of gravity.

The cure is Feet Forward design (known as recumbent in bicycle circles). This puts the rider lower down, in a stretched out comfortable position. Steve at Scooter Scoop posted a video of the "ComforTMax", a Yamaha TMax modified to a Feet Forward design. FF design is also more aerodynamic. If you are looking for the ultimate in lightweight scooter design, FF is probably a good choice.

-Mark

[ericalm]

The cure is Feet Forward design (known as recumbent in bicycle circles). This puts the rider lower down, in a stretched out comfortable position. Steve at Scooter Scoop posted a video of the "ComforTMax", a Yamaha TMax modified to a Feet Forward design. FF design is also more aerodynamic. If you are looking for the ultimate in lightweight scooter design, FF is probably a good choice.

There are a bunch of scoots & MCs—mostly prototypes or concept bikes—which sport FF designs, including the futuristic new Honda Griffon which is going into production. But the Suzuki Burgman, Piaggio X9 and other maxis have similar semi-feet forward designs. Not quite the Akira bike of my dreams.

A composite monocoque body is an interesting idea. But just like the steel, you lay it down and dent your fender, it's a costly repair, right? I'm no metallurgist... Can these materials be punched out? Patched?