Modern Vespa

Some time ago Old As Dirt came up with a simple lowering idea for the Mp3 and posted his ideas in this thread: my lowering idea on a mp3

There was a lot of interest and response on that thread.

I had added a couple photos and a write up in that thread showing the 40mm lowering brackets I made and installed following OAD's idea, and indicated I had a couple extra sets (minimum quantity had to fabricated). Those couple sets quickly sold and the owners of them can pipe in here if they like (and post pcs!).

I have had a few PMs about availability of these brackets and I have no plans to make them for others; this was just a one time deal so I could make my own. However, recognizing that others may want to make their own and could benefit from what's been done, I assembled a document and files on how I did mine.

I have attached a PDF with full scale drawings of the brackets and a complete material list, with installation details (under pics below). Also, I can email you two DXF (drawing exchange files), one for each of the two shapes for the brackets, if you want them. The DXFs can be used by a local metal shop with waterjet or laser capability to make the bracket plates (best results). I bead blasted mine as well for a nice finish.

The total drop is 40mm (1.57").

I hope this is helpful for others. It's one of the few things I can do to give back to the Mp3'er and the MV site since it's been so helpful for me.

Of course, all risks are your own, and this is provided strictly for fun and information only.

Here's pics of my install taken a while ago.








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someone please add this to the Wiki .... good for future reference.

BRAVOTWOFOUR
Your post regarding the details on the lowering brkts you created are extremely generous and I'm sure well appreciated by many! I for one would be delighted to take you up on the offer for the two DXF files for the dimn. on the two plates. My email address is (stahldanny@hotmail.com). Many thanks in advance, I have located a shop, to be confirmed, near Daytona Beach that I'm told has the capabilities required.
Regards, D stahl

Done. Post some pics when done!


. . . .

thank you very much for sharing.

Hi, are you planning to make this for sale? I am willing to buy a set if it not too expensive.

So you are lowering the back only?

How much does that lower the back and what does that do to the handling of the scooter and effect seat comfort?

Also is the headlight beam alignment possible w/o altering that too?

If you need others to go in on the machine shop build I would love to lower the rear a little so you can count on me to join.

I think all of that was pretty well answered in the original thread, linked in the first post. For me, I'm pleased.


. . . .

So I guess you just lowered the upper body, not the drive train. Ever have the rear tire run out of room on compression bumps?

According to the people who have had this one from the first thread, they have not experienced having the rear tire running out of room on bumps. And I supposed if that's one's worry, he/she can always set the dialing on the shocks to the 3rd or 4th position.

That's pretty much the case. The earlier thread had a lot of detail on this. I have a hugger fender installed and a 150 tire, and when I first lowered the rear of the scooter I leaned hard on the tail and could force contact (not riding, just tilt-lock parked). I was concerned about this, to the point I pinged a couple of the others that had lowered theirs to see what results they got, and it was mixed; this seem based on rider weight and loadout as well as the type of road and surface on which they were riding.

However, I found that in actual riding I have not had a problem. I dialed the shock preload up one (from minimal to +1) and I don't weigh much (150) so it works fine for me. But YMMV.


. . . .

Count me in as well for a group buy, if it pushes through.

I forgot to ask. How much was the overall drop from your brackets. I think most of the ones from the 1st thread were 1"-1.25". Thanks.

I hope to install the brackets on Dawn's bike over the next few days and I will post before and after pictures.

Good point, it's not immediately evident so I'll go back and edit. You see the name of the PDF of the drawing I made available states 40mm. That's the drop height (1.57").


. . . .

oops... my bad. Should have paid attention to the file name.
Thanks for the clarification.

Awww. Thank you.. Will post pics when done

Sorry to ask this again. Anyone planning to make this for sale? I would like to buy one.

I dont know any blacksmith in my area who would do this custom job.

I sent the download sheet to a machine shop. A lot of the important info is missing. Here is the response I got today:

Hi Mike, I did not see a material thickness for your project.

I see the material as 304 CRES but no thickness???

Also can you provide a DXF file for the part geometry if we were to cut these parts?

Let us know, then I can quote the project.

I made mine out of 1/4" plate and they work fine for me. And you see in the opening post I offered DXFs to anyone wants them.




. . . .

Please share that dxf please.

>I see the material as 304

Guys - be careful on using 304. Let me put it another way: don't use 304.

304 is what I use in the UFPs and UPPs, and it's great there. I choose it deliberately because of a unique property that 303/304 has: it rebounds under small loads, but collapses (turns to jelly for a fraction of a second) under extreme loads.

That property has saved several MP3 riders when they dumped their bikes. Instead of the UFP digging into the ground, it gave way. That's how it was intended.

But every time a UFP is exposed to a shock over a certain level, it will bend. That bend may be imperceptable, but it can and will build up over time: I've had reports of UFPs bending inwards, and when I asked closely I discovered that the owner routinely drives over a particular set of train tracks and keeps their feet on the pegs. Over many encounters, the tiny bends from each instantaneous shock (with each one close to a thousand pounds, for a tiny fraction of a second) add up and the entire bracket is visibly bent.

That's annoying, but easily fixable (bang them back into shape, and take your feet off the pegs). But as a frame lowering device, this property is definitely undesirable. The best material would be a 400PH, but that's expensive both from a material and, for just a single set, a manufacturing perspective (cheaper to do a bunch of them at once). The compromise I would suggest would be 316, which while less workable than 304 (which does not seem to be an issue here at all since these are just flat pieces and don't have to survive a press brake), it is both slightly stronger than 304 and, critically, does not have a plastic transition phase. The other solution is to use 304 that is much thicker than otherwise needed, but that will only reduce, not eliminate, the tendency to creep over repeatative shocks. Using a metal that does not share this basic characteristic is the best solution.

One other suggestion: people love to paint and powder-coat things. These lowering brackets should be left bare metal so you can spot any cracks developing.

Good golly. It's totally in shear. 304ss is fine at 1/4".

And it's stainless - why paint it?


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I believe 304ss is actually STRONGER than 316. 316 does offer a better corrosion resistance.

Not to nitpick but 316 is harder (79 Rockwell vs. 70), and "stronger" depends on what you're talking about. They have identical bulk moduli at around 28,000 ksi. The big one when talking safety is yield strength, and there's no comparison: 316 290MPa, 304 only 215 (0.2% ASTM test). 316 is far more resistant to corrosion but in this application neither one will ever rust enough to matter.

I will say it one more time, and then I will shut up about it. 304, by its very design, plasticizes under point loads, most other steels including 316 does not. Even if 316 was a weaker metal, which it's not if equivalently annealed, you cannot compare them just by looking at their properties on paper. If you expose 304 to a very large point shock, the point where it is most compressed undergoes a stress phase transition and gives way. This is a completely different phenomenon than gradual bending, you can use a piece of 304 under a load for a thousand years and it not move a millimeter and you can expose it a sudden impact and it will bend - the amount of the bend depends less on the value of the impact (provided it exceeds the pastic limit) than it does on the duration, and its tendency to bend depends less on the value of the impact than on the concentration and distribution of the force. Without performing an actual FEA or doing actual stress experiments you cannot know what it would take to overstress 304 to the point that it will start to creep. This is in no way saying that 304 is a poor material; it is simply designed for a different purpose. 304 is designed for use with brake presses specifically because of this property.

Does that mean that a lowering bracket made of 304 is dangerous? Not necesarilly. But you could bottom out in a pothole at a particular lean and put a stress on it and it could bend along that stress line. Maybe a lot, maybe (that one time) only an unnoticeable fraction. In my opinion, this application if possible should avoid metals that are designed to bend under point loads. I realize that on this subject my opinion is no doubt misinformed and uneducated, and yet somehow I still manage to hold multiple patents on implantable medical devices that rely on this same metalugical principle (martensitic shape-memory nitinol). I wonder how I managed to fool the patent office and a billion-dollar corporation into thinking I know what I am talking about!

Oops, I seem to have clicked "Submit" instead of "Just Walk Away," sorry.

Yep. That convinces me.
In the Island of life, I am definitely a Gilligan.

I like that!

If that were all to say about then fine, but I would hope you'd continue as you have useful knowledge of materials. And you do so like share.

I would like to hear from you on the specific mechanical application here. Specifically, I'd like to understand where these two pieces of non-formed, jet cut 1/4" thick 304 stainless steel plates on each side of the scooter, in the bolted application as shown (see the dwg), may suffer point load fatigue and failure. I don't accept that the 1/4" 304SS plates in this application are somehow structurally inferior to the stamped and formed thin steel OEM bracket, but I've not run FEA on it - just working from experience. Loading on these plates is not significant or concentrated and only in bottoming out with a heavy load on the scooter could it see some shock - which apparently has never been enough to cause the thin OEM steel or cast aluminum case to which they are bolted to fail. That kind of shock load would cause tension in the metal of course, and shear on the bolts and the metal through which they are bolted. And yet it is used structurally in countless applications and is the most common of the stainless steels available. Well that's good. So could the OEM steel bracket. Or any other component on the scooter depending on the "But you could..." event. That seems a bit of a broad worry.

So expound on the application itself. I am not convinced I should be concerned.



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I got a price quote of $85 for a shop to cut the set, but they told me they can't cut regular steel, just mild steel. I have a feeling that won't cut it.

I would be interested in 2 Sets for my MP3/250, if someone organizes a Group Order.

Keith,
Marietta, GA

this is why I didn't pursue this too far. you can get bolt on shocks for the same money and lower the scoot, plus you have the added benifit of a more adjustable preload shock. Not just 4 positions.

Unless I'm mistaken, the shock brackets are different for a 250 than they are for the 400/500, so it wouldn't work for your bikes.

Like OAD said, you're probably better off just getting other, shorter shocks...

Which makes the most sense. I was able to cut plates much cheaper than Mike's quoted price and wanted to retain stock shocks, but I'd just get the shorter shocks if I were to do this again.

....

Which shorter shocks work on the 500? That would be the safest bet.

This is a thread that should, at least partially, answer your question:

Look What OAD Found For Me...

OK... I missed that...

Maksor knows I have an interested in 2 sets of Shocks from him.
So I will wait to see what he comes up with on what he has on order.

Keith

I can only speak for the 12" rear tire version of the 250 since that is what I own. The rear suspension on the 250 is totally different than the 400/500 and the OAD/B24 style lowering brackets as discussed here are totally incompatible. Particularly based off the right side suspension, I don't believe there is even a way to make a modified version of this idea that would work. Shorter shocks and seat modifications appear to be the only way to decrease the seat height.

I just installed a pair of 14.5 inch gas shocks on my MP3-500. The worst part of the entire operation was getting the spacers to stay on the bolt. After a short test drive I can say they are not as smooth as the standard shocks, but not bad. It was a much nicer experience being able to flat-foot it, especially with my bad heel.

I feel much safer with lowered shocks then I do making my own lowering brackets since I don't have a good way to inspect the soft metal most folks are using now. Either way I hope that either type of lowering works in the long run. Us vertically challenged people need some help.

http://www.ebay.com/itm/14-5-Shocks-Absorbers-Eye-to-Eye-Mount-One-PAIR-Expedited-Shipping-/291031612813?pt=Motorcycles_Parts_Accessories&hash=item43c2d5fd8d&vxp=mtr

awesome... so they took the 16" back without issue? what kind of spacers did you use?