Modern Vespa

Current Status:

I think I've got all the needed parts now for Plan A. This consists of converting from 220mm to a 240mm disk, and from a floating caliper to a 4 piston radial mount caliper.



Next step is installation.

I have a bit of an obsession with brakes. As evidence I submit:

LX brakes > GTS brakes, NOT!
Rosebud Brakes
...

Anyhow, for quite a while I've wanted to upgrade the brakes on my GT as I consider floating calipers to be unclean. The goal is not really more powerful brakes, but more efficient. I find the brembo conversions to be overkill as well as a bit of a mess in the way it all fits together.

There are two ways you can increase the braking force
1. increase the pressure of the pads on the disk
2. increase the lever arm (or size of the disk)

Toward that end I've been looking for a 4 piston caliper of about the same size as the stock pistons (25mm). I've also been looking at using the 240mm disk off the MP3 (as opposed to the 220mm disk on the GT).

Last week my eye was caught by a caliper that looked right for the job. The Stage 6 S6R/T, so I ordered it. Then I started planning out how I'd mount it and stumbled on a really beautiful caliper mount.

And so it goes...

Waiting for pictures and updates.

The Caliper

While browsing the Jet200 site I noticed the Stage 6 four piston caliper. A bit of searching came up with the piston size being 25.4mm, vs the GT/GTS 25mm. Bit bigger but not enough to change the lever travel much.

So, off that order goes:

Caliper Mount

As I was searching for info on the caliper I found quite a few adaptors to fit it to different bikes, but not to the vespa. In general I don't like adaptors as they are never as strong and rigid as they ought to be. I found that Stage 6 did make a replacement caliper mount for the piaggio Zip (same fork setup as the LX) but I was not found of the design.

Then while doing an image search I stumbled on the site of Antoine Fleury. His portfolio is quite impressive and in his personal projects there was a caliper mount for vespas for the stage 6 caliper. The images looked like renderings with maybe one or so prototypes, so my hopes of getting my hands on one were not high. But as I looked into it more, I found that a batch had been made late last year.

After a few emails, that was on its way as well.

Disk

The diameter of the various disks on Vespas are as follows:
PX 200mm (10in wheel)
LX 200mm (11in wheel)
GTS 220mm (12in wheel)
MP3 240mm (12in wheel)

On my LX I was able to fit the 220mm disk inside the 11in wheel. The larger diameter gives a greater lever arm increasing the braking force without any added lever force or travel. If I can I want to pull off the same party trick on the GT, so that is plan A.

Plan B is to stick with the 220mm disk of the GT but now that I have a fixed caliper, I can go with floating disk.

The caliper mount is made to fit the 200 and comes with a stepped spacer 11mm long that goes between the mount and the caliper. Being a radial mount caliper, fitting a larger disk is as easy as making new spacers.

VERY nice looking stuff!
I hope the quality is as good.

spent some time with the lathe and got one of the spacers done.

So far, so interesting.

Just visited his website. What a guy!! He has everything from Vespa parts to blood analyzers to hammers.

Another very interesting thread. Great find on the brackets.

Finished the spacers to go with the 140mm (MP3) disk.

Picked up the 140mm MP3 disk.

Nice project - Any progress ? Pics, thanks

Started installation today.

The caliper mount comes with 3 shims that can be placed on either side of the axle to line the caliper up with the disk. I used two between the caliper mount and trailing link. I also found that the holes to mount the shock are a bit lower than the stock mount. This would probably still fit the stock shock but the RS24 doesn't fit by about 1mm. I could make it work but for now I just swapped to another shock I'd been wanting to try.

Even with the 240 disk the caliper has plenty of clearance to the rim and the brake line even lines up nicely.

Here's some more pictures to show the clearance between the caliper and rim.

48% increase in braking force over stock, mostly coming from the larger diameter disk so the lever travel is unchanged.

For comparison the Brembo gives a 60% increase but increases lever travel.

Is that an air/oil shock you are running on the fork?

yes, verdict is still out on if I can dial that in on the GT.

Having two separate spacers was allowing it to flex and let the caliper rub under hard braking.

Designed this bridged spacer to resolve this and also included a mount point for a speedo pick up.

That's a 3D part, right?
Melting?
Fluids inert?

the part is 3D printed in plastic (as part of the sfmototype prototyping challenge), just to test form and fit.

Next one will be CNC in Aluminum.

Finally getting back to this project. The new spacer is done.

and, installed. test ride when the rain stops.

Test ride went perfect, feel of the caliper is great.

compliments! really a great project

Took the bike on a 150 mile ride today. Combination of high speed freeway, fast sweepers, and lots of goat trails. They performed perfectly all day.

Next step is a working speedo

How is dong compared to original brake?

I need to do a back to back ride with a stock GT/GTS to make sure I have an objective view. That said the braking feels very smooth, direct, and linear. Lever force seems lower (as it should) for equivalent braking.

Is the shock a Fournales ?

BTW : I'm using Zellioni type III discs, Malossi sintered pads & Dot 5,1 fluid.
In my opinion a nice improvement over the original set up.

A1 project!

New bracket to hold the speedometer pickup and also installed the SIP speedo.

Couple questions:
1. Is the disc you used part # 56394R?
2. Do you know of any other disc sizes for 13" wheels? I checked a few MP3 parts catalogs, they all seem to be the same part number.
3. The front caliper carrier on a MP3 looks very similar to the GTS... any chance this would be a direct swap for the larger disc & caliper? I can't seem to find any good photos of one.

Also, Maru's Factory now sells a radial caliper adapter. It is for 100mm calipers instead of 82mm, but would allow the oem speedometer & caliper carrier to be used. The only 100mm calipers I have been able to find are Brembo, and cost at least $500...
https://www.plus8.com.tw/product/detail51

I didn't want to drag up another old thread... so I will post this here.

I see that the MP3 caliper pistons are 30mm vs the GTS's 25mm. Do the MP3 calipers share the same bolt spacing as the GTS?

The MP3 caliper is the same as the the LX in piston size and mounting. The GTS is different.

I considered using the MP3 mount, but getting my hands on one never worked out.

Does seem a bit odd they didn't go for a 108mm mount as then you'd have a larger choice of caliper, there are other manufacturers of 100mm radial calipers like Accossato & Beringer, but they are just as pricey.

*edit* spotted these cheap with 100mm mounting, not sure just how well I'd trust them though

https://www.aliexpress.com/item/ADELIN-ADL-12-Radial-Mount-Caliper-Motorcycle-Master-Cylinder-Street-bike-for-Honda-Kawasaki-Suzuki-KTM/32837978197.html

I wonder if Maru's adapter has enough extra material to machine it for 108mm spacing. Only a 4mm "slot" per hole would be needed, possibly less depending on the attachment hardware used.

And WOW those are cheap... too cheap for piece of mind though.

Ahhhhh... so the MP3/LX caliper is two opposing pistons, rather than the GTS's floating with two pistons on the same side. Using eBay listings for knowledge isn't always the most accurate...

Here is a MP3 hub that I think is the correct orientation for a GTS
There are some mounting holes that would not be used, and I'm not sure how the speedometer functions on an MP3.

https://www.ebay.com/itm/2009-Piaggio-Mp3-500-LEFT-Speed-Hub-With-WIRE/201874419724?hash=item2f00a7300c:g:g5wAAOSwuLZY3lJ3&vxp=mtr

Any thoughts on 260mm rotors with 13" wheels? I think the 200/250/300 Beverly uses an adapter for the caliper mount with a 14" rear wheel: https://www.ebay.com/itm/03-06-Piaggio-Beverly-BV200-BV-200-Rear-Brake-Caliper/292058940471?hash=item440011c437:g:pg0AAOSwCU1YzCr~&vxp=mtr

Might be a good swap for the rear on a GTS

The mp3 has an electronic speedo. the wire in the picture has an Hall Effect sensor that triggers off the bolts mounting the disk. Same idea as the SIP speedo.

Not a big fan of the caliper adaptors. There is a lot of force in the brakes and looking at the load path in the adaptor, I just can't bring myself to trust them.

Sorry if you were planning to grab that mp3 bracket, at $35 I had to snatch it up.

not sure about the BV rear, that caliper looks the same as the GTS front, but maybe the mounting holes are offset.

LOL... I'm actually glad you bought it... or else I would have. Also I'll be happy as long as you report your findings.

I would hope that an OEM caliper adapter would have been engineered to some standard. I haven't heard any Beverly owners complaining about their rear brake either. I have a 13" Gilera Runner wheel on the way, will be taking some measurements when it arrives.