Selasa, 15 September 2009
1950's Electrical Diagrams
1950's Electrical Diagrams | ||||||||||
Vespas
| Lambrettas
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1960's Electrical Diagrams
1970's Electrical Diagrams
Vespa Large Frame Gearing
Vespa Large Frame Gearing
The Vespa gearbox has used basically same set up since the first bike rolled off the assembly line. Small frames, wide body bikes, and large frames all use variations of this system.
Below is an overview of a typical large frame Vespa gearbox.
- The Primary Drive - A small gear is attached to the drive plate of the clutch and it mates with a helical cut gear which is riveted to the input shaft. These rivets can be drilled out to change the primary drive but usually the small clutch gear must also be changed.
- The Input Shaft- This has the 3 or 4 gears machined into a single piece sometimes called a 'Christmas Tree'. The kickstart gear turns on the end of this shaft.
- Output Shaft/ Separate Gears- These mesh with the Christmas Tree and a small selector engages a single gear with the output shaft.
The Primary Drive
This is where the Vespa gearbox is less flexible then the Lambretta gearbox. In most cases the large helical gear and the smaller clutch gear must be changed as a pair. In comparison, a Lambretta gearbox allows each of these two items to be changed independently because a larger chain can take up the slack. With a Vespa, if one gear diameter increases the other must decrease because since they physically meet, their relationship must always be the same. There are kits on the market from Polini and Malossi that require drilling the rivets out of the gears and allow you to retain the standard Christmas tree gear cluster, while changing the primary drive to a higher, non-standard ratio. A list of some combinations are listed on the Vespa gear calculator page by small gear/large gear teeth (ex 23/65 for a P200E).
The Input Shaft
Other than a few exceptions the input shaft gears and the separate gears on the output shaft must be changed as a pair. An exception is the T5 4th gear that can be installed in a P200 standard box to give higher RPM in 4th gear. Most after market expansion chambers create more power at higher RPMs than the standard exhaust, but less power than a standard exhaust at lower RPMs. There is a larger gap between the P200E 3rd and 4th gears than any other gear gap. This means that with an expansion chamber you may not have the power to reach the type of RPMs the pipe needs to perform well in 4th gear. Surprisingly if you make the gap smaller you may actually have a faster top speed.
The Output Shaft
The output shaft gears are independently machined but should always go in as a group. This is the final drive, and a small machined cross locks each gear rotation independently to the output shaft rotation which is rigidly attached to the rear wheel. So all the gears spin when the bike is moving, by rotating freely on the output shaft, but only one gear at a time drives the shaft. The metal cross is moved up and down the output shaft by the gear twist grip on the handlebars.
The next section allows you to mess around with different gearing options. Keep in mind that some of the combinations involve drilling out the rivets of the clutch drive which is a bit of a pain.
Vespa P-Series Gearing Calculator
The scope of Vespa gearing is less broad than Lambrettas but still complicated. There are 2 things that can be changed to result in higher or lower than standard gearing. The primary drive consists of a smaller helical gear that is integral with the clutch assembly and a larger helical gear riveted to a cluster of 4 toothed gears.
These must be installed as a matched pair except in some cases where a free gear with one less tooth can be added to the output shaft and still mate with the cast gear cluster (such as a T5 4th in a P200 gearbox. Lastly the tire size can be adjusted with slight modification to fit a nonstandard 4.00x10 tire. I also included a 3.00x8 tire for anyone who replaces their engine with a P-Series one on an older 8" wheel large frame and wants to keep the original 8" look.
Below are calculators for the three main Vespa gearbox options that will give gearing for a range of standard Vespa gearboxes without mixing separate gears from different models. These are currently only for P-series bikes. If anyone has info on 150 Supers and other 70's bikes please email me.
- The helical primary gear - "Primary Gear"
- The gearbox group (from a standard Vespa model) - "Gearbox Type"
- The tire size used - "Tire Size"
I have included some primary drives kits by Malossi and Polini. P125 & 150 ratios have also been shown in the P series calculator as they can be modified to fit a P200 clutch by unriveting the central clutch gear from a P125 clutch and reattaching it to a P200 style clutch. The final ratio of a conversion like this will be pretty low but try it and see if it works for what you are trying to achieve. The resulting page will show gear ratios for each of the 4 gears and show an RPM to speed analysis at various engine revolutions. Also I have added some Vespa Cosa clutch options that I was sent by email.
P-Series Gearing Calculator
Miles per Hour
Kilometers per Hour
Primary Gear
Gearbox Type
Tire Size
Vespa Small Frame Gearing Calculator
The scope of Vespa gearing is less broad than Lambrettas but still complicated. There are 2 things that can be changed to result in higher or lower than standard gearing. The primary drive consists of a smaller helical gear that is integral with the clutch assembly and a larger helical gear riveted to a cluster of 4 toothed gears.
These must be installed as a matched pair on small frames. Lastly the tire size can changed.
Below are calculators for the two main small frame Vespa gearbox options that will give gearing for a range of standard Vespa gearboxes without mixing separate gears from different models.
- The helical primary gear - "Primary Gear"
- The gearbox group (from a standard Vespa model) - "Gearbox Type"
- The tire size used - "Tire Size"
I have included some primary drives kits by Malossi and Polini. The resulting page will show gear ratios for each of the 3 or 4 gears and show an RPM to speed analysis at various engine revolutions.
Small Frame Gearing Calculator
Miles per Hour
Kilometers per Hour
Primary Gear
Gearbox Type
Tire Size
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