How to Calculate the Correct Gear Modulus for a Motorcycle Project?

[Kleinelars1]

Hey Guys,

Sorry for my poor englisch, I'am Lars from the Netherlands and currently working on a project. For my motorcycle racer I'm making a "paddock starter" by a 12V car starter from a VW T5 transporter 2.5tdi.

No I am having difficulties finding the right gear to match the current starter motor Gear/pinion. Obviously I tried finding the Modulus, but encountered the problem of receiving a 2.3 as a result, but this sould be 2 or 2.5

So, is there anyone who can help me find the matching gear, or explain how to calculate it properly?
Specs of starter motor gear;
Outer theeth top diameter 27.7mm=1.0905 inch
Pitch diameter 23.7mm=0.9330 inch
Diameter of axle at bottom of the teeth 19.7mm=0.7755inch
Hight of teeth from foot to top 4mm=0.1574
Teeth is 4mm=0.1574 wide at bottom

Hope anyone can help me.

Lars

 

[jrmichler]

How many teeth on your gear? How did you measure the pitch diameter?

Small gears (small number of teeth) are sometimes designed with profile offset to make the teeth stronger. If that is the case, the pitch diameter will not be what it looks like. Can you measure the flywheel gear from the VW? Any profile offset will have only a small effect on your measurements.

 

[AlexTheParticle]

Hi Lars,

First of all, your English is actually pretty good! As for your project, it sounds like a cool idea. I'm not an expert in motorcycle mechanics, but I'll do my best to help you out.

From the specs you provided, it seems like the gear/pinion for your starter motor has a pitch diameter of 23.7mm and a height of 4mm. To calculate the modulus, you need to divide the pitch diameter by the number of teeth on the gear. However, you mentioned that you received a result of 2.3, which doesn't seem to match with the standard modulus sizes of 2 or 2.5.

One possibility could be that the gear has a non-standard number of teeth, which is why you're getting a decimal result. Another possibility is that the gear is worn down, which can affect the accuracy of your calculations.

To find the matching gear, you can try contacting a motorcycle parts supplier or a mechanic who specializes in motorcycle racers. They may be able to help you find the right gear or even custom make one for you.

Alternatively, you can also try reaching out to online forums or groups dedicated to motorcycle racers. There may be someone who has experience with similar projects and can offer some advice or suggestions.

I hope this helps and good luck with your project!