Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties Servi car gearing

Servi car gearing

Moderators: Curt!, Pa

Post Sat Sep 10, 2011 11:49 pm

Posts: 42
Location: seattle, washington
Needing some information from anyone who has played around with gearing to make a servi car have better hi speed.

i have experiances changing gearing on WR,s for racing and understand that.

Looking to find out what others may have done to servi cars working within their limited power and heavy weight.

What about the rear sprocket, i have not diss-assembled the rear end to know, but can i fabricate a different sprocket to change my gearing ??

Post Sun Sep 11, 2011 4:33 pm

Posts: 386
The easiest way to change gearing on a Servi-Car is with the motor sprocket. The rear end has little room for change. The trans the same. Standard Servi engine sprockets are 22 tooth if I recall correctly. Side car sprockets are 27. There are also sprockets in every tooth increment from about 17 to 34. Most are hard to find as they were for competition use but they are out there. Depending on your elevation, your size, what you intend to carry, etc, a few teeth bigger is usually no big issue. And motor sprockets are relatively cheap compared to machine work.

Post Mon Sep 12, 2011 4:54 pm

Posts: 37
Location: central IL.
mine doesn't do to bad with a 29 tooth sprocket, loses a little bit on takeoff but picks it up on top end, but you'll never make it into a speed demon though, good luck

Post Mon Sep 12, 2011 5:02 pm

Posts: 53
My WLC with sidecar is going to get a new eng sproket ( was overlooked during sidecar install .....sidecar rookie here). I mostly do in town riding with little run 5-10 miles max on hihway. Read about 27t sproket Would that be correct or for best in town there's something better. I'm a heavy dude for that 45 ( 230 lbs) but still lolll Thanks Frank

Post Sat Sep 17, 2011 9:38 pm

Posts: 42
Location: seattle, washington
thanks for the info,
i am aware of motor sprocket changes as i have done that with solo racers.

The trans sprocket would be hard to increase in size due to case limits.

What about the rear sprocket, i guess i will need to find a diss-assembled one, but the question would be can i modify a smaller teeth size sprocket to fit the carrier ??
My rear end is still together and i have never had a rear end appart before.

Post Sun Sep 18, 2011 12:05 am

Posts: 2677
Location: Los Angeles, CA
I have a 33 tooth motor sprocket on mine. A little doggy coming out of the hole but lots better top end.

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