I am planning on running a 4-cell/17.5 in a 12l3oval car and my question is: do I have enough motor movement to run the proper gear ratio? I have been told that small spurs and huge pinions are needed but am in the dark on what to try. Also, what gear ratio would I need to be competitive with a stock motor?

12th scale onroadguy's are rolling out at 93mm,oval in inches 3.8 to 3.9,get the smallest prs you can i think 72 is the smallest now.you may need to get some of the kimbrough offset ride height adjusters to get the spur back just a little more,or even go to longer irs side plates.

You may have to run just a little bigger tire to get the rollout needed running 12th scale oval.

Thank you, KOZ.

76T is the smallest that I've seen. PRS makes it. (http://www.precisionracingsystems.com/products/26)

at crc we run 88 tooth spurs on the 12th scale road course cars without a problem. not so sure if 76 would work but u could try it.

My VELO car is a 10L3o with CRC Lowered/Standard Length Pod plates...

I stuffed a 21.5 motor in it for our race this weekend - and have a 76/60 gear on it to start with. I know PRS goes upto 65 or so now, but 60's the biggest I got (There's plenty of room to go up at least another 2 or 3 teeth.

Thanks, guys I also have a set of crc pod plates.....maybe they are what I should use.

Most of the pod plates have the same amount of motor movemenet.. The way the pod plates sit on the bottom plate is what lowers movement.. The t bar is to close to the motor plate on mos cars.. They make 10mm extended pod plates to get more gear.. I wouldnt recomend them because it changes the rear geometry and extends the wheel base.. With the PRS 76 tooth spur you should be fine..

well, I ended up with a 76/63 on the 21.5 motor this weekend (VELODROME) Didn't notice much difference with the 63 vs the 60, but it wasn't any worse...so I stayed with it.

The car ran 27 laps with my Son driving it, although it wasn't as fast as the other guy running 21.5. We were both rolled out really close to the same (He was running a 78 spur)

4 cell STOCK on this track has a track record of a FAST 25 lapper in 5 minutes. So the 21.5's right out of the box were 2 laps quicker (and will GET quicker yet with a little work)

We plan to run a 17.5 1/12th class at our track as well. We have been running stock. I am going to start out with a 76 spur and see how it turns out.