How fast am I'm going

Bob Pickell · #1 (**permalink**) 08-06-2007, 10:16 PM

New member - I appreciate any info I can get. I have owned a 88 Spider Quad since 1993 - only has 30,000 mile to this date - the speedo has never worked, sender is OK - don't know what the problem is - anyway - who cares about that - I drive by the feel of the car - but I guess it would be nice to have an idea of how fast I am going - does anybody have a ratio of rpms per gear to how fast you are going?

**modena782002** · #2 (**permalink**) 08-07-2007, 06:12 AM

Welcome to the bb Bob, you will soon be addicted!

I have the formula at home, but am away on business until Wednesday. If no one else chimes in, I will post Thursday.

Again, welcome to the bb. Best of luck!

Bob Pickell · #3 (**permalink**) 08-07-2007, 07:19 AM

Thanks Nick - I look forward to your info.

**modena782002** · #4 (**permalink**) 08-08-2007, 06:03 PM

Bob,

Here is the formula, courtesy of Dennis Simanaitis at Road & Track some years ago:

rpm * pi * d / gear ratio * final drive ratio * 1056 = v

d= diameter of tire in inches.
v= velocity in mph.

Hope this helps.

bianchi1 · #5 (**permalink**) 08-09-2007, 12:30 AM

when you start seeing a glow on the front end of your car, and it's getting quite warm, and you are creating sonic booms along your travels......slow down...