Bud,
I did the same with the OSHIT BA2BE Rally car while getting it ready
for the rallye. We had thought that we had a 4.2 rear and a 4.2
speedo in the car. Upon using the GPS to record some trial data for
the rally, I noticed that the speedo was off about 8 mph at 50mph on
speedo. I thought, "OK, we can adjust speed 8 mph on the rally."
Luckily, I noticed on another run that the speed was off 6 mph at
30mph on speedo. This was what I found:
30 on speedo = 36 on GPS
40 on speedo = 47 on GPS
50 on speedo = 58 on GPS (proven by police Radar......don't ask)
60 on speedo = 69 on GPS
70 on speedo = 80 on GPS
75 on speedo = 86 on GPS That was the limit.... road was too bumby
for any faster.
It's progressive.
After some number crunching by the team members.... we found that we
had a 3.9 rear with a 4.2 speedo.
This all leads to: "Check the speedo at different speeds, if you are
unsure of the speedo."
Just my 2"
-
Rob Valentine
74 Yellow Bugeye Midget
On Jun 20, 2006, at 8:12 PM, Bud Pazur wrote:
> A GPS is a cool way to check a speedometer. It's easier than finding a
> measured mile. I recently swapped out the non-working speedo in my
> street Bug
> with another one I de-munged w/ liquid penetrant and WD-40. Tonight
> I got a
> GPS speed of about 55 MPH vs. a speedo indication of 60 MPH. Which
> is good
> enough for me. Next step is to check the odometer and trip meter
> vs. the GPS.
>
> Bud
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