Speedo gears/rear end matching

oldmachdriver · #1 (**permalink**) 07-19-2005, 06:15 PM

Ok i got my first ticket wit the cobra......officer says i was doing 54 in a 35, now I admit i was geting on it a bit BUT i argued with the PO, about the actual speed......he then offered to run radar on me again at a predetermined speed (55)....i did what i thought was 55 and in turn was reading 44 on his falcon. so im figuring my gear on my speedo is wrong...lol....how do i know which gear to get for my car?....

4spd toploader, 3:54 gears, with BF good, P295/50R15 with the reverse smith gauge....PO told me if i show a receipt showing i tried to fix it he would recind the ticket....

427sharpe · #2 (**permalink**) 07-19-2005, 06:46 PM

19 tooth gear, and you should be on IF
1. the toploader still has it's orig 7 tooth drive gear
AND
2. The speedo is set for 1000 revolutions at 60 MPH

terry251 · #3 (**permalink**) 07-19-2005, 06:48 PM

Hmmmm...so your speedo was showing 65 (in a 35) or so when you got radared??? "getting on it a bit..." I guess so!

Sounds like you encountered an officer who has his head screwed on straight...take advantage of the fix it offer he made!

Terry

oldmachdriver · #4 (**permalink**) 07-20-2005, 09:32 AM

lol i actualy dont know what my speedo was showin...but i swear i didnt think i was doin that fast....and he got me just as i enterd a 35 mph zone from a 45mph zone....kinda vague and i was slowing down....but he nailed me just as i crossed the zone change....i think he was waiting for me...

EarlsflyinCobra · #5 (**permalink**) 07-20-2005, 09:57 AM

I've seen questions such as yours a few times here on the forum and was just wondering..............

Is there no place close to you
9probably Savannah) where they can put your car on their equipment and adjust the speedometer to be more accurate.

We have a shop here that does it and it is not real expensive. They have numerous gears and shims on hand to make adjustments. They do the certification on all the area Police cars for clocking purposes and can fix most any speedo.

Just my 1.5 cents worth........

Ron61 · #6 (**permalink**) 07-20-2005, 10:08 AM

Quote:

Originally posted by oldmachdriver

......he then offered to run radar on me again at a predetermined speed (55)....i did what i thought was 55 and in turn was reading 44 on his falcon. so im figuring my gear on my speedo is wrong...lol....how do i know which gear to get for my car?....

If I read this right, your speedometer is reading fast and not slow. As Terry251 points out, this would equate to it reading 65 MPH when you were doing 54. You got a nice officer and should take him up on this. I think they figure about 4 MPH per tooth as a rough estimate of the driven gear if you have the corect drive gear. Some police depts. will take a patrol car out and check your speed if you go in and ask. I did that years ago when I had to change a speedometer and wanted to be sure the computer chip in it was correct. They checked mine with a radar at 50,60,70, and 80 and it was right on with their readings. I now noticemy speed when I start to pass to many cars as I know most of them are driving above the posted limits. Itis really easy to creep up there in one of these cars.

Ron