Just wondering about it as I haven't been able to check in on the road, and dont want a broken speedo orso :p
Low speed speedo accuracy
Race Director
Joined: Mar 2017
Posts: 11,929
Likes: 4,497
From: Virginia
How accurate do you need it to be? Do you need to fight a speeding ticket issued on private property?
A GPS speedometer app on your phone can get you dialed in to a fraction of an MPH. I use "SpeedOverlay" when biking. It's also handy to calibrate vehicle speedometers.
A GPS speedometer app on your phone can get you dialed in to a fraction of an MPH. I use "SpeedOverlay" when biking. It's also handy to calibrate vehicle speedometers.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Funny... i posted this in another thread last night. The speedo calibration chart from the AC Delco book states that the margin for error on most speedometers is 3-5 mph at any given point. Crazy I know... Some had a tighter range but this was pretty much the given.
Willcox
Willcox
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
I know most of these old speedometers can be dialed in close at lower speeds, but most of them start to get off as you go faster. The speedo in my 75 Vert is almost dead on up to 60 MPH since I calibrated it, but it starts reading slow after 60. I know this is backwards from what I have seen in the past and what most people report. My transmission was setup for the 3.08 gears and I have 4.11 in this car. I changed the drive and driven gears both to get it right.
In response to Ernie's post, I know the federal government used to recommend a 5 MPH leniency for speeding tickets. I don't know if that is the case anymore.
Mike
In response to Ernie's post, I know the federal government used to recommend a 5 MPH leniency for speeding tickets. I don't know if that is the case anymore.
Mike
Last edited by v2racing; Mar 23, 2019 at 12:02 PM.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
I know most of these old speedometers can be dialed in close at lower speeds, but most of them start to get off as you go faster. The speedo in my 75 Vert is almost dead on up to 60 MPH since I calibrated it, but it starts reading slow after 60. I know this is backwards from what I have seen in the past and what most people report. My transmission was setup for the 3.08 gears and I have 4.11 in this car. I changed the drive and driven gears both to get it right.
In response to Ernie's post, I know the federal government used to recommend a 5 MPH leniency for speeding tickets. I don't know if that is the case anymore.
Mike
In response to Ernie's post, I know the federal government used to recommend a 5 MPH leniency for speeding tickets. I don't know if that is the case anymore.
Mike
.The only exception I've encountered is on most military installations. If the limit is 25, it's 25, not 27, or 26, it's 25! After 31 years of active duty, I learned well there are few things more dangerous (or lacking in common sense) than a 19 year old with a gun and a badge!
Good luck... GUSTO
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
Except for the one time I got pulled over while cruising in downtown Sioux Falls in the late 60's for doing 1 mile over. I've never been stopped as long a I stay under 10 over on the highway or interstate. When I got stopped back in the 60's for 1 mile over, it was just an excuse to pull us over to see if we were drinking or smoking anything. I didn't get a ticket.
Mike
Mike
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Joined: Oct 2008
Posts: 19,178
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From: Long Island
My 72 is +/2 most of the way from 10 to 60ish then it gets in the + bracket and is +5 at 75. I'm going 75 it says approx. 80. My 71 is low up by 1 or 2 up to approx. 70 then is + 2 to 4 after that.
From memory last summer .. Both cars are stock ..
From memory last summer .. Both cars are stock ..