Previous in Forum: Mitsubishi Canter Gearbox M035 T4   Next in Forum: 2006 GMC Sierra Truck Electrical
Close
Close
Close
12 comments
Rate Comments: Nested
Participant

Join Date: Apr 2011
Posts: 2

Speedometer is Too Fast

04/27/2011 7:59 AM

i have a 1997 ford ranger and it has the corect size tires on it but the seedo is 10 mph slow. any ideas on what to check?

thanks

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#1

Re: speedometer is to fast

04/27/2011 8:04 AM

The sending unit for that truck is probably defective.

http://www.therangerstation.com/tech_library/speedometer.htm

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru

Join Date: Feb 2011
Posts: 7025
Good Answers: 207
#6
In reply to #1

Re: speedometer is to fast

04/28/2011 7:36 AM

Nice link, I just learned something.

Register to Reply
Guru

Join Date: Sep 2009
Posts: 1056
Good Answers: 88
#2

Re: speedometer is to fast

04/27/2011 8:22 AM

FIRST check mile counter accuracy at a known distance. If it's OK and 10mph is a constant error in whole range, definitely meter problem, just disassemble and twist lever by 10mph. (You could also mess with biasing on it's Freq to Voltage converter if it's an analog meter). If error is a function of speed AND meter is analog, one could mess with converter's gain. If it's full digital stepper controlled you can safely dispare.

__________________
Life is complex. It has a real part and an imaginary part.
Register to Reply
Guru
United States - Member - New Member Engineering Fields - Mechanical Engineering - New Member Engineering Fields - Petroleum Engineering - New Member Hobbies - Target Shooting - New Member

Join Date: Jan 2008
Location: Spring, Texas
Posts: 3403
Good Answers: 150
#3

Re: Speedometer is Too Fast

04/27/2011 4:16 PM

following a link on kramarat's link takes you to an area that discusses recalibration of the system. it is entirely possible that the gear ratio in the rear differential has been changed throwing off the calibration.

__________________
Who is John Galt?
Register to Reply
Power-User

Join Date: Dec 2010
Location: 1144 n meta okc,ok73107
Posts: 104
#4

Re: Speedometer is Too Fast

04/28/2011 12:12 AM

During that year some of the american made autos were produced with wheel

equipment that was set for 55 mph as the constant speed.Could that have worn down

the mph detection system after driving alot faster for a long time.

__________________
dsuzmay@gmail.com
Register to Reply
Guru
United States - Member - New Member Engineering Fields - Mechanical Engineering - New Member Engineering Fields - Petroleum Engineering - New Member Hobbies - Target Shooting - New Member

Join Date: Jan 2008
Location: Spring, Texas
Posts: 3403
Good Answers: 150
#5
In reply to #4

Re: Speedometer is Too Fast

04/28/2011 12:58 AM

um, no.

__________________
Who is John Galt?
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#7

Re: Speedometer is Too Fast

05/01/2011 3:19 PM

Before doing anything, please tell us how you know that the vehicle is showing a 10 MPH discrepancy? The method used may be at fault.

My personal method is to use a GPS with a MPH display and drive on a road that is mainly straight or only very long slight corners. Sharp corners will ruin the accuracy. A straight road is the best for testing!!!

Generally speaking a speedo may show a higher speed than actually being achieved, but never a lower one.

Also maybe your vehicle was originally sold with smaller than standard tyres/wheels.....its possible!!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Participant

Join Date: Apr 2011
Posts: 2
#8
In reply to #7

Re: Speedometer is Too Fast

05/01/2011 4:20 PM

i went through a road side "your speeds is" set up more than once and my speedometer always reads 10 mile an hour slow. wether it is on the hi way or in town.

Also i have had people follow me with the same results.

Register to Reply
Guru
United States - Member - New Member Engineering Fields - Mechanical Engineering - New Member Engineering Fields - Petroleum Engineering - New Member Hobbies - Target Shooting - New Member

Join Date: Jan 2008
Location: Spring, Texas
Posts: 3403
Good Answers: 150
#9
In reply to #8

Re: Speedometer is Too Fast

05/01/2011 8:20 PM

of course those "your speed is" things are probably calibrated on the low side too... they have an agenda to make you drive slow.

__________________
Who is John Galt?
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#10
In reply to #8

Re: Speedometer is Too Fast

05/03/2011 3:30 PM

Borrow a GPS and find out exactly, then get a workshop to adjust it correctly....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Hobbies - RC Aircraft - New Member Hobbies - Automotive Performance - New Member Hobbies - DIY Welding - New Member

Join Date: Jul 2007
Location: Fort Lauderdale Florida
Posts: 5708
Good Answers: 123
#11

Re: Speedometer is Too Fast

05/05/2011 2:05 PM

Lyn -Door Industries sells peel and stick numbers to recalibrate your speedometer.

__________________
Bob
Register to Reply
Participant

Join Date: Nov 2010
Posts: 3
Good Answers: 1
#12

Re: Speedometer is Too Fast

06/17/2011 2:52 AM

Hi guys... some instruments have settings behind the speedo to set up for different wheel sizes or differential ratios etc;.. I would 'assume' it is an electrical system & not mechanical.. also some speedo sender units (down on the transmission) are adjustable with letters/numbers in relation to wheel & diff ratios as well.. check this first.. Is easier than removing instrument cluster.. less swearing involved .heehee....

cheers for now...

A.J

Register to Reply
Register to Reply 12 comments
Copy to Clipboard

Users who posted comments:

Alhardy (1); Andy Germany (2); AVERAGE JOE (1); bob c (1); ds (1); Fredski (1); kramarat (1); Rorschach (3); SimpleMind (1)

Previous in Forum: Mitsubishi Canter Gearbox M035 T4   Next in Forum: 2006 GMC Sierra Truck Electrical

Advertisement