Pusher speedometer 5mph at rest?

[Bucky1320]

1998 Harney Pusher on Magnum chassis with CAT engine. I noticed that when it says I am going 60, others tell me I am going 55. Sitting idling it shows 5mph. Weird. Any ideas?

[tatest]

If it is mechanical, parts can get sticky, magnets weaken. Typical mechanism was a rotating cup trying to pull a magnet attached to the needle, held back by a spring. (When the spring breaks on those, the needle just spins around, or spins until it hits something to stop it).

If it is electronic, with the indicator measuring voltage or current, the bias voltage for the instrument panel can shift. That is regulated either by resistor packs, a solid-state voltage regular, or combination of the two, and other instruments might be reading wrong values.

[WILDEBILL308]

I always felt that my coach was going faster than the speedometer was showing. I installed a Banks IQ that has a speed calibration feature using GPS. it will show actual speed and a correction factor. I have to use a correction factor of +5.8% to get actual mileage. I have checked the accuracy of the GPS sped on several 10 mile trials. It is right on the money. I am betting that a great many coaches out there are getting erroneous speed readings.
Bill

[wa8yxm]

I think I covered this elsewher but my suggestions are as follows.

Get a GPS or a speedometer app for your smart phone.. This includes the Torque-PRO app for use with an OBD-II bluetooth sender (FEE) and Compass Free (Free of course) and a host of others.

USE the GPS to "Calibrate" the speedometer

If the dash reads +5 at all speeds.. Just make the mental adjustment

IF it's random... See a speedometer shop.

IF you have the kind of engine that the plug in OBD-II to Bluetooth devices work with Torque Pro is great.. in my car I have a display of RPM (not provided on dash) Engine Load, Timing advance and manifold pressure (not provided) battery voltage (Digital, not provided) coolent temp (Provided non-labeled analog but the phone shows didital) and compass heading (phone GPS) Fantastic.. I can replace compass heading with vehicle speed sensor or GPS speed sensor if I choose but speedo came out within 1 MPH so I do not.

[frankdamp]

Some speedometers from that era actually had a stop-pin that stopped the needle from going down below 5 mph. Does it start to move immediately you move off or does it pick up at 5 mph? The 60 mph indication when you're actually only doing 55 could be influenced by the tire size difference.

I'd suggest doing a check at 10 mph increments to see if the "error" varies with speed, then do an occasional verification that it's consistent over time. It could be that either the speedo is a bit gummed up internally or there's some inconsistency at the engine transmitter end. 1998 electronics weren't the highly reliable ones we've come to expect nowadays - may even be analog rather than digital.

[robatthelake]

At least The Police will leave You alone ! Mine reads the other way at 55 on the Speedo the GPS says I'm going 58 !

[Dachristianman]

Don't balk.....5 mph at rest gives you head start when you're going on a trip. 🙂

Tom

[Bucky1320]

A cable on a pusher would be a long one for sure! This is an electronic speedometer. When you turn the key to the on position, the speedometer tests and goes full sweep, then all the way back and then...I thing....ought to go to zero. Was just wondering if this was a common problem or something someone else has experienced.

[the_vfox]

My old Bounder (1988)speedo said I was 65 GPS said 59
The Kountry Star was 65 when the GPS said we were doing 60
Our Horizon 65 equals 62.
Point is they all have variations. Reading 5MPH at a stop could just be dust holding the arm up.

[rgatijnet1]

No, not really. Your coach is 17 years old and if there is a speedometer cable, it is not unusual for them to start sticking, especially on vehicles that sit for long periods of time. They are lubricated from the factory but from then on, they are exposed to the elements and the lubrication eventually starts to fail.
Even if it is electrically fed, anything that sets tends to get stiffer and not swing like new. Meters are no different.

[Bucky1320]

Ahem....ok. Does ANYONE think it is weird that is shows 5mph at rest?

[Triker33]

275-70R/22.5 Diameter 37.6 to 38.0"
265-75R/22.5 Diameter 38.4 to 38.5"

Smaller tires make the odometer show faster speed and miles will be more.
Good thing is it will make the MPG seem better. 🙂

Check the odometer with 10 Mile marker signs to see your gain on miles driven.

[Bucky1320]

GPS agrees with those who tell me. And sometimes it is even greater than 5mph difference.
275-70R22.5 on it now.
265-75R223.5 originally....so there may be a little difference in circumference. But the tires aren't going to make the speedometer read 5 mph when at rest.

[wolfe10]

First thing I would do is compare speedometer readings with a GPS. More accurate than "others tell me"....

Do you have the OE tire size?