My speedometer reads accurately (using a GPS to compare) below about 35mph. Once I start climbing above that the speedometer almost seems to double the speed so that when I get to around 55mph the speedo is reading 70mph. What would cause this? The speedo seems to jump around a bit as well.
I don't know if this is a new thing since the truck is relatively new to me and all my driving to date has been has been limited to about 35=40mph. Today I took it out for a spirited drive and noticed this anomaly.
Speedometer Anomaly
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- Sweptline.ORG Pioneer
- Posts: 7362
- Joined: Wed Dec 31, 1969 6:00 pm
- Location: Walnut Creek, CA
Re: Speedometer Anomaly
Dirt and dust built up in the head, between the magnet and rotating can. They also have to be lubed thru the tiny hole in the top of the casting just in front of where the cable connects. That hole is usually solidly plugged with dirt and requires a sewing needle, or similar, to clean out.
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- Sweptline.ORG Member
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- City: Niagara, ON
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Re: Speedometer Anomaly
Thanks. Not being familiar with these (I assume mechanical?) is the head at the gauge end or where it screws into the transmission? Is it worth removing the entire cable, unscrewing at both ends (I assume this isn't arduous?) and cleaning/lubing the entire cable? Or am I talking a pipe dream? I notice cables are reasonably cheap. Appreciate the assist.PwrWgnDrvr wrote: ↑Sat Apr 24, 2021 3:03 pmDirt and dust built up in the head, between the magnet and rotating can. They also have to be lubed thru the tiny hole in the top of the casting just in front of where the cable connects. That hole is usually solidly plugged with dirt and requires a sewing needle, or similar, to clean out.
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- Sweptline.ORG Pioneer
- Posts: 7362
- Joined: Wed Dec 31, 1969 6:00 pm
- Location: Walnut Creek, CA
Re: Speedometer Anomaly
By head I am referring to the needle and mechanism that moves it in the dash cluster. Pretty simple to pull the entire gauge assy and disconnect the cable from it. Then disconnect from tranny and clean/lube as you mentioned. Then remove the speedo from the cluster to work on it. Its a delicate mechanism so be gentle and careful with it.
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- Sweptline.ORG Member
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- Joined: Mon Nov 23, 2020 3:14 pm
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Re: Speedometer Anomaly
OK I get it now, thanks. I was fixated on the cable and you were talking about the gauge. I will try to clean and lube the gauge and see if that sorts it out.PwrWgnDrvr wrote: ↑Sat Apr 24, 2021 8:10 pmBy head I am referring to the needle and mechanism that moves it in the dash cluster. Pretty simple to pull the entire gauge assy and disconnect the cable from it. Then disconnect from tranny and clean/lube as you mentioned. Then remove the speedo from the cluster to work on it. Its a delicate mechanism so be gentle and careful with it.
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- Sweptline.ORG Member
- Posts: 173
- Joined: Mon Nov 23, 2020 3:14 pm
- City: Niagara, ON
- State: Foreign
Re: Speedometer Anomaly
Worked perfectly. thanks again. Just pulled the dash cluster, unscrewed the speedo cable and sure enough the hole on top was full of crud. Cleaned it out, a couple drops of oil and now the speedo no longer jumps around and pegs exactly the speed showing on my GPS, even at 60mph.PwrWgnDrvr wrote: ↑Sat Apr 24, 2021 3:03 pmDirt and dust built up in the head, between the magnet and rotating can. They also have to be lubed thru the tiny hole in the top of the casting just in front of where the cable connects. That hole is usually solidly plugged with dirt and requires a sewing needle, or similar, to clean out.
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- Sweptline.ORG Pioneer
- Posts: 7362
- Joined: Wed Dec 31, 1969 6:00 pm
- Location: Walnut Creek, CA
Re: Speedometer Anomaly
right on!