So recently I was driving around my neighborhood and I got my speed measured by one of those stationary Radar posts.
(Might be a California thing)

Anyway, I noticed my speedometer read 40mph when the the Radar post read 29mph.

I'm not quite sure where to start fixing this problem

1999 Ranger XLT
Manual transmission
2.5L 4-cylinder Engine

**EDIT**

I'm currently using stock tire size.

I am assuming you have stock tire size?

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1991 ford ranger ext. cab 4x4. 3.73 l/s 8.8, 315/75-16 tires fenders cut, 1.5 inch lift. 4.0 OHV 5 speed manual trans
build!

Have a GPS? I got a cheap one that shows my speed. Been accurate on every vehicle so far, so maybe try this to make sure it is your truck and not the sign?

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2006 Ford Ranger XL "Dirty Girl" (Build Thread) TRADED

Yep, stock tires

x2

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White 2011 XL Reg Cab | Tint | 2.3L | Daily

2001 Ford F250 4x4 lariat 7.3L | Tint | 5" turbo back exhaust | Riff Raff 6637 intake | Hydra | Glowshift gauges | 6.5 lift | 20x14 | 36x15.50's

Wow! that's a huge discrepency in speed!
The police departments around here have small trailers they park randomly to remind people of the speed limit, and show their speed.
There are some stationary mounted ones too.

At 30 mph as read by the radar, my speedometer reads 28.
Stock size tires and all.

PS,
For fun when I see one of those radar trailers I like to speed up and watch it freak out at my increasing speed. Cheap thrills.
There are no cameras in them to worry about tickets thanks to the MN Supreme court ruling traffic enforcement cameras unconstitutional.

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Dale

2003 XLT Ext Cab. 3.0 2wd. Auto. Current driver.
1996 XLT Reg Cab. 2.3 2wd. Manual. My 1st Ranger.

An expert is someone who knows everything about something they've never done before.

yeah, tell me about it...

I'm not to concerned about cameras and tickets and such, I usually drive within the means of surrounding traffic; can't ticket us all is my thinking lol

but yes, as you can see by the huge difference in outputs I'm really eager to get this problem fixed ASAP.

Have you done any transmission work on it? Can't speak for a 99 but the 80s manuals had 2 different speedo gears. My 83 was built with the wrong one making my speedo WAY off.

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2003 xlt 4x4 4.0 automatic

was there a car infront of you?

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2003 Ranger Edge ... crashed

2011 sport 4x4 with a little modification

Try my idea? May not be your Ranger...

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2006 Ford Ranger XL "Dirty Girl" (Build Thread) TRADED

I really like ur idea, but i don't own a GPS at the moment
so I must wait till I find a decent one around town before I can your idea, but thank you!!

That sucks :/ I think you would probably notice you was going that much slower then the speedo said. Still thinking it might have been the radar sign

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2006 Ford Ranger XL "Dirty Girl" (Build Thread) TRADED

Only major work done so far was replacing the clutch.

If you have an Andriod or Iphone you can download an app that will do speed by the GPS built into the phone...

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Dan

2004 FX4 4.0 4X4 Extend cab...
265/75/16 tires

I was thinking it may have been the signs but I have felt that my truck does run a little bit slower than the rest of traffic surrounding me on the freeway.

I'm gonna search for more radar posts since I don't have a smart phone to get a GPS app. Hopefully it was that particular sign.