Instrument Needle changes

[GS450-Junkie]

Couple questions about gauges and needles.


I noticed when I run past a radar sign that my speedo is about 3 mph off. Can this be fixed by popping the needle off and putting it back on so it is reading more accurately? I've never taken the needles or gauges apart.

Also, has anyone on here messed around with painting the needles? I really want to try this...seems intriguing, but I can't decide on what color to use. Red would make the most sense, but is still kinda boring. I Googled some pictures and I like the ones that are 2 colors. Perhaps red with a white tip, etc. I'd really like a needle that lights up but I'm sure that is not an option on our cars. Perhaps paint that is more fluorescent with the binnacle LEDs would be a cool effect.

Anyone have any thoughts or experiences?

[Nicholas R]

The needle is just pressed onto the shaft that rotates, it can be easily popped off. In fact if you replace your trip reset, removing the needle is part of the process. Stil, if you're within 3 mph, I'd live with it. It's pretty unlikely that you're going to rotate the needle enough to be perfect. Plus, before you do anything, you need to find out if it's off throughout the entire speed range. Mine reads low at the bottom, is correct in the middle, and high at the top. (Ie: at 25 it reads 20, at 45 it reads 45, and at 75 it reads 80.) if yours is anything like mine, moving it so that it's right at one speed will likely make it read even worse at the other end of the range.

[DMC5180]

+1 with Nick

I have a Speedometer App on my iPhone that gives me GPS speed. I've compared both my daily drivers and the D. My 05 prius reads 2 mph fast across the speed range. My 93 Cougar reads 3 mph fast at highway speeds. (73 indicated = 70 actual) The Delorean is dead on at 60 and gradually begins spreading the indicated to actual the farther away from 60 you get. I think I'm off 2-3 @ 80 indicated vs. GPS. I don't recall which direction though.

The standard used in calibrating a new speedo face say (140MPH) is 1000 rpm = 60 MPH. This is what the Speedometer shop guys would use to configure an upgraded unit or check the old face calibration. Also there are variances in tire manufactures. The Tirerack gives you Revolutions per mile for all of the tires they sell. It is interesting how the same size spec 195-60/15 can have various RPMile numbers between brands or even different models in the same brand.

[David T]

+1 with Nick

I have a Speedometer App on my iPhone that gives me GPS speed. I've compared both my daily drivers and the D. My 05 prius reads 2 mph fast across the speed range. My 93 Cougar reads 3 mph fast at highway speeds. (73 indicated = 70 actual) The Delorean is dead on at 60 and gradually begins spreading the indicated to actual the farther away from 60 you get. I think I'm off 2-3 @ 80 indicated vs. GPS. I don't recall which direction though.

The standard used in calibrating a new speedo face say (140MPH) is 1000 rpm = 60 MPH. This is what the Speedometer shop guys would use to configure an upgraded unit or check the old face calibration. Also there are variances in tire manufactures. The Tirerack gives you Revolutions per mile for all of the tires they sell. It is interesting how the same size spec 195-60/15 can have various RPMile numbers between brands or even different models in the same brand.

The speedometer is affected by tire size and inflation pressure. Even if you have the correct tire size, as the tire wears the accuracy of the speedometer is affected. As pointed out above, speedometers are calibrated at 60 mph with a + - tolerance of 5% so they are most likely to be very close to the indicated speed of 60 MPH, getting more and more inaccurate the further you get from that speed. Besides cross-checking with GPS you can also check it against the mile markers on the highway. If the speedometer is inaccurate the odometer may also be off too. If you want to experiment with painting the needles you can use a colored marker. Remember it has to be easily visible at night too!

[DMC5180]

The speedometer is affected by tire size and inflation pressure. Even if you have the correct tire size, as the tire wears the accuracy of the speedometer is affected.

+1

Besides cross-checking with GPS you can also check it against the mile markers on the highway. If the speedometer is inaccurate the odometer may also be off too.

Yup! With my daily drivers. I get different Odometer readings for the same Long distance travel route I do on a weekly basis. One will say 282 miles and the other 289 with zero deviation in the driven route stop to stop. Google maps says 283.

[hmcelraft]

A note about painting the needle. Paint will change the weight of the needle - If you change the weight you will add to your accuracy issue.

[Jonathan]

Another thought on painting gauge needles...

If you pick something bright and distinctly noticeable, it may seem like a terrific improvement cause it really pops, yet find yourself getting irritated by it later on after the novelty wears off.

I've seen manufacturing control systems with all kinds of clever animations for valves or pumps and instruments on the interface terminal and while they look neat at first, they get annoying very quickly once you've seen them every day and they become a distraction. Most of the time they get taken out and replaced by the boring non-animated icons in a later rev.

Less is more with these things sometime.