1st Gen Spedometer Error

[CrazyHorse]

Is there a fix for 1st Gen Speedometer error. Mine is off 6-7 mph at 35 mph and at higher speeds it is off by 10 or more mph. Now I calculated this with those radar speed signs and by doing mile markers on the highway. (Its reading a higher speed than I'm travelling.)

[Venturous Randy]

Hey Jim, 6/7 off at 35mph sounds like an awful lot. I tweaked on mine, an 83, and it reads about perfect now. What I did was to determine how much I was off, then I pulled the speedometer. I then lifted the needle over the stop pin and let it come to a rest. I flipped it a few times to see how consistant it stopped. When I was satisfied where it stopped at, I made a small mark and then pulled the needle loose. I then moved the needle in the direction and amount it needed to go and pressed it back on. I then lifted the needle back over the stop pin, put it back together and tried it out. I think I was about 4 /5 mph's off at 60, but after I tweaked it, it is real good.

What you will need to do is move the needle counter clockwise. If it was off a quarter of an inch, move it that much and put it back on. It should come to rest that distance from the first mark.

That was at least 60,000 miles ago.

RandyA

[Guest Popeye]

Is there a fix for 1st Gen Speedometer error. Mine is off 6-7 mph at 35 mph and at higher speeds it is off by 10 or more mph...

 

I have often heard that 1st gens read ~60 mph at actual 70 mph.

Checked mine with wife in her new SUV [OEM tires], side-by-side for a few miles.

She set her cruise control at 70 mph on flat stretch & my speedometer read 65 mph with Dunlop 491 Elite IIs, OEM size with proper inflation checked on both vehicles.

Just knowing how much it's off is good enough for anything I do.

 

We also checked odometers for 62.2 miles & had only a 0.1 mile diff. ??

 

Myself, I could live with speedo reading 10 mph high at 70 & do math in head. Any greater acuracy just wouldn't matter to me.

 

However, my odometer/trip meter, better be exact since I need more precise info regarding distances & gas mileage.

[CrazyHorse]

Hey Jim, 6/7 off at 35mph sounds like an awful lot. I tweaked on mine, an 83, and it reads about perfect now. What I did was to determine how much I was off, then I pulled the speedometer. I then lifted the needle over the stop pin and let it come to a rest. I flipped it a few times to see how consistant it stopped. When I was satisfied where it stopped at, I made a small mark and then pulled the needle loose. I then moved the needle in the direction and amount it needed to go and pressed it back on. I then lifted the needle back over the stop pin, put it back together and tried it out. I think I was about 4 /5 mph's off at 60, but after I tweaked it, it is real good.

What you will need to do is move the needle counter clockwise. If it was off a quarter of an inch, move it that much and put it back on. It should come to rest that distance from the first mark.

That was at least 60,000 miles ago.

RandyA

 

Interesting, so basically the needle is almost forced naturally to the pin so much so if the pin werent there it would go beyond it, so your resetting the 0 point then I guess is how I'm reading it right? I'm gonna try this hope I dont break it. Thanks Jim.

[Venturous Randy]

What you have is a clock spring that pulls the needle back to the stop pin. There is a bell with a magnet that spins from the cable drive. The faster the magnet spins, the more the bell pulls against the spring. What you are actually doing is adding more or less spring tension to the bell which controls the needle.

I am not real anal about things, but I do want my speedometer to be dead on if possible. I remember going into a Chevy parts department and asking for a plastic driven gear to change my speedometer a little on my car. The different number of teeth have corresponding colors as they are made out of plastic. The counter guy asked what color I wanted. I told him I did not have any idea, but if he would show me the various bins to look in, I could count.

I have found to pull the needle off, a set of curved needle nose plyers work good. Just be sure you are comfortable where the needle comes to a stop before you pull it off.

An easy way to calculate speed with a stop watch in a mile is to determine the number of seconds it took you to go thru and if it is less than 60, you divide it into 60, them multiply it by 60. An example would be a reading of 54 seconds. Divide that into 60 and you get 1.111 and then multiply that by 60 and you are going 66.6 mph. If it took you one minute and twelve seconds, that would be 72 seconds to go the mile. Then you divide 60 by 72 and you get .833 and then multiply that by 60 and you get 50 mph. Are you confused yet?

Yes, to some extent you are resetting the zero point, or actually a point less than zero. Now you should really be confused. Actually it is real simple, but to get it real close, you may have to do it a couple of times. And be careful of using highway mile markers as they are not always spaced correctly, as in 5,280 feet apart.

RandyA

[CrazyHorse]

Thanks Randya Ill try it. I'm gonna work on my fuel sender also dont like inaccuracy in that either.

[safetyguy]

Checking with a handheld GPS, my 88 VR reads about 1 mph to 1.4 mph high at 45 mph. (i.e 45 indicated on the speedometer is about 43.6 mph on the GPS).

 

I believe that the tolerance in new automobiles is plus/minus 3%, so my VR's speedo error is in the ballpark.

 

Let me know what you find out re: the fuel level sensor. The last half of the tank seems to go faster than the first half does.

[CrazyHorse]

Well using a gps my speed is off bout 7mph in low speed at high speed its off by 11 mph. I'm gonna try you idea Randy.

 

Yes safety guy Im down to 2 bars and all I put in the tank is 2.5 gallons I like accuracy so I going do something about this too.

[Condor]

An easy way to calculate speed with a stop watch in a mile is to determine the number of seconds it took you to go thru and if it is less than 60, you divide it into 60, them multiply it by 60. An example would be a reading of 54 seconds. Divide that into 60 and you get 1.111 and then multiply that by 60 and you are going 66.6 mph. If it took you one minute and twelve seconds, that would be 72 seconds to go the mile. Then you divide 60 by 72 and you get .833 and then multiply that by 60 and you get 50 mph. Are you confused yet?

 

Dang..... where's that asperin....:rotf:

[Keemez]

Hey Jim, 6/7 off at 35mph sounds like an awful lot. I tweaked on mine, an 83, and it reads about perfect now. What I did was to determine how much I was off, then I pulled the speedometer. I then lifted the needle over the stop pin and let it come to a rest. I flipped it a few times to see how consistant it stopped. When I was satisfied where it stopped at, I made a small mark and then pulled the needle loose. I then moved the needle in the direction and amount it needed to go and pressed it back on. I then lifted the needle back over the stop pin, put it back together and tried it out. I think I was about 4 /5 mph's off at 60, but after I tweaked it, it is real good.

What you will need to do is move the needle counter clockwise. If it was off a quarter of an inch, move it that much and put it back on. It should come to rest that distance from the first mark.

That was at least 60,000 miles ago.

RandyA

 

I performed the exact same procedure here- was reading about 4mph on the high side of actual and now is dang close according to GPS. Couple things to be aware of- having steady hands and a good set of dental picks (preferably a 90* angle one) will make this much easier than with big tools. Just pry the outer cap off one side at a time, then carefully work on the indicator needle. It'll kinda let go with a snap/bang, but it will come off. See below for detail of how the needle and cap assembly fit onto the speedo unit.

[Trader]

any of you guys come across this problem. My speedo works on my 84 standard...but the odometer does not work.

 

It makes for better resale value but I'd rather have it working.

 

any suggestions?

[Keemez]

any of you guys come across this problem. My speedo works on my 84 standard...but the odometer does not work.

 

It makes for better resale value but I'd rather have it working.

 

any suggestions?

 

I would guess that the gear teeth are chewed up. The bellhousing and needle shaft would still be free to rotate like that. Only way to know is to yank it apart and get a good look at it.

[MiCarl]

Why are you guys pulling the pointer off? It'll turn on the shaft.

 

Here's how I'd do it:

 

Pick a speed midway in the range (say 50mph). Use mile markers, gps etc. to find out what the speedo actually reads at that speed (lets say 55 in this case).

 

Pull the speedometer out and rotate the pointer to 55. Then hold the bell so the shaft doesn't turn and rotate the pointer back to 50. Now your speedometer will be spot on at 50mph.

 

You shouldn't need any tools to turn it, I've done it with just my fingers.

[CrazyHorse]

I did the Randya thing about a year ago works great at cruising speeds around 55 slighty off at low speeds but I can live with that.