Speedometer reading fast.

So was curious if anyone knew if there was a way to change the gearing so that I could get the speedometer to read correctly? Am obviously concerned that on several different neighborhood radar guns I am being clocked doing exactly 25 MPH yet my speedo say I'm doing 30! So doing the basic math for every 100 miles I travel I am adding 20 additional miles to the odometer. Also want to add that I am driving this car so not afraid to put miles on it but would rather they be accurate miles for all the right reasons. I performed a search already and although there is plenty of information on odometers/speedometers none address an issue of correcting... at least that I could find.

thanks in advance for any info

 

The speedo is not gear driven, all electronic. There is a thread somewhere about disassembling the speedo face, pulling the needle and reseating to a more correct position. Sounded too scary to me. My speedo reads consistently 10 mph too slow, so when it reads 50 I'm really doing 60. Not good! But I just live with it.

 

My speedo is exactly 5mph off too. There are a few threads about speedos being off. Mine is 5 off if I'm going 25 or if I'm going 105. There's no progression in being off, it's just like the needle is in the wrong place. Also, I thought it would affect the odometer but it doesn't, I've proven my odometer to be dead on even though the speedo shows wrong.

 

There are some speedo correction modules that can be used

 

Does anyone know if... if the speedo is off... i.e., a constant overstatement of 5 mph... if that impacts the odometer/overstate the mileage or does it not impact the true mileage?

 

Mine is about 5~8 over and probably saves me allot of tickets so I leave it as is.

 

Mine reads high too. Varies with speed. It does affect the ODO!

 

I have a perfect fix that I did on my 348. Here is a link to the step by step procedure to correct it. This allows you to correct it if it is too slow or too fast and is very simple to do,

http://www.ferrarichat.com/forum/348-355/303123-speedo-off-2.html

 

I remember this thread Jim. I have yet to do it. I guess I better get to it soon as my ODO is 10% higher than actual miles.

 

My needle must just be slipped to the wrong place and showing 5 over all the time but getting the right signal because I have checked it with mile arkers over 100s of miles and my odometer is dead on even though the speed shows high. But mine does not change with speed like yours.

 

Hi all, does anyone have a working link to this speedo fix. Mine over reads by 10mph. When the gauge says 60mph I am actually only doing 50mph. Yet to see if it effects the odometer but if it does this will be significantly over stating the cars mileage.! Thanks

 

Try this link, I think this is what you are looking for to repair for a token amount. I have about the same error in mine as well so I will be following.
https://www.ferrarichat.com/forum/threads/speedo-off.303123/page-2#post-140081708

 

Thanks thats very helpful. Though I am not sure it’s fixing the right issue, i will do some more calibration checks. It appears to be a constant 10mph very read where this link suggests a calibration issue which is a percentage error over the speed range.

 

I believe, for cars sold in the U.S. market, speedometers must NEVER read low. They are allowed to read up to 10% high/fast. Obviously, to avoid reading low due to manufacturing tolerances, companies will probably shoot for a somewhat high/fast reading. Some could read even higher for various reasons.