Speedometer faster vs slower

I have sent my TR speedo to three speedometer experts with sending unit. None could fix it correctly. Had to use a (SpeedoDRD Y1 Speedometer Calibrator)

 

Check your GPS I did the same test with 2 GPS monitors (2 different manufacturers) in the car and there was a 3 mile difference between the two so I don’t know what to believe

 

Italian cars always read faster. Reading faster also means youre less likely to be speeding through a town. Realistically you should be watching the road and driving according to conditions the rest of the time, a Speedo is to take note of speed.

its seems int he 60s speeds normally read 10% fast made the car feel faster too, in the 70s speedos were crap and not allowed to read over 85, maybe in the time of digital speeds late 80's they got more accurate. Also consider tyre pressure, and at speed tires grow diameter, so however calibrated any speedo is there are going to be other factors.

 

Id say this Diffendal relates to tire diameter decreasing and increasing with speed. Seems really accurate to me.

 

I never checked different speeds. sometimes the odometer moves when car is stopped. TR speedo is not accurate. You can not always believe true mileage on these cars!

 

That's the one, it works on electric speedos. It splices into the wiring going to speedo gauge, simple and programable.

 

yes I got one too.. its the only way to make this speedo "more" accurate...

note: this may not be a big deal to some, but work it out, over say 20years, how many extra Kms/miles your odo will read, if its 10-15% reading over.. you can do the quick maths on that.

 

Is this the right one? My Testarossas Speedo is significantly off at high speeds, and it actually reads slower than actual increasing the risk of a ticket. https://soloracer.com/speedodrd.html?srsltid=AfmBOor4cr6tbPjKyQ_zNqrtSAPH2eVTgrfykbJF31uYxYfaZJtFjc9p

 

Yes, that is the one.

 

Thank you! This was driving me crazy and no mechanic seemed to know how to rectify it. At high speeds, the inaccuracy is extreme. At a read speed of 90 mph the actual speed is more like 104 mph. Its to the point that I’m relying more on the GPS speed reading of my radar detector. I will order this immediately.

 

Oh, I did not even realize there were different model options until I went to order. @ago car nut which model did you use?

 

When I ordered mine, there was only one model. I know they updated. Best to contact them. They were very helpful setting mine up.

 

That speedo doesn't seem too bad. A possibility for the differential effect is a sticking speedo spindle shaft. I was able to get a tiny amount of lubricant on the 308 Veglia gage, and it made a big improvement in reading consistency. 25 ++ year old car which spends much time under a car cover.

Tach accuracy? For tuning, the error is a problem when setting idle. Mine was indicating ~400 hundred high, that was an 'oops' to trust it. BBi doesn't want to idle at 600. I calibrated the gage and got smarter on what tools to use for critical measurements.

 

Sorry, but this is a lame question for a classic Ferrari, old analog gauges read what they will.
I understand it's different in Europe with all the speed cameras and such, and the accompanying fines, but just keep your speed reasonable when you can and don't depend on your gauges, your GPS is much more accurate.
Alden

 

Most vehicles speedometers read a little high from the factory. Give you a little leeway when Barney type PD was out for revenue.