Speedo Overreads

[sprintgtvgus]

I realised this weekend that the speedo in my car Overreads.

That's a first, I've had a few that read massively under, but not this time.

At an indicated 60 I am doing 65 according to say nav, and at an indicated 30, 32-33 according to say nav.

So it seems to consistently over read by about 10%

It's not a really big deal, but obviously it would be nice if it was accurate or a little under.

I do have 15" wheels when I presume 66 Belvedere II would have come with 14" wheel, so that's probably the difference?

The car has also had a 440 and 727 transplanted, with 8 3/4 rear end, different gearing again...

Again, not that worried, but is there anything I can do?

[MilesnMiles]

Yes, you can change the speedo drive in the transmission. Bolts in, can get messy so Jack the car up at a goodly angle to keep it a clean job. Easy to do.

http://www.drivinithome.com/mopar-speedo-gear-chart/

http://www.ebay.com/bhp/727-speedometer

[RobTwin]

...At an indicated 60 I am doing 65 according to sat nav, and at an indicated 30, 32-33 according to sat nav.

So it seems to consistently over read by about 10%.....

Surely that's under-reading then?


Either way, yes it should be an easy fix, tho earlier 60's gears can be tricky to source...

[sprintgtvgus]

...At an indicated 60 I am doing 65 according to sat nav, and at an indicated 30, 32-33 according to sat nav.

So it seems to consistently over read by about 10%.....

Surely that's under-reading then?


Either way, yes it should be an easy fix, tho earlier 60's gears can be tricky to source...

Oops yes that was a bit dyslexic.

Thank you for the info ref speedo drives etc.

[MoparRichard]

I've got a problem the other way ! Going down M1 felt like I'm doing 65/70 speedo reads 40mph also at about 30 mph it's showing 15/20 mph very scary near cameras ! Help

[MattH]

I've got a problem the other way ! Going down M1 felt like I'm doing 65/70 speedo reads 40mph also at about 30 mph it's showing 15/20 mph very scary near cameras ! Help

As a short term fix I got a free app on my phone to tell me speed from GPS. Just wanted to check how far out my son's Mini speedo was.

My Challenger speedo stopped working altogether, it sounded like a cat in a tumble drier so i just pulled the cable out, and rely on the phone and my own judgement.