Speedo Underestimating

[josh 0]

sorry me again, i've fixed my first issue, thanks for the help

 

 

I have searched about this but they only describe with engine changes and different ratios.

 

i snapped the speedo cable when repairing my dials (needed to resolder a connector) so bought a new one and fitted it.

The cable works as it should, but it seems to be out..

Before the break my satnav would be around 2mph under what i was doing at 30 (so satnav reads 28 when indicated speed it 30), but now its the other way round but worse.

If i do say 30 indicated the satnav says im doing around 35ish.

 

I'd just hate to go through a speed camera thinking i was doing 30 when i'm not

 

Now i know it can't be the wrong sized drive as i didn't touched it. Is it just something as simple as the cable needing a little wd40 or silicone spray to let it spin more freely?

 

cheers in advanced

Edited February 24, 2010 by josh

[notamondayfan 44]

I'd personally say sat nav's arent the best piece of kit for testing your speedo. Maybe an average speed over a longer distance of flat straight road may be accurate enough?

 

I would compare your car to a newer car, that is totally standard, with standard tyres fitted too. Then get them to travel at a constant speed and compare how fast you are going.

 

Can rolling roads test car speed too?

 

Deano

[Cameron 16]

Depends what satnav you have I guess, but they're all pretty accurate.

According to mine, the Mondeo does 80mph when the speedo reads about 84 / 85, and the 205 reads over 90!

[happygoron 2]

As long as you are oon a reasonably long flat road I'd say the sat nav is the most accurate tool you could use. My speedo under reads too, I just always go through speed cameras ~5mph below the limit (indicated).

[Cameron 16]

I generally go through speed cameras at 10% over the limit.

[josh 0]

cheers for the reply, i took the inner cable out and gave it a good helping of grease and made sure the cable was routed with as smaller kinks as possible,

its now alot more accurate, still not perfect, but thats what makes every 205 unique

 

i'll still be going 5mph under just in case