digi dash speed

[iceman_674]

just fitted a digi dash all works fine except the speed is not reading fast enough i have switched the red switch on top and it just showed double the speed, just wonded if i had the wrong transducer????

thanx

[Aragorn]

well theres a few reasons

1 uve got the wrong sender - tell me the code off the side of the sender and the type of dash and we can clarify this

2 the sender is m0nged

3 your old dash was shagged making u think u were goin faster than u were - easiest way is to get to about 60-70mph and note the engine rpms

then tell me them along with the gearbox u have and ill tell ya how far out it really it

[pickle]

a lad i know had that problem, but his wouldnt g over 115mph, so it probably isnt your dash.

[dikharvey]

Mine reads 5mph over sonstantly (tested with GPS softawre) cant get to the switch at the top to change it. The switch only just chages it sligtly

[Aragorn]

seems strange for it to be out by a fixed amount?!

ie if your driving at 10mph it reads 15 and if your driving at 100 it shows 105

means its over reading by 50% at 10mph and 5% at 100

this aint right and its prolly gonna be out by a reasonably constant percentage which if anything will get greater at the top end of the scale

gorra remember also that your gps has an accuracy range - couple this with the dash's accuracy range and u could get quite a difference if ones at the top end of its accuracy and the others at the bottom (for instance if ones +-5% and the other is +-10% - you could be driving at 100 - the dash it showing 110 and the gps is showing 95 makes u think theres a 15mph difference but theer aint ;)

[dikharvey]

Accuracy range with GPS?

Whent hey can track you to with 2m any where on the suraface of the earth?

It aint guna be out by far!

Yeah, it was reading 35 instaed of 30 and 85 instead of 80. Strange, probley just done on purpose.

The GPS agrees with the caluations for gear ratios and the tyres sizes with th RPM.

[iceman_674]

took it out for a run and noted some speeds, here they are

50mph - 3000rpm - 3rd gear
60mph - 4100rpm - 3rd gear
78mph - 6000rpm - 3rd gear

f10 5 speed box

if you could work it out and let me know if you think its out,

cheers

[Aragorn]

well there are 2 F10 5 speeds and ive assumed your running 195/45r15 (although the tire size wont affect the dash readings since they are taken direct from the diff)

if its a wide ratio box...

3000rpm = 38mph in 3rd
4000rpm = 50mph in 3rd
6000rpm = 75mph in 3rd

if its close ratio...

3000rpm = 33mph in 3rd
4000rpm = 44mph in 3rd
6000rpm = 67mph in 3rd

so judgeing by the numbers u gave me its a wide ratio box (ie standard 1.2 5 speed or summat)

but theres summat strange goin on at the bottom end

maybe give us some readings in other gears too and well try and see whats up with it

[iceman_674]

will do some more tommorow,
when i had the original clocks in the speedo showed

48 - 1st gear
60 - 2nd gear
87 - 3rd gear
carnt remember rest,

thanks for help

[Aragorn]

ok im assuming your talking on the rev limiter?

in 1st gear with the WR box u should manage 31mph @ 6800rpm - u'd need 10500rpm to get 48mph outta first so i seriously doubt your old figure ;)

2nd u should manage about 57mph @ 6800 so the 60 aint too far out

3rd u should manage about 87 @ 6800 which is what uve said

summat seems wonky with the lower end of your speedo :/

[iceman_674]

yeh sorry it used to show 40 in first gear must have been half asleep when i posted that.

the speed's you given arnt far off so carnt work out whats wrong with digi.

done some more tests in other gears

25mph 2nd gear 2100rpm
34mph 2nd gear 3200rpm
45mph 4th gear 2100rpm
57mph 4th gear 3000rpm

any more info you need let me know, startin to P**S me off now its just one of them little annoying thing.

cheers