Speedo Under-reading

[Ow]

Hi all

Took the car out for a little drive earlier, and had a gps speedo running on my phone.

worryingly the speedo seems to underestimate my speed slightly, rather than over estimate.
If I'm doing around 40 per the car, it's more like 43/44 on the gps.

It is a bit less at higher speeds, so 60 is fairly close, but I'd rather it be over reading my speed!

Does anyone else have this issue, or do you know what could be causing it?
I don't know if it's always done it, so it may be since I took my dash apart.

Thanks

[Bassfiend]

Ow said:

Hi all

Took the car out for a little drive earlier, and had a gps speedo running on my phone.

worryingly the speedo seems to underestimate my speed slightly, rather than over estimate.
If I'm doing around 40 per the car, it's more like 43/44 on the gps.

It is a bit less at higher speeds, so 60 is fairly close, but I'd rather it be over reading my speed!

Does anyone else have this issue, or do you know what could be causing it?
I don't know if it's always done it, so it may be since I took my dash apart.

Thanks

Mine reads low if I'm accelerating and high if I'm decelerating - I've always put it down to a sticky mech which is why I bought a Road Angel.

Phil

[Ow]

Bassfiend said:

Mine reads low if I'm accelerating and high if I'm decelerating - I've always put it down to a sticky mech which is why I bought a Road Angel.

Phil

I think I found an old thread of yours earlier when I was searching on google.

I may look into getting a Road Angel as a more permanent to my phone gps.
How quick/slow are they to refresh? Can they be used as a speedo replacement?

[Bassfiend]

Ow said:

I think I found an old thread of yours earlier when I was searching on google.

Fame at last...

Ow said:

I may look into getting a Road Angel as a more permanent to my phone gps.
How quick/slow are they to refresh? Can they be used as a speedo replacement?

They update every couple of seconds - not really quick enough to stop you (me) accelerating away from a roundabout, seeing a copper with a speeding camera and getting done for 46 in a 30 but at least I knew exactly what speed he was going to get me for.

They're responsive enough for normal use though ...

Phil

[Ow]

Thanks Phil

I'll check it out.

At least I now know to be a bit more cautious, as an indicated 45 is closer to 50 than 40!

[Quietlybonkers]

Are you on standard wheels and tyres?

[Ow]

Quietlybonkers said:

Are you on standard wheels and tyres?

Yeah all standard (forgot to put that on the OP)

I'm sure last time I used my phone GPS it was over-reading, so maybe my dash dismantling has something to do with it.

[SILICONEKID340HP]

Try it with another car ,you may find its the GPS not speedo,it is slighly behind ..

[Ow]

SILICONEKID340HP said:

Try it with another car ,you may find its the GPS not speedo,it is slighly behind ..

Possibly, but it's always seemed about right when I've used it before.

Will try tomorrow with my other car.

[Bassfiend]

Ow said:

Thanks Phil

I'll check it out.

At least I now know to be a bit more cautious, as an indicated 45 is closer to 50 than 40!

Mine's anywhere up to 30mph out at times.

Phil

[jim.2007]

fibre glass car less magnetic field to home on?

[Bassfiend]

jim.2007 said:

fibre glass car less magnetic field to home on?

How do you mean?

Phil

[V8OW]

Seems as if it may only be at lower speeds, as it seemed to be spot on at 60/70 compared to my phone gps speedo.

I may still invest in a Road Angel though! Does anyone have one they want to get rid of?

[Ant.]

V8OW said:

Seems as if it may only be at lower speeds, as it seemed to be spot on at 60/70 compared to my phone gps speedo.

I may still invest in a Road Angel though! Does anyone have one they want to get rid of?

What gearbox does it have fitted, if its a T5, check your speedo sender gap.

[V8OW]

Ant. said:

What gearbox does it have fitted, if its a T5, check your speedo sender gap.

Yeah it's a T5. Thanks, I'll check that this week.