10kms out?

[Lukeprusher 13]

so i got a speeding ticket the other.day saying 62 in a 50, but now i drive past thpse signs thst read your speed and says 60 when my speedo says 50.

any advice on what the problem could be, the car is stock

[sp8s 1]

Changed diff or gearbox or tyres take your pick

Or you speedo is knackered

[*Glenn* 854]

so i got a speeding ticket the other.day saying 62 in a 50, but now i drive past thpse signs thst read your speed and says 60 when my speedo says 50.

any advice on what the problem could be, the car is stock

Ring me in the morning

[_Matt_ 42]

borrow a gps or use a speed app on an iphone to check your speed via satellite. If that is way different to your speedo then check for problems.

wheel/tyre size, stretched speedo cable, dif sensor etc.

[Arma 134]

You should get that checked if your speedo reads less than your actual speed. Mine is the same, just the other way around.., which isn't as bad I guess? :S Speedo says 60, when electric speed signs detect ~52, and my GPS detects about 52-53. About 6-8km/h off. Always assumed that's just how it should be for 'safety' or something, didn't know something can cause this - maybe should check it too.

[e30ftw 393]

Can only really be wheel size as the gearbox diff ratio have nothing to do with it, they all use the same speed ring in the diff with a pickup sensor.

If you have over OE spec sized wheels you will throw the speedo off as the wheels have more of a rolling diameter (cover more distance per revolution) which means your covering more distance and going faster than what the speedo is calibrated for, where as having smaller ones will cover less ground per turn and thus less speed. Science.

[_ethrty-Andy_ 2122]

What car is it in? If E30, speed is taken from the diff, doesnt matter what diff you have in there, the spinning wheel is the same. Unless maybe its damaged? Has on either an oversized tyre/wheel combo, or maybe the speedo cluster is out. But all E30s are wrong to start with lol

E: its also electronic so no cabel to stretch

Edited July 11, 2013 by _Ethrty-Andy_

[Lukeprusher 13]

okay thanks for the help guys

[IPLEZR 0]

You should get that checked if your speedo reads less than your actual speed. Mine is the same, just the other way around.., which isn't as bad I guess? :S Speedo says 60, when electric speed signs detect ~52, and my GPS detects about 52-53. About 6-8km/h off. Always assumed that's just how it should be for 'safety' or something, didn't know something can cause this - maybe should check it too.

Mine is the same, Car is moving around 8km/h slower than speedo reads and im running 18" wheels

[Carl Wiggins 0]

You should get that checked if your speedo reads less than your actual speed. Mine is the same, just the other way around.., which isn't as bad I guess? :S Speedo says 60, when electric speed signs detect ~52, and my GPS detects about 52-53. About 6-8km/h off. Always assumed that's just how it should be for 'safety' or something, didn't know something can cause this - maybe should check it too.

Maybe it's one of the safety features you get from BMW that you won't get from other car brands.

[Allanw 1051]

basically all speedos are off by a percentage, and they usually over-read, for "safety" sake - you don't want a ticket in your new BMW because the speedo is wrong.

By the time it's been messed with etc over the years, it can end up reading anything though.

Most new cars seem to over-read by 6 to 8 %

[liyi_92 37]

I thought most speedos were off reading usually 4kms above the speed you are going at hence we have the 10km leeway?

[hybrid 1039]

I got the same issue in the e30 too ... running 18s however I have the correct driveline for my wheels. Just that speedo is expecting 15inch wheels not 18s:D Ive taken a mental note using GPS of what is the limit.

[albert72 0]

Have the same problem, faulty speedo but my mine is reading 10kms over the actual. Took the speedo needle off and put it back about half an inch before the zero mark. All good now but still a temporary fix until I get a decent speedo

[_ethrty-Andy_ 2122]

Easier to just make a mental note. I know in my E34 bang on 70mph on speedo is 100km/h on GPS

[Surge 1]

I thought most speedos were off reading usually 4kms above the speed you are going at hence we have the 10km leeway?

No such thing as the 10km leeway. I made the Police give me a full disclosure of all their equipment etc... when I got a ticket in the holiday period for 4km over the speedlimit. I could reasonably argue a couple of km off that speed to bring it down to 102 etc... but it's still over 100km and it's strict liability.