BimmerFest BMW Forum banner
1 - 20 of 20 Posts

·
Registered
Joined
·
17 Posts
"notorius" is a strong word. The actual word to use is "purposely". German speedo's are set to read a little high because of German laws requiring that speedometers NEVER may read lower than the actual speed, for safety purposes, supposedly. They're all set to run two to three MPH high.
 

·
Registered
Joined
·
322 Posts
No.
Move the needle. I'll be doing that soon.
Mine with stock wheels is four MPH low at 70.
I don't believe moving the needle will solve the problem since the built-in error is a percentage of the actual speed. I've calculated the error on my M6 to be about 7% and my Z4M is about 5%. I think it's something we'll all just have to live with.:thumbdwn:
 

·
///M
Joined
·
1,371 Posts
I just changed to 19" CSL's and my speedo is off by about +5 mph at 70. Can the speedometer by calibrated -- by the dealer?

Cheers
What tires did you use? I know it's probably too late to change now, but for future reference, the tires have a lot more to do with your speedo error than the wheels themselves.
 

·
S54=Living on the Edge
Joined
·
1,496 Posts
German speedos are notorious for reading too high.
Very true for VWs and BMWs. However, the 2 Audi TTs I had before were accurate and matched the Garmin measured speed ...
 

·
Registered
Joined
·
70 Posts
Discussion Starter · #10 ·
What tires did you use? I know it's probably too late to change now, but for future reference, the tires have a lot more to do with your speedo error than the wheels themselves.
I have 235/35 and 265/30 Toyo T1R's, according to Toyo they are 25.5 and 25.4 in. tall. I knew they would lower the gearing going in, just hoped I could get the speedo calibrated. The Toyo's run a little small, if I replace with same I'll probably try 245/35 and 275/30 next time. Just .1 wider but .3 taller.

Cheers
 

·
///M
Joined
·
1,371 Posts
Very true for VWs and BMWs. However, the 2 Audi TTs I had before were accurate and matched the Garmin measured speed ...
That's kinda strange. The reason most german cars have a speedo "error" is that german law prohibits cars from displaying a speed that is slower than the actual vehicle speed. So BMW purposefully calibrates the speedo to indicate 5-10% higher than actual speed.
 

·
///M
Joined
·
1,371 Posts
I have 235/35 and 265/30 Toyo T1R's, according to Toyo they are 25.5 and 25.4 in. tall. I knew they would lower the gearing going in, just hoped I could get the speedo calibrated. The Toyo's run a little small, if I replace with same I'll probably try 245/35 and 275/30 next time. Just .1 wider but .3 taller.

Cheers
I think as long as the speedo is within the BMW specs for error reading they can't help. I'm not sure if there is anything they can do software wise if it is out of tolerance.
 

·
Registered
Joined
·
33 Posts
I know of three methods to change speedo settings.
1. Change the needle position. I did this on a '74 BMW motorcycle with good results. This is a tedious procedure at best simply because the plastic face plate of most speedos are not designed to be easily removed. I used a simple table fork to pry up the needle.
2. Maybe, the engine computer can be reset. This is a "maybe". I know that with GM autos one can change the ECU's rear end ratio settings quite easily. This might be the case with BMW if they use the same basic ECU software for all applications.
3. There is an Australian outfit www.blackrobotics.com that makes a "Yellow Box" for speedo recalibration of any speedo which uses a hall-effect speed sensor. The Yellow Box is about the size of half a cigarette pack, and is installed inline. It can be set to "correct" by making percentage changes. I paid about $100 for one several years ago, and installed it on a Honda motorcycle.
 

·
19,585 Miles
Joined
·
11,141 Posts
I know of three methods to change speedo settings.
1. Change the needle position. I did this on a '74 BMW motorcycle with good results. This is a tedious procedure at best simply because the plastic face plate of most speedos are not designed to be easily removed. I used a simple table fork to pry up the needle.
2. Maybe, the engine computer can be reset. This is a "maybe". I know that with GM autos one can change the ECU's rear end ratio settings quite easily. This might be the case with BMW if they use the same basic ECU software for all applications.
3. There is an Australian outfit www.blackrobotics.com that makes a "Yellow Box" for speedo recalibration of any speedo which uses a hall-effect speed sensor. The Yellow Box is about the size of half a cigarette pack, and is installed inline. It can be set to "correct" by making percentage changes. I paid about $100 for one several years ago, and installed it on a Honda motorcycle.
2. Is not going to happen.

3. Will make the oddmeter off in the same amount the speed was.
 

·
Registered
Joined
·
33 Posts
Ron correctly points out that if you recalibrate your speedo using a Yellow Box your odometer will now read low by the same percentage. That may be a problem to you, but in my case the few times I needed exactd odo readings I just recalculated with the percentage change. It was no big deal to me. I did disclose this to my buyer when I sold the bike. In my case the speedo was reading 9% high, which was distracting to say the least.
As for whether the ECU can be itself recalibrated, I don't accept Ron's statment that "it isn't going to happen." Perhaps not by any of us, but all auto computers can be hacked with enough patience. They are not that complicated.
 
1 - 20 of 20 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top