Odo Whoes
- Thread starter Alan
- Start date
I would speculate slippage. Not all of the pulses from the encoder are reaching the reader in the speedo to make it slow. On the 461 at least, the old 460 gear drive on the transfer case is still employed, but instead of a cable it has a rotary encoder attached with a coupling which might be slipping. Also the encoder plug gets moisture in it and causes havoc with the speedo and odo. If that is all OK then another speculation is "noise." Maybe somewhere along the wiring there is a nice thick alternator wire or DC to DC installation messing with the pulses.
Makes sense Andrew, but surely the speedo and OSO are connected within the speedo and if there was slippage both would be affected and not have such a big difference.
I will check the noise issue as well as I do have a 30A DC to DC installed although I think it would be far away enough from the speedo cable.
I will check the noise issue as well as I do have a 30A DC to DC installed although I think it would be far away enough from the speedo cable.
So, after some research and googling I think I found out why my odo is not reading correctly.
Obviously, the tyres make a difference. So, since the speedo drive ratio has not changed, it should read slower but not as far out as the odo suggests. It seems the odo is driven by three gears of which one determines the odo reading namely the E3 gear. This is what google AI had to say:
The E3 gear in a Mercedes speedometer plays a crucial role in the odometer mechanism. Let’s delve into the details:
I think there might be other variables at play as well but I'd like to be prepared before dismantling the lot.
I have however found a site in the States hat manufacture these gears and have a whole lot of options.
{If you cannot count the teeth on the main gear, then count the teeth of the next gear it meshes with. If your tooth count is 39=48x21, 41=48x19, 42=48x18, 43=48x17, 44=48x16, 45=48x15, 46=48x14, 47=48x13, 48=48x12}
Now it is a question of checking what is in there currently and possibly change it.
There a many Youtube videos showing you how.
Obviously, the tyres make a difference. So, since the speedo drive ratio has not changed, it should read slower but not as far out as the odo suggests. It seems the odo is driven by three gears of which one determines the odo reading namely the E3 gear. This is what google AI had to say:
The E3 gear in a Mercedes speedometer plays a crucial role in the odometer mechanism. Let’s delve into the details:
- Odometer Gears and Their Purpose:
- The speedometer and odometer in a Mercedes-Benz use a series of gears to track and display the vehicle’s speed and distance traveled.
- These gears are responsible for translating the rotation of the vehicle’s wheels into meaningful readings on the instrument cluster.
- Specifics of the E3 Gear:
- The E3 gear is one of these gears, and it has a unique design.
- It has 48 teeth on the outside and then between 12 and 21 teeth on the underside gear.
- The original E3 gear is typically amber in color.
- Function of the E3 Gear:
- The E3 gear is directly involved in calculating the odometer reading.
- As the vehicle moves, the E3 gear meshes with other gears in the system, translating wheel rotations into distance traveled.
- When the E3 gear turns, it contributes to the incremental increase in the odometer reading.
- Material and Noise Considerations:
- Some aftermarket companies, such as Odometer Gears, offer replacement gears made from hard, self-lubricating plastic.
- However, users have reported that these hard plastic gears can be noisy, especially when installed dry (without lubrication).
- The noise can manifest as a tap-tap-tap sound, particularly at speeds below 40 mph, resembling having a large rock in a tire.
- In contrast, the original gears from Mercedes were made of softer urethane, lubricated with grease, which resulted in quieter operation.
- Recommendation:
- If you experience excessive noise due to the E3 gear replacement, consider using the softer OEM gears (if they are still in good shape).
- Applying a judicious amount of multipurpose grease to the gears can significantly reduce noise and restore a quieter driving experience.
I think there might be other variables at play as well but I'd like to be prepared before dismantling the lot.
I have however found a site in the States hat manufacture these gears and have a whole lot of options.
{If you cannot count the teeth on the main gear, then count the teeth of the next gear it meshes with. If your tooth count is 39=48x21, 41=48x19, 42=48x18, 43=48x17, 44=48x16, 45=48x15, 46=48x14, 47=48x13, 48=48x12}
Now it is a question of checking what is in there currently and possibly change it.
There a many Youtube videos showing you how.
So to update this thread.
This little gear became brittle and only had 7 of the original 12 teeth left. It is fairly easy to remove and after some searching I found some designs online. These were taken and modified a little and 3D printed. I installed the printed gear and all is well again.
These gears are available on the internet from various vendors but I could not wait that long nor could I justify the price of shipping. Local speedometer repairs were also prohibitively expensive just to see what was wrong never mind fixing.
Here a link on the internet. https://www.odometergears.com/products/Mercedes-Benz/G-Wagen+(460-461)+79-99/134
This little gear became brittle and only had 7 of the original 12 teeth left. It is fairly easy to remove and after some searching I found some designs online. These were taken and modified a little and 3D printed. I installed the printed gear and all is well again.
These gears are available on the internet from various vendors but I could not wait that long nor could I justify the price of shipping. Local speedometer repairs were also prohibitively expensive just to see what was wrong never mind fixing.
Here a link on the internet. https://www.odometergears.com/products/Mercedes-Benz/G-Wagen+(460-461)+79-99/134
