Speedometer question for 2.47 differential swap - PeachParts Mercedes-Benz Forum

moog · #1 08-02-2005, 06:21 PM

I've read a lot about changing out the speedo, and I see how that would work, but I want to keep the odometer mileage original. I also read that just swaping the speedo dial face would do the trick. Not wanting to mess with adjusting the odometer, would it work to just change the face, or does the whole speedo need to be dropped in?

Breckman99 · #2 08-02-2005, 07:28 PM

I do not know if the face swap will read correctly. If you drop the correct speedometer in, all you have to do is match the mileage to yours. Pull the assembly apart, it is pretty self explanatory. Be very cautious of small parts and springs and all should go smoothly.
Another option is to send the replacement speedometer to a speedometer shop and have them adjust the mileage accordingly.

Snibble · #3 08-02-2005, 08:46 PM

Correct me if I am wrong, but isn't 2.47 differentials from 560's? If so... aren't they LSD?

t walgamuth · #4 08-02-2005, 09:01 PM

is also found in older cars i believe such as the 450se and perhaps the 380se. changing the face will not make it read correctly. the working pars must be changed too.

tom w

boneheaddoctor · #5 08-02-2005, 09:42 PM

Quote:

Originally Posted by t walgamuth

is also found in older cars i believe such as the 450se and perhaps the 380se. changing the face will not make it read correctly. the working pars must be changed too.

tom w

I agree...you need the properly matched speedo assy...

Milage can be tweeked to read correct for the body. Doing this is legal, changing it to some number less than actual is when it becomes illegal. Most states anyway.

H-townbenzoboy · #6 08-02-2005, 10:16 PM

You can have the speedometer recalibrated for a 2.47 differential.
-Joe

moog · #7 08-03-2005, 01:25 AM

Thanks for all those helpful responses. I guess I'll just trade speedos, but how would I go about adjusting the odometer? I've tried searching here, but only with mediocre results. Can anyone point me in the right direction?

t walgamuth · #8 08-03-2005, 06:15 AM

is a electric drill in the speedo slot. i think it will work. never tried it. some mention taking the odo apart and rearranging the numbers. i havent done either thing.

tom w

boneheaddoctor · #9 08-03-2005, 08:20 AM

you can't use a drill to run the numbers backwards like they tried on "ferris Beullers day off"...just like the movie the odometer will not go backwards. Trust me I learned that over 20 years ago.

You have to dissasemble the odometer and set it with the milage that is accurate for your car....only shortcut is paying a speedo shop to do it for you.

t walgamuth · #10 08-03-2005, 09:21 AM

you could turn it over and start from scratch...but how long would that take?

tom w

boneheaddoctor · #11 08-03-2005, 09:29 AM

Quote:

Originally Posted by t walgamuth

you could turn it over and start from scratch...but how long would that take?

tom w

I would be concerned about the wear from abvancing it the slow way.(drill motor)...these things wear out .....

Pop it out and just reset the odometer by reassembling the assy. to the right milage. or leave it the way it is...(milagewise)

Pete Burton · #12 08-03-2005, 09:43 AM

I would think the best way would be to change the pickup right at the transmission output shaft, whether mechanical or electronic. That way, you can leave the speedometer/odometer alone. This would mean changing a gear or pickup plate behind the rear output cover of the trans.

boneheaddoctor · #13 08-03-2005, 09:50 AM

Quote:

Originally Posted by Pete Burton

I would think the best way would be to change the pickup right at the transmission output shaft, whether mechanical or electronic. That way, you can leave the speedometer/odometer alone. This would mean changing a gear or pickup plate behind the rear output cover of the trans.

I thought the pickups were the same for the benz and the speedos were calibrated differently...depending on the rear end ratio.

moog · #14 08-03-2005, 11:23 AM

I think the whole speedo needs to be switched, not only because the speedos are calibrated differently but also because the maximum gear speed markings from the old speedo will not match up anymore. As for the odometer, anyone got a link to a helpful thread about odometer disassembly?

leathermang · #15 08-03-2005, 12:19 PM

There is absolutely nothing wrong with just putting new speed marks on your present speedo... if you calibrate it with a police radar it will probably be more accurate than the set up you started with...
cut out two new faces... one with degrees ... put it in and get your major settings... like 30, 45, 60 and whatever the max legal speed is in your area... then convert that to your new printout and paste that on top of the calibration face....
Old Hot Rodders did this all the time.. they did not have the luxury of having just changed one or two parts... the tires, rear end, transmission, and engine were often new to the vehicle... but they wanted to keep their dash looking the same.....

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