A few months ago, I swapped an 85 300D differential into my 84 300D as well as the odometer/speedometer.

Just today, I got around to pulling the odometer to set the correct mileage. While working on the unit, I found this plastic gear on the ground (bottom right on first pic). I have checked a dozen pictures online and cannot identify it anywhere else.

Can anyone tell me what this plastic gear does and where it belongs?

Thanks,

Dkr.

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First off, you are going to love having the 2.88 diff.
One of the best things I did.

Take a better picture from the topside.
I have a 123 '85 speedometer in the garage I can look at to compare.

Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

Thanks. I'll work on getting a pic tomorrow.

Once installing it, it appears the odometer is working, but the trip timer is not. Both worked previously, albeit with the incorrect number of miles.

Dkr.

and this would appear if the trip odometer shaft came loose.


snapped_bolt

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'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

I'll check the shaft again. I remember it had more play than the odometer, but I didn't see the plastic gear in any of the photos and it didn't quite fit on the end... If it was for the shaft, it must have been on the end since the shaft never got disconnected...

Dkr.

Check out Dieselgiant site for speedo repair .

This link is to an Odometer Repair DIY and it doesn't show such a gear: How to Repair Your Broken Odometer

This link is to a place that sells Mercedes Odometer gears and it shows the lowest cog count as 10: Odometer Gears - Mercedes-Benz - Mechanical Speedometer

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Baton Rouge, LA
1977 300D Non-Turbo

I believe I know where this part goes and what it does. However, how to put it back in is another thing. I found a part where the top speedometer can connect to the trip timer and I believe this sprocket connects the two here (see where I have it circled in the middle). It would make sense the force I used to drive out the main shaft could have dislodged this as well.

Rooster300SD: if you could get a pic of your unit in the same place, I would really appreciate it.

Thanks,

Dkr.

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Yes its right it lines up with the worm one that sits in the bottom . Replacment should be made of brass .I have done mine .My pot gear was loose on the shaft also . One tip is ,on refitting the pointer, you fit it on the left side of the end stop ,then after you lift it over to give you the pre tension you need. When you take it apart did you lift it over and mark it will pencil.If you did not then the speed will be out..

dkr,
Yes, that is where that gear goes.

Jeff

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__________________
1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

They use gears too.


snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....