Hi, I just saw this now. Did you ever resolve this issue?

Hello Kamran,

Do you know if the gears are original or have they been replaced?

Do you know if your car's differential has been replaced? The odometer/speedometer are matched to the cars differential. 40% sounds like someone might have swapped the differential or instrument cluster? Is your speed accurate?

-Kris

not sure
 

Has this problem always been there??
A 280SE sounds like an EURO to me that at one time got federalized.
During the federalization process of mine, they build in a new speedometer.
If that is true for your's, too, maybe they didn't pick the right one?
The rear diff ratio could be different, leading to a wrong speed indication?
So maybe the gearing works, but you have the wrong gears....

Just an idea.

Definitely a possibility. I would get a GPS out and check the speedometer and see how accurate it is.

It might just be a case of the wrong gears on the odometer.

Hi
Unfortunately I don't know the previous history of the lady. But it is euro type.
How can I be sure about diff or trany?

I think the only way really is to physically inspect the trany/diff and get the part numbers off them.

Might also help if you got the part number off the speedometer/odometer unit too.

From there we could check it against the EPC and see if it is the proper parts or if they were replaced at some point in time, etc

Hi
My cluster S/N is 126 542 60 01
but could not go behind and check the trany/ diff.
could any one help me.
Is it possible changing capacitors with other cap may cause calibration?
Thanks

Hmm i could not find that part number in the Mercedes EPC. I'm not saying it does not exist, just that they don't have it in there..which is not uncommon.

Changing capacitors would not cause that large of a calibration error.

Does anyone know how many teeth I need to order for the 85MPH speedometer? Mine stopped counting the other day at 399,647. It pissed me off because I am waiting for it to roll over to 400,000. I'm not looking forward to pulling the cluster, opening it, counting the gear teeth, putting it all back in and doing the same thing again to swap the gears.

The gears from garagistic are only $17 - has anyone bought from this company?

I've never bought from them. I pretty much just buy from OdometerGears.com.

I had one customer that bought cheaper gears, maybe from the above company but I can't be sure. They were not as robust and one was the wrong size. Not saying the $17 ones won't work just sharing my experience.

I think you should just bite the bullet and pull the cluster.

Check out this photo album. I took these when I re-did my dad's 300SD clock and a buddy's 560SEL clock/tach.

W126 Odometer / Speedometer / Clock Repair - Imgur

EDIT: I took some notes when I repaired a customers 85 MPH speedometer.

http://www.odometergears.com/products/Mercedes-Benz/S+class+%28126%29++79-91+Diesel/53

Note my reference designations might not be equal to OdometerGears, check my drawing below:
E1 = 12
E2 = 48x12
E3 = 48x36
E4 = 48x12

http://i.imgur.com/LdLXjnWl.jpg

Instead of counting the teeth, just read the numbers on the gears. The number of teeth is marked on each gear. On the larger gears, the number has a "Z" in front of it. You'll see something like Z12 Z45. Sometimes reading those numbers is easier than counting a bunch of little teeth.

I grabbed one of my spare 85MPH clusters and took it apart to see that the 12 tooth gear has fallen apart. I did get one of the other gears out and the smaller inner section has 12 teeth. It looks like the other one like it had 12 teeth on the inner part as well. Is it safe to assume that MB did not change these parts over the years of the 85MPH speedo and that 12 tooth gears are what I need? If so, I will take a risk and order the $17 gears. If they suck eggs, I will let everyone know. If not, it may be a cheaper source for gears.

I don't see any markings on these gears. It looks like the plastic has sweat and may have destroyed any markings if they were there.

The markings are either engraved or cast, not printed. All the OEM gears I've come across have the markings. They're really tiny on the innermost white gear, but the others are a bit bigger. They're hard to see with all the lube/grease/grime on them, but the markings should be there. You may have to wipe them clean to see them.

This has been my experience as well. All of the factory gear should have numbers on them. If yours don't I would wonder if they were replaced at some point?