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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,223 Posts
Discussion Starter #1
Many of our MBs will suffer from a sudden non-working odometer.
The gears inside the speedometer were lubed at the factory to insure smooth operation, but over time this same lube reacts with the plastic odometer gears turning them into a waxy consistency. At this point the gear teeth start to crumble stopping the odometer function completely.
Replacing the gears is a fairly simple job but like most MB repairs..one thing leads to another.

To remove the gauge cluster that houses the speedometer, the steering wheel needs to be removed.


Instructions for removing the steering wheel can be found:

MB Chassis manual job# 46-610
Haynes manual 63025 job# 11-20
Chiltons manual 48300 job# 8-27
Steering Wheel Removal Video


Instructions for removing the gauge cluster can be found:

MB chassis manual job#54-250
Haynes manual 63025 job#10-18
Chiltons manual 48300 job#6-17


Instructions for removing and replacing the odometer gears can be found:

Odometer Gears - WELCOME




Steering Wheel Removal


Fairly simple task. You need to determine if you have a tapered allen head bolt or a hex nut holding the steering wheel on.
Some of these have been known to be VERY TIGHT due to the torque used and/or thread locker.
If it seems too tight a little heat can be applied to the head of the bolt to loosen up the thread lock.
When I loosened mine, steering turned all the way to the left with the steering UNLOCKED.
Make sure you mark or scribe the position of the steering on the shaft before removing.





















Replacement Hex Screw P/N 1269900312




I had replaced my steering wheel so my current steering wheel removal was a little easier.










Moderator Edit for airbag equipped 107s:
2) Any tips or instructions on how to pull the air bag, I need to access the odometer gears.

KCM said:
First disconnect the battery cable. Then remove the right side front carpet. There is a large plastic panel against the firewall. Remove the four fasteners and remove the panel. There will be a connector with a red top for the air bag. Unplug.

To remove the air bag, you will need the appropriately sized torx bit to remove the two screws on the back side of the steering wheel. Don't remember off-hand what size torx you need, but it is readily available at any parts store. Once the screws are loosened, lift off the bag and disconnect the push-on connector.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #2
Gauge Cluster Removal


Once the steering wheel is removed, the cluster is easy. It is friction mounted. In other words, it is just shoved in being held by a rubber gasket.
The cluster can be pushed out from behind or pulled out using home made hooks or the correct MB tool part number 140 589 02 33 00.
It needs to be pulled out evenly.






















Once the cluster is extracted, the electrcal harness, vacuum line and, for some, the speedo cable and oil line need to be disconnected with care. Remember..........there are many old plastic connectors and solder joints. Work everything off slowly. UNDER NO CIRCUMSTANCES should the engine be started while the oil line is disconnected. Seems obvious but others have forgotten this tidbit and the resulting oil bath was the stuff of legend.

In addition to the above, I also had an additional ground wire from the cluster to the chassis which has a spade connector to allow for easy removal.



















 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #3
Odometer Gear Removal



Once the gauge cluster is removed, find a clean spot to work. I used the kitchen table.
I put a towel down on my work surface so that parts wouldn't be bouncing or rolling off.
Four screws holding the speedo unit to the cluster need to be removed and then the speedo can be carefully removed from the cluster.










The cover has 4 slotted screws that need to be removed to expose the inner guts of the speedo. Once the cover is off you can: A) remove the four rubber bushings or B) let them fall off on their own and roll under the table.
Choose A










Two small slotted screws hold the odometer cover on. Remove these and be careful not to drop them.






Remove the gears one by one.



















 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #4 (Edited)
Here is the culprit.



See the tooth that is missing?






The OEM gear on the motor drive shaft is in two pieces.
The plastic gear itself and the brass bushing it is mounted on. The gear can be cut or lightly pried off. It shouldn't be hard as the plastic is probably mush by now.
The brass bushing can be removed using side cutters across the diameter. A firm squeeze should cut it in half which will allow it to slide off the shaft.
DO NOT PRY THE BUSHING OFF. Damage to the electric motor may occur.











You now need to confirm the tooth count on the three gears you need to replace.
E1 should be 12 teeth.
E2 should be 48 X 12
E3 should be 48 X ??>>>>>>>>this is the important tooth count. Could be 12, 13, 15, 16, 17 or 18 teeth. I found it hard to count due to shitty eyesight so I used a black felt pen and blackened the small gear face to allow for some contrast.
Others have scanned the gear and blown up the picture.








I bought the gears from these guys. Helpful, friendly and fast. $69.00 USD at my door.

Odometer Gears - WELCOME


Another supplier used by 107 members with success:

Odometer gears (mix and match)





Installing Odometer Gears



Prior to installing the new gears, make sure that the odometer gear area is free and clear from any broken gears or other debris. I used compressed air to blow it out.
DO NOT LUBE NEW GEARS.
There is no requirement for it.
Install the gears in reverse order of removal checking to see that everything spins after each gear is installed.
The small 12 tooth gear is press fit on the motor shaft. Look at the gear closely....one face has a bigger hole than the other. Big hole on first. Support the opposite side of the motor with a flat surface when you push the gear on. It should bottom out............but not go to the bottom. Make sure the gear on the motor shaft lines up with the top most gear.










You can now re-assemble everything in reverse order of removal.
Ta Da!
You're done.







 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #5 (Edited)
GO ALL OUT!



While waiting for the mail to deliver my gears, I went all out and dis-assembled the whole cluster.
I cleaned everything, polished the glass and replaced the bulbs.
Nice.






























Before


Observe the orientation of the knobs if you dis-assemble everything.




For a Gauge Face upgrade discussion read THIS










 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #6
More all out.



























Before




After




 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #9
Took more time to put this thread together than to do the actual job.

Thanks for the assistance Dave and Tom.


Everyone....Feel free to add any info that is relevant.

Or hijack after post 10.
 

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Always Remembered RIP
1979 280sl 4 sp w/ac 1957 MGA 1998 volvo xc/70 2004 F150
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6,050 Posts
Nice job Nobby.
I thought I'd add one more bit about removing the clock. Remove the needles, faceplate and tach. Loosen the clock mounting screws but do not remove. There is a pin on the back of the clock that is soldered to the backplate. In your picture there is also a small brass ring that it is soldered to. (circled in red). Apply heat there and the clock will come loose but not fall because the screws are still attached.
 

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Always Remembered RIP
1973 450 SLC AMG, 1995 Chevy Tahoe
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3,381 Posts
So the price plus shipping is?:bowdown:
 

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Registered
1998 SL60 ///AMG, 1970 280SL Pagoda
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159 Posts
Thanks Nobby.

I actually spent yesterday removing the odometer gears from both of my 500SLs to identify how many teeth gear sets I needed to purchase to replace. I found on both the 82 and 86 500SLs that it was possible to remove the speedo unit from the cluster without removing the entire cluster. Although a little fiddly I reckoned that this would save me from re-connecting something in the wrong place or experiencing oil leaks etc.

I took my car to a local chap who I thought had a gas torch to heat up the steering wheel nut (mine both required a 10mm allen bolt). Unfortunately he didn't have a gas torch, just welding kit and was not prepared to use that given the amount of plastic around the bolt head. Instead he used a cold chisel and a hammer plus pentrating spray to break the steering wheel bolts loose by cutting into them at an angle in the anti-clockwise direction.

I will replace the bolts with new ones once the odometer gears arrive and I repeat the job to effect the repair. I am intending not to apply loctite to avoid problems in the future but may be swayed if other forum members consider I would be foolish not to use it.

Thanks to your posts I now know exactly wich bit I will cut away.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,223 Posts
Discussion Starter #15
So the price plus shipping is?:bowdown:
It was in my original draft. I've edited the post.
$69.00 USD at my door in 5 days.
 

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Registered
1986 560 SL
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7,306 Posts
It is a good opportunity to refresh the needle colors, which are likely yellow instead of the original orange.
A jar of model paint and a steady hand are all you need.
 

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Premium Member
2010 Mercury Milan Hybrid, 1993 BMW 325i convertible
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6,077 Posts
A jar of model paint and a steady hand are all you need.
I found having a paint brush in my steady hand made the application easier.
 

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Registered
85 380sl, 06 Jetta TDI, Wagon
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233 Posts
Great procedure Nobby, did this job myself last year (painted my needles @ the same time) I would also add to be careful tightning the screws when you are putting it all back together, old plastic strips easily. Oh and when it came to getting the steering wheel removed, I asked my shop to do it when they were doing other work on the car. Took it in with the center star removed, and it was done no charge, no problem. they just cracked the glue on the screw and left the rest for me. Now if I could just fix the clock....
 
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