I filled up with fuel again today with B20 and checked my mileage again. 21.8 MPG

After a quick ride with my GPS (again) I found that 10 miles traveled according to the GPS is only 8 miles on the odometer in the car! That is a massive difference. This would mean my actual fuel economy is 26MPG which is what I was expecting when I bought the car.

My first thought was that at some point someone swapped rear ends. But, I just went out and looked at it. The little tab off to the drivers side says 2:88. So, that is the right rear for a 1985. So is it possible that someone put a cluster from a car with a 3:07 in there? Or would it be more related to the transmission?

The weird thing is that the speedometer is pretty accurate. On the GPS an indicated 60 MPH is 61 on the cluster. At 70 MPH on the GPS the cluster is showing 69 MPH.

RPM's @ 60 MPH are 2,600. RPM's @ 70 MPH are 3,100.

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AJ

1985 300D (SOLD)

One of the gears in your odometer has started slipping. It is usually the main drive gear for the whole assembly. The two fixes I know of are to remove the gear and scuff up the bar it is installed on so that there is more friction, or judicously place superglue where the gear meets the shaft. I have not tried the former, but got over 150k of troublefree service after trying the latter.

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1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

Yeah, shadetree may be right. My tripmeter started hanging up at 9.9 or 29.9 or similar .9 reading because the gear was slipping on the brass pin inside the speedo... Look at the DIY article at Dieselgiant I think, it was helpful to me. You just have to be careful and patient when doing that kind of work. I did it the hard way disassembling the whole thing, but I would try shadetree's easy fix first.

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83 300TD 219K HOMER

Everything is still working. The ODO is just 20% off. The speedometer is right on the money for the most part.

I did some more searching on what you have described. Do I need to score the shaft just in the pot metal gear area or the pot metal and brass gear areas?

I found a site that describes a fix for a broken ODO. But that is not the case here. It still works. I need to KNOW which gear to fix if there is indeed a problem.

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AJ

1985 300D (SOLD)

So, It could be either of gears? Is one more likely to slip than the other?

Shadetree mentions the main gear. Is this the brass gear?

Over at DieselGiant they do a fix on the pot metal gear. But their odometer was completely inop.

I have had expierence with other odometers (Volvo). I just don't want to screw anything up.

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AJ

1985 300D (SOLD)

Ok, I have this thing out and I am looking at it.

Both the brass gear and pot metal gear are on the shaft pretty tight. I cannot budge either of them. Even prying with a screwdriver will not move them. Also, the plastic gears are in great shape. Nothing is broken.

It looks like that at some point someone replaced the back of the speedo head or did this repair before.

Is it possible that someone replace the back of the speedo head with one from a different car? I'm trying to decide what to do next.

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AJ

1985 300D (SOLD)

The correct 85 speedometer should have a part# at the bottom of the face
MB# 1235422757.
the brass gear has 15 teeth.

I have one in front of me too. but not apart.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Thank you for the help.

The # you mentioned for the odometer is correct. It does say MB# 1235422757 on the face. However the brass gear on this one has 18 teeth.

I think I need to re-name this thread "Cluster Bomb"! I'm pretty close to lighting the fuse.

What do you think? Someone did a swap?

If I know that a 15 tooth brass gear will fix the problem... I will order it. I just need to know.

Here is what I got. Sorry for the bad pictures. It is late and I am tired:

Numbers



Teeth



I'm tired

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AJ

1985 300D (SOLD)

I actually have two 85 spedo`s, and both have 15 teeth. the white worm gear that drives it has 9 teeth or 10 depending how I look at it as mine has.

the needle can be popped off with 2 spoons. place some tape on them so not to scratch the face, and pry up. remove the 2 srews and the face comes off. makes it easier to work on.

your pictures are great.
Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Sorry to create confusion with my "main gear" reference. It has been a few years since I was into a cluster. It would be nice if someone with a cluster for a 3.07 rear could count the teeth on their gear for confirmation, but it sounds like you may have found your problem.
Its nice that you have a brass gear. On my 126 that gear is made of soft plastic and is missing 3 teeth. I have worked on other vdo speedometers where the drive gear was plastic, they never seem to last.

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1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

I have a spedo off a 83 300D, assuming the diff that yr is a 3.:07. the brass gear has 21 teeth. the white worm gear has finner teeth that are closer together.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

So do you think it is safe to say that replacing the brass gear with a 15 tooth count gear would fix my problem? Does the speedo that has 15 tooth gear have the same # of gears on the plastic shaft as pictured above?

You say you have a speedo from a 2:88 car and 3:07 car. Are the pot metal gears in both speedo's the same?

I hate to spend $29 on a gear only to find out it will not work.

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AJ

1985 300D (SOLD)

I counted the pot metal gear (the one behind the brass gear) on the 83 and 85. they both have 20 teeth.

The white gear on mine looks just like yours when I line it up as you have your`s set. 9 teeth, and the other end has 15 teeth.

There is one more worm gear deeper inside that drives the one that drives the brass gear. I don`t know if that one is the same in all spedo`s.


when you are at a PNP grab some instrument clusters when you see them, usually I see them ripped apart for what ever reason with the face and needles bent. why people destroy them is beyond me. one of my 85`s was all bent up, but I wanted it for parts for mine if it decides to crap out. can`t have too many parts.

I think a whole cluster is $35.00.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Charlie,

It really sounds like all I need is that 15 tooth brass gear.

I have already ordered the 15 tooth gear from ODOgears.com. Not many salvage yards around here.

Is it possible to remove just the brass gear without sliding the whole rod out and removing the lead gear, etc....?

Thanks for taking the time to look at the above components!

AJ

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AJ

1985 300D (SOLD)

I finally got around to fixing this thing this morning. The gear I ordered from ODO gears was not the right type. You apparently cannot get the brass gear. So, I got a used speedo/odo from daw_two that has the 15 count brass tooth (for a 2:88 diff.) and that fixed the problem. Obviously at some point the speedo was swapped out with one from a different car with a different diff. ratio.

After a quick ride with the GPS both the speedo and odo are so close to what is indicated, it is not worth worrying about. Now I can check my mileage and figure my oil change intervals with out doing math.

Thanks again for the help Charlie!

If anyone needs a speedo/odo in good shape with the 18 tooth brass gear... Let me know... I have one available.

__________________
AJ

1985 300D (SOLD)