the tach is electric, not the spedo.. the W126 has the electric speedo

Advancing the odo
 

I think the safest way is to get an old odometer cable, chuck it in your drill and in the back of the odo and have at it.

I recommend some kind of a jig so you can walk away because I think it will take some time. The upside is that you don't have to take the little number wheels out. They are PITA to get back in and still have them change at the right time.

Going from a 3:58 to a 3:07 wil be a jump down from off line performance. a 2:88 will drop it a little more.

I have the 2:88 with the 4-spd manual, It isn`t all that bad. now if I had the 3:58 and going to a 2:88 I might feel different about it. MPG wise I would want the higher geared Diff. with the 4-spd I have been getting in the 27 to high 30`s. quite a jump from the automatic.

all depends what you want, performance or milage. also depends on the age group of who wants what. with fuel costs only to go higher, I prefere milage.

using a drill and a spedo cable to advance the spedo that many miles, will take some time. I used my miketa cordless, and I think it only turned it 45mph.
I have a spedo I have taken apart to see how it works down to just the main guts of it. the number assenbly. it looks like if the shaft that holds the 6 grey little cog wheels that keep the numbers lined up was pulled out, the numbers could be turned to where you want them, then the shaft and cogs replaced one at a time, and the end of the shaft peened again.

Charlie

^^that will take forever but thats the only way to do it.

Anyone got one with about 214K on it?

At 45 mph, 64,000 miles will take over 1400 hours. :eek:

There was a guy on this forum, Jason Schoenfeld I believe, that redid a speedo for me and set the numbers where they belonged. I'll see if I still have his contact info.

As a side note, how funny is it that MB diesel owners want to advance their odometers to read the true mileage instead of rolling them back (dishonestly) to try and increase the price of the car? :D

Found his e-mail. Email me and I will give it to you if you need it.

Easily, you can make it say (exactly) whatever you want if you take it apart and change the number positions....

2.88 Differential for sale on Ebay
 

Not my listing. But an FYI for those looking for a 2.88. There are two from the same seller on EBay.

http://cgi.ebay.com/ebaymotors/Mercedes-w123-refurbished-2-88-differential-300td_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c240Q3a1318Q7c301Q3a1Q7c293 Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem2c4f52b422QQitemZ190309381154QQptZMotorsQ5fCarQ5 fTruckQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/Mercedes-w123-refurbished-2-88-differential-300td_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c240Q3a1318Q7c301Q3a1Q7c293 Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem2c4f519649QQitemZ190309307977QQptZMotorsQ5fCarQ5 fTruckQ5fPartsQ5fAccessories




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Here is info I found on the forum a while ago, I think it was posted by ForcedInduction originally:

1976-1983 240D 3.69
1976-1981 300D/CD= 3.46
1978-1980 300TD=3.46
1981-1984 300TD=3.07
1982-1984 300D/CD=3.07
1978-1984 300SD=3.07
1985 300D/CD/TD/SD=2.88

The last link has a one day 25% off sale for a good deal at $168.75.

http://cgi.ebay.com/ebaymotors/Mercedes-w123-refurbished-2-88-differential-300td_W0QQitemZ190309307977QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item2c4f519649 &_trksid=p4506.c0.m245&_trkparms=65%3A12|39%3A1|72%3A1205|240%3A1318

79Mercy,

Better yet get a dremmel or some high speed rotary tool. I pegged the replacement speedo/odometer replacement for my 240D with one and it took about 10 minutes to get it where I wanted it. Just be careful going too high in RPMs on it, you'll know what feels right.

I still bit hesitant to make the swap. Will I really kill my acceleration??