Speedometer way off - Page 2 - PeachParts Mercedes-Benz Forum

vstech · #16 12-26-2007, 01:38 PM

what car would a 3.48 rear be from? a 240D? a manual tranny car? all the turbo's from MB had the 3.07 rear except for the 85, which had the 2.88, and all vehicles built in 82 had the 85MPH speedo regardless of the tranny or rear ratio.

winmutt · #17 12-26-2007, 02:06 PM

My 84wagon has a 110mph speedo, did feds change rules between 82 and 84?

He needs to look at the diff and make sure its a 3.07 (it will be stamped on it iirc).

vstech · #18 12-26-2007, 02:19 PM

late 81, to early 83 all had 85MPH speedo's thank you very much jimmy carter...
and thank you very very much Mr. Reagan for fixing it.

Dewhite2485 · #19 12-26-2007, 09:46 PM

well looked at the number on the back of the diff and its a 3.07, turned the drive shaft and watched the tires to make sure some one hadnt changed out the gears and its for sure a 3.07 so Im back to stage 1 what in the world could be making it that far off ? the tires might do a couple mph at the most so im kinda at a loss

winmutt · #20 12-27-2007, 07:24 AM

Quote:

Originally Posted by Dewhite2485

well looked at the number on the back of the diff and its a 3.07, turned the drive shaft and watched the tires to make sure some one hadnt changed out the gears and its for sure a 3.07 so Im back to stage 1 what in the world could be making it that far off ? the tires might do a couple mph at the most so im kinda at a loss

Remember tires are a sliding scale, the faster you go the farther offset they are.

vstech · #21 12-27-2007, 09:14 AM

the 300 must have had a 240 speedo in it,... either that, or you mixed them up during your swap... as the 240 had anywhere from a 3.46 to a 3.69 rear depending on tranny.

Dewhite2485 · #22 12-27-2007, 01:27 PM

unless some one changed the speedo in the junk yard car before I got it I know it came from the 300D and it has a tach that the 240 didnt have also. Anyone with an 82 300D want to check there part number on the speedo face and see if it matches mine ?

dieseldiehard · #23 12-28-2007, 01:05 AM

better to look at the K factor on the rear of the instrument. VDO calibrates them to a factor that MB uses, its the "Konstant" or K factor.
I never wrote down the K factors over the years I've messed with VDO speedometers but that is the key thing a speedo shop uses. Not the faceplate p/n.
Are you aware that speedometers also age as the magnets lose some of their pull against the rotating drum inside the speedometer? Swapping in a used one may still leave you with an error as most old speedometers are off
If you like the speedometer and its got clean odometer wheels, I'd just carry it to a speedometer shop that knows what they are doing and let them cal it. Or leave the car off and they will nail it down to within 2% (as close as you can read the pointer)
BUT if you insist on using the faceplate# here's a thread on this subj.
Speedometer part #
I note that 123-542-03-67 isn't listed.
Also I suggest you use the search feature on this matter as there is lots of info already available

Dewhite2485 · #24 12-28-2007, 08:11 AM

I think that a speedo shop is probably the best thing for me to do, I hate to change the speedometer again this one only has 60K on it and is in great shape. Thank you for all your help on the subject it was driving me up the wall trying to figure out what was going on

t walgamuth · #25 12-28-2007, 08:19 AM

The 300d non turbo came with the 3:46 gear. Maybe someone put in a speedo from the 300d non turbo not knowing the difference. Did you check against the mile markers?

The hash marks on the speedo for maximum engine speed will tell the tale of which rear end they are for.

204ds all came with the 3:69 rear except the limos which were never brought here, or the cars equipped with the 15" wheels and tall suspension for extra ground clearance which came with the 3:92.

Tom W