1983 300CD speedometer - PeachParts Mercedes-Benz Forum

rocky raccoon · #1 11-03-2011, 08:43 PM

Help me out here Gurus. I have a recently acquired (about 5 months) 1983 300CD and am working through a few problems. It shows promise of being a reliable and handsome daily driver. It looks good, runs good and I have found nothing I can't fix.

This car has an 85mph speedometer. When driving however, my innate velocity sensor tells me I am going faster than the speedometer indicates at any given speed.

Basic question is; Did these cars (1983 300CD) come with an 85mph speedo or did the P.O. change it out. Should it have a 100 or 120 mph speedo and am I doing 75 in a 55.

If it is so I am pissed and how many miles are really on this thing.

rscurtis · #2 11-03-2011, 08:50 PM

My first MB aquisition was a $500 '82 CD. It had the 85 MPH speedometer. My '83 sedan, built in Oct. of '82, has the 120 MPH speedo. if that answers your question. It would seem your speedometer may have been switched.

Yak · #3 11-03-2011, 10:29 PM

I sold my '83 300CD, but it had a 120 mph speedo.

p/n from the pics is (was) 123 542 18 57. It's visible on the front. You should be able to check the p/n on EPC. A replacement speedo should be easy to find from a JY, or I think vstech says he has a few clusters.

vstech · #4 11-03-2011, 10:43 PM

x3
83 and up had at least 120mph speedos...

ROLLGUY · #5 11-04-2011, 12:12 PM

Quote:

Originally Posted by vstech

x3
83 and up had at least 120mph speedos...

That would explain why my '82 300CD has an 85 MPH speedo. It even has a decal on the windshield just above the left dash speaker that has a warning about the 85 MPH max, and not to exceed that speed.

Air&Road · #6 11-04-2011, 12:31 PM

Also, the calibration for gear ratio is done in the speedometer as opposed to most cars that use a changable spur gear for adjustment. If it is reading incorrectly, it might have been replaced and be for the wrong gear ratio.

shadetree77 · #7 11-04-2011, 10:13 PM

on the w126 the 85mph and 120mph speedo's are interchangeable; i would assume the w123's are the same

vstech · #8 11-04-2011, 10:25 PM

Quote:

Originally Posted by shadetree77

on the w126 the 85mph and 120mph speedo's are interchangeable; i would assume the w123's are the same

not all 123's used the same rear end ratio...
85mph should have been from 80 - 82, the 80 and 81 diesel sedan speedometers were 3.47 I think, the 80-82 240D would have had a 3.69 ratio, and the 80-82 280e or ce would have had a 2.47 ratio... all would have had an 85mph speedo...
all diesel 126 speedo's up to 85 were 3.07 rear ratio...
the gassers were available in various ranges, from 2.24 - 2.65 I think...
anyway, not the same unless pulled from the same type car.

79Mercy · #9 11-04-2011, 11:31 PM

Quote:

Originally Posted by vstech

not all 123's used the same rear end ratio...
85mph should have been from 80 - 82, the 80 and 81 diesel sedan speedometers were 3.47 I think, the 80-82 240D would have had a 3.69 ratio, and the 80-82 280e or ce would have had a 2.47 ratio... all would have had an 85mph speedo...
all diesel 126 speedo's up to 85 were 3.07 rear ratio...
the gassers were available in various ranges, from 2.24 - 2.65 I think...
anyway, not the same unless pulled from the same type car.

correct except for

280E/CE/TE had 3.58 rear end
1977-1981 300D/TD/CD had 3.46 rear end

ROLLGUY · #10 11-06-2011, 06:33 PM

Quote:

Originally Posted by vstech

not all 123's used the same rear end ratio...
85mph should have been from 80 - 82, the 80 and 81 diesel sedan speedometers were 3.47 I think, the 80-82 240D would have had a 3.69 ratio, and the 80-82 280e or ce would have had a 2.47 ratio... all would have had an 85mph speedo...
all diesel 126 speedo's up to 85 were 3.07 rear ratio...
the gassers were available in various ranges, from 2.24 - 2.65 I think...
anyway, not the same unless pulled from the same type car.

That's interesting. I was told that ALL 123's had the same ratio. I thought that was wrong, as my '82 CD seems a lot quicker than my former '83 D. It would seem that in a drag race, the CD would get to 85MPH sooner than a D.

shadetree77 · #11 11-06-2011, 08:34 PM

yeah sorry i meant 300SD's

79Mercy · #12 11-06-2011, 10:00 PM

Quote:

Originally Posted by ROLLGUY

That's interesting. I was told that ALL 123's had the same ratio. I thought that was wrong, as my '82 CD seems a lot quicker than my former '83 D. It would seem that in a drag race, the CD would get to 85MPH sooner than a D.

a 82 CD and a 83D have the same rear end. 3.07