Hi all,

I need a new speedo for my 3.46 diff S124 230TE (UK model) and it's proving very hard to find one with the ASD warning triange as they weren't often specced on the 4-cylinder cars, and the original part isn't available anymore. I've found one new that is for a 230CE but the diff ratio for that is 3.27 ... does anyone know how bad the speedo error would be if I fitted the one for the coupe in the wagon?

Cheers.

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1993 320TE M104
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past:

1983 230E W123 M102
1994 E300D S124 OM606 (x2)
1967 250SE W108 M129
1972 280se 3.5 W108 M116
1980 280SE W116 M110
1980 350SE W116 M116
1992 300E W124 M103
1994 E280 W124 M104
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"music and women I cannot but give way to, whatever my business" -Pepys

Looks pretty close. 2 or 3 mph? I'd use it.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

346/327= 1.058, so your speedometer will read 5.8 percent low at all speeds assuming the original setup was pretty close to right on.

Duke

Actually, a speed head calibrated for a 3.27 final drive will read high when driven by a 3.46 final.

You are correct!

Say tire revs/mile are 850, then the revs at 60 MPH in a direct drive gear = 850(3.46)=2941

With a 3.27 axle revs at 60 = 850 (3.27) = 2780, and if the speedo gearing is set up for a 3.27 axle the speedo will read 60 at 2780 regardless of the installed axle ratio.

So with an installed 3.46 axle and the speedo gearing set up to read 2780 at 60, actual speed at 2760 is 2780/2941(60) = 56.7, so the speedometer is reading 60/56.7 = 1.058, which is about six percent high, and this percent error is constant over the entire speed range.

Duke