Instrument cluster for 85 MB W123 same as an 83?
 

Hi there, anyone know if the instrument cluster for a 1985 300TD wagon (W123) would be the same as 83 f the same model? Im looking to buy a used one off someone but without seeing it I cant tell if it looks the same and would have all the same instrumentation connections.

Im switching the cluster from Miles to a metric cluster as I'm in Canada. I thought I would try and advance the kms to reflect the same milage as is recorded on the original odometer. Is there any simple way of moving numbers up about 100 000 kms? (i.e. hooking up a drill or electric motor to the cable that turns the odometer etc..)
Thanks

I thought 85s had a different rear end ratio?

-Jason

Not sure what that means exactly, but would it affect the odometer? I thought the reading came from the front wheels.

No the reading comes from the back of the transmission. Having a different rear end ratio changes how fast the drivesahft spins compared to the road sped.

-J

As noted above, it will not be compatible. Your speed reading and odometer will be off. You would have to get one from a 1985 model in order for it to work as a drop in replacement.

The mercedes transmission final drive is 1:1, except for the 5-spd manual which is an over drive.

But for all tense and purposes here, the W123 240D, 300D and 300TD final drive is 1:1. the spedo cable drive is connected to the transmission.
the spedo head has to be matched to the differential gearing

83 is a 3:07 Diff and 85 is 2:88.

The 83 US spect cars use a 123 542 18 57 spedo head. the 85 uses a 123 542 27 57. the # is at the bottom of the spedo face.
can`t help you with the canadian spedo.

To turn the spedo with a drill motor, you need to spin the cable to the left to advance the numbers.

Charlie

As above and the tach has a different pick up point, so just take the tach out of the '83 and put it in the cluster of the '85, you'll note different plugs on the back. Using your existing wiring.

I know the 83 gets it`s tach signal off the front crank.

The 84 & 85 get the tach signal off the rear of the eng. the adapter plate has a flat spot a cable with a sensor fits into. The sensor has a pin that picks up a signal off the flywheel.

I wasn`t aware the back of the tach it`s self, had a different plug from the wiring harness.

I`ll have to check in my stash of stuff, and look through my pile of instrument clusters for the difference.

Charlie

Sounds like there may be a bit of hope, The fellow who I was hoping to buy it from for $50 says you can get an adaptor to make up for the difference. Not sure how to go about that or what it would involve.

different tach

The 83 gets it`s tach signal off the front of the engine. the cable runs up to the L/F fender. the round plasic moduel about 2 1/2 t0 3 inches hi
is the tach amp. this is what gives the tach it`s signal.

the 84 & 85 get`s it tack pick signal off the flywheel.

the plug on the back of the tach for the 83 is a 2 pin plug, the 84 is 3. I don`t have a 85, but should be the same.

Charlie

There used to be / may still be speedo-cable adapters / calibrators for American cars but I'm not aware of any such devices for Mercedes.
I believe someone 'federalised' my '84 Euro NA 300TD with a turbo 300D speedometer, so both odometer and speedometer in my car now read way too fast. But I got lucky last summer at a local salvage yard and found the correct instrument cluster off an '84 Euro NA 300D. Hope it solves this problem.

Happy Motoring, Mark

There are speedometer ratio adapters that are installed on the cable. The box is based on percentage of error of actual and as shown.

http://www.peachparts.com/shopforum/...1&d=1259765304

http://www.peachparts.com/shopforum/...1&d=1259765318

Can be purchsed here.

http://www.nhspeedometer.com/

Or maybe here.

http://www.transmissioncenter.net/speedometer_calibration_______va.htm?gclid=CPqj2Of9t54CFR5HagodTxAKmQ#era



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