STD
Rev counter picku - Printable Version

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Rev counter picku - STDGer - 06-25-2016

Cheers mates, now i ve build a w202 om 605 smoker with mechanical pump and He351w and swapped the 722.6 to 716.657. The speedo works fantastic, but my rev counter does nothing.

Ive read that the 605/6 get the revs by the flywheel, but that's what changes too.

So how could i get the rev counter work again?

Greetings from germany.
Maurice

RE: Rev counter picku - Hario' - 06-26-2016

w202/605 tack picks up 5 tags from the back side (engine side) of the flywheel. Sensor is right hand side of the flywheel housing, half way down.

Your manual flywheel obviously doesn't have the tags. Perhaps get a flywheel from a manual w202/605? Or weld on the 5 tags..
?

RE: Rev counter picku - STDGer - 06-26-2016

Shit, no other Way to get the counter working? The car is running so good, would be my last opinion to get the tranny out again.Sad

Do u think it's possible to strip the sensor from W204 in?

Or get a Signal from the Generator?

Greetings Maurice

RE: Rev counter picku - Petar - 06-26-2016

I can think of a couple of solutions:
1. Install a trigger wheel on the front pulley, just like on those gasser megasquirt conversions.
2. Use the sensor that reads the ring gear teeth, feed the signal to a microcontroller which would convert the frequency so that rpm is correct. Ring gear has 144 teeth. You would have to drill a new hole for the sensor.
3. Use a sensor mounted on the front pulley, reading the single tab there. Again would need a microcontroller to convert the frequency of the pulses.
4. Remove flywheel and weld tabs.

I'm curious if the AC works with no rpm signal ??

RE: Rev counter picku - STDGer - 06-28-2016

Thanks petar,

The ac is out, was not much room for ic.

Evrywhere in the net i read stick a wire to conect w on Dynamo and stick it with a Poti direkt Into the counter.

Does that really work??

Do u know where the OEM sensor goes to? Tach or to ecu?

RE: Rev counter picku - Evgeniy1987 - 06-28-2016

I would say ECU, as 144 teeth would be nonsense for the tach only Smile and, the ECU also needs RPM signal, because of reasons.. and there is no other place to pick it up?

RE: Rev counter picku - Petar - 06-28-2016

The 144 teeth are actually teeth on the starter ring gear, that's why there's a lot of them  Big Grin

Stock C250 uses 5 tabs welded to the flywheel, right in front of the ring gear
[Image: 13536106_1100213596717114_1937934420_n_zpspvmmikxo.jpg]

And the signal is read by the ECU... Which sends the speed signal via CAN to the instrument cluster... I'm not 100% sure it works that way but i think it is correct.

RE: Rev counter picku - bruno_pinho - 06-28-2016

off topic...

Where can I know more details of your projec?

RE: Rev counter picku - STDGer - 06-28-2016

Shit, dont want to stick the gearbox off for such a Little mistake.

Ive Seen some aftermarket counter on ebay, Most of them should work with plug w on the Dynamo. They have a Poti inside to find the right point of Signal from the Dynamo. Someone USE such a counter and could say what Poti is inside?

From my Std beginning Ive Got 2 Potis for the resistor mod. 1 with 20 k 1 with 5 k. Would be nice if one of the electric junks knows something ( i hate wires Big Grin)

Bruno, sorry man, till now i had no time to get an own topic. A year ago i liked to Start a 602 building on my old 124 but skipd it of rust
The 202 is in very good condition.

But i would answear at all questions u have

Maurice

RE: Rev counter picku - maxypriest - 07-04-2016

(06-28-2016, 07:15 AM)STDGer Shit, dont want to stick the gearbox off for such a Little mistake.

Ive Seen some aftermarket counter on ebay, Most of them should work with plug w on the Dynamo.  They have a Poti inside to find the right point of Signal from the Dynamo. Someone USE such a counter and could say what Poti is inside?

From my Std beginning Ive Got 2 Potis for the resistor mod. 1 with 20 k 1 with 5 k. Would be nice if one of the electric junks knows something ( i hate wires Big Grin)

Bruno, sorry man, till now i had no time to get an own topic. A year ago i liked to Start a 602 building on my old 124 but skipd it of rust
The 202 is in very good condition.

But i would answear at all questions u have

Maurice
I got the tach working on my w124 by fitting an alternator with a W wire. This is connected to a Dakota digital box and the output is wired directly to the back of the tacho via the old loom.

The car was originally Petrol K-Jetronic.

The tach works perfectly and is adjustable.

I had a tooth counter but could not get it to work. I believe you can retro fit a ‘w’ output to any alternator, or just get another from a breakers that does.

RE: Rev counter picku - STDGer - 07-07-2016

Thanks for that Info, could u say the full Name of this Box or where to buy one?

Greetings Maurice

RE: Rev counter picku - STDGer - 07-19-2016

Hi, get it working.

Modified my valeo flywheel with 5 tags, and Got 4 kg off.

Calibrated it by myself in help with Evgeniy1987 and swatmugga.

Drivin now the valeo clutch, really nice and smooth,  not a comparison to my sinter clutch.