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Discussion Starter #1
I know you can get 2 different types of F28 gearbox, mechanical speedo and electric.
Do the electric ones have a wire coming out that connects to your dash then? or do you use the abs to give the dash its speed signal?
Are turbo speedos electronic? and would a set of V6 cavalier / calibra clocks work properly with the F28 as they are also electronic.

sorry for all the questions!

cheers.
 

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there are two types of system.

Mechanical - cable driven. The cable drives the speedo directly, and is then converted to an electronic signal for the ecu, trip comp etc.

Electronic - Uses the abs sensors to produce an electronic signal which the speedo reads.

Early turbo's had the cable driven system, 94 on had the electronic system. Mechanical speedo starts at 10mph, electronic speedo at 0. Not sure about the V6 clocks though.
 

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Discussion Starter #3
so theres no speedo connection coming out of the later type box's then, not sure how id get my speedo working then as I dont have ABS.
Can I connect an abs sensor directly to the speedo blue/red wire? without having an abs system?
 

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No, there's nothing on the gearbox for later models. Don't know much about the electronic system tbh. I think if you have an abs sensor, you can build a simple amplifier circuit so that the signal is strong enough for the speedo to read. Don't know which wire though. Think the circuit was on cavweb in the how2's somewhere.
 

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Phil349 said:
so theres no speedo connection coming out of the later type box's then, not sure how id get my speedo working then as I dont have ABS.
Can I connect an abs sensor directly to the speedo blue/red wire? without having an abs system?

As you don't have ABS you'll need to fit an ABS rear Hub, or front CV Joint and sensor.

Without an amplifier it will work from about 15-20 mph.

The amplifier reduces this to about 5mph, and also stops the ABS ECU throwing up a fault, where ABS is already fitted.

It's on my How Tos.
 

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Discussion Starter #6
cheers mark will try it I think.
What are the wires on an abs sensor as ive not seen one properly. is it just +12v, -12v and the output signal?

what combination of c1 and r1 values do you recommend, going off your curcuit diagram? and would think be accurate?
at the moment I am using a GTE 8V digi-dash transducer connected to a set of cavalier V6 clocks and it seems accurate below about 50mph but higher speeds over read. When doing 100mph the clocks say 110, and it gets worse the higher the speed.
 

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ABS sensor is a mini generator.

Ground one side, and signal the other.


resistor and cap values, whatever it says on the How To.

470nF and 1000 Ohm is what's in the wife's car I think.
 
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