stock gauges and EFI

[bs009]

So my car will be using the complete drivetrain out of a 98 Camaro with a 3800/T5 and I'm trying to find a way to make the stock speedometer and tachometer to work with these two.

From what I understand, the stock speedometer is cable driven, but inside the speedometer the cable rotation is converted to a 4,000 pulse per mile signal that it uses to determine the car's speed. Has anybody ever tried to intercept this signal and input your own from the EFI speed sensor?

Will the tachometer work with an EFI computer system? I've heard the tachometers have a 6 cyl/ 8 cyl switch on the back of them. Is there a setting that would be accurate at all?

I'd rather not buy aftermarket gauges if I can avoid it because all of the other gauges should play nice with this setup.

 

[ssn696]

Try a tailhousing from an earlier F-body with the mechanical sender. I think I have seen that the reluctor and speedo gear can be swapped by just pulling off a clip. Then, I have seen an in-line rotation sensor that threads in between the gear housing and speedo cable (may be aftermarket). Sorry, no exact details, but that seems like the right direction.

For more money, I have seen a speedo generator that spins the cable with a motor, driven by the speedo signal.

Others may have more accurate data.

 

[bs009]

ok, Thanks for the info.

I think I was having issues with my cables or something. One of them may have been binding or something. I'd like to dump the cable drive because of that, and so the PCM can read it. Worst case scenario is using my aeroforce to read vehicle speeds and engine rpm...

Any ideas on the tachometer signal? According to the FSM the ICM sends the tach signal straight to the gauge with the EFI system.