G4x wrx11x speed input/output question

[SidewayzSkyvia]

Currently have a g4x in my 2009 Impreza. Making it into a drift car. Currently have 350z rear hubs, so no abs sensors there. Front angle kit will remove front abs sensors as there isn't provisions for them. I'm expecting this to render my speedometer useless. I am curious if anybody knows if there would be a way to regain the speedometer function by using something like a driveshaft tone wheel and sensor. Or would my best bet be to try to add sensors to the front? I'm not sure if the ecu sends speed to the cluster or if the cluster gets the signal from the abs module first then sends it to the ecu. 

 

Any help is greatly appreciated. 

 

Thanks. 

[Adamw]

The ABS unit sends all 4 wheel speeds and and a calculated averaged/filtered wheel speed (front I think) signal onto the bus, the speedo uses the averaged one as far as I could tell.  If you have removed the ABS unit then you could try wiring ecu CAN 1 to the vehicle bus and we coulkd send out a replacement signal for the missing ABS.  There are quite a few error checking type strategies in the ABS CAN though so its hard to know how closely it will need to be replicated for the speedo to be happy.    

[SidewayzSkyvia]

I still have the abs unit in the car. It just won't be getting any wheel speed Inputs. And I'm only worried about the Speedo working. If there are abs/track lights on that's fine with me. And I'm guessing I would just need to do a single digital speed input to the expansion header then we could try to use that over the can network? 

[Adamw]

No you wont be able to do that if it still has the ABS fitted.  The ABS ecu will already be sending out "0 wheel speed" on the ID's that the speedo is looking at, you cant have another device sending a different speed on the same ID.