Board logo

Speedo
sammini7 - 4/12/19 at 10:58 AM

Hi Guys,

Whats the best way to get a speed reading utilising a sensor, drive shaft or wheel hub?

Any advise would be a great help

nick205 - 4/12/19 at 12:18 PM

What sort of sensor is it?

On my MK Indy I glued the small magnet to the prop shaft and made a braket across the prop shaft tunnel to hold the sensor in line with and above the rotating magnet. Each time the magnet passed the sensor it sent a signal to the speedo. I then followed the speedo manufacturers instructions to calibrate the speedo to read the correct speed per signal pulse. Pretty simple to do - more fiddly fitting the speedo into the dashboard really.

Angel Acevedo - 4/12/19 at 04:45 PM

Depends on your setup.
If you already have ABS equipped hubs, you could use ABS ring and Sensor for speedo.
To use the propshaft, remember to install where movement is at a minimum...
That is, if you have live axle, use the foremost part of the Propshaft.
Also, there is a thread where they used the bolts on a CV joint as triggers.
HTH

Oddified - 4/12/19 at 10:59 PM

I've used the unused abs ring on one front hub on my current fun car and it works very well. Some have a lot of teeth though (60 or so..)and you may need to machine (evenly) a few off for many electronic speedo's to work at all speeds.

Ian

nick205 - 5/12/19 at 08:56 AM

quote:
Originally posted by Angel Acevedo
To use the propshaft, remember to install where movement is at a minimum...
That is, if you have live axle, use the foremost part of the Propshaft.



Good point.

My MK Indy was IRS using a Ford Sierra diff bolted into the chassis so the diff didn't move. My speedo magnet was bonded to the prop shaft just before the prop went into the diff so the prop wasn't moving up/down, left/right either. The sensor bracket was fixed across the prop shaft tunnel with the sensor fixed into the bracket (not moving).

If I'd been building a live axle car then I'd have used the same arrangement, but at the front of the prop shaft where it wouldn't have moved like the rear would have.

sammini7 - 10/12/19 at 07:23 AM

Thanks guys