Speedo not working

[alickswud]

I have spent the last few days of my Xmas break fitting a new rear disc to my 796. Completed the job and have just been out on a shakedown run to find the Speedo is not working and the odometer is not going up.

Is this because the OE rear disc somehow activates the rear wheel speed sensor to create the feed for the speedo? This is one of the early non ABS versions.

Any one got an idea?

Many thanks

[Luddite]

The non-ABS 796 has a speedo sensor that operates from the rear disc. The disc itself has four dimples that are read by the sensor:

49240761A
https://i.postimg.cc/xThPXgpL/Photo-Note-s-l500-2-7255.jpg (https://postimages.org/)

The ABS 796, on the other hand, uses a similar disc but without dimples:

49210051A
https://i.postimg.cc/Nf54GZDg/s-l500-3.jpg (https://postimages.org/)

It sounds like, either you've got an ABS disc by mistake, or you disturbed the speed sensor when fitting the disc.

Did you fit a Ducati/Brembo disc or an aftermarket one such as EBC or Galfer?

[alickswud]

I fitted a cheapo wave disc as I'm light on the rear brake and didn't fancy the cost of an OEM one.

Are the dimples magnetic do you know?

Looks like I'll have to fork out for a proper replacement��

Unless any one has a part worn one looking for a home, I got an advisory on my MOT for mine, 29500 miles on the clock, (changed the fronts over two years ago).

Many thanks

[Luddite]

Are the dimples magnetic do you know?

The speedo pickup will be a hall effect sensor so the dimples would be magnetic.

If you can't find a second-hand disc on the forum, budget for about £40-£45 on eBay. https://www.ebay.co.uk/itm/Ducati-Monster-M-796-3-11-Brembo-Rear-Brake-disc-Bremsscheibe/322669630398 (just be sure you get the one with the dimples!).

[Capo]

They are not magnetic

[Luddite]

They are not magnetic

You're quite right, of course. I should have said 'ferric'. The important thing is it must be a material that will alter the magnetic field around the sensor as it passes by.