Guys,

I know this is out there, but humor me on your thoughts on this:

I have a 2017 Dyna FXDLS. Some of the specs for the discussion:

Stock rims and tires:
Front rim and tire: 19x2.5 - 100/90x19 - 26.09" Diameter
Rear rim and tire: 17x4.5 - 160/70x17 - 25.82" Diameter

Size rims and tires planned:
Front rim and tire: 17x3.5 - 120/70x17 - 23.61" Diameter
Rear rim and tire: 17x5.5 - 180/55x17 - 24.80" Diameter

While it is easy enough to swap tires and rims, I came upon the issue with ABS. After doing some research and talking to the dealer, the difference in diameter is going to throw the ABS off. As I understand it, the ABS electronic system is comparing the the speeds of the two wheels, and it determines if one tire is rolling faster than the other one, and modulates the brake pressure if one wheel locks up. The way the system determines the speed of the wheel is by spaced magnets in the wheel bearings, which the wheel sensor picks up. I did some additional research, and no one makes a wheel bearing with different spaced magnets or a modified sensor for the above planned wheel sizes. Until I discovered this.....

2019 Street Rod

Front tire: 120/70x17 - 23.61" Diameter
Rear tire: 160/60x17 - 24.56" Diameter

It uses the same wheel bearings, but a different wheel sensor and EHCU. I am thinking I can swap the wheel sensors (they only have 2 wires) only and I should be able to maintain my ABS with the new tire sizes. I can't see the EHCU being smart enough to tell the difference, as it is just reading the frequency of the magnetic pulses from the front and rear sensors and comparing them.

I understand I may need to modify the brackets holding the wheel sensors, but that is easy enough. The size difference between the 180/55 and 160/60 is small, and in speaking with the Harley tech before, small differences the ABS system can adjust to.

What do you guys think?

And before you ask, yes, I am modifying my Harley for track use, and want to put better tires on it and STILL keep ABS. I want my cake and to eat it too, lol.

I posted this also in the electrical section in case an Harley electrical engineer visits that section, hehe.

Thanks guys,

Dave

 

can't help you, sorry to say. but this thread is bookmarked for me, as i changed the stock front wheel 21 x 2.15 with scorcher tire to a 21 x 3.5 with night dragon, and lost the ABS

is there a table of wheel sensors for wheel diameters?