Fitting a wheel speed sensor on a 2002

[jimk]

I obtain road speed with 6 evenly spaced 1/4" pins mounted radially on one of the differential output flanges.  Pins are mounted in drilled and tapped holes on the flange.  Signal is from a Cherry Hall effect sensor that reports the the Haltech Elite ECU.

Differential is a Quaife and there is no one wheel spin.

Speed is calibrated using signal count per mile.  ECU calculates the transmission gear and displays both ground speed and gear on Haltech Dash.

[ray_]

On 8/30/2022 at 9:56 AM, jimk said:

I obtain road speed with 6 evenly spaced 1/4" pins mounted radially on one of the differential output flanges.  Pins are mounted in drilled and tapped holes on the flange.  Signal is from a Cherry Hall effect sensor that reports the the Haltech Elite ECU.

Differential is a Quaife and there is no one wheel spin.

Speed is calibrated using signal count per mile.  ECU calculates the transmission gear and displays both ground speed and gear on Haltech Dash.

I obtain road speed with torque!

 

 

  

Edited September 1, 2022 by ray_
wonky phone edit

[Lorin]

1 hour ago, ray_ said:

I obtain road speed with torque!

 

???️

 

Until the wheel falls off !

[ray_]

1 hour ago, Lorin said:

 

Until the wheel falls off !

I fixed my wheel torque problem thank you!

 

??

[tomorrowcalling]

Quote

I'd like it to be as accurate as possible, I like the thinking of bringing the studs back a bit. I also had the idea of drilling and tapping the hub with m5 bolts with really short heads. Maybe space them in between each stud? 

 

That's what I did for my 2002 rally car - works great

[sczapiga]

Ok, thank you for all the ideas. I appreciate it and love that about the 2002 community. 
 

I have decided to drill 4 holes in the rotor and tap them for 6mm bolts that will sit just inside of the braking surface. There’s 7mm of clearance to the spindle and the bolt heads are 5mm. The two mounting tabs across from the caliper will hold a aluminum bracket that holds the sensor. 
 

There’s a cool video of Don Barrow installing a Brantz computer with a wheel sensor on a 2002 but it has ti struts that have a different rotor mounting setup. I’ll post more as I finish the install but here’s a few photos. 

[Tommy]

Your solution looks simple and solid. Be sure to fix the bolts so that they won't back out and kill the sensor. Maybe couple of hammer blows on the tips that come through.

[TobyB]

I would hesitate to drill holes in a rotor, if the car's to be used with heavy braking.

 

Especially right there.

 

That's a thin section, to keep heat out of the hat, and putting 4 stress raisers there would 

make me...  be afraid to brake hard. 

I've seen what happens when one front brake works-

and the other does not.  

I've also seen a LOT of cracked rotors- and I try to keep mine from doing so.

 

As to tire slip affecting accuracy, I would posit that with a 2002 in 'vintage' trim, it's

far easier to lock a front wheel than it is to break the rear loose, lap after lap.

And while there will be a low percentage of rev gain under acceleration, there will

be a higher percentage of rev loss under braking.  Modern cars have wheel speed sensors

on all 4, but BMW uses the right rear sensor alone to determine car speed.  I'd just

measure the driveshaft stud heads and be done with it- either off the diff input OR output.

 

Quote

Differential is a Quaife and there is no one wheel spin.

...until one wheel lifts... Mine's welded, and there is no comfortable cornering in the pits!!!

 

t

couldn't justify the cost of a real LSD when the welded was already paid for...

[Tommy]

Toby has a point. I haven't seen rotors fail, but I haven't seen stock brakes run hard.

[Son of Marty]

1 hour ago, TobyB said:

As to tire slip affecting accuracy, I would posit that with a 2002 in 'vintage' trim, it's

far easier to lock a front wheel than it is to break the rear loose, lap after lap.

Assuming you're on pavement not dirt, gravel or snow?.

[tzei]

Glue magnet(s) and use reed relay. Has been done and works.

[TobyB]

I love the glue answer.  JB Weld, just because the 'iron' filler looks so cool when you use it with magnets.

 

Point taken about the on/ off tarmac!  Gravel's meant to be driven on sideways...

 

t

 

[sczapiga]

17 minutes ago, TobyB said:

I love the glue answer.  JB Weld, just because the 'iron' filler looks so cool when you use it with magnets.

 

Point taken about the on/ off tarmac!  Gravel's meant to be driven on sideways...

 

t

 

I agree about gluing the magnets on. I think I’ll get the other type sensor and some magnets to try. I already drilled the rotor and mounted it all up so I’ll use it this way to get it all setup and learn the system. But the idea of a railed rotor is scary so I’ll go the glued magnet direction. Thanks for the suggestions and inputs. 
 

Here’s some photos of what I ended up with. 

[Son of Marty]

34 minutes ago, TobyB said:

Point taken about the on/ off tarmac!  Gravel's meant to be driven on sideways...

All hail the Dukes of Hazzard.

[uai]

the thing in the speedo cable works really and doesn't need anything glueing or drilling