If any of you have ever tried to remove a brake rotor after having installed an after market speedo that uses magnets for the hall effect sensor,,, you know the pain of trying to get those little round devils out of the fastener head.
6mm socket head head cap screws are typical of rotor fasteners, and the magnet OD is just under 6mm so they fit really close leaving no room for even a thin dental pick, or sewing needle to get in there and "pick" it out.


Stronger magnet to remove does not work either, nor does compressed air....

What does work???? The one thing that excels at gluing your fingers together but never seems to be near as "super" of a glue as the name implies


ethyl-2-cyanoacrylate AKA Super Glue.
Clean the nice flat steel magnet, just a tiny drop of glue on a equally clean steel flat bit, say a small hex bit driver that was close at hand, the magnet even holds the two parts together for the 60 sec it takes the glue to cure.

And out it comes.


Magnet comes right off with a pair of pliers, and the dried glue with just a wipe of a bit of acetone on a rag.

I have almost zero luck with super glue, gluing things as the TV commercial advertise, but this time it actually worked.

 

That is a great "pro tip".

 

Great tip!

 

Instead of the rotor bolt heads, I machine a hi-strength magnet to fit and epoxy it into one of the small "webs" of the rotor carrier. You need to look closely in the pic with the OEM rotor, and the magnet on the EBC wave rotor (which I installed after putting over 100,000 miles on the OEM rotors!) is hidden behind the fork. I installed the magnets for my Sigma bicycle computer (good up to 180 mph) sensor, which I run for a second trip meter and speedo for my 98's gauges. Wireless BC usually don't work due to ignition coil field RF interference, hence the old tech hard-wired BC.

 

A nice option for those that can machine the material for sure..
But one other consideration, I prefer the higher sampling rate of more then one magnet if the unit in question allows for it.. the Koso gauges Ive been using lately do.

 

All the magnets I've machined (NdFeb, SmCo & Ferrite) are very brittle and if the tool is not sharp and you push too hard, whamo the magnet shatters. Also, inducing too much heat can reduce the magnet's properties, so a cutting/cooling fluid is a wise choice.

I understand how for a some speedos multiple magnets increases the sampling rate but for most BC it would double your speed. BTW, I started running a BC years before GPS was available (which have made them obsolete to an extent), and I've checked the BC's accuracy against two GPS simultaneously (and the speedo on my FJ-09) and found the BC to be extremely accurate up to about 110 mph. Whereas a GPS logs average & maximum speed, distance, trip time (versus rolling time on a BC) and even MPG, so does a BC (except for the MPG) in a lot more compact and relatively inexpensive package. However, cell phone GPS apps like Google maps and Waze do not, though I believe Copilot and another app that escapes me now, may.

 

I thought I read a post that said they could not see the magnet skokievtr made for his bike, though now I dont see the post ????

Anyway, here is a close up

 

Rever I believe is the other GPS app that logs most pertinent data and tracks routes traveled.

This photo shows the rather crude machining job I did on the magnet I installed in left EBC rotor, also held in with epoxy.