Adhesive Advice Needed

[Downeaster]

Working on an ATV for a neighbor kid.

He bought a digital speedo/tach for it which is actually pretty cool. The speedo part uses a neodymium magnet on the wheel to trigger a sensor. You get to program the unit to calibrate the speedo by figuring the diameter of the rim (I assume).

Problem is, the rims are aluminum.

So the question is, what adhesive would one use to have a reasonable chance of a small magnet staying on the rim under ATV conditions?

Alternatively, if that's too much to ask (and I suspect it may well be...) what other methods of attachment occur to you?

 

[Beags64]

Perhaps if you could break the tire down would there be room to epoxy the magnet somewhere on the horizontal flat inside the rim? Not sure what the magnet/sensor requirement needs to be. Guess it would also depend on how the sensor mounts. Just a thought.

 

[xjwmx]

Maybe if you melt the lead off a balancing weight it's steel underneath.

 

[gggGary]

AFAIK you can mount the magnet up by the axle get it away from alot of the abuse I like 2 part flexable bumper epoxy. tough'r n rat snot otherwise The better formula of JB weld. can you find a spot to drill a hole the size of the magnet, even a little bit recessed will really help hold it in place

 

[Downeaster]

All good suggestions. I'll let you know which way I jump and how it works out. Thanks!

 

[Jim]

can you find a spot to drill a hole the size of the magnet, even a little bit recessed will really help hold it in place

That would probably be your best bet in my opinion. Even JB Weld would be iffy with a kid on an ATV

 

[MaxPete]

I was going to suggest a small depression drilled into the rim - set the magnet in and glue it with JB Weld and then peen the aluminium edges over to help retain it.

On my ST1300, the speed sensors (I guess they are actually ABS sensors) are mounted up on or near the brake rotors. That way the centripetal forces are reduced (closer to the centre of rotation) and it is out of the way of mud/rocks etc.

Because it’s an ATV, I sure wouldn’t worry too much about the balance issues related to attaching a weight to the wheel. Besides, if you place it closer to the centre, any out-of-balance effects will be greatly reduced.

 

[Downeaster]

I was going to suggest a small depression drilled into the rim - set the magnet in and glue it with JB Weld and then peen the aluminium edges over to help retain it.

On my ST1300, the speed sensors (I guess they are actually ABS sensors) are mounted up on or near the brake rotors. That way the centripetal forces are reduced (closer to the centre of rotation) and it is out of the way of mud/rocks etc.

Because it’s an ATV, I sure wouldn’t worry too much about the balance issues related to attaching a weight to the wheel. Besides, if you place it closer to the centre, any out-of-balance effects will be greatly reduced.

I'll look again before I finalize things, but with the disc brake rotor and caliper and their size in relation to the wheel, I don't think any place but the bead flange of the rim is an option. I do like the idea of putting a divot in the rim and gluing the magnet there. Should be doable as the magnet is only about 3/8" in diameter.

 

[Jim]

but with the disc brake rotor and caliper and their size in relation to the wheel

Here's a thought DE, drill a hole in the disc and press the magnet into that, then make a mount for the the sensor that can attach to the caliper mount.

 

[Downeaster]

Pretty sure the magnet is thicker than the rotor and won't clear the calipers, but I'll look at that as an option.

 

[grizld1]

Years ago I had to mount a sensor magnet for a Veypor data logger; drilled a shallow mounting hole the same depth and diameter as the magnet in the head of a steel sprocket bolt, did a test fit with no adhesive, and couldn't get the magnet back out. It never did come out. That rascal stuck like, uh, glue.

 

[gggGary]

griz; I like that one!

 

[mrtwowheel]

I know it's an ATV, but that double stick tape, like on the stick on wheel weights, is some durable stuff. 3M brand in the hardware section at Walmart.

Scott

 

[MaxPete]

The only fly in the ointment about it sticking from magnetic force is that (I think) the wheels are aluminium and so not magnetic.

 

[grizld1]

Uh, I'd guess that brake rotor bolts and sprocket bolts are steel, Pete. Might have to replace an Allen or button head fastener with a hex head and get creative in mounting the pickup. Digital speedos with Hall effect sensors are usually programmable for a wide range of rolling circumference, so mounting the magnet inboard of the rim shouldn't present a problem.

 

[Downeaster]

Decided to drill a little divot in the bead flange just big enough and deep enough to accept about half the depth of the magnet and epoxied it in with JB Weld. Between the mechanical and epoxy connection, I expect it will be good to go.

 

[Iowa Mark]

I'm still trying to decide just how accurate all this is going to be? With the magnet on the constantly moving target, the wheel bouncing up and down, and the receiver/transmitter on a fixed point on the body or frame, those two points are always in a different spot in the rotation.
compared to each other. Maybe its one of those + or - 25% kind gadgets?

 

[Max Midnight]

If it has disc brakes then I'd use one of these and you can use the caliper mounting bolt(s) to support a bracket for the pick-up.

 

[Downeaster]

Haven't decided yet where to mount the pickup, but it will either be on the A-arm or the caliper/caliper mount. Either way, it will be static in relation to the wheel.

 

[Downeaster]

Sensor/Pickup mounted on the rotor dust shield.

Wheel mounted showing proximity of sensor to magnet.

Now all I have to do is figure out how to calibrate the thing to the wheel diameter. Neither line of the Chinglish instructions mention that other than "match the frequency setting to the speed accumulation".