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how accurate?
jabbahutt - 7/5/08 at 11:03 AM

Morning all

Well seeing the weather's nice tonight I'm going to try and strike a few jobs off the old to do list.

I'm going to Araldite the speedo sender magnets to the prop shaft and as the pick up is nearer the front of the car than the rear I can't use the ususal reference points such as diff bolt heads etc with any accuracy.

I'm going to try and rotate the prop so the bolt heads one at a time are at the top by eye and then try and put the magnet on the shaft in line with the bolt again by eye and repeat 4 times

If I'm slightly out with the magnets and they're not exactly 90 degrees apart will it significantly affect the speedo accuracy? as won't the number of times the magnets pass in a set time/distance be the same number?

Sorry for the long post just wanted to give as much info as possible.

Cheers for any assistance
Nigel

nick205 - 7/5/08 at 11:11 AM

Should be absolutely fine to do this by eye.

One thing to consider though is the distance between the pickup and the magnets (most require quite a small gap to pick up effectively) and any possoible movement of the prop when rotating. You don't want to knock your magnets off or smash the pickup!

Mr Whippy - 7/5/08 at 11:15 AM

if the magnet were well out, would the speedo not bob up and down?

02GF74 - 7/5/08 at 11:22 AM

quote:
Originally posted by Mr Whippy
if the magnet were well out, would the speedo not bob up and down?


good point but that sould happen. this variation should be "damped" out by the sample rate of the speedo - in effect averaging in out.

it may happen at very slow walking speeds but if your speedo is like my racetech; nothin much happens below 5 mph and the dial is not graduated below 10 mph.

i..e. do the spacing as you evenly can and don't worry about it.

mike smith1 - 7/5/08 at 12:59 PM

make sure you use a tube of new araldite and make sure you give it plenty of time to harden of before testing! i would also recommend wrapping the magnets in tape as well, because eventually they decide they've had enough of spinning around like mad and decide they're off!!

Mike

jabbahutt - 7/5/08 at 02:09 PM

is there a specific type of Araldite or will any do? The stuff I have comes in the twin syringe type thing so both parts come out in equal measure. Is this any good or do I need something else?

Cheers
Nigel

nick205 - 7/5/08 at 02:27 PM

quote:
Originally posted by jabbahutt
is there a specific type of Araldite or will any do? The stuff I have comes in the twin syringe type thing so both parts come out in equal measure. Is this any good or do I need something else?

Cheers
Nigel


My magnets have done nearly 3k miles held on with the exact same stuff

Mr Whippy - 7/5/08 at 02:35 PM

Surely if fitted to the front wheels the forces on the glue will be minimal due to the magnets being force into the wheel.