QUESTIONS: SPROCKET CHANGE & SPEEDO & WEATHERPROOF C

Message

Nooj · #16 Post by **Nooj** » Fri Sep 05, 2008 6:10 pm

Fausto wrote:
sabestian wrote:Confirmed. The sensor counts the rear brake disc bolts.
so don't go changing those for stainless.

How come my iron rotor doesn't confuse it then?

Fausto · #17 Post by **Fausto** » Fri Sep 05, 2008 6:42 pm

Nooj wrote:
Fausto wrote:
sabestian wrote:Confirmed. The sensor counts the rear brake disc bolts.
so don't go changing those for stainless.
How come my iron rotor doesn't confuse it then?

Good question.....don't know.....are the bolts proud of the disc and therefore within range of the sensor?

Falcopops · #18 Post by **Falcopops** » Sat Sep 06, 2008 12:54 pm

Nooj wrote:
Fausto wrote:
sabestian wrote:Confirmed. The sensor counts the rear brake disc bolts.
so don't go changing those for stainless.
How come my iron rotor doesn't confuse it then?

I reckon it's all to do with the pulse. The rotor is constantly moving past the sensor, but the bolts are once in a while so thy cause a blip that is translated into a speed reading. The sensor probably has a limited range and can't read the rotor.

Nooj · #19 Post by **Nooj** » Sat Sep 06, 2008 5:14 pm

So if I used titanium bolts that would bugger it up then.

Fausto · #20 Post by **Fausto** » Sat Sep 06, 2008 5:20 pm

'pends......

.....is titanium magnetic? I don't have any to test.

Actually - i probably already know this. Is it correct that Iron is the only magnetic metal and therefore only alloys of Iron should be ?

Sorry to turn this into a physics lesson

Nooj · #21 Post by **Nooj** » Sun Sep 07, 2008 8:34 am

Nickle and Cobalt are also magnetic. Lots of magnets for the speakers in guitar amps are made from Alnico, an alloy made from Aluminium, Nickle and Cobalt, hence the name.

Stainless steel is not very magnetic compared to 'normal' steel due to the higher amounts of Chrome in the mix, so my ductile iron rear brake rotor should have more influence over the speedo sensor than the stainless bolts holding it on.

Samray · #22 Post by **Samray** » Sun Sep 07, 2008 9:33 am

Good job you don't have ABS.

Falcopops · #23 Post by **Falcopops** » Sun Sep 07, 2008 12:06 pm

I'm sure I've read that Ti bolts can be a problem.

You sure your bolts are stainless?

If they are they must be giving enough of a pulse.

Doubt the rotor is even being read by the sensor, IIRC it needs to be pretty damn close to get a reading.

D-Rider · #24 Post by **D-Rider** » Sun Sep 07, 2008 10:16 pm

Yes, need to be close - detects change in reluctance.

Ti bolts are not a good idea if you want your speedo to work

Nooj · #25 Post by **Nooj** » Sun Sep 07, 2008 10:48 pm

Pretty sure they're stainless, they've not rusted like the Fazer ones anyway.

Samray · #26 Post by **Samray** » Sun Sep 07, 2008 11:02 pm

The lower the quality of stainless, the more magnetic it is, ... and even cheap 'brass' is magnetic.

Viking · #27 Post by **Viking** » Sun Sep 07, 2008 11:54 pm

Falcopops wrote:I reckon it's all to do with the pulse. The rotor is constantly moving past the sensor, but the bolts are once in a while so thy cause a blip that is translated into a speed reading. The sensor probably has a limited range and can't read the rotor.

Correct.

A magnetic sensor (also called a 'Hall Effect Sensor' ) detects a piece of magnetic or ferrous material (ie, an iron bolt) moving past a magnet by virtue of a generated electrical signal.

The brake rotor is a fixed distance away from the sensor and does not generate any inductive effects in the sensor.

Replace your brake rotor mounting bolts with something non-ferrous (eg: Titanium) and your speedo sensor stops working.

(Can you tell I'm really bloody bored at work this morning??

)

Nooj · #28 Post by **Nooj** » Mon Sep 08, 2008 10:00 am

Hmmm, there's a chalenge then. How to have titanium disk bolts AND a working speedo.

Tweaker · #29 Post by **Tweaker** » Mon Sep 08, 2008 1:57 pm

Nooj wrote:Hmmm, there's a chalenge then. How to have titanium disk bolts AND a working speedo.

Glue little magnets on the bolt heads

D-Rider · #30 Post by **D-Rider** » Mon Sep 08, 2008 3:00 pm

Tweaker wrote:
Nooj wrote:Hmmm, there's a chalenge then. How to have titanium disk bolts AND a working speedo.

Glue little magnets on the bolt heads

... or rusty bits of iron .... that will set your titanium bolts off a treat ....

(could be a good match for the bolts in those callipers you had on ebay

)