Do they often do that? Speedo

[akakubi]

My speedo goes wacky above 85mph. I think the speed sensor at the rear wheel is getting confused. The speedo is very accurate below that threshold. Is there a standard fix (like the size of the gap between the wheel sensor and the hub)? I went by the book, but it does not seem to be correct...

[stevefoster]

Is this a standard speedo? The drive is from the gearbox if standard.

They can do whacky things. Not had mine on for quite a while (Sigma bike speedo).

Jason B (high miler) got some very odd / weird readings before going bike speedo I remember..

 

If yours is bike speedo then yes make sure you have the magnet close enough. I've only ever run on wheel rim and proximity once reasonable does not seem an issue.

 

Add lightness, says the man with a VX :-)

My 2002/2003 racing pics

here

General pics (mostly of 7's and cars).

here

 

Edited by - stevefoster on 14 Jul 2008 14:19:14

[akakubi]

Well, mine came that way stock, so I guess CC switched to bike-style sensors now. How much of a gap do you have? Mine is very small (1-2mm I think tops). Should it be further away of even closer?

[John Vine]

I had exactly this problem (although at running-in speeds -- on the way to SVA). Also, the odometer under-read by around 30% as well.

 

Jack up the rear, then check that the speed sensor illuminates every time one of the reluctor ring teeth passes by. I found the adjustment to be pretty critical as the ring didn't seem to be perfectly circular, and I ended up with a gap of 0.5mm (set with a feeler gauge) rather than the 1.0mm recommended by the Assembly Guide.

 

So far, the speedo seems reasonably accurate (compared to my GPS), although I think it may still be misbehaving at higher speeds.

 

JV

[akakubi]

Thanks, John. Will try that.

[John Vine]

Let us know how you get on, as I'm not sure I've completely fixed the problem.

 

JV

[akakubi]

Will do this weekend. Yesterday, when i drove, it seemed to go crazy sometimes from 65mph, sometimes after 70mph. At least it was accurate where the speed cameras were (fingers crossed 😬). I'll let you know.

[Colin S]

Had the same problem with mine at over 80mph. Adjusted the gap to about 0.5mm and all was well......so far anyway

 

Colin

[akakubi]

The problem is fixed. I adjusted the gap to within a 1/3mm and it is all sorted. Test-ran it to a ton and it worked like a swiss watch. 😬

[John Vine]

Glad to hear you've fixed the problem, akakubi. As I feared, mine still misbehaves at an indicated 75+, and the speedo stopped working entirely at 80-ish. I think I'll have to try reducing the gap a little more.

 

JV

[akakubi]

John,

 

I moved the sensor so close, the light barely passes through. I was afraid the teeth of the gear would touch the sensor if they were not all straight, but it worked just fine.

[John Vine]

Well, I've now reduced the gap to between 0.20 and 0.35mm (it varied because the toothed ring was not perfectly circular). The speedo now seems to work much better (although I've yet to try the upper ranges ), and the odometer is more accurate.

 

JV

[akakubi]

Glad to hear! I think you should be fine all the way "up" in the illegal ranges.