Electronic Speedo

[Jon Green]

Hi,

 

I have a VDO speedo fitted to my 2b. Today was my first drive to a garage to get the headlight alighment and tracking sorted. I was brilliant, everything worked great except the speedo. It smoothly accelerate to 35 then struggled to go faster even though the car was doing 45mph.

 

I have a hall effect sensor mounted above the drive shaft to diff flange with 2 metal tangs on opposing bolt heads.

 

I have read some post that talk about magnets. I have none. Could this be a reason why my hall effect sensor fails to read more pulses than i get at 35mph?

 

How have you lot set it up.

 

P.s. SVA in 40 hours!

 

Cheers Jon

[Guest mike]

Hi Jon

 

I quite recently fitted an electronic speedo to my bike powered westfield, my sensor kit was the magnetic type, which ment fitting 4 magnets equally around the propshaft and part of the calibration calculation was times by the number of magnets(4). now i did knock one of the magnets out of position and it read alot slower than i was going, so could be something similar not picking up every pulse or calibration calculation is wrong.

 

Mike

[Guest Wick12]

If you have no magnets that will be the problem.

You need to stick 4 arround the prop flange with about 3 to 4 mm clearance from pickup I used 24 hour araldite on cleaned surfaces and smeared over faces of magnet to keep then sealed from water as the rust will eventualy blow them off.

there will be a calibration chart for the speedo which you will have to set 10 dip switches based on your diff ratio and the number of magnets per revolution.

 

Good luck

[Snapperpaul]

I bought a telemetrics speedo and was given a hall effect sensor. I didn't like the look of it so swapped it for a perception head with 4 magnets on the prop. Now the instuctions are s**t but it seems that the three types of sender are... driven by the gearbox but electric to the speedo. prop shaft 4 magnets and magnetic sensor which is what i have and is only 5mm in diameter or the hall effect which i think is much thicker and works off a slotted disc or tone wheel and has a formular of number off slots in disc x tyre revs/unit distance my instuctions for what their worth says front wheel mounted.

Hope that helps a bit..if you need a copy of what i have mail me. just read the posts before mine, they posted while i was typing and researching. Got my bits from Europa and the perception head that came with magnets ( looks like it fits most electric speedos) was made by Caerbont Automotive Ltd the part No. is EMP30-1KIT

[Guest Bob Rowell]

I have the VDO electronic speedo. Using four 'bits' of a broken fridge magnet stuck to the edge of the rear brake drum. I used the pick up from a bike speedo (Halfords), cos it's nice and small, mounted on a small bracket fitted to the shock lower mounting.

The way to get it accurate is to use the 'Autocalc' function of the speedo over a measured mile. I have done this with mine then checked it against my sat nav. It is absolutely spot on.

Let me know if you need any more details.

[Jon Green]

Thanks Guys

 

I'll stick a magnet on each of my tangs and see if there's any improvement.

 

Cheers for the advise!

 

Jon

[Guest trickytiker]

i use 2 magnets and a small house allarm reed switch cost less than a quid

my speed onow works pefect

 

best regards

kev