Speedometer Daisy Wheel

[StellaHong]

It's interesting seeing how many people are moving over to GPS setups now. Definitely saves a lot of the headache with mechanical sensors or worrying about matching up teeth on a trigger wheel!
Out of curiosity for anyone running the GPS route, how spot on do you find the speed readouts? I've been using a basic web tool called https://pocketspeedometer.com/ on my phone just to verify my dash readings against a clean GPS signal during calibration runs, and it seems surprisingly accurate.

[GDCobra]

Ive been using a GPS encoder into an ETB speedo for 2 years now. No problem with MOTs

Yeah, I wouldn't expect MoT to flag it up, don't really see how they'd know unless they put it on rollers or took it for  a test drive.  SVA presumably is a different matter.
In my daily driver I generally use the GPS speed readout on the sat' nav' in camera controller areas. It can be a bit frustrating when you're in a 20 mile stretch of roadworks on the motorway with the speed down to 50MPH and so many are running a 45 or so due to reading the speedo.

[gaxor]

Ive been using a GPS encoder into an ETB speedo for 2 years now. No problem with MOTs

[GDCobra]

ive just converted my hall effect sensor smiths speedo too gps.  bridgwater electronics ( lot cheaper than smiths ) had a lot of bother wither sensors

Are there any implications with GPS?  I'm assuming you couldn't do this prior to SVA but an MoT wouldn't pick it up so as long as accurate unlikely to be an issue.
I've been toying (for a while!) with making a motor drive for a mechanical speedo which could take its reading from either a gearbox pulse or GPS switchably then drive the speedo needle to the required speed.  Unfortunately other things keep getting in the way.

[gnc]

ive just converted my hall effect sensor smiths speedo too gps.  bridgwater electronics ( lot cheaper than smiths ) had a lot of bother wither sensors

[Tony]

Could you do a quick sketch with sizes of disc, holes etc and ask one of the online laser cutters to quote having one cut? Or order a dozen and put the rest on ebay.......

[Ian C]

Jim,

Yes think you are right about terminology, I had widened my search to include trigger wheel and was getting more hits but still unable to find a source to buy one.

You are also right re "bashing it flat", I did try to straighten it whilst it was still bolted between prop shaft and diff, obviously not very successfully - not the easiest place to reach!!.  As I would need to take the propshaft off to fit a new one it is just as easy to straighten the existing trigger wheel so that is now the plan.

Thanks to all who replied, take care,
Ian

[Happy Jim]

It's normally called a Trigger Wheel I think, however the hall sensor is just on/off so the size of the hole isn't critical - bash it flat and pop a new sensor on and you should be good.

Regards

Jim

[Ian C]

Is the wheel a unique part that is dedicated to your speedo setup ?
If so it would be obvious to just get a replacement or was it sourced from some thing like a normal abs wheel, then you
need to try and match one that suits or can be re-worked to suit your requirements .
Other thing would be to infill the damaged slot with either a braise / weld then drill and reshape, bit of a pain and
would be a lot easier to just be able to buy one .
Good luck .

Chris,

Thanks for the response, no it isn't.  When built the drive for the speedo came from speed sensor in the LT77 gearbox, when the LT77 was replaced with a Cosworth T5 gearbox I fitted the daisy wheel (slotted disc, encoder disc - still not sure what the correct name is!) between the prop shaft and the LSD.  This was done in 2018 and I can not find where I sourced the disc from, very frustrating.

Think I may be heading to try and repair - hammer flat as the problem is the distortion of the disc rather than hole size - the existing disc.

If anyone else has any potential sources I would be delighted to hear.

Take care,
Ian

[Ian C]

Hi,

ETB may be able to assist. They supply speedo and sensors etc...

https://www.etbinstruments.com/index.php?route=common/home

Thanks for the response, they have the sensors but don't appear (in common with all the other suppliers I have checked) to stock the disc that activates the Hall effect snesor.

Still looking!!

Ian

[Chris]

Is the wheel a unique part that is dedicated to your speedo setup ?
If so it would be obvious to just get a replacement or was it sourced from some thing like a normal abs wheel, then you
need to try and match one that suits or can be re-worked to suit your requirements .
Other thing would be to infill the damaged slot with either a braise / weld then drill and reshape, bit of a pain and
would be a lot easier to just be able to buy one .
Good luck .

[JING]

Hi,

ETB may be able to assist. They supply speedo and sensors etc...

https://www.etbinstruments.com/index.php?route=common/home

[Ian C]

Hi,

Having problems with sourcing the slotted disc (aka daisy wheel) that activates the speed sensor and wonder if any one has any ideas?

The problem started when the hall effect sensor became loose on the mounting that secured (or rather didn't secure it) to the differential.  The tip of the sensor made contact with the daisy wheel, that is bolted between the prop shaft and the input flange of the differential.  The sensor tip was sheared off and the daisy wheel disc was distorted and one of the holes enlarged (see pictures attached).

I have been searching for a replacement daisy wheel but all I get is information on daisy wheel printers, does anyone have a source for the slotted disc?  The current disc is 150mm in diameter with 24 holes.


Thank you & take care,
Ian