Fitting a digital speedo

[almyland]

My standard speedo has developed a serious twitch across the speed range and changing the cable hasn't helped a lot. So, I'm thinking of fitting something like an Acewell 3100 digital unit so that I know the speed I'm actually doing rather than guessing. Has anyone got any experience of these things and what is the best way to install the sensor/magnet? Thanks in advance for your thoughts.

Cheers Alan

[lil_red_roadster]

Re: Fitting a digital speedo

As a backup I once installed a Halfords cycle computer (less than a tenner). Apparently they're good up to about 120mph and you just need to cut & splice some additional wire in and set the wheel circumference. I glued the penny-size magnet to a wheel rim using JB Weld & it's still there 5 years later. The pickup was cable-tied to the upright.

Admittedly display visibility isn't great but it worked...and as a quick, cheap & dirty fix it ticked all the boxes..!

As an alternative I also had a quote for fitting an electronic speedo head into the Marina cluster - Speedy Cables wanted about £120+VAT for that (add in a sensor as well)...which works out cheaper than a whole new set of gauges (2009 prices).

[stevejgreen]

Re: Fitting a digital speedo

Oooh, going techie. I presume we are talking Marina gearbox.
IMHO its easy to araldite a the magnet sender on the gearbox drive flange, good for 6000+ rpm,and bracket the sensor, jubilee clipped to the gearbox tail housing.
On some gearboxes there is movement between the front UJ and the box itself. Simply move to the Diff casing and do the same thing.

For calibration, compare speeds with a Sat-nav. Best done with two people as as driving, watching a sppedo, sat nav and writing things down is not a good combination.

Good luck, I hope I have helped.

[chris_cussen]

Re: Fitting a digital speedo

When I built my Cabrio I used ETB for the instruments and used their electronic Speedo. It needs a supply, earth and light connections and two fine wires (which I had to extend) which ran to a pickup. There were two small magnets that I bonded to the diff flange, an I mad a small ally brackt to hold the sensor.

A few sums to calculate the correct number of pulse per mile ( you have to know the diff ratio and wheel diameter for this) and a very easy set up method. I checked the setting by getting my wife to follow me to make sure the sums were correct. It went through IVA OK with no problems with the speedo.

[b_caswell]

Re: Fitting a digital speedo

Hi Alan,
If you want to try and cure the flicking on your existing speedo you could try taking the head out of the can and then dismantle the drive end under the spinning disc is a thin shim that breaks up and jams the head and finally causes the cable to snap.
I assume you have change the complete cable both inner and outer also try and avoid tight bends when routing the cable.

Quite a few Caterhams use electric speedos with the sensor on a front wheel.

[almyland]

Re: Fitting a digital speedo

Many thanks for your thoughts. I'm looking at a Speedwell unit but not sure whether to fit the sensor to the front or rear wheel. I imagine the front would present less of a problem although it might be possible to glue the magnet to the inside of the brake drum on the back; not sure I fancy that approach. These units are usually fitted to motorcycles and don't therefore have a diff to enter the equation. I'll have a rumage around on the Cateram pages to see if they can offer any good solutions.

Cheers