Five speed gearbox speedo correction

[PeterSprot]

My TC has a ford type 9 gearbox. I bought a small speedometer ratio correcting gearbox from Speedograph Richfield which goes on the car end of the cable and it has a ratio worked out to correct the roughly 50% slow error the speedo shows without it.
Unfortunately it keep snapping the cable of this small gearbox where it fits into the car. It looks like the tiny gears are locking and as they keep being driven the small cable stub snaps. If I take off this little gearbox and re-connect the original cable everything works with the speed error so I can only conclude it must be the little gearbox Speedograph supplied this and the special cable. Giving them credit Speedograph have tried really hard to work out what is wrong and have repaired it three times now at no cost to me but today after 50 miles it snapped again. I think it was when I reversed but I couldn't be sure.
Do any of you have the type 9 gearbox and what did you do to correct the error?
I'm a bit worried as I'm planning a 5000 journey starting in a month and I'd feel better if it worked if only to help remind me when to fill up with petrol.
Thanks for any advice you can offer.

[dirk w dondorp]

Peter, why don't you use a dipstick , easy to make, in case you are uncertain. I do because I did away with the ever leaking fuel gauge on the tank. Info on making in tech. dept of this forum.

[PeterSprot]

I calculated that if I leave the uncorrected speedo as it is then roughly 140 miles shown on the speedo equals 210 actual so I can use that to tell me its time to fill up. The sat nav can tell me my speed.
I made a dip stick out of a very small plastic funnel and a bakelite rod and the light on the dash should work so maybe I'm just being a little paranoid!
I haven't yet worked out the fuel consumption yet because of the speedo constantly failing. I will have a good idea before I start the trip. (I'm sure I will by day two!)
I'd still like to know how others have addressed the speed correcting issue.

[dirk w dondorp]

With the proportionally big fueltank on the TC you should be able to find enough gasstations on your route, Europe is well covered with staions all over. That will certainly lower your "stressfactor" Only in mid/south of France driving through the country, I had sometimes a hard time filling up in time, but always managed.

[frenchblatter]

Cables normally break when there is a kink in the outer cable. Does the needle waver when it's working?

I know it's not perfect but I marked my Caterham rev counter with little dots at the 30, 50, 70 MPH speeds (as verified by satnav). I've now got a GPS speedo.

By the way, if it helps 50 kph is 30 mph, 70 kph is 42 (I put a dot on the 40) and 10 kph is 70 mph.. The French motorways 130 kph is 80 mph. These are the common limits in France but there's also 30 kph (call it 20 mph) in some town centres or by schools.

[Chris C]

I have a type 9 gearbox and had the speedo head recalibrated - by Speedograph Richfield!

Very accurate compared to GPS.

[PeterSprot]

Eventually Speedograph Richfield found the problem after I sent them my speedo and my cable.
Their persistence is admirable.
I kept telling them that when I put my cable on without the correcting box everything worked fine so it must be the box!
What it turned out to be was the square end my cable where it fits into the speedo was a bit shorter than theirs so theirs was jamming as it was tightened causing it to lock and snap the stub which comes out of the correcting gearbox. They told me there was a small bit of cable jammed in the head of my speedo which was causing the problem.