VDO Speedometer calibration

[Tnick]

My 'new' Berinetta is fitted with a VDO speedometer which reads about 20% slow (an indicated 40 mph is actually 50mph).

Can anyone suggest somewhere that can recaibrate one of these? Speedograh Richfield suggest a small gearbox to fit on the cable (Cost £95 + VAT etc).

It is an older mechanical speedo rather than on of the newer programmable electronic models.

I am wondering about changing the speedometer drive pinion? There seem to be 22,23 and 24 tooth ones avaialable. Though this will depend on what is currently fitted. Can any one advise on how easliy they are removed?

Regards Nick

[Dane_Rescueman]

Re: VDO Speedometer calibration

Hi Nick,
If you have a type 9 gearbox then the speedo drive gear is held in by a pressed steel cap opposite the speedo cable fitting. Lever off this cap and the drive can be pushed out from below with the cable removed. The snag is have you anough space above the gearbox tailshaft to get at this cap?
Replacement is as simple. Drop the little gear's shaft down to engage with the bearing and when seated firmly replace the cap. I always fit a new oil seal to the bearing. This is easily fitted before refitting the cable.
I don't know how other gearboxes such as the MT75 fit their speedo gear. Good luck

[Dane_Rescueman]

Re: VDO Speedometer calibration

Sorry, I forgot to mention that the four speed "rocket" gearbox speedo works in an identical fashion.

[dogoncrazy]

Re: VDO Speedometer calibration

Nick
My son used one of those gearboxes on his last Roadster[2 litre pinto/5 speed]as the error was to great for recalibration. With regard to the drive pinion if they are as easy as the Triumph/Marina you should have no problems as they could be removed from the gearbox casing once the cable was removed and the 'forked' retainer unbolted

[danny_nelson]

Re: VDO Speedometer calibration

Hi Nick, I hope that you are enjoying the Berly. As you know yours is the type9 box and Dane is spot on. I may have some other instruments if you do not solve it, but I am sure you will.
Danny.

[stevejgreen]

Re: VDO Speedometer calibration

The calibration will be depend on tyre rolling circumference, axle ratio and finally the gearset in the gearbox.

You will be lucky if you can find a good combination.
Easier to use a satnav or fit a cycle speedo. The right type can be fitted on the tail of the gearbox keeping wires short.

There used to be several recailbration services but I guess as everything has gone digital, the have become outdaated.

[b_caswell]

Re: VDO Speedometer calibration

Speedy Cables (London ltd) Authorised repairer of VDO gauges among others Now in Swansea. They need the rollong radius and cable turns per wheel revolution.,
www.speedycables.com
Tel 01639 732238

[austinm]

Re: VDO Speedometer calibration

Hi Nick,
I used Speedy Cables to calibrate my Veglia instruments several years ago and checking against my V70 the speed displayed is as close as makes no difference.

Hope you get yours sorted.
Regards Austin