Tacho reset / recalibrate

[CTD]

Hi,

I have 2 questions:

First: I have this cable in the 'storage compartment next to the steering wheel that resets the day counter on my tacho. There is a bracket on the knob at the end of the cable that isn't attached to anything. I this cable supposed to just dangle inside there? If not, what/where is the bracket attached to.

Second: My speed indicator is way off. When I drive 70km/h on the dash, I actually drive 59km/h... Is there a way to adjust this? I have the correct wheel/tire sizes on the car.

 

[Peter Coomaraswamy]

On the trip odometer there is a sort-of triangle shaped bracket that holds the knob that is riveted to the panel under the dash. Most people lose that when they take the under-dash apart. The correct way would be to remove the hex screw and remove the knob and leave the little bracket riveted in place. If you are lucky, the bracket may still be attached to the cable.

As far as the speedometer goes, you probably have to have that repaired, mine bounces allot until I travel 70-8- MPH.

 

[CTD]

My cable still has the bracket on it, together with 2 broken-off rivets... The thing just dangles there. I don't see where these rivets were attached to the under dash.
Do you maybe have a picture of where it's supposed to be?

 

[Peter Coomaraswamy]

Here you go!

might be tricky re-attaching it-

 

[CTD]

Wow, so there it is!

Is the rivet visible from the other side?

 

[Peter Coomaraswamy]

nope.but I think there is a metal plate in the dash piece so you could drill in and use a small pop-rivet. should not be seen from the outside-

 

[lloyd]

Hi,

My speed indicator is way off. When I drive 70km/h on the dash, I actually drive 59km/h... Is there a way to adjust this? I have the correct wheel/tire sizes on the car.

Your speedometer could be inaccurate for several reasons. Speedometer gearing was matched to the rear axle ratios. So it is possible that either your speedometer or ring and pinion assembly were changed.

Recalibrating a speedometer to match an existing gear set usually involves a change of gear in the speedometer itself. http://www.speedometergears.com/bmw-mercedes-odometer-gears and http://paspeedo.com/vdo_odometer_gears.htm Another possibility is wear in the speedometer and there are several shops that specialize in rebuilding-refurbishing-recalibrating. See for example http://paspeedo.com/ and http://www.nhspeedometer.com/ .

It is unlikely but possible that the speedometer gear in the transmission (responsible for driving the speedometer cable) is mismatched. And if the speedometer drive cable is in dire need of lubrication it might result in erratic speedometer operation (jumpy needle).

You mention correct tire height. Surprisingly, not all tires are exactly equal diameters despite what the sidewall says. Yours are 175-195mm X 14"? 205 55 x 16"?

coULDn't resist

 

[wazza.csi]

Re speedometer! If the needle is fluctuating the problem will be faulty Speedo cable, after many years of use the cable looses tension, The speedometer reading incorrect, check the speed at 30mph and at 60 mph, if the difference a percentage (30 reads 35- 60 reads 70) could be altered by changing the speedo drive gear in the gearbox, or having the the speedometer recaliberated by an instrument Specialist. if is constantly 10mph fast at all speeds you can just move the needle back 10 mph!