norseman

norseman

Well-Known Member
I have recently installed a used speedometer into my '87 RRC after the original become far too erratic to judge speed & neither of the mileage recorders would work. I sent the instrument to a 'specialist' but apparently spares cannot be sourced.
The replacement works & records the mileage correctly but the donor RR had obviously covered many more miles than mine, to the extent that the odometer is showing 57K extra miles. Should I decide to sell the vehicle, I do have the original 'clock' plus a shed load of MOT's to verify the vehicle's true mileage .. but is it actually possible, or indeed legal, to 'wind back' the odometer reading on a cable driven speedo to that extent & if so would the instrument itself suffer damage in the process ?

Thanks guys.
 
You can change the mileage on a vehicle so long as it's properly documented, so sorting an odo to 'match' shouldn't be a problem, some will do it automatically.
Whether it's really achievable or not is a different question
 
norseman said:
I have recently installed a used speedometer into my '87 RRC after the original become far too erratic to judge speed & neither of the mileage recorders would work. I sent the instrument to a 'specialist' but apparently spares cannot be sourced.
The replacement works & records the mileage correctly but the donor RR had obviously covered many more miles than mine, to the extent that the odometer is showing 57K extra miles. Should I decide to sell the vehicle, I do have the original 'clock' plus a shed load of MOT's to verify the vehicle's true mileage .. but is it actually possible indeed legal, to 'wind back' the odometer reading on a cable driven speedo to that extent & if so would the instrument itself suffer damage in the process ?

Thanks guys.
Click to expand...
Mechanical odometers can be turned back usually quite easily
 
Datatek said:
Mechanical odometers can be turned back usually quite easily
Click to expand...
Thank you for your reply .. what method would you recommend?

Strange that the original odometer & trip packed up at exactly 63k, the specialists seem to think it was caused by the trip-reset device, which is possible as it always needed more than one press to align all the zeros. By contrast the replacement has clocked 120k & is still working o_O

No problem with legal documentation as I have all the MOT's to verify the true mileage covered by the car.
 
norseman said:
Thank you for your reply .. what method would you recommend?

Strange that the original odometer & trip packed up at exactly 63k, the specialists seem to think it was caused by the trip-reset device, which is possible as it always needed more than one press to align all the zeros. By contrast the replacement has clocked 120k & is still working o_O

No problem with legal documentation as I have all the MOT's to verify the true mileage covered by the car.
Click to expand...
 
Clocking used to be a common practice. I used to repair Volvo instrument clusters for a garage, I always used to reset the odometer to zero as the cluster was unlikely to go back in the same car. Turning the individual counter wheels back is not something I can easily explain, I was shown how to do it.
 
I tried the electric drill method on a mechanical Odo many years ago, but it would only go forwards !! Never tried moving the cogs in case I damaged it.
 
I appreciate everyone's input, the replies have left me deciding to leave well alone for fear of damaging the instrument plus I don't want to remove & then dismantle the entire binnacle again.
In the event of a sale I'll rely on my stack of documentation as to the true mileage.

Thanks again guys :D
 
Now that I've had a chance to use the car I have two problems with the replacement speedo.
Although the 'clock has a steady needle it appears to read around 10% fast according to the rev. counter (but at least I won't be done for speeding) which is strange as the coding on the instrument is identical to the original.
Problem (2) is that the needle illumination optic seems to have detached itself since installation !

I will have to live with these annoyances at the moment as I can't face binnacle removal again, my joints need to recover !
 
For problem 1 you need to find a measured half mile as used by the Police for checking their own speedos & run it over that with a decent stopwatch at 30mph & 60mph.
30 it should take 60 seconds & 60 it should take 30 secs.
You'd need to find a friendly cop to tell you!

Not a lot of help to you, but I used to know where there were several around the Leicester area.
Only one I can remember now (it's an age thing!) is on the A6 between Kibworth & Market Harborough on a straight section just down from Kibworth Shooting ground with the second marker towards the Foxton turn.
A large square of white line paint at each end on the road surface.
 
Ratae said:
For problem 1 you need to find a measured half mile as used by the Police for checking their own speedos & run it over that with a decent stopwatch at 30mph & 60mph.
30 it should take 60 seconds & 60 it should take 30 secs.
You'd need to find a friendly cop to tell you!

Not a lot of help to you, but I used to know where there were several around the Leicester area.
Only one I can remember now (it's an age thing!) is on the A6 on a straight section just down from Kibworth Shooting ground with the second marker towards the Foxton turn.
A large square of white line paint at each end on the road surface.
Click to expand...
A smart phone app like DigiHud will give very accurate speed readings over the whole speed range.
 
+1 on using smartphone. I have compared my iPhone to my Android stereo GPS & TomTom, and they all give the same speed.

My Green P38 reads about 5mph high at 70mph, but my Blue P38 is almost spot on (maybe 1mph fast.) Either way I'm never speeding when using the speedo !!

Nanocom info for Cruise ECU matches the GPS apps, so I guess the wheel sensors are more accurate than the speedo. That probably wont work on Classic though !!
 
pwood999 said:
+1 on using smartphone. I have compared my iPhone to my Android stereo GPS & TomTom, and they all give the same speed.

My Green P38 reads about 5mph high at 70mph, but my Blue P38 is almost spot on (maybe 1mph fast.) Either way I'm never speeding when using the speedo !!

Nanocom info for Cruise ECU matches the GPS apps, so I guess the wheel sensors are more accurate than the speedo. That probably wont work on Classic though !!
Click to expand...
You'll find on most cars, the ecu is pretty much on the mark, speedo is adjusted high on purpose
 
My conviction that the speedo is over-reading by around 5mph is based on the fact that I had previously noted the readings of my original 'clock against the rev. counter. Although the seller sent me the complete cluster I only swapped the speedo over, so the tacho is still the original.
A couple of clues; the overall final drive ratio of the manual car is given as 3.25:1 whereas the ZF auto is 3.08. I never saw the donor Classic so maybe the replacement 'clock came from a manual car, though the label indicating mph/1000 is identical on both instruments.
The second is that the needle on the replacement 'clock tends not to sit at zero mph when the car is stationary & interestingly makes a clicking sound when the car is reversing, something the original never did, so that kills any idea of 'winding' the odo reading back.

I appreciate everyone's input on this subject .. hope no-one is getting bored :oops:
 
norseman said:
My conviction that the speedo is over-reading by around 5mph is based on the fact that I had previously noted the readings of my original 'clock against the rev. counter. Although the seller sent me the complete cluster I only swapped the speedo over, so the tacho is still the original.
A couple of clues; the overall final drive ratio of the manual car is given as 3.25:1 whereas the ZF auto is 3.08. I never saw the donor Classic so maybe the replacement 'clock came from a manual car, though the label indicating mph/1000 is identical on both instruments.
The second is that the needle on the replacement 'clock tends not to sit at zero mph when the car is stationary & interestingly makes a clicking sound when the car is reversing, something the original never did, so that kills any idea of 'winding' the odo reading back.

I appreciate everyone's input on this subject .. hope no-one is getting bored :oops:
Click to expand...
If the needle is not sitting at zero, then it will over read by roughly the amount by which the needle is displaced.
 
Datatek said:
If the needle is not sitting at zero, then it will over read by roughly the amount by which the needle is displaced.
Click to expand...
True, that's probably the simplest answer.
I'll check if my other 'arfs smartphone can help as I know she has a satnav app. Meantime I'll rely on my knowledge that the 'clock is 5mph 'fast' & the rev. counter.
 
norseman said:
True, that's probably the simplest answer.
I'll check if my other 'arfs smartphone can help as I know she has a satnav app. Meantime I'll rely on my knowledge that the 'clock is 5mph 'fast' & the rev. counter.
Click to expand...
DigiHud on Android is a good app for speed and distance, my wife uses it a lot as she cannot get her head around MPH to KPH, the P38 is MPH and France is KPH, handy too when the speedo packed up on my Transit.
 
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