5000 Mile insurance - odometer over reading

[lachouette]

My insurance limit is 5,000 miles. I've just done an indicated 4,500 miles taking part in the Norway grand tour organised by our Norwegian friends. So I am getting close to the limit. However my odometer overreads by around 15%, so in reality I've only driven just under 4,000 miles, which leaves me 1,000 miles for the rest of the year, which this year is probably enough for me.

 

Has anyone argued this point with their insurance company?

[iain]

Probably safer, knowing how Insurers argue, that you recalibrate your speedometer. At least speed and distance recording will then be accurate (ish).

[TR 2100]

A 15% under-read is significant - how do you know

and what is the cause?

 

AlanR

[john.r.davies]

Or, consider the difference in cost between recalibration and paying a larger premium for more miles per year.

 

John

[lachouette]

Easy. Comparing satnav distances with odometer readings over 4,500 indicated miles!

 

Not so easy to deduce the cause. The overdrive is a later fitting to a USA car. A-type on a 74 reg car. Messing with speedo/odometer beyond my capability at present.

[McMuttley]

My speedo is 10% fast, are my miles 10% over too ?

[RobH]

Very interesting question and one which is not easy to answer.

The mileometer is driven by gears so is directly related to the drive ratio while the speedo needle is a magnetic coupling and the needle position depends on the speed of the drive, the strength of the magnet and return spring and finally on the position of the needle relative to the spindle. An error in the drive gearing will affect both the miles and the speed so if that is the reason for yours over-reading on speed the answer to your question is yes the miles will over-read too.

However, it is possible for the drive ratio to be correct and the mileometer to be reading correctly but the speed indication to be wrong because of errors in the magnet, spring or pointer position. The only way to find out which it is, is to have the speedo calibrated somehow.

 

Rob

[BrianC]

Maybe the rear axle currently fitted is a different ratio from original and hence mismatched to the speedo.

[Paul Down]

The Magnetically coupled speedometer is rather a crude affair which may be calibrated reasonabally accurately for a single speed but I doubt very much if it is ever accurate over the complete range. Mine is at least 10% fast at 70.

 

All gearing on my 3A is spot on so it has to be limitations of the instrument.

 

More expensive cars used Chronometer speedos i.e. gear driven internals not dragging a magnet around which has too many potential variables. I just live with it.

 

Compared to a TVR the TR speedo is quite accurate!

[peejay4A]

My old D3 Bantam had a chronometric speedo so they weren't restricted to expensive forms of transport.

[Paul Down]

Is a D3 Bantam a bike?

 

For some reason motor bikes seem to have had Chronometric speedos, perhaps someone knows why?

[Don H.]

15% is a massive odometer error. Hard to imagine anything but gearing. Tire circumference couldn't explain that much under any realistic condition. Magnetic drag will certainly affect speedo but shouldn't impact odo at all.

 

Do TR6s have the speedometer gearing in tiny print on the dial face like earlier cars? If so, ensure it's correct for the final drive installed. Note that if other changes have been made -- like gearbox type to non-standard -- all bets are off.

 

My speedometer is accurate within 3 to 5% at typical road speeds. In my case the remaining error is likely tension on the indicator return -- I recently adjusted that and got it close, but not quite perfect as shown. I'd rather have a speedo over-indicate than under-indicate as well.

Edited August 6, 2015 by Don H.

[Lebro]

If the gearbox is from a saloon the speedo gearing is different (TR=2.5:1, Saloon =3.5:1) but that would give a 40% error reading slow.

Ask me how I know !

 

Bob

Edited August 6, 2015 by Lebro

[Eddie Cairns]

If you get close to 5,000 miles on the odometer just phone the insurance company up and pay the £30 or so additional premium.

 

Life is just too short and you will be arguing with a clerk that has no idea what you are talking about.

 

Just pay the premium and go out for another run with the hood down!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[MikeF]

Hmm.

When people look at our cars they nearly always ask the age to which I say just over 50 years. Often they then ask the mileage. To which the answer is who knows? After 50 years it's whatever you or the previous owners want it to be......so I suppose you could make an adjustment for the over recording. First though I would suggest doing a measured mile or similar just to be sure.

 

Legally speedo has to be no more than 10% out so probably not a good idea to open a debate with insurance company.

 

Mike

[Mick Forey]

Having also done the trip up to Nordkapp I have done 4200 miles in my TR3 since insurance renewal in June and we are planning a trip to Angouleme in September, so we will be way over my 5000 mile limit by then. Just called those nice people from TR Register Insurance this afternoon and for the princely sum of just over £11 extended the cover up the 7500 miles, so don't mess with the speedo, just pay up.

 

Mick