Question about mileage......

[Dannyboyo]

Hi guys,

I read a thread somewhere here where alot of Chimmy owners said that their speedos read about 10% higher than the actual speed. Not sure if this is common or not, but anyway, heres my question........

If the speedo is showing 10% faster, doesn't that mean that the total mileage reads 10% more aswell??

So a car that says it's done 70000 miles has actually only done 63000 miles?!?

Does this also mean that services are been done every 5400 miles instead of 6000 too?

Maybe I'm way out on this, but please, feel free to debate away!!!

Dan

[shpub]

No not necessarily as speedo is taken from the driven wheels and every bit of wheel spin will screw things up as well. then there is the case of the speedo going out as the tyre tread reduces and the circumference changes. Then of course there have been many tyre size changes so...


1. Either really worry about it and shorten your life
2. Get the car serviced on 6000 mile intervals and not worry.

I suggest no 2.

Steve
www.tvrbooks.co.uk

[ribol]

Dan,

The speedo will be out in both ways, the car will have done less miles than it says and sadly you will have broken less laws than you thought you had

As the distance from the centre of the rear hub to the road surface alters so does the accuracy of the speedo and that is on top of the inaccuracy of the speedo to start with. I suppose in theory you could wait longer for services, depends on you views on how service history reads, but then that is another debate............

Ivan

[RolandM]

I was just wondering where the speedo take off is on a Chim. as far as accuracy goes if it bothers you then borrow a hand held GPS and do a good run to compare, my Alfa 75 is spookily spot on with slighty larger tyre sizes than the standard car, I have yet to do a test on the Chimaera, but from the point of knowing how many laws I am breaking it will soon be done, But also does Speedo accuracy always equate to mileometer accuracy, not so on the old motors I used to play around with, mileometer accuracy can be checked using two known landmarks (but don't spin the wheels)

[dannyboyo]

Cheers guys!

Just curious really!! I was on a night shift and slightly irrelevent thoughts pop into my head as a way of keeping myself awake (doesn't always work though!)

Definately not trying to skimp on service intervals though!! Actually thinking of doing the next one 2000 miles early, as I've only just got the car (Maneks old one) and thought it could be worthwhile for a bit of peace of mind!

BTW, are any of you either around the Watford/Hemel area, or West Wales area (I spend a couple of weeks a month in both) as I'd like to meet a few owners, drink a beer maybe, swap stories, have some more beer, drool over more TVRs, etc etc

[manek]

...and with that car, I installed 245/45/16s on the rear when they first needed replacing but the previous owners had used the originally-specced (from memory) 235/50/16s which, if I recall the calculation I did at the time correctly, means the speedo now over-reads by a whopping 3% more than it did before, since the circumference of the tyre is that much less.

[alfredeneuman]
What, me worry?
[/alfredeneuman]

[the dodger]

manek said: ...and with that car, I installed 245/45/16s on the rear when they first needed replacing but the previous owners had used the originally-specced (from memory) 235/50/16s which, if I recall the calculation I did at the time correctly, means the speedo now over-reads by a whopping 3% more than it did before, since the circumference of the tyre is that much less.

[alfredeneuman]
What, me worry?
[/alfredeneuman]

Alfred E Neuman (MAD)! - hadn't heard from him in years!