4 replies to this topic

[1275S+TRMan]

1965 Mini  Cooper 1275 S. Does the fitting of 165x70x10 tyres alter the speedo MPH reading drastically please?  Also since getting the vehicle from long term storage the odometer has read backwards!! NO it has not been clocked!! Would this be a speedo fault or gearbox issue maybe? Many thanks,

[Ethel]

The rolling radius will be within millimeters of 145/10's, all Mini tyres are much closer in diameter than any different final drive ratios that were fitted.  The odometer works similar to a ratchet, it can't go backwards 

[alpder]

It'd be mechanically possible for an odo to fail so that the rollover of (say) the 100's-and-beyond stops working. So you'd see, for example, 12399 miles, then do one more mile, and you'll see 12300 miles. Which sort-of looks like it's going backwards.

 

Usually, though, they just seize-up during the extra effort required for a rollover, and then they do nothing after that except make a very faint clicking as the ratchet pawl slips.

[Designer]

Hi,

 

I cannot find it but there is a post on here where a member shows and describes in detail how to take one to pieces and rebuild it.

Hopefully someone can post a connection to that topic.

 

Paddy

[Spider]

The Odometer is operated with a Ratchet mechanism, it can't ordinarily go backwards. It does sound like a Speedo issue.