Hi members,
When installing 126 motor &gearbox into a 500f is there any other factors that influence overall gearing..? other than tyre size & crown & pinion (8/39)
my 126 felt like it was higher geared but now that motor & box are installed into the 500 it appears lowered geared...( similar to standard 500 gearing)
any help greatly appreciated ?? Dave

I'm assuming that the final drive ratio is a little higher (smaller number :1) than on the 500. Iirc 4th gear is not a direct ratio (i.e. 1:1) so may be slightly different between the 2 models also?

I think you're correct in your assumption than only tyre size and final drive ratio affect overall gearing. (plus 4th gear if indirect).

So, which speedometer are you using? Different final drive ratios will require either different speedos or different speedo drive gears at the gearbox (where the cable is attached).

You say the gearing feels lower, are you going by the speedo readings? If the speedo being used is for a car with a lower final drive ratio, the speedo will still show the same speeds at e.g. full revs in each gear but the car will actually be going faster.

Or is it a feeling that the car is lower geared because it now accelerates faster, as if the gearing was lowered. The extra power will make the car accelerate faster.

They used to give the overall gear ratios plus mph per 1000 rpm in each gear in road test magazines, back in the day e.g. The Autocar, The Motor etc.
Also gave the actual speed at different speedo readings e.g. @ 30, 40,50 mph.

All I can suggest is maybe check your current speedo readings against a SatNav/Mobile phone App? or another car.


AL.