Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Differential gear ratio

Works only, if they rotate faster😉

A small engine may not provide enough power, especially in low and mid range

Smaller diameter for acceleration and bigger for top speed ..... if ground clearance is an issue then a gearing change may be your only option ..... I don't know what ford box your car has but the type 9 is much used in competition and I'd guess the internal ratios could be changed to give you just the gearing you wanted (maybe higher first and lower fifth) ..... is there any scope through mapping etc to boost the torque (even at the cost of ultimate power) ? ....might help you pull the higher gear

K

The gradation of the gearbox is quite nice at the moment.
But the engine does not provide sufficient torque for this setting. I think the Plus4 had the right engine for that box

Getting a shorter ratio at the differential would provide increased revs and torque at the mostly driven speed was my thinking.

Yep ...the differential would be the best bet, just thinking out loud for alternatives..... as regards internal gearbox ratios .... if the gearing is just nice for you as it is (other than a too high 5th gear) then dropping just that 5th gear ratio would leave your sweet gearing just as sweet ....changing the diff will disturb everything

K

I know that Jays, (John) has written here that making the ratio of the rear axle of his 4/4 shorter was the best of all the measurements to make his Sigma 4/4 much more agile and give her more torque (in the shorter moment). So if your diff is possible to be changed...
(I have learned that coincidently the production time of mounting the salisbury axle which allows to change the diff ratios was the same as using the Ford gearbox, so the best combination would be an MX5 gearbox with the 4.1 ratio which no one has realized so far and with the Ford box you could sacrifice the range of the first and second quite a bit)

...why not doing so if you find someone who will make the job. The whole axle shipping to England is may be not such a good solution but perhaps you can drive her to Milan if the times are more normal again or you may find someone in your region when your Morgan shop is hesitating to make the job (BTW it is much better that they are honest because not every shop has the required skills and routine).
I think that your 4/4 is most of the time driving nice mountain roads and you must not fear that the 5th gear will become too short as it is said that the Ford box 5th is too long anyway.

It is mountain roads where a shorter sequence of different gears should make more fun.
The 5th gear will never get too short, even at highway driving. Present ratio would fit for top speed exceeding 130mph

. I think 13inch midget wheels have the same splines they
would increase accelerating times. But would look very odd in the wheel arches.