Thanks IanI do love your threads Robert, but sometimes you are just too clever and lose me altogether.
Maybe I'll have to phone you for more "break it down" type explanations!
Er, so why can't you just use the original gearbox as it is?
i probably made a hopeless job of explaining above , i'll try again , i am still using the automatic box that came with the car , but it will give me much lower gearing than i want , about 5'000 rpm will equal 100 mph .much too low .
to solve this , i am fitting a second gearbox , behind the first , and i am fitting this backwards ,so the gears work to make the ratios higher . eg , if i am in 4th gear on the front gearbox , and 4th gear on the back gearbox , its all 1:1 and no change ,happens , i am still at 5000 rpm =100 mph . but , if i now change the second box to 3rd gear , instead of going lower geared , because the box is fitted back wards, it raises the gearing to 34 mph per 1000 , so my 5000 rpm would now be 172 mph . much better for cruising it will do 80 mph at 2300 rpm.
those numbers in the post way up above,near the top of the page,, are the speeds it would attain for the rpm , in the 4 different gears on the back box , with the front box in top gear .
i know the idea of running a box backwards is a bit weird , but it does work, i used it many years ago on the tvr .
the concept that is actually raises the gearing as you shift from 4th to 1st(on the back box) is even stranger in a way ,and counter intuitive .
i hope that makes a bit more sense ?
oh and feel free to call ian