As i'm currently in the process of converting my 308 into an (almost full) trackcar i was wondering about the gears. For tracking purpose they should be a bit shorter on ratio. I was wondering if any had some experience putting smaller diameter tires on to increase revs? I think this could be an easy way to shorten all gears which, except for the 1st gear mayby, i think would be an advantage. How about it? Any downsides in this approach?
Hi. I'm not a Ferrari expert, but in general a lower profile tire will heat up quicker, prevent sideways movement in turns and make a harsher ride (no problem with race-cars imho). I see no problems going with lower profile tyres. My old Porsche 911GT ran 305/660-18 in the rear.. -=Thomas=-
I have a set of straight cut gears with 2 ratios ... I was going to use them for autocross but once I got my motor dialed in I realized I really didn't need any more bottom end ... you might find the same thing once you get 'er built.
Just another observation I'll share. When I go thru 1-3 I basically shift at 7700 rpm or close to which puts me right around 5500 in the next gear and from data acquisition the acceleration tq in the next gear is right where the previous gear left off, but after 3rd gear I find I really don't have to wind the car out as far to hit the tq peak in the next gear, meaning 3-4 and 4-5 I really only have to wind the car up to about 7200 to be on the tq peak in the next gear. 6600 rpm in 5th is "only" 139 mph approximately and I think you'll find with a properly built car you'll be hitting that on big tracks ... braking at the speed is "interesting" ... I run the Porterfiled R4 pads too FWIW ... not the R4-S.
And on tire size: The front ones on my GT4 are rubbing. I've been thinking of stepping down one size (205/50/16 rather than the 55's.). Anyone ever done this? How did it look? Thanks Hans
