I have a stock 97 formula and it did have a 3:42 gear in the rear, i took it to the track about a month ago for the first time. I ran a 14.5 in the 1/4 @ 99.5 mph and my 60' was 2.6, I have since installed 4:10s and am wondering what kind of gain if any can expect to see?
The car is a m6 and has goodyear 245/50/16's in the rear, I know the 60' sucked and the 4:10s might make it worse, just need to know what kind of mph i will see at the top......thanks

 

You will see a gain of maybe 1-3 tenths, IF you can get good traction. Get some DRs and some lower control arm relocator brackets and you should be set until you get some serious mods that require even more traction mods.

 

And possibly a broken 10 bolt if it hops at all

 

but wouldnt the 4.10's make it easier on the rear end?

 

No not at all in fact even a little harder on it as the teeth are smaller on the gears in order to fit more of them on there to acheive the desired gear ratio.

 

i was always under the impression it would be easier because the gears woudl want to spin easier so the tires move easier so there isnt as much stress on the gears cuz they move a lot easier

 

Nope. You got it backwards. The engine gets the mechanical advantage. It's like using a longer wrench to turn a bolt. Meanwhile, the poor pinion gear gets smaller and even more spindly and weak and more stress gets put on the spider gears and axles.

 

You have it backwards actually... a 4.10 set has fewer teeth on the pinion gear VS a 3.42 pinion gear - ring gear has the same number. IIRC:

3.42 = 12/41 teeth
4.10 = 10/41 teeth

 

nice.. i take the win