tire size to gear size

going to start racing sand drags again after taking a couple off years off right now the old setup is 34X17X16 super scooper gears are a 5.32 and a c-6 in 4 high I hit second gear around 200 feet out, in 4 low I cant shift fast enough to go thru the gears I use a shift solenoid and it will hit 2nd right off the line but doesn't have enough time to rest the shifter for the 2-3 shift rpm set to shift at 7200 rpm. what I am try to figure out if I go to a shorter tire how will it effect the overall gear in 4h so it will hit 3rd gear what height should I look at since I cant change gears to a lower ratio but I can go the other way say a 3.73 or 4.56 and run in low.

When in hi what rpm do you hit at the finish line in 2nd gear?

right at 6800 RPM I think I would be faster if I can hit all 3 gears

Do you only sand drag this thing, no street? How much power? Weight?

Personally i run mine on the road too so i gear it to run low range on the dunes or sand drags. Mine is a 5000lb bronco though.

no street driving at all just sand drags gutted am thinking around 3500 lbs. and about 750 hp, trans has a 5800 stall torque convertor luanch at 5500

What transfer case? 205s are 1.96 in lo but BW 1356s are 2.68 (?).

4.11s with a NP205 in lo will give you the same wheel speed at 6800 in 3rd gear as 6800 in 2nd gear t-case in hi with 5.32 gears.

You'd have to use a 3.08 gear if you have a BW1356 or NP208 t-case

sorry for the late response I have a NP 208 transfer case, trying to decide to go with a shorter tire or change gears

ok I forgot to mention the bronco went on a diet from 5000 to 3500 lbs. so this will change the truck a bunch

muddog899 wrote:sorry for the late response I have a NP 208 transfer case, trying to decide to go with a shorter tire or change gears

What sizes do they come in?

a 33 tire plus paddles would be a 36 so only a inch difference

So you could only drop down one size, from a 34 to a 33?

yes that is what it looks like so am thinking gears are my best bet now but I cant go any shorter then what I have so I will need to go to a taller gear and run 4 low

How well do those 208s hold up to the sand and paddles, all the mud guys I know that run those are running them in hi.

they hold up pretty good the only time that I have had trouble with it was mud bogging cracked the case

Try taking off in 2nd gear using 4lo. I tried this and picked up a tenth of a second. I'm running a 79 f150 with 33x16 super scoops with 4.56 gears and 205 t case. I was having same issues as you 4lo taking off first gear to much wheel speed racing thru gears. 4 hi holding first gear for 250 ft then shifting to second. Using 4lo second gear take off shift into third about 125 ft. about 6800 thru the traps. I do plan going to more gear in future maybe 5.13 would like to see 7200 rpm thru the traps.