I am going to switch from a Typhoon to a new, modified F-150 in a few weeks.

One of the mods will be a supercharger, probably a Procharger, after a couple of thousand miles break in and debug. I have been reading the posts to this site and find them highly educational. However, I have never seen any discussion of rear end ratios.

I drag raced fairly successfully for many years (8 nat'l records) and was almost always of the opinion that it was best to run the highest numerical ratio that the engine would tolerate through the lights, or the one that netted the best ET, (usually the same).

I realize that there aren't too many choices but I am going for the 3.73:1 option. With a truck that weighs almost two tons, I can only see this as beneficial.

Am I missing something? Has anybody experimented with various ratios? Any comments, input?

 

I am sure a lot of the guys that are running lifts and larger circumference tires are running higher gears (4.10/4.56) just to retain their output stock gearing.

I myself am looking forward to putting 4.10s (aftermarket) in my truck, but I am not doing a lift/tire combo but as a performance "pep up".

IIRC the tallest gear that Ford offers stock in the 1/2 ton is the 3.73... It would be nice to get something a little taller off of the dealership lot though!

 

Most of the Lightning guys are going to 3.73 or 4.10 for the best 1/4 mile times.

Ian

 

if you're drag racing on the weekends, just keep your stock gears and run with smaller diameter tires (you may have to get low profiles on 18" wheels so that you can get the widest tire possible). It will take less effort and you'll definitely be able to find the proper diameter that prevents you from completely smoking the tires (when you really want traction)

Also, the smallest wheel and narrowest tire on the front.

This method is preferred over swapping gears because it's easier, you still keep decent fuel economy for daily driving (when you put your normal wheel/tires on) and smaller tires & wheels generally weigh less.

 

Rear end ratios are discussed here regularly in the "Other Drivetrain" section. Get the lowest gears that you can from Ford (highest numerically). If that isn't enough, there is plenty of choice in the aftermarket.

 

I think a lot of what you read here is from people who like to go to the strip ocasionally. Well for a couple, more than ocasionally. I think that for most, these are our daily drivers. It isn't possible to have the best of both worlds, so we settle. I agree with Crash!. The 3.55 seem middle of the road to me. You'll get going good enough and have half way decent milage.
Now that I have said that, perhaps you can give us some pointers on ho to improve times with what we have.

Tom

 

It also depends on your curb weight and wheel size. In my case with a (heavy) Expedition, auto and 31.5" tires, the 4.10's make a big difference in go without making the highway revs too much. They should be available from the factory but CAFE prevents that happening.

If I had a Reg cab, 5 speed, short box with 28" tires, 3.55's would probably be fine.

Ian

 

I just ran a test at the track last night that might be of interest to the gang. I am running 4:10 gears and for the track last night I installed 275x40x17 Nitto Drag Radials with 245x45x17's up front. Normally with my stock 275x60x17's, I go through the trap in the 1/4 at about 4300 rpm. Last night I had the O/D on just incase I ran out of third gear with the small rear tires. I went through the traps at 5200 rpm! My shift point is 5400. The temp was 70 degrees with 80 % humidity and I ran a 14.716 @ 93.54. This is street trim, spare tire, 150 lb bed cover, class III hitch all the seats and just under 1/2 tank of gas! Yes, I broke the Drag Radials loose on that run.

 

HI!... I have 4.10 gears and run 30 inch tall tires on the street and 27/28 inch tall tires at the dragstrip.