Help me pick my gear ratio.

[1982 flareside]

308 be good

If you don't want to use your truck like a truck. 3.08s don't pull worth a damn.

We had a 1980 Ford F100 with 300 4 speed with 3.08s it did good it pulled a 20 ft boat with it.

[Redcap]

308 be good

If you don't want to use your truck like a truck. 3.08s don't pull worth a damn.

We had a 1980 Ford F100 with 300 4 speed with 3.08s it did good it pulled a 20 ft boat with it.

A 20ft boat and trailer isn't much of a load.

[gregamorton]

with a 3/4 ton you more than likely pull weight more often than he ever will. And if I was driving 50-100 miles a day I would not be driving a old 3/4 ton either. I am just stating that a 3.00 or lower will be what he needs if he is highway driving most of the time. I never got very good mileage with a fe engine anyway. My 79 lowrider I had with a nice 460 c6 and 2.50 gears pulled 12mpg most of the time. So for with my new orange pickup I have got 12.5 to 14mpg but I am still tinkering with it. need to get the new shocks on and new tires and balanced. Little stuff makes a difference especially if you are going to be putting 500-700 miles a week on your old bump. I am crazy when it comes to fuel mileage because I hate wasting money. My mercury so for on its worst tank has gotten a little over 18mpg. I am going to try either 3.08s or 3.55s in a sterling 10.25 to see if I can get around 25mpg. I have gotten around 22 at best so for.

[1982 flareside]

If you don't want to use your truck like a truck. 3.08s don't pull worth a damn.[/quote]

We had a 1980 Ford F100 with 300 4 speed with 3.08s it did good it pulled a 20 ft boat with it.[/quote]


A 20ft boat and trailer isn't much of a load.[/quote]

It is more than you think. It was a good truck. My dad hauled a 65 impala and a trailer and did good. Remember f100 was like a ranger in the 80s it only had 3 leafs.

[Redcap]

If you don't want to use your truck like a truck. 3.08s don't pull worth a damn.

We had a 1980 Ford F100 with 300 4 speed with 3.08s it did good it pulled a 20 ft boat with it.[/quote]


A 20ft boat and trailer isn't much of a load.[/quote]

It is more than you think. It was a good truck. My dad hauled a 65 impala and a trailer and did good. Remember f100 was like a ranger in the 80s it only had 3 leafs.[/quote]

Your boat must have been MUCH heavier than the 22ft jetdrive with a Chrysler 440 that lives in the back of my barn.

[1982 flareside]

Ok wat is a load for a swb 2wd f100?

[gregamorton]

if you have a car on a trailer behind you or a good size boat you will be overloaded behind a f100. just because it will pull a load doesn't mean it is safe. That is where the 3/4 tons and 1 tons come in. If you haul a heavy load once or twice a year just drive slow and watch out for stuff. If you work your truck all the time get a one ton cause most people overload there 3/4 tons just cause they think its ok. This post was for help on picking the right gears for a daily driven truck not a 3/4 ton hauler.

[1982 flareside]

Thank you he is wanting a driver redcap wants a puller.

[mr_josh]

Agree that a F-100 is not intended to do a lot of towing. Turns out pickup trucks do a lot more than tow things. Can't haul bark or fill with a Civic, can't haul lumber with a Corolla. A few hundred pounds of lumber isn't going to slow down a 390-powered F-100 with 3.08s.

[texrodder]

I agree with the higher gear ratio(3.00-3.55) range,a 1/2 ton truck is only designed to tow/carry so much ,especially old ones like ours,with out of date brakes,steering,suspension,etc it pretty much limits our 1/2 tons to light duty use(safely). But a 390 has a good amount of tourque so running higher gears would be a logical choice.Plus why put your drive train through more abuse running low gears and give up more of the limited mpg that the FE gives.

[bb429power]

I think these are taken at 55 mph.


Entire shaded area is the acceptable cruise rpm of 2000-3000
optimum is the lighter shaded area which is 2300-2600 rpm's
for mileage choose a ratio in the shaded area above the lighter shade
for power choose a ratio in the shaded area below the lighter shade
the numbers on the top are the tire diameter while the ones on the sides are the gear ratio

M.P.H X gear ratio (over)
tire diameter X 336 = RPM

[Brokenarrow]

If you aren't going to pull extremely heavy loads with the truck and you are running a fairly strong FE, higher rear gears are the way to go. These engines are very strong on the bottom end (1800-2500rpm) so they handle the gears very well. Contrary to popular belief you don't have to settle for 8-12 mpg from a 390 ford, trust me.

[sgs]

Broken Arrow is right. The old LTD's with 390's didn't get 8mpg. It was a long time ago but....... 16-17 on the highway is what my memory tells me. So who makes something lower than 3.50 for a Dana 60?

sgs

[Redcap]

So who makes something lower than 3.50 for a Dana 60?

Lower gears are easy to find, clear up to 7.17:1. Higher gears than 3.54:1? Good luck on that.

[68muscletruck]

I've got a 68 lwb f100, 390, the manual trans, 9 inch rearend, popped the 3.25's on my way to school one morning on what we call the 'Van Winkle Raceway' they were good, did alright I was doing just below 4 grand past 85, and they came off the line alright, Being just outta high school I don't have any toys to pull and if i did i have the powerstroke to do so, but the plan for my 68 was to hot rod and do some trips and get good highway... so after popping the 3.25's I did some searching on this site through the tech articles looking at various gear ratios for the 9 inch and tag numbers... I tracked down a set of 2.75's from an old Merc Cougar, the truck's acceleration off the line feels no different than the 3.25's and now i can do 85 around 2000rpms and not watch my fuel gauge move at the same speed but opposite direction of the speedo... they're a ball to pass people on teh highway with, a guy caught up to us at a gas station one time saying man i was doin around 80 in my honda and you came flyin by me in that old thing! thats sweet! just make sure the third member you get to plop in your housing has the right spline count 28 or 31, that was the biggest pain to deal with when the junkyard ones i got were wrong...