Ford F-100/F-150
1973–79 4x4

Factory gearing, tires, angles and brakes for the F-100/F-150, and what the usual upgrades do to it. Every number is from the maker's own figures unless the calculators say otherwise. A few figures here are still waiting on a factory document; the calculators mark them.

Use this truck in the calculators

133 in wheelbase

Axle ratio3.5–4.11Factory, by trim

Crawl ratio55.3:1Best trim: F-100 4x4 (1974 spec) (G78-15B tires)

Angles37.5 · ~17.2 · —°Approach, breakover, departure (~ estimated)

Highway mpg9Estimate, not EPA rated

Trims

3 we have figures for

Trim	Tire	Transmission	Axle	Angles	Clearance	Open
F-100 4x4 (1974 spec) (G78-15B tires)	27.6	4-speed manual, 3-speed automatic	3.5 / 3.7 / 4.11	37.5^* · ~17.2 · —	7.8 in^*	Use →
F-100 4x4 (1976 spec) (H78-15B tires)	28.1	4-speed manual, 3-speed automatic	—	37.5^* · ~17.2 · —	7.8 in^*	Use →
F-150 4x4 (L78-15B tires)	28.9	4-speed manual, 3-speed automatic	—	37.5^* · ~17.2 · —	7.8 in^*	Use →

* The maker doesn’t publish this figure for that trim, so it shows the closest trim’s (same tire where we have one), or a close relative’s that shares the same body or front end. Hover the star to see which.

~ Estimated from the wheelbase and ground clearance. No maker has published it for this truck yet.

Size

Wheelbase: 133 in
Height: 76 in
Body: Pickup
Stock tires: 27.6, 28.1, 28.9

Transmissions and low range

4-speed manual (New Process NP435, 6.69 low): 6.69 · 3.34 · 1.79 · 1
3-speed automatic (Cruise-O-Matic / SelectShift, C6): 2.46 · 1.46 · 1
Low range, np205: 1.96:1
Low range, np203: 2.01:1

Axles

Front: Dana 44 solid front axle (full-floating drive axle per Ford)
Rear: Ford 9-in (light-duty half-ton rear)
3.5 ratio: F-100 4x4 (1974 spec) (G78-15B tires)
3.7 ratio: F-100 4x4 (1974 spec) (G78-15B tires)
4.11 ratio: F-100 4x4 (1974 spec) (G78-15B tires)

Brakes

Front rotor: 11.72 in, 298 mm
Front caliper piston: 73.0 mm
Rear drum: 11.03 in, 280 mm
Rear: drum

Suspension

Front: 4x4: radius arms, coil springs
Rear: leaf springs, solid axle
Rear layout: Leaf springs

Fuel economy

Highway, not EPA rated: about 9 mpg
Where it comes from: Owner average, 22 trucks, mixed driving (1979 F-150 (mostly 302/351M/400 V8, mixed manual/auto))
Source: fuelly.com

Aftermarket bumpers

5 listed

Makers almost never publish angles, bottom heights or how far a bumper tucks, so these fill in as owners measure them. Measured yours? Add it on the rig page and every owner of this F-100/F-150 sees how it does on their tires and lift.

Front 3

Rear 2

Every calculator, set up for the F-100/F-150

Tire sizeBigger tires: speedo, clearance, angles and brakes.Compare tires RegearHighway RPM on every ratio and mpg.Pick your gears Crawl ratioHow slow it creeps, against other trucks.Work out crawl SpeedometerWhat it really reads on new tires.Fix your speedo LinksAnti-squat and what a lift does to it.Check your links Your rigBuild sheet and measured angles.Start a build sheet LeaderboardsWhere the F-100/F-150 ranks against every stock truck.See where it ranks

Source: oldcarbrochures.com.

Use at your own risk. These calculators are here to help you plan and to inform your decisions, not to sign off on a build. Many numbers are estimates worked out from factory figures, and some factory figures are not yet confirmed. Check every number against your own truck, its manuals and a qualified shop before you buy parts, cut, weld, lift, regear or drive on it. Long Range Desert Tools is not liable for anything you do based on these calculators or their results. The full terms are in our policies.

Ford F-100/F-1501973–79 4x4