Isuzu Trooper
1984–91 1st gen

Factory gearing, tires, angles and brakes for the Trooper, 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

104.3 in wheelbase · 29.5 in front · 41.4 in rear overhang

Stock tireP225/75R1528.3 in tall

Axle ratio4.555Factory

Crawl ratio32.2:1Best trim: 1984–86 2.3 gas / 2.2 turbodiesel

Angles41 · 29 · 31°Approach, breakover, departure

Clearance8.3 inFactory figure

Highway mpg17EPA, 20 with the manual

Tire upgrades, worked out

1984–86 2.3 gas / 2.2 turbodiesel, 4.555s, from P225/75R15

Tire	Height	Under the diffs	Speedo at 65	RPM at 65	Gears for daily	Open
235/75R15	28.9 in	+0.3 in	64 mph	3,446	Keep 4.555s	Open →
31x10.50R15	31.0 in	+1.4 in	59 mph	3,210	5.13	Open →
32x11.50R15	32.0 in	+1.9 in	57 mph	3,110	5.13	Open →
33x10.50R15	33.0 in	+2.4 in	56 mph	3,016	5.29	Open →
33x12.50R15	33.0 in	+2.4 in	56 mph	3,016	5.29	Open →
35x12.50R15	35.0 in	+3.4 in	53 mph	2,843	5.71	Open →

Stock turns 3,518 rpm at 65 in top gear. Flotation sizes are nominal; most measure a little short mounted.

Trims

2 we have figures for

Trim	Tire	Transmission	Axle	Angles	Clearance	Open
1984–86 2.3 gas / 2.2 turbodiesel	P225/75R15	4-speed manual	4.555	41 · 29 · 31	8.3 in	Use →
1987–91	P235/75R15	4-speed manual	—	41 · 29 · 31	8.3 in	Use →

Size

Wheelbase: 104.3 in
Front overhang: 29.5 in
Rear overhang: 41.4 in
Height: 72 in
Body: SUV
Stock tires: P225/75R15, P235/75R15

Transmissions and low range

4-speed manual (Isuzu MSG) with integral transfer: 3.785 · 2.165 · 1.413 · 1
Low range, msg-tc: 1.87:1

Axles

Front: Isuzu IFS front differential (hypoid, 194 mm ring gear)
Rear: Isuzu solid rear axle (hypoid, 194 mm ring gear)
4.555 ratio: All trims

Brakes

Front rotor: 10.14 in, 258 mm
Front caliper piston: 60.0 mm
Rear drum: 10.00 in, 254 mm
Rear: drum

Suspension

Front: double wishbone IFS, torsion bars
Rear: leaf springs, solid axle
Rear layout: Leaf springs

Fuel economy

EPA highway, automatic: 17 mpg
EPA highway, manual: 20 mpg
Rated years: 1984–1991, 4WD

Every calculator, set up for the Trooper

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 Trooper ranks against every stock truck.See where it ranks

Source: archive.org.

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.

Isuzu Trooper1984–91 1st gen