Jeep Regearing

You put 35s or 37s on your Jeep and it felt slower the same day. It hunts between gears on the highway. It downshifts on hills it used to hold. Fuel economy fell off a cliff and the transmission runs hotter than it used to.

Nothing is broken. You changed the final drive ratio the moment you changed tire diameter, and the factory gears no longer match the tire. Regearing puts it back where the engineers had it.

• Hunting between gears at highway speed, especially with the overdrive locking and unlocking
• Downshifting on grades it used to pull without thinking
• Noticeably slower off the line since the tires went on
• Fuel economy down well beyond what the tire weight alone explains
• Transmission temperatures running higher
• Having to work the throttle hard just to keep up with traffic

On a Wrangler or Gladiator, once you are past 35 inches this stops being an opinion. Bigger, heavier tires plus a factory ratio meant for stock rubber is what cooks transmissions.

There is no single right answer, and any shop that gives you one without asking questions is guessing. The ratio depends on four things:

• What you have now — the factory ratio in your axles
• Tire diameter — actual measured, not what the sidewall claims
• Engine and transmission — a 3.6 and a diesel want different things
• How you drive it — mostly highway, mostly trail, towing, or a genuine mix

Tell us those four and we will tell you the ratio and why. A Jeep that lives on I-35 and one that lives on a trail should not get the same gears, even with identical tires.

• Front and rear ring and pinion — both axles, always, so the ratios match
• Complete install kits — bearings, races, seals, crush sleeve or shims
• Proper setup — pattern checked and backlash set, not bolted in and hoped for
• Lockers or a limited slip fitted at the same time if you want them, since the axle is already open
• Fresh gear oil and the correct friction modifier
• Speedometer correction so your Jeep tells you the truth
• A break-in explanation you should actually follow — new gears need it

Gear setup is measured work. It is the one job where doing it fast and doing it right are genuinely opposed, and we do it right.