How to Build a Mud Bog Truck

by Phil Whitmer
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race image by krysek from

Mud bogging, also called mud racing or mud drags, is a popular form of off-road four-wheel drive truck racing. A long narrow pit of slippery mud is prepared beforehand for the trucks to plough through. There are different types and lengths of mud bog tracks; most are flat, while some have hills and holes. The winner is determined by the distance traveled or by times if the full length is covered. The American National Mud Racing Organization (NMRO) oversees the motorsport and determines class and safety rules. A competent mechanic with a properly outfitted shop can build his own mud bog racing truck.

Step 1

Get a copy of the American NMRO list of recognized classes to determine the type of truck you will build. Study the allowed engine sizes, motor modifications and tire sizes of each class before you start working on your truck.

Step 2

Set up a shop with plenty of room to work on your truck, preferably one with a professional shop-size hydraulic lift jack or a grease pit. Assemble a full set of mechanics tools. Locate a parts supplier dealing in stock and modified parts, including aftermarket racing and off-roading parts.

Step 3

Buy a truck to modify according to the class you want to race in. Get a truck with the appropriate engine size and preferably an automatic transmission to keep the wheels spinning in the mud.

Step 4

Raise the body, engine and power train above the wheels with a suspension lift kit of modified leaf springs. Get an inexpensive, entry-level lift kit if you are a beginner, or a higher quality more expensive kit if you are a serious competitor.

Step 5

Install numerically low differential gears for the appropriate mud racing wheel speed. Put in a limited slip differential or a locking differential to maximize engine and tire performance. Outfit the differential with a set of lockers to control traction. Add inexpensive and easy to install spool or mini-spool lockers if you are on a budget.

Step 6

Prevent hydrolocking of your mud bogger's engine by using a snorkel system to raise your air intake well above the level of mud and water, or reroute your air intake to draw from inside the vehicle's cab. Seal your electrical components, controls and connections with silicon to keep the water and mud out.

Step 7

Modify your engine with performance parts and tuning to add extra horsepower and torque according to the class regulations. Buy and install appropriate sized mud tires or cut and modify your existing tires. Slice the upraised tread on tractor type tires to increase traction.

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