Universal Spares — All Vehicles
These items belong in every rig regardless of year or platform. The TJ-specific failures follow below.
Driveline
- U-joint set — matched to your driveshaft (front and rear)
- Slip yoke eliminator hardware — if you’ve lifted more than 3"
- Differential cover gasket — carry one per axle
Cooling
- Thermostat + gasket
- Upper and lower radiator hoses
- Coolant (premixed) — 1 gallon minimum
- Radiator stop-leak — field emergency only, not a repair
Belts & Hoses
- Serpentine belt — exact match to your year
- Heater hose sections — 3/4" and 5/8" ID, 12" lengths
Electrical
- Full fuse assortment — blade type, 5A through 40A
- Spare relay set — 30A and 40A, SPDT
- Crank and cam sensor — if your rig is over 100k miles
Fluids
- Engine oil — 1 quart, matched to your viscosity
- Gear oil 80W-90 — 1 quart for axle emergencies
- Brake fluid DOT 3 — 8 oz
- Power steering fluid — if equipped
Fasteners
- Assorted M8, M10, M12 bolts and nuts
- Grade 8 hardware assortment — 3/8" and 1/2"
- Cotter pins, various sizes
TJ-Specific Spares
These items address failure modes that are specific to — or significantly more likely on — the TJ platform. Build and tire size affect which of these you actually need to carry.
Crankshaft position sensor (CPS)
Same failure mode as the XJ. The CPS dies in heat, the engine stops, and it won’t restart. Under $20, part varies by year — write the part number on the bag before you go. This is the TJ’s highest-probability strand.
Upper radiator hose + thermostat
Same 4.0L engine as the XJ. Same cooling habits. Carry both.
Front axle U-joint set (Spicer 5-760X)
Dana 30 front joints wear fast with larger tires. If running 33"+ and pushing the front axle hard, carry a U-joint set.
Rear axle shaft (Dana 35)
Dana 35 rear shafts snap under aggressive locker use or with 33"+ tires. If you’re running a locker and bigger tires, carry a spare shaft. Write the part number on it before you leave. This is the TJ’s second-most-likely mechanical strand.
ASD relay
Same relay, same failure mode as the XJ. Carry one. It’s the same part.
Body Control Module (BCM) awareness
TJ BCM issues are documented and can cause intermittent electrical gremlins. If your TJ has had unexplained electrical issues, carry a spare BCM programmed to your truck or at least know the reset procedure.
Contact cement + zipper repair kit
If running a soft top on dusty or brush-heavy terrain, the zipper teeth are the first casualty. Contact cement handles seam repairs.
Correct drivetrain fluids
Auto: ATF+4. Manual: check your transmission type. NP231 transfer case: ATF+4. Dana 30 and 35: 80W-90 GL-5.
TJ Field Verdict
The Dana 35 rear under load is the TJ’s most common trail failure once you add a locker and 33"+ tires. It’s not a matter of if — it’s when. If your build qualifies, carry the spare shaft. The CPS costs $20 and prevents the most common strand. Those two items define the TJ trail parts list.