Universal Spares — All Vehicles
These spares belong in every rig. Carry them regardless of platform.
Driveline
- U-joints — 1–2 that fit your driveshaft; both sizes if front and rear differ
- Driveshaft slip yoke grease — lithium grease
- CV axle boot repair kit — if applicable
Cooling
- Radiator stop-leak tablets — Bar’s Leaks
- Upper radiator hose — OEM equivalent
- Thermostat + gasket
- 1 gallon premixed 50/50 coolant
Belts and Hoses
- Serpentine belt — write the exact OEM part number on the bag
- Lower radiator hose
Electrical
- Fuse assortment — blade style, 5A–40A; double your tools kit
- Spare relay — 87/30/85/86 style
- Spare bulbs — headlight fitment, brake light, turn signal
Fluids
- Engine oil — 2 quarts correct viscosity (label it)
- Power steering fluid — 1 qt
- Brake fluid — 1 small bottle DOT 3 or DOT 4 (label which)
- ATF — 1 qt if automatic (label the spec)
- Gear oil — 1 qt 75W-90 or 80W-90
- Transfer case fluid — 1 qt (label the spec)
Fasteners
- Grade 8 bolt assortment — M8, M10, M12 in common lengths
- SAE bolt assortment — 3/8-16, 7/16-14, 1/2-13
- Nylock nuts to match
- Cotter pins — assorted
- Safety wire — stainless, .032"
JK-Specific Spares
The JK has a short list of high-probability failures. Know them before you go.
TIPM fuel pump relay bypass harness — carry this in the cab
The TIPM (Totally Integrated Power Module) is the JK’s most notorious failure. It can strand the vehicle by killing the fuel pump relay circuit. A bypass harness ($30) plugs in under the hood and runs the pump directly, bypassing the TIPM entirely. This is a proven field fix. It’s the single highest-value spare on this list.
Vacuum cap plugs for the CAD actuator
The disconnect axle vacuum line cracks with age and heat cycling. If the vacuum fails, the front axle won’t engage or disengage cleanly. Vacuum cap plugs let you lock the front in or out manually until you can replace the line. Costs $5. Also carry Rubicon locker actuator O-rings if equipped — they fail and are a known rebuild kit item.
Track bar, drag link, front upper control arm bolts
JK death wobble is as bad as it sounds and as common as it is on the XJ. If you’ve felt any shimmy at speed, carry the track bar (OEM or aftermarket, whichever is on the truck). The drag link bends on rock hits. Front upper control arm bolts back out — carry two.
Bar’s Leaks Copper tablets (3.8L specific concern)
The 3.8L has a known head gasket issue between cylinders 1 and 6. Carry Bar’s Leaks Copper tablets — not a fix, but they get you to a shop. Also carry the water pump if the weep hole plug has ever shown moisture.
Timing chain tensioner awareness (3.6L)
The 3.6L Pentastar is more reliable than the 3.8L. The known issue is a cold-start tick from a faulty tensioner on early engines. If your engine ticks cold, carry the updated tensioner part number — it’s a cheap hedge.
Universal exhaust clamp
The JK belly is low. If you run without full skids, the catalytic converter and midpipe are common rock strike points. A universal exhaust clamp is a field fix for a cracked flange or separated joint.
Correct fluids — double-check your powertrain spec
3.8L: 5W-20. 3.6L: 0W-20 (don’t mix them). Dana 44 Rubicon (front and rear): Mopar Friction Modifier + 80W-90. NSG370 manual: Mopar-specific fluid only — it’s picky, don’t substitute. NP231 transfer case: ATF+4.
JK Field Verdict
JK Field Verdict
The TIPM bypass harness is the single most important item on this list. Buy it, put it in the glove box, and never think about it again — until you need it. After that, focus on death wobble hardware and the CAD vacuum system. The rest of the list is standard off-road prep.