Don’t Ignore the Grind! How to Shim a Jeep Starter Like a Pro
If you’ve ever turned the key and heard that heart-stopping metal-on-metal grind, you likely have a shimming issue. In Jeep Mods E12, we took a deep dive into replacing a dead starter and why getting the gear alignment exactly right is the difference between a smooth start and a ruined flywheel.
🛠️ The Technical Tool Kit
To do this right, you need the technical baseline tools. Don’t try to eye-ball gear clearance.
- Jeep Starter Motor: The direct replacement unit.
- Starter Motor Shims: Essential for adjusting the gear gap.
- Husky Mechanics Tool Set: You’ll need the 1/2″ and 5/16″ sockets for the wiring and mounting bolts.
- Milwaukee 18V Impact Driver: For pulling those mounting bolts quickly—especially if you have to pull the starter multiple times.
🔧 The “Forensic Sharpie” Trick
One of the hardest parts of shimming a starter is knowing if you’re too close or too far from the flywheel. Here’s the “Chris Does What” forensic method:
- Color the Teeth: Use a black permanent marker to color the teeth on the new starter gear.
- Pull the Coil Wire: Disconnect the coil wire from your distributor cap. This allows you to turn the engine over without it actually firing up.
- Analyze the Wear: After cranking for a few seconds, pull the starter back out. The wear marks on the black ink will show you exactly where the flywheel gear is hitting.
- Hitting the bottom of the tooth? You need more shims to push the starter away.
❓ Frequently Asked Questions (FAQ)
- How do I know if I need starter shims? A high-pitched whine usually means there is too much gap. A heavy, labored grinding sound means the gears are too tight. Use the Sharpie trick to verify the contact point.
- Why did my new starter still fail? As Brandon found out (after pulling the starter 8 times), sometimes “new” parts are just defective. If your shimming is perfect but the solenoid isn’t engaging the flywheel consistently, swap the unit out.
- Is it safe to work on the starter with the battery connected? Negative. Always disconnect your positive battery wire first. Touching that live lead to the frame will give you a “shocking experience” you won’t forget.