This question comes up from time to time. Having just done it, I figured I’d post the process for people to learn from / improve on.
If you follow this, it should take you no more than 15-20 minutes to remove two pinion gears that were secured with Loctite 638/648 High Strength Retaining Compound without percussive maintenance (hammers), giant pry bars, or struggling.
Tools:
-
Aluminum foil
-
THIS Gear Puller - Lisle 54150 Battery Terminal and Wiper Arm Puller . It has thinner arms that can slide into the tight space between pinion and mount.
-
Blow torch [A handheld lighter does not get hot enough] - I use the Bernzomatic Premium Torch Kit, $54 but you could probably get away with a regular propane cylinder just fine (Bernzomatic Torch Kit, $20). This is also really useful if you ever need to braze anything (next level soldering).
-
5 small (~6-8mm dia) neodymium magnets (what I had within reach) or a similar standoff (or just remove the tip of the puller)
-
Small flat head screwdriver, just in case
Guide:
-
Gather all your tools. DO THIS OUTSIDE. Do not catch yourself or your house on fire fucking with a blowtorch. And protect anything that can’t get hot - the rest of your board, battery, etc
-
Get a generous amount of aluminum foil, rip it off, and fold it over and over. The final product should cover your drive assembly. Aluminum conducts heat quite well, but the air pockets in your foil sandwich act as excellent insulation. More layers the better.
-
Poke a hole in your foil with your screwdriver. Make the hole big enough for your pinion gear, but just barely.
-
Install. This protects your assembly (and motor) from heating up.
-
Test your torch safely. Make sure you know how to use it and it works, no leaks, no smells. OUTSIDE
-
Aim your torch at the loctited shaft and hit it for about 10 seconds. The hottest part of the torch flame is the tip of the inner flame, so you want your torch pretty close.
-
The top layer of foil will burn/melt, but your mount should be cool enough to touch immediately after you finish if you have enough layers (BE SMART, DON’T BURN YOURSELF.)
-
Install your magnets/standoff to the tip of the gear puller, so you have enough travel to pull the pinion completely off the shaft before bottoming out on the larger diameter puller tip. Magnets make it easy because they stay in place while you’re working.
-
Install your gear puller. I recommend you adjust your puller to the right size before you start all this, so you’re not fiddling around too long.
-
Pull
If your key is stuck in the keyway, now is the time to carefully wedge your flathead screwdriver into the crack and pry it out.
Congrats! You’re done. Right tools, right job (results vary dramatically if you choose to half-ass this with other non-ideal tools). Time to install helicals / new pinions / disassemble / whatever.
