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Thread: Replace Engine Bearings

  1. #1
    I beat out of love. AliveoutofSpite's Avatar
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    Default Replace Engine Bearings

    So, with my recent foray into removing bearings, I ran into an issue (operator error, not with the procedure). I realized then that BYT didn't have a bearing replacement how-to.
    Having fixed the issue on my first engine, I commissioned a professional photographer (no, seriously) to document me doing my second engine so I could do a nifty little write-up.
    Mods, please sticky for ease of finding.
    If I missed anything or goofed, please let me know via PM rather than post; I'd like to keep this thread 'clean', please.

    Step 1- Slated for disassembly. This is when you should put your new bearings in the freezer. I'll explain that later.


    Step 2-Preheat it, Betty Crocker! 350 should do the trick. By time you're done cleaning your engine, it'll be nice and hot.


    Don't forget to check the oven before you preheat. Fires in the kitchen suck, and the woman in your life will NOT be happy.


    Step 3- Gotta...get...clean! I prefer to clean AFTER disassembly because you can get to ALL the dirt more easily (no more little cracks for it to hide in or parts to hide behind). Make SURE you dry all steel parts (crankshaft, starter shaft) as rust is evil.


    Step 4- Get to bakin'! Just put it on the rack for about 10 minutes.

    In the mean time, pop a few potatoes into the next neighborhood!


    Step 5- Ding, Fries are done! It's a tad warm, so oven mitts are a necessity. Unless you're Chuck Norris, but then you wouldn't have to do this anyhow, because no bearing would even think of going bad on Mr. Norris.


    Step 6- Push it. Using (carefully!) a screw driver, push the front bearing out. Or, if you have something else that will fit that's not metal and you feel better using, go with that. The screwdriver worked for me.


    Step 7- Beat it, just beat it... Lesson learned from this-preferably on a block of wood on the counter, not just on the counter. Now I have to come up with a good excuse why the coffee maker is at the edge of the counter. Just smack it a few times, and it should come out. If not, repeat the baking process and try again.
    Another alternative, if you still can't get the main out, is to use a wooden dowel and large screws. Make sure the dowel will just barely fit into the main, and from the front side, drive a screw (or several) into the front to expand the dowel into the bearing. A quick tug should do it, but make sure the block is still hot. (Thanks to Kevin Van for the tip!)


    Step 8- Back into the fire. Pop the block back in the oven for a few minutes, so it stays nice and hot. In the time you had it out, it will have cooled off quite a bit, causing it to contract and making putting the bearings in difficult.

    Step 9- Fire and ice. Take the bearings from the freezer, and the block from the oven. The front bearing can be tricky, if it's not aligned straight it will bind.
    The main bearing is easier. Once the front bearing is in, slip the main bearing onto the crankshaft. This will make sure it goes in straight, and easily. The front part of the crankshaft
    will be held in line by the new front bearing. Just slip it in, and if needed, use the handle of a small screwdriver to tap it into place.
    Now here's the explanation I promised- Heating the block expands the Aluminum. Al expands at a rate faster than the steel bearings, so they pop out easier. The new bearings go into the freezer for the exact opposite reason-they'll contract. This just helps make installing them easier.


    Step 10- It's all coming together... When the block has cooled enough to handle, lube and reassemble. I use WD-40, but your favorite ARO is perfect also.


    As an added measure of leak-security, break out the trusty RTV and seal it up, now that it's all clean and apart. A small bead around the carb, cinch bolt, backplate and your starting device (Roto Start, Tiger Drive, EZ-Start, Pull Start, and whatever-Start I missed.). Threadlock is also a good idea. Always use a star/cross-pattern when torquing AND loosening backplates, cooling heads, etc. This will prevent possible warping.

    Step 11- Operational Re-test!
    Burn it up, baby! Taped tires not required, I was just messing around with a little drifting.


    I hope you guys find this useful!

    And, a special thanks to Brigit from Timeless Photography for taking my pics!
    Last edited by Chris; 09-11-2009 at 08:41 PM.
    BEAT. FIX. REPEAT.
    Warning: Objects in the air are more screwed than they appear.
    S.C.A.Bs-South Carolina Association of Bashers
    There is a long way, too long, that I have to travel.
    Quote Originally Posted by RCJohn View Post
    i did something pretty stupid the other day as well. i went out with my crawler and thought that the esc was all buggered up cause every time i hit the forward it went backwards and vice versa. when i got home i took it to the bench... i put the body on backwards

  2. #2
    BYT ring leader Chris's Avatar
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    Default Re: Remove and Replace Nitro Engine Bearings

    A big thanks to AliveoutofSpite for doing such a nice writeup on this! Thanks dude!

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