Bottom Bracket Maintenace (photo heavy)

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Vital BMX member sundaybmxRR
8288 sundaybmxRR,8288/all 07/13/07 237 236 109,8288/setup 340 11317 1227 20 663

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Joined: 7/13/2007

Location: Hanover, PA USA


3/24/2014 4:57 PM

Okay, some of you may remember my Headset Maintenance thread. This will be the same deal, for future reference for anybody wanting to do routine maintenance to their bottom bracket. I remembered to take photos after I already took the cranks off, so before you start make sure you do that. Always use the correct sized tools & if your cranks have a pinch bolt, always loosen that one first, then the main bolt! Let's get started with what you'll need

6mm allen key (or correct sized allen key(s) for your crank)
A small razor & small flathead screwdriver
Rubber mallet
(Optional) Loc-tite if your cranks don't stay tight

I used a rubber mallet to take my cranks off, that fucker was on there. Laid out my cranks & BB spacers

To get started, wipe down the bearings on the outside, this way when you pull the seals off, more dirt won't get inside the bearings. Also check to make sure the internal spacer is still good. Sometimes they can deform & won't make proper contact.

Next you wanna take the small razor, or something that can pop the seals off without messing them off, and slid it into the small crack & just pop it off.

Wipe the seal down

and wipe out the bearing, sometimes the screwdriver can be used here to get into the little areas

With everything wiped down, put some grease in there. Using the screwdriver helps get it in there better if you have bigger fingers, or just can't seem to get it to stick in there

Pop the seal back on & as you can see, there's some excess grease so just wipe that down & repeat the process you just did to this bearing to the other one

Wipe down the inside of the BB to remove any dirt in there also

Next, take the sprocket off. Should've mentioned this earlier, loosen the sprocket bolt before you take the cranks off. It's sometimes easier. So remove the sprocket & wipe down the spindle

Also wipe down the sprocket & sprocket adapter, loose dirt in there can cause creaking noises!

Next, wipe down the area in the crank arm(s) that makes contact with the spindle. I have the Thunderbolt cranks so obviously I don't have 2 sides to do, but do this to both of your crank arms thoroughly. Lots of times with 48 spline cranks, dirt can sit in there causing creaking noises. So be sure to wipe that down really well!!

And finally for us Wom/Twom/Thunderbolt users, clean up the wedge!

Now we start putting it back together, so we'll start with the sprocket. Put a tiny tiny lick of grease on the adapter where it meets the sprocket, and also on the crank arm if using the Wom/Twom/Thunderbolts where the sprocket will be sitting.

Horrible photo, but put the sprocket bolt on (put a lick of grease on the threads!) & thread it in but not all the way! A lot of times, people will tighten it right up the whole way, but this can cause the sprocket to appear bent since it can cause the sprocket to not sit evenly. So tighten it up, but leave it backed out a little bit like so

Next we'll put the drive side spacer on against the sprocket, and lightly lube the spindle up so it slides through the BB easier. Little extra grease in there can't hurt, but the majority of it will just push out as you slide the spindle through

Go ahead & slide the spindle through and put the spacer on & lube the splines. This goes for any type of crank, always ALWAYS lube the splines on the spindle thoroughly

And for us Wom/Twom/Thuderbolt users, slide the wedge cluster on correctly & give that a lubing as well! Then just slide the crank arm on

With the crank bolt cleaned off & lubed (or even loc-tited), tighten the cranks up & as you snug it up slightly, be sure to go back & tighten the sprocket bolt up! A thing I like doing with the sprocket bolt is making the sprocket rest against the bolt as if it were being cranked on, then tightening that up. That way it can't shift during pedaling or pedal pressure tricks. With that done, go ahead & tighten the cranks up the rest of the way!

Personally, I put a bit of loc-tite on the bolt because mine had a tendency to come loose in the past. Hope this will help a lot of people in the future, thanks for viewing!


Vital BMX member Dennon21
109887 Dennon21 /images/default/avatar/c50.png,109887/all 01/19/14 19 116

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Location: CAN

3/24/2014 8:05 PM

Just did this, thanks!


Vital BMX member mitchovich
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3/24/2014 8:06 PM

I already knew this but it's a great guide and if I didn't know how I'd of learned it. Nice write up

"Of course theyre compatible theyre cranks"


Vital BMX member isnowyaznV2
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Location: Elk Grove, CA USA

3/25/2014 12:23 AM

Kinda common sense but great tutorial for the beginners. And don't take the seal off and re-grease the bearings so much unless they're feeling gritty! Some people tend to use more grease or less than others, but I'd suggest grease mainly on the splines and bolts out of all things, which is already basically the whole crankset, haha.

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Vital BMX member T-rider
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3/25/2014 7:25 AM

Great tutorial!



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Vital BMX member Shockster585
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3/26/2014 6:12 AM

Nice tutorial! and just a tip if your bearings are REALY dirty inside you can take some type of degreaser, finish line speed clean, gasoline, etc before you grease em up so there extra smooth dont do it to much to bb bearings cuz those dont get that dirty compared to Ur headset just a little tip.