I used 600 grit clover compound on a bottom bracket
 

Today I used some 600 grit "Clover" silicon carbide impregnated grease (valve grinding) compound to on the fixed and adjustable cups of a Shimano BB-7410 bottom bracket that I'm getting ready to use. I bought the bottom bracket used off ebay - its the 103mm square drive one that goes with Dura Ace FC-7410 8-speed cranks.

The aluminum bottom bracket cups were corroded onto the steel body of the sealed bottom bracket. It took me quite a while just to get the seized cups separated from the body. But once I did, the corrosion and residue of some thread locking compound was so nasty that I had to resort to abrasives to smooth out the mating surfaces. I actually used some fine emery cloth then moved onto the 600 grit Clover compound. The cups were like an interference fit even after the corrosion was gone and even as the surface became more polished. I kept rotating the mating parts back and forth against each other with a generous amount of the Clover compound until I was satisfied that I could assemble and disassemble the parts by hand with minimal persuasion every time. I may have even gone a little overboard and induced the slightest amount of slop into the equation.

Anyway, I just thought I would share a shop application for valve grinding compound in bike mechanic work.
Does anyone know of other bike mechanic applications for this product?

One other question, was it Shimano's customary practice with their sealed bottom brackets to use adhesives or permanent loctite on the aluminum fixed or adjustable cups? If not, I'd say the former owner of this bottom bracket nearly butchered what should be a very serviceable sealed bottom bracket. :mad:

Very interesting concept. Poor mans tap and die! It makes sense, because you are doing with an abrasive what a tap and die do, taking off material that shouldn't be in the threads, albeit in a crude way. I'm going to try this, thanks!

I guess I made it sound like I was cleaning up threads with the fine abrasive, but no, what I'm talking about is different. I'm talking about what should be a smooth inner surface of the fixed and adjustable cups. this is the part the secures the sealed bearings. I didn't like the corroded in one fixed position condition. I want to be able to put some quality grease on all the parts when I reassemble the thing and have it go together slick without any binding so that I know I have done a quality install. I think tomorrow morning I will take a picture to illustrate what I'm talking about.

Taking abrasives to the threads would maybe smooth off the burrs and the high spots, but would make a mess of all the nooks and crannies.
:)

Good idea. I'm wondering if a wire brush could be used to accomplish the same.

Maybe a superfine brass one on a bench grinder for the outside diameter corrosion. For the internal corrosion maybe a fine brush on a dremel. I tend to shy away from using wire brushes on dremels for several reasons: 1) they're really little and individual wires start breaking off and flying everywhere pretty quickly 2) they get ruined in like the first minute when the rotation of the dremel makes them bend back away from the rotation of the Dremel. I guess if Dremel or one of their competitors would realize that what is needed it a REVERSE setting on one of these things to balance out the wear. 3) they cost like $5 each - not at all cost effective.

A Dremel is really too fast for that. The Dremel speed control may have a reversing switch; I don't have mine any more so I can't look.

A big problem with using a wire brush or any non-rigid tool to grind/polish is that you get cycloidal patterns in the work because the tool oscillates at the system's resonant frequency. Once the patterns start, changing the frequency won't even help. If you've tried to drill an unguided hole, even with a drill press, you've seen the problem. The hole is anything but round.

Great idea with the compound.

Campagnolo grease has an ultra-fine abrasive in it to provide continuous polishing of the bearings, which is why Campy hubs always look so good when you take them apart.

Here's a picture of the bottom bracket: http://i5.photobucket.com/albums/y17...1/IMG_2246.jpg

This should give folks an idea of why I need the grinding paste. If you look at the left hand parts you'll see corrosion and some kind of leftover adhesive. When you look at the right hand side and right hand cup notice that most all of that has been carefully removed.

It looks like half of this bottom bracket came new with the adjustable cup semi-permanently affixed to the body of the bottom bracket. Or did the former owner just glue the thing in place? I'm a little baffled.

Tell me what you think.

It could have been in the weather laying on its side.

I have similar Shimano cartridge BB (square-taper spindle, from 1995/1995) and the right-hand cup was permanently affixed (the side with the flange that prevented the BB from being threaded too far into the BB shell.)

That BB looks like the exact opposite of what i imagined-- it appears as if the adjustable cup had been glued/corroded in place and the fixed is clean as a whistle!

Weird.

How'd you remove it?

Doesn't look like corrosion to me; looks more like dried-out gunk of some sort.

I'd try a soft wire brush or even gently scraping with a straight-edge (like a putty knife) first.

I bought it off ebay for about 24$. I was expecting it to be in better condition. Sometimes you just learn your lessen and wind up with something sub-par. The clean side looked just like the dirty side. It got clean thanks to the procedure I'm talking about in this thread. I believe the former owner must have removed the drive side (fixed cup) then just threaded out the whole bottom bracket out of the other side, so, yes, it appears to be the opposite of the normal convention.

I'm pretty sure that the side with the groove cut in it is the side that's supposed to come off. Old XT-level and above bottom brackets had the other side stuck on with some blue loctite-type stuff. They were never stuck on all that tightly when they were new. You could usually hang the BB from the jaws of a loose vise (with the flanges sitting on the jaws) and gently tap the center section out with a hammer.

When building nicer bikes in the shop, I'd tap the "fixed" cup off and grease the inside. This not only prevented the situation you ran into, but it also helped prevent squeaking that could sometimes develop in there.

Speaking of which, I wouldn't go too crazy getting the corrosion off. Those cups are supposed to fit snugly. Once you tighten the cups down, you should be ok, but any free play is asking for trouble. I'd just grease it liberally and put it back in as-is.

why not buy a new one? I'd throw that garbage in the garbage.