Is there a fix for rounded square taper cranks?
 

Long story short, I was dumb and didn't tighten my Deore LX crankset enough when I installed it. It got rounded and now it creaks. Is there anything I can put between the BB spindle and arms to stop this? Or do I need a new crankset? By the way, I use a torque wrench now... :(

Re torque the crankset and use a bit of tri-flow lube :thumb:

Probably won't help. New crankarms and a torque wrench are the only real, permanent solution.

You can also buy single crank arms.

maybe new current manufactured cranks left arms , are sold ,
got a loose sense of good enough ?,
then just matching the length will do, even if they look different.

Lube and more foot-pounds; your gear's already kinda junked so it won't really matter unless you overdo it.

If it's the drive side you may need to readjust the FD.

I've read you're not supposed to put grease on the BB spindle. The normal oil from your fingers is enough. I only grease the BB spindle bolts and the pedal threads. I've greased the cartridge BB cups too, makes removing them much easier. Chris

yeah, grease the threads, not the spindle itself.

I had the same thing happen a couple years ago. Torquing it down more (about 20 in/lbs over spec) worked.

There was a $20 BB on that bike though. I might be hesitant to go over spec on a fancier BB.

Just keep tightening it up,it will broach the hole out.Keep checking it until it holds torque or the crank bottoms on the spindle.Depending on how bad it is,it may work,it may not,it may split the crankarm,worth a shot.

loctite 609 on the spindle

You might try some Loctite 222 (purple) or 242 (blue). Barnett's suggests that this will help seal out dirt, reduce creaking and not increase the removal force. Just be sure to clean all of the grease off first and then wait for it to set up before riding (they say 24 hours).

I've been using the blue loctite on my square taper cranks for several years now and they have not loosened and have not been difficult to remove. It will take a little more work to clean the cranks and bb the next time you overhaul them.

Barnett's also suggests a stronger version of loctite (RC680) for badly damaged cranks.

Nothing at all wrong with using grease. I can't think of a single reason why oil would be any better than grease for this application. The whole point is to avoid a dry galling of the aluminium socket of the crank arm against the steel of the BB axle. Any lube will do but grease stays in place a little better and provides more protection and is longer lasting for avoiding galvanic corrosion. It's all I've ever used on my BB axles and none of my bikes has suffered from any BB axle to crank arm woes of any sort.

No it won't. If the metal has been swaged out so it's all bell'ed out then tightening it harder won't do diddly. You're talking about cold pressure forming of the socket. "Broaching" is a cutting action. But poor terminology aside the socket is damaged from riding it loose so the ends are belled out and won't come back. If you force the arm on with excessive torque you will only end up with a small contact area in the center holding things in place. Not anywhere near enough to deal with the racking forces at work in a hard pedalled crank arm.

Only fix is replacement.

Seen a customer who tried the overtightening 'fix' on his rounded out cranks. Every other week he had to keep retightening, and the hole kept getting bigger. he'd use a pneumatic socket wrench. eventually gave up and showed up at my shop when it bottomed out and was still loose. Pretty darn scary, his cranks were at near 135degrees from one another...

Also seen a hilarious attempt, customer attempted to drill holes into crank arm then screw sheet metal screws into it to try and squeeze down on the spindle...

and another involving wood glue.
:rolleyes:

Just replace it.

Gnarly. That guy must've had a full on wobble, not just a creak. I've had those before. Had to retighten every ride. Until replacement.

My recent one was just a minor creak. I don't think I got my left crankarm on good enough on initial install. Creak developed. I cranked it down as described in post #9 and it's been good ever since. Logged about a hundred miles on her this weekend alone. Cranks are quiet as a mouse and solid as a rock.

I never lube the facets of a square taper BB, but I never strip them of factory lube or rustproof prior to assembly either.

Of course there have been lengthy arguments about whether to lube the tapers or not in the past.

Thanks all for the responses. I've read plenty of grease/no grease arguments for the taper, but that wasn't the problem here. I simply didn't tighten them nearly enough. When i torque them to spec now they creak immediately, so as I feared, they are probably shot. Both sides too, not just the left arm.

Oh well, lesson learned.

If it moves and it shouldn't: JB Weld.