I recently completed my first fg build. All went well for a few months, til I rode it in some pretty wet and wild conditions. Was making a funny noise, so I took the cranks, bb off, cleaned and put back. Everything was going well, til I noticed one the new crank bolt had come loose. I figured I just hadn't tightened it enough, until today same thing happened but on the drive side. I tightened it up, then took to the forums to see what was going on.
I see a lot of people saying never grease spindle, cranks, bolts (which I had done...). I read this can cause the alloy cranks to lose shape. Is it possible I can just wipe off all the grease, reinstall and go on my merry way? I guess I already know the answer is try it and see how it goes, but if anyone has any suggestions/advice/similar experiences, I'd appreciate it.
Cheers

I'm assuming square taper here:
IME lube or not lube isn't immediately critical - but a sufficient installation torque is.
Not enough installation torque, the crank can begin to wiggle, which quickly damages the interface between BB and crank.
Sometimes, reassembly with correct/more torque is OK to sort things out.
Some have reported success through using various fillers, and then torqueing. Even home made recipes of epoxy and aluminium shavings have been used.
Some even say they've been able to rescue a messed up crank by taking a file and carefully reshaping the crank hole back to square before reassembly.

Yup, square taper. I did wonder about the torque. I used the same torque wrench when I first installed the cranks though, with no probs, so I guess that rules that out. Hopefully it'll all be sweet once I take it apart and wipe the grease off, but I'm not holding out too much hope...thanks for the help

Messing up square taper DESPITE using a torque wrench, that's quite rare.
I wouldn't worry about lube or no lube. I don't think there's an overwhelming majority for either option.

Sorry, I don't quite understand what you're saying. You mean the grease shouldn't have caused the bolts to loosen?

Sorry to sound dim. I read these forums a bit, and half the time I don't have a clue what people are talking about...

without seeing your setup I can only speculate but, Id say you're probably going to be ok. to wear away enough material from your cranks that you have rounded a square hole would be quite extreme. not saying that it cant happen but it would take a bunch of slippage and sloppiness.

I use blue lock tight on my crank bolts. you should too. that will prevent the bolts from coming loose on their own.

That's great to hear, cheers. It's only been about a week since I greased the cranks, so I hope you're right. I'll be sure to use some Loctite, too.

I no longer have any square taper crank setups but when I did (20 + years of them) I ALWAYS USED GREASE on the spindle/arm interface to prevent squeaking.

So keep them greased but loctite the bolts you're saying? Maybe I just overdid it with the grease? A couple of the old threads seemed to emphasise using the slightest amount

It's just that you have stepped into one of those issues that can start flame wars. We haven't seen a good, to grease or not to grease square taper battle here for a while, so hang onto your hat.

ive heard abouth such battles, in books and told by the old folk. I had no problems with my cranks til I applied grease last week, so obviously greasing them is stupid... *turns and runs*

I grease, greatly appreciate the value of Loctite and check my torque wrench calibrations. Bicycle torques have a wide range but a cheap, dropped, never calibrated wrench could give you a false security.

[QUOTE=Danclark;17477128]Yup, square taper. I did wonder about the torque. I used the same torque wrench when I first installed the cranks though, with no probs, so I guess that rules that out. Hopefully it'll all be sweet once I take it apart and wipe the grease off, but I'm not holding out too much hope...thanks for the help[/Q

They should be greased when installed. I believe the proper torque is 25 pound feet. Installing Cranks by Jobst Brandt

Don't worry they don't either.

I don't grease spindles, but I don't degrease them either, and after a loose ball repack, they're often greasy. Factory cartridge ones have rust inhibitors on 'em and I don't clean that off either.

Whether cranks are still good or not depends partly on how much loose riding they endured.

I like to put cranks on, fully torqued, then ride 20-50 miles, then recheck torque.

20-year-old cartridge BB spindles with no grease at all on them work just fine. They don't squeak, never greased them. Had cranks off and back on several times.

I mean that there are plenty of people who do it either way and are fine. Lube or dry does not appear to guarantee either success or failure.
But mounting with insufficient torque is a near-guarantee for the cranks working loose and possibly getting damaged.

In more critical engineering it's sometimes specified whether something is torqued dry or lubed.
Thing is, you have to choose. Can't both lube and threadlock the same bolt.
Although some will say that the threadlock will act as a kinda-sorta lube during mounting.

Make sure that the crank is not going too far onto the spindle (unlikely, but possible). If the spindle is flush with the the crank opening, then the bolt cannot make it tight enough, because the bolt & washer are bearing on the end of the spindle, not the crank arm.

You can verify by tightening the bolt, then removing it to see how much gap there is between the spindle end and crank bolt face.

See the gap between the end of the spindle and the washer/bolt.

I thought we were talking about lubing the faces of the spindle.

But yeah, clean threads well before using loctite

How loose were the bolts?

It isn't unusual for the bolt to loosen up after first install. Just re-tighten and continue.

BTW The same rule applies for lug nuts on a car. After installing a wheel, drive 10-25 miles, and re-tighten. You'd be surprised by how loose (scary actually) even properly torqued nuts can become.

BBTW LesterofPuppets deserved credit for first mention in this thread. Sorry, didn't see at first.

All combinations occur. Probably tried them myself too before I started paying structured attention to what I was doing.
But yeah, the lube on the taper - or not - is the more heatedly debated item.

Wearing a square hole round would indeed be extreme. However, the damage needed to stop a crank from staying on the BB is a lot more subtle. It doesn't take much wiggle for the inside faces of the crank to become slightly convex, and that's enough for the crank not to engage properly any more.

...this ^^^. I have been doing a controlled experiement for the last 20 years, and grease on the taper makes no difference.

But it is not uncommon for a recently reinstalled square taper crank to loosen a little after 50-60 miles of riding.
And it takes very little riding on one loose enough to make a "funny noise" to damage the crank taper faces on the arm to the point where it won't stay tight any more.

Your best shot is just tighten the sucker back on there, with substantial torque this time, and see if it will remain in place without loosening again.