Proper procedure for square taper BB
 

This is how I do it. Can someone tell me if I am doing it right? I lightly wipe a thin film of grease on the square taper, apply blue loctite liberally to the threads, and torque to the required value with a torque wrench. I know there is a huge debate online about greasing tapers but from my own mechanical experience I agree with Sheldon. I like to prevent galling of aluminum on steel.

By doing it this way with loctite, do I need to ride for a few miles and then re torque or just torque once and leave it?

I got stripped dust cap threads on one side (not deep...a puller still engages.....just the outer threads where the cap would thread in) and it would be nice to just leave the caps out. I believe the blue loctite should prevent my nuts from falling off.....while we are on the subject....opinions on this as well?

Not to revive the greased spindle controversy or anything, but the Shimano UN-55 BB I got in the mail recently arrived with the spindles already covered in a thin film of grease. Don't know what to make of that.

I think grease makes sense. The main question I wanted to know about was if I needed to re torque one time after the first ride even with loctite. I just added that I believe in grease

Way back when I learned to use skin oil to lube tapers. Clean both male and females and just before installing the crank arm wipe the tapers with clean fingers. Assemble, test ride, check arm retaining bolt tightness and re check a few rides later. Andy

This is all the lube a square taper crank needs. Bonus points if you use Brylcreem and run your fingers in your hair before wiping them on the tapers.

Seriously though, absent a manufacturer's specific instructions, a dry taper is traditionally preferred. The aluminum of the crankarm is supposed to form to the steel of the axle. A heavy load of grease or anti-seize inhibits that and enables overtightening.

Keep in mind that this "tradition" was because race bikes were serviced regularly, meaning at least every week during the racing season. A greased taper would have allowed the cranks to be overtightened repeatedly, and ruined within a season of racing.

I've never in my life not been able to extract a dry crank from a square taper axle, no matter how long it's been on there. On rare occasions a judicious amount of heat to the crankarm will expedite the removal.

Use either lube, or some anti-seize paste (like "copper grease", or similar) - to make later removal easier. But do lube the square taper axle before mounting the cranks.

Once you've lubed them, put the cranks on, tighten them to the appropriate torque and be done with it. Lube allows them to move all the way up they need to from the first time the bolts are torqued - that's why you should grease the axle.

Bolt should not come loose, even without the Loctite (I don't recommend it), as long as it's tightened to the proper torque.

Why dry mounting makes no sense (in spite of some manufacturers recommending it) is nicely explained on this link:
https://www.sheldonbrown.com/brandt/...ng-cranks.html

Have you ever seen a galled carbon steel spindle or aluminum crank?

I do not agree with trapping the particulate of anti-seize between the tapers. The whole point of a taper fit is that it should be hard to get off - the tapers are doing the work, not the bolt.


This topic is over thought. If you have been using grease at all to assemble the BB, there will end up being more than enough on the spindle. So unless people are removing the last bit of oil from the spindle with acetone, you're going to be fine.


People generally have very few problems with their cranks if they just put them on to the proper torque and leave them alone after that.

I'm a (bike) mechanic. What are you aiming at?

The attachment does not rely on friction to transfer the force and stay in place, but on elastic deformation of the metals. Using anti sieze, especially for alu-cranks is safer for when they need to be removed, than using "ordinary" grease. Anti sieze providing long term protection from galvanic welding, while being still "slippery" enough to allow for proper mounting.

I agree: if an effort to remove any lubricant is not made, the result is practically the same as if it was deliberately lubed. However, I prefer to put some lube, just to be on the safe side, anti sieze paste being my favorite for the reasons explained above.

Most people, most of the time. However, if there's not enough lubricant, proper torque on the bolt will not result in the cranks moving "high" enough and engaging properly, due to friction. That causes bolts to unscrew, cranks to move and the interface gets permanently damaged. For alu cranks - they take all the damage, while if using steel cranks, both the cranks and the axle will need to be replaced.

It's all nicely (and in better English) explained in the link I've posted previously.

That carbon steel and aluminum don't gall against each other. Galling is a stainless or Ti issue.

I've been a shop mechanic since 1990.

I have never, ever heard of using anti seize for something like this, and I could see anti seize preventing the spindle from wedging properly because of the particulate. I've been around awhile, trained with people that have been around far longer, and anti seize is not a thing for this application. You'll have a much greater problem if your crank keeps wanting to move against the fixing bolt instead of just staying put, and anti seize is not designed for press fit type interfaces.

Galvanic corrosion is not a real issue, either. I've seen it other places on bikes, but not on the spindle interface.

Never had problems using the anti sieze - cranks don't slide off because of it. You still need the crank puller to take them off.

Anti sieze paste is designed as a "mounting paste" - can't see it causing problems with engagement. I for one have never had any. No cranks coming loose or anything. After a few years time, however, anti sieze makes removing stuff easier than just using grease in my experience.

I am not an expert by far, but did the same last week. It wasn’t but a film, and as wet as Florida is I figure it helps protect the metal. Maybe my old bearings and races were that bad, but dang this new BB is smooth.

When I say grease I mean a thin film. You can feel it but u can’t see it unless you shine a light on the taper and see the glare. I could see if someone put s large amount on but a thin film shouldn’t hurt anything. Anyways so somewhere a while ago I read that you should use blue loctite on the threads. Even Sheldon says it is normal for a crank bolt/nut to lose its torque so the loctite should keep it from spinning off. According to Sheldon the reason people split cranks is because every time they checked the bolt and it was a little loose they would re torque and eventually the crank would split out.

No dog in the lube fight or the use of Loctite. But in my experience with Loctite I don't like the putting a wrench to the Loctite on the crank bolt which will break the Loctite bond. If you have to check it, clean off the dried Loctire, reapply and re-torque and leave it alone.

Yeah I definitely wouldn't want to re torque once loctite has set up.

I salvage a bunch of square tapered spindles and BBs at the co-op, and I've never seen loctite on any crank nuts or bolts.

Maybe not but what could it hurt. Blue loctite is not permanent and is a little insurance

I do just the opposite - using anti sieze, not a thread locker. :)

Never had problems with cranks, or bolts coming loose (not the ones I had serviced).

Blue loctite can't hurt on the bolt threads. I started doing that for both Campy square taper and Shimano Octalink 1. It might not keep the bolts from moving initially. So maybe recheck them a day to two later. As far as greasing the BB spindle, I don't bother. With rainy riding I still get the usual creaky bike. But I just remove the crank arms to clean them and the spindle. What also helps for creaky bike is having teflon tape on the BB threads. A guy that I ride with gave me that idea and it has helped.

I do not re-torque with or without a thread locker.

Some brands of square taper BBs come with a little blue Loctite on the bolt threads, so they must figure it's a good idea, too. :thumb:

I'm with Kontact on this one.

I use anti-seize on threaded fasteners and connections, unless manufacturer recommendation is for threadlocker. I don't use it where it might contaminate grease like on hub axles (though that would not be a problem because the metallic particles are so much softer than hardened steel balls and races. But it makes it hard to tell what other sort of contamination might be in the grease. So on traditional BBs, I put very little on the shell threads, and wipe it off with a finger. A bit more goes on the cup threads.)
I also use it on slip fits like quill stems and seatposts (metal-to-metal, not CFRP).
I do not use it on interference fits like headset cups, and I don't use it for tapered press fits, neither crank tapers nor crank cotters. They all go on dry.

You'd press an alloy headset into a Ti headtube dry?

It doesn't reach the bearing grease - there's about 1+ cm of axle between them. Of course it should never mix with other greases, especially inside the bearings. It is put on the axle part where the cranks are placed, nowhere near the bearings. Dirt and water are a lot more likely to contaminate the bearings, than the mounting paste - especially if the excess is wiped off after mounting (as it should).

Kontact's argument that mounting paste will somehow hinder the engagement is something that both the theory (it's a mounting paste, that's what it's made for) and my practical experience so far do not agree with. On the other hand, it's better than grease for preventing the interface getting stuck together through rust, and it should provide better protection from fretting damage compared to most "multipurpose greases".

Having said all this - using any old grease should do the job - just not do it "dry" - crank mounting that is. :)

https://www.compasscycle.com/wp-cont...2016_03web.pdf

The grease from a mechanics hand is all you need on spindle.
I use blue threadlocker instead of grease on the threads, and I re-torque one time, without reapplying thread locker.

I've also been a mechanic for decades and would never use Never/Anti-Seize on a spindle face. I lightly grease mine with white lithium grease and have never had a problem with install or later removal. I also have never actively applied Loctite on any BB bolt. I grease or Never/Anti-Seize those. On looseball, it's all white lithium unless it's a winter bike, then I'll use something thicker, like Phil's. And the only time I will ever use Never/Anti-Seize on the cups is if it's a cartridge BB.* I have never even used Loctite on a cup thread as I've worked on way too many bikes where cup removal ended up being quite difficult. I did have someone come to me with an Italian BB that kept threading loose. Instead of Loctite I used a few rotations of plumbers Teflon tape and the problem was solved. BTW, interesting how many guys here use Loctite on all their threads. I literally have rebuilt hundreds of BB's with never a one coming loose at the BB, spindle or crank arm. Good to know how other guys prefer to re-build.




*looseball and a possible touch of Anti-Seize don't make good friends