Crank bolts keep loosening

[MMcG]

So here's the deal.

My Karate Monkey has some LX cranks on it, Liam's Kona has some Deore cranks on it. On both bikes I've been having problems with the crank bolts loosening up after a decent ride.

Did I do something wrong while installing them, or is this a common issue with these older (but not super old) Shimano cranksets?

I make sure to tighten things up before each ride, but I keep thinking that I shouldn't have to do this before every ride.

Any advice?

[binary visions]

I'm a bad mechanic with my cranks and bottom brackets.

I torque the crap out of them because I hate creaking bottom brackets and I had a crank bolt back out on me mid-ride, causing half the splines of my crankset to shear, and it scares me to think what would have happened if I had been doing any kind of decent drop or riding fast when it happened.

Not that I necessarily recommend it, just saying how I keep that particular item from backing out. You can try a dab of blue loc-tite and see if that solves the problem.

[MtnBikerChk]

So here's the deal.

My Karate Monkey has some LX cranks on it, Liam's Kona has some Deore cranks on it. On both bikes I've been having problems with the crank bolts loosening up after a decent ride.

Did I do something wrong while installing them, or is this a common issue with these older (but not super old) Shimano cranksets?

I make sure to tighten things up before each ride, but I keep thinking that I shouldn't have to do this before every ride.

Any advice?

are the bolts old? are the cranks old?

[MMcG]

are the bolts old? are the cranks old?

Not that old.

[patineto]

Mark are the cranks and BB square taper or the octalink kind...!?

if they are square taper start by cleaning the taper piramide extremlly well and then make sure you have the Four surfaces flat and paralel to each other (in pairs oviuslly) yes they have a radius at the edges, but if they are worn out the whole taper will look somehow rounded it..

if roundness is the case is not much you can do unless you are a master with the hand file and can revive the tapers to be paralel again (I have done it out of necesity but is very dificult) plus the cranks seat closer to the Bottom bracket, sometimes much to close...


torquing, or ussing locktyde for the bolts is only a temporary measurement since the forces at the cranks are pretty intense, also make sure you don't have Titanium crank bolts since the stretch (elongate) if you do have titanium just use steel bolts first to set the cranks all the way in and then install the steel bolts in for riding...


Ps: I never got the Stems,, did you send them...!?!?

[MMcG]

Ricardo - check your email.

and your Private Message box is full - you need to clean it out.

Cheers,

Mark

[dirtydirtysouf]

try the red loc-tite instead of the blue.........blue is good for anything you have to take off with a screwdriver, but if you have to use a socket/wrench use red...........much stronger and vibe resistance

[binary visions]

:nono:

Don't use red loctite for anything you don't want to be permanent.

[MtnBikerChk]

:nono:

Don't use red loctite for anything you don't want to be permanent.

AGREED!

[MMcG]

Even I know the pitfalls of red loctite. ;)

[skatetokil]

My cranks do this as well. My theory is that they were undertightened when the bike was built (got it complete from a shop) and I didn't notice until my crank actually fell off while riding. This screwed up the splines so now it comes loose much easier. I just try to remember to crank on it pre ride, but eventually the bb and cranks are gonna need replacing.

[binary visions]

Red loctite should come with an End User License Agreement:

"The user agrees not to hold Loc-Tite Corporation responsible in the event that applicable threads become bonded together, with the strength of ten thousand men, for all eternity, and can only be seperated by explosive devices. The user also agrees not to hold Loc-Tite Corporation responsible for any damages, mental or physical, that result from screaming, swearing, stomping, bashing or the breaking of tools while trying to seperate the aforementioned threads."

[dirtydirtysouf]

:nono:

Don't use red loctite for anything you don't want to be permanent.

everyone says that but i have never had a problem with getting red loc-tite to break loose when i needed it to................i use it to keep my lugnuts on my jeep from falling off when wheeling, but have never had a problem taking them off when i had to change a tire out in the woods..........

[dirtydirtysouf]

Red loctite should come with an End User License Agreement:

"The user agrees not to hold Loc-Tite Corporation responsible in the event that applicable threads become bonded together, with the strength of ten thousand men, for all eternity, and can only be seperated by explosive devices. The user also agrees not to hold Loc-Tite Corporation responsible for any damages, mental or physical, that result from screaming, swearing, stomping, bashing or the breaking of tools while trying to seperate the aforementioned threads."
:rofl: :rofl: :rofl: :rofl:

[binary visions]

i use it to keep my lugnuts on my jeep from falling off when wheeling, but have never had a problem taking them off when i had to change a tire out in the woods..........
THAT'S what you use it for? Well no wonder :p. Big bolts, big threads, steel, and a big wrench. You can put a lot of torque on that.

Have you used it on a bottom bracket or another small bike part? The splines in a bottom bracket are pretty shallow and small, and the lightweight allen bolts... I mean, there's a pretty good chance that it won't be a problem, but for that majority of times that it's not a problem, the minority of times that you strip something can make your life very, very difficult. Round out one bolt and you end up doing what I just had to do to my Thomson stem last week - break a couple drill bits and spend a long time drilling everything, ending up with a ruined part. God forbid you do something like strip your bottom bracket splines - you could ruin a whole frame.

Just MHO.

[dirtydirtysouf]

THAT'S what you use it for? Well no wonder :p. Big bolts, big threads, steel, and a big wrench. You can put a lot of torque on that.

- you could ruin a whole frame.

Just MHO.

didnt think about that..........im still used to the 4 tired wheeling not 2 wheels:banghead: :banghead: :banghead:

[goofy]

I put red loctite on my BB a couple of years ago because it would loosen up during every dh run i did (yes it was brike but i didn't want to fix it). So I thought I was screwed until 2 months later it loosened up again (and wouldn't stay tight).

[Spunger]

Well crank bolts do need to be pretty tight. I know that I torque mine to whatever the instructions say to do (30-40 ft lbs) and I've never had one loosen up. If you really torque them down they shouldn't back out.

I use blue locktite on everything, I've seen the green stuff on some of my bolts and I think that is less permenent than red. I know there's purple too (parents get it from work) and that stuff is like a permement glue.

I grease the bolts, splines, everything and just torque it down right. If you are using some wimpy allen wrench then that's a problem. I use a ft lbs torque wrench, an allen socket, and torque it. You'll never be able to apply enough torque to it with anything other than a big rachet or torque wrench. For the BB and the Cranks you gotta have this!

All the other stupid parts (stem/clamp, headset adjustment, seat rails, brakes) you can get by with what feels tight with the typical allen head set. Those are good because they won't allow you to overtorque a smaller bolt. Yeah yeah I know everything is in inch lbs but I've gotten by with feel and haven't had an issue yet. Someday I'll pick up an inch lbs torque wrench.

[MtnBikerChk]

I have a torque wrench :)

[SKYWAYBUZZ]

Clean everything up with alcohol and use gel super glue or epoxy. Holds em in there and can still be removed. Think I tried red loctite initially.

[V-Dub GTI]

Clean everything up with alcohol and use gel super glue or epoxy. Holds em in there and can still be removed. Think I tried red loctite initially.

thats what i do too. the super glue works really good. i even use it on my cleats for my spd pedals, i used to have trouble wuth them comming out mid ride and being stuck in my pedals and have to take my shoe off to get out.:help:

[metalhead119042]

I had the same problem and what I did to fix it was put a washer on the crank bolt. You could give it a try, but i'm not sure if it'll work on every crank.

[mshred]

my crank kept falling out because of the bolt falling out. i kept putting it back on until i lost the bolt.. then i went to the bike shop (with my crank) and it turned out i needed new cranks (even tho only 1 was wrecked) its cause the crank was tapered... so i was pretty bummed that i had to spend 250 bucks for a new set of cranks.. but luckily the lbs owner found 1 used crank! YES!! and it was only 30 bucks :D

[nycurse]

use thread lock

[valve bouncer]

Why wasn't I surprised to see this happening with LX cranks. Mine did that, so I gave an extra crank down on the wrench and that seemed to fix it...by fix it I mean they still get loose but far less frequently.

[trailblazer]

i suggest new bolts...and less ham

[Slider]

MY SS does the same thing I think it is from all the torque that comes with powering a sinlgle speed up a hill. just check you bolts alot

[johnbryanpeters]

I have a torque wrench :)

:stupid: werd

[partsbara]

clean all surfaces thoroughly... remove all grease / dirt etc... loctite and torque to spec (around 35 foot lb - a little less with square taper)...

my RF square taper cranks on the bianchi SS are rounded out, thanks to the last a$$ clown that owned the bike... i m 220 and using loctite and a torque wrench they are still as tight as the day i 'fixed' them... that was 18 months ago... removing ALL the greases etc is the key...