Why does my left-crank arm come loose every.time.I.ride?!?!

http://www.loctite.com/

What cranks?

If they have a pinch bolt, tighten that.

If they don't, then make sure you have a spacer between your bearings, crank it down and USE BLUE LOCTITE.

dave lawrence wrote:

What cranks?

If they have a pinch bolt, tighten that.

If they don't, then make sure you have a spacer between your bearings, ...more

dave lawrence wrote:

What cranks?

If they have a pinch bolt, tighten that.

If they don't, then make sure you have a spacer between your bearings, crank it down and USE BLUE LOCTITE.

...more

if you use red it will never come off , unless you use a blowtorch

bmxsteve99 wrote:

if you use red it will never come off , unless you use a blowtorch

bmxsteve99 wrote:

if you use red it will never come off , unless you use a blowtorch

...more

Not always, my friend has the Animal BPE pedals and he used red loc-tite on the threads because they kept coming loose, and they STILL came loose even when we caked that shit on and let it sit for awhile. I know it wasn't the loc-tite's fault cause it's the same stuff I've used on other stuff that needed a blowtorch to take off.



As for the original question, a lot of factors can be the issue, check the following

-if you don't have an internal BB spacer, they can come loose
-if your crank arm isn't on the spindle enough or too much, it can come loose (you want the arm to be at least 3/4 the way on the spindle, but not on so much that the spindle pushes through the other side & bottoms out.)
-if your crank is developing the "profile wobble", check and see if when the bolts are tight, if the crank arm can be moved up & down on the spindle slightly (not side to side), this indicates that your splines are wearing out & is why it keeps coming loose
-if your threads in the spindle and the bolt are still good and not stripped
-if your bearings are still good, bad bearings can cause wobble and wiggle the cranks loose overtime


check those & report back.

Blue loctite, Grease the bolts, tighten the compression bolt first then the pinch bolt. If those methods don't work, I would get some new cranks (if it were me)

your having problems with it staying on, and repeatedly reattaching it, did you install the spindle and cranks yourself or did a bikeshop? seems to me the most likely situation is that your spindle's threading is stripped.

take your cranks off, and screw the bolt in, then tie a rope around the bolt head and try pulling, if u feel it give, its stripped.

I have an idea but you probably have it right.

make sure they aren't on back to front. If they are they will always come loose

If it keeps coming loose and you've ridden it this way, the splines on the arms and spindle are likely to be pretty worn.

If this is the case, it will probably keep coming loose.

It might be time for a new crank.

what i'm thinking :/ thanks

Now that I saw this post, my 48 spline cranks are coming loose every once in a while. damit

MidWestBMX wrote:

Now that I saw this post, my 48 spline cranks are coming loose every once in a while. damit

MidWestBMX wrote:

Now that I saw this post, my 48 spline cranks are coming loose every once in a while. damit

...more

thats profile wobble, and nothing short of welding the crank boss to the spindle is going to stop the wobble after it develops fully

good thing they are 2 pc cranks and the left is coming loose!
great. -_-

MidWestBMX wrote:

good thing they are 2 pc cranks and the left is coming loose!
great. -_-

MidWestBMX wrote:

good thing they are 2 pc cranks and the left is coming loose!
great. -_-

...more

Is the left the removable arm or is the right?

Snug them. Add a BB spacer so you can crank em tight. Add spindle spacer if your bolt bottoms out.

My 48 spline 1948s loosen up about once a month or so.

Just give your bike a good check over once a week, and carry some basics to check it when out and about.

MidWestBMX wrote:

Now that I saw this post, my 48 spline cranks are coming loose every once in a while. damit

MidWestBMX wrote:

Now that I saw this post, my 48 spline cranks are coming loose every once in a while. damit

...more

bmxsteve99 wrote:

thats profile wobble, and nothing short of welding the crank boss to the spindle is going to stop the wobble after it develops ...more

bmxsteve99 wrote:

thats profile wobble, and nothing short of welding the crank boss to the spindle is going to stop the wobble after it develops fully

...more

Call Profile, they will hook you up IF you have Profiles. I have always just called Mat and he sends me a new arm/spindle/bearings whatever the problem is.

If they aren't Profiles, what type spindle and what brand? Example: Spline 48/Kink...if I know the information I might be able to help you out. Thanks to how long I have rode, I have some friends at nearly every company. They really come in handy

Mine did that but I changed the bolt to another one and it was fine. Mabey just by new bolt.