Sugino GT Crank Problemo

[Jamroll]

Fello Radsters,
I've used many a  3 piece Crank "Back in the day" 
Have recently started using a Sugino 3 Piece crank on my daily ride and the left crank arm keeps loosening its self off 
Before i go and do something stupid do you guys (and Gals) have any sugestions to sort this fooking irritating problem?
I have tried tightening the nut to within an inch of its life but still it lets go......
I just want to ride and ride some more but i'm getting a little fooked off having to walk my little beauty home 
PLeeeeease sugestions 

[bobafett]

Spring washer ? 

[stidds]

Red thread lock will probably do the trick.

[jT Racing]

is it the right axel for the crank? them square tapered axels are not all the same.

[magna13]

I use this red Loctite stuff, works a treat Go in to your local bike shop. If they're nice enough then they'll do it for you right there and then with no charge

[Jamroll]

Thx Radsters 
I'm gonna try a differnet axel tonight ..... and see how that goes, I assumed that as this was the one that came with the crank (NOS) that it was correct (Mother of all Fook Ups assumption  )
Failing that I'll give the red thread lock nut a go.........I really dont want to loctite it though... wot if i need to remove again..surely that would be a pain in the arse then?

[soll36]

Thx Radsters 
I'm gonna try a differnet axel tonight ..... and see how that goes, I assumed that as this was the one that came with the crank (NOS) that it was correct (Mother of all Fook Ups assumption  )
Failing that I'll give the red thread lock nut a go.........I really dont want to loctite it though... wot if i need to remove again..surely that would be a pain in the arse then?

you can get different types of thread locker mate..the red loc-tite stuff the guys are on about is summat like no.253 and is not a permanent lock like some you can get so it works enough to hold the bolt but can be removed when needed..   

[MartyC]

Dare I say it, the alloy may have stretched and no longer biting on the axle fully when tightened up  .  Was quite common on Sugino's alloy cranks bitd.

[moley]

When you do tighten it.  Is it fully tight with no play in the cranks?

If it is then it just needs something to stop the bolt coming loose.

We use Loctite 390 screw lock.   It can be hard to get bolts undone afterwards.  This is small bolts like m3-m5 but should be alright with bigger bolts.

Try loctite on the bolt and allow to dry.  DONT loctite and screw the bolt in in case it becomes stuck.

One the loctite has hardened then screw it in.  It should provide enough resistance to stop it from coming undone but still allow you to undo if need be.

Maybe some ptfe tape that plumbers use on threads.  It would work similar and provide enough resistance.

If the cranks have play when fully tightened then dont bother as you'll never get it right as its stretched!! 

[jT Racing]

measure the thinnest and thickest part of the square taper. i'll compare it to one i have and see if it's a match. could have been a nos arms and any old BB set cobbled together.

[oldtired]

if the crank arm is stretched out and it is the correct axle you can shim the axle with cut up pop cans or thin brass sheet, done this before,i found the arms tend to keep opening up once they started,so it might only be temporary,somthing to do with the stress in the alloy makes it go soft.

[Jamroll]

Radsters,
Talk about community spirit 
Just wish i'd read your comments last nite before going down the route i did!
Got some of the loctite red stuff and sealed the bugger good and proper.....placed on the srcrew thread and the bolt though so could be a real pain in the arse to remove! Didn't get a chance to see if its done the trick as it was raining last night and i'm not taking my new baby out in the wet
The Alloy doesnt appear to be strectched and there is no play when the bolt is first tightened up. I do hope this sorts the problemo.
I guess i should put some pics of my new daily rider up.