Rear axle nut won't stay tight

[SpectraSVT]

I recently purchased a brand new axle and nut from Yamaha. The old nut made a popping noise and came loose when I tightened it. It had never done that since I got the bike 2 yrs ago. I thought the axle or nut was just worn out so I bought new stuff. It still does it. The brand new nut pops and comes loose. I have never ever needed to use loc tite to keep it on but now its a must or the nut will come off and then all hell breaks loose!

Any ideas as to why its doing this now and never before? I'm not even getting a chance to crank it down...it just starts to get tight, then pop goes the nut. This nut was $13 and the axle was $44...they are both crap. :bang:

 

[darringer]

I woulld return the new parts and try another set. It sounds like they are defective. Thet should be able to hold close to 100 lbs of torque.

 

[Studboy]

Return them for sure! Mine are very strong, it would take more than my wimpy little arms to over torque it.

 

[sodflyer]

wrong size match up...get the right one to fit the axle dia and thread pattern. don't have to go to Yamaha for this, you can try a local hardware store. jeff.

 

[Rooster]

Be careful when tightening that nut. I trashed an axle and nut a while back, because I was following the manual recommendations. If you have the same axle and nut as on my '00 (should be the same) if you gall those threads, you may end up with something like this:

http://www.dirtrider.net/forums3/showthread.php?t=58005

 

[Studboy]

Dang! You guys have me all paranoid now... I usually give it about all I've got with a 10" wrench and call it good. I also usually put a little bit of grease on the threads.

 

[evenslower]

I have had the misfortune of ruining a few nuts/bolts on my previous Yamaha by following torque specs. from the manual. Thought wrench was out of adjustment so I had it checked and it was fine. I'm not very sure of the quality of some nuts/bolts on Yamahas. I'd try to replace with with stuff from a bolt supply house when possible. Never had issues with an axle though.

 

[biglou]

I go kinda easy on the axle nuts too. On the rear I use a 1/2 breaker bar with socket. "Nice and firm" is how I would describe it. If sitting on a stool behind the rear wheel, it takes a firm pull to break it loose, but by no means having to force downward on the handle like a frozen lug nut or anything. I think the 75ft-lb or whatever in the manual is a bit much. I think that's the anti-"I was just riding along and the rear axle came out" lawsuit spec!

 

[Patman]

www.mettec.com should have just what you need as long as you have what they need $$$$$$$$$$$$$$$$$$$$$$$$

 

[SpectraSVT]

Its a little late to return them now...been about 4 months. Came off once already but no damage.

Are you guys saying to purchase a new nut at the local hardware store? or am I supposed to replace axle as well?

I used to torq it down good without probs...

 

[Rooster]

If the axle has no stripped threads, then the nut must be stripped. I have used a nut from a local fastener place in an emergency.

If it makes a "pop" noise and comes loose, something is damaged and needs replaced. Sounds to me like there are some threads that stripped off.

Check both parts very closely for damaged threads and determine which, if not both, is the damaged part.

I side with Lou on the "firm" tightening of the nut (especially after cashing out all that dough for new parts). I take it far enough to feel sure it won't work loose, but that's about it. Then I check it a couple times first loop, making sure it's still tight.

Good luck!

 

[darringer]

I have had 20 year old bikes with the original axle and nut and never had the problem you have. Maybe just a defective run. I would definitely replace both with new parts as having the nut give out while riding is a recipe for disaster. Maybe use never-seize on the threads to keep them from corroding. I torque mine to 65 lbs and have never had it work loose.

 

[reelrazor]

The Yamaha torque spec is based on using a NEW nut each time. The nut is 'ovaled' a little on the outer couple of threads as a locking feature. Once those threads have been used they get hogged out to being round and thus not locking. Since they are a very fine pitch you can 'pull' the threads fairly easily.

 

[SpectraSVT]

It happened the very first time I torq'd it down so I don't think it was abuse. I'll check everything close tonight but after inspecting the first axle and nut I had, I came up with a big ? as to why it was doing that.

Would a hardware store not have this cheap factor? or is the pitch of the threads too fine and it don't matter what nut I use?

 

[BBdotcom]

If the nut is not stripped and the axle isn't either,
and its making a popping noise... it sounds to me like you ran out of threads, and its popping on the last thread as the beginning of the thread of the nut and the end of the thread on the axle meet.
Are you sure all the spacers or washers are all in place?
Just something to think about
Tom

 

[sodflyer]

One of them is the wrong size if it's not stripped....yes a good store will have the size you are looking for. Jeff.

 

[LukeRips]

If the nut is able to come off, you must not have a cotter pin through the axle to keep that from happening. I always tighten until I make a funny face and then safety wire the nut.

 

[SpectraSVT]

Yamaha doesn't use cotter pins. No hole in the axle...I would have to drill which don't sound that easy. And there are more than enuff threads still left. No way is the nut even coming close to the end of the threads. I checked the axle and nut; they both look perfect.

The stock axle and nut were ok for 2 years so I don't think its a sizing issue.

Thx for all the replies though...any more?...lol

Safety wire the nut?? Is this a cotter pin set up or are you doing something different?

 

[LukeRips]

There is a safety wire kit you can buy at any bike shop. My mechanic uses it everywhere. It's hard to explain how it works but it's an odd shaped washer with holes in it that goes on before the nut, then the safety wire goes through the holes and as you tighten the wire the washer folds over the nut.

 

[darringer]

If both the nut and axle are look perfect, then there must be a mismatch of parts, i.e. wrong nut for the axle. Sometimes a SAE nut will actually thread onto a metric stud. Have you taken the parts to Yamaha to see what they say? If that won't work, do as suggested above and find a nut that will fit the axle at a fastener supply or good harware store. I know ACE Hardware stores here in San Leandro has a large selection of metric nuts and bolts. Probably the same is true in SJ.

 

[SpectraSVT]

These are factory spec Yamaha parts and all the part numbers ae correct. Oh well, its on there pretty tight right now with globs of loc-tite. I'll go looking for that washer...not sure how it works though. If it only hooks to the nut then if the nut turns wouldn't the washer turn with it? once again thx for all the replies..you guys are awesome!

 

[sodflyer]

no, it has two tabs, one bends in the swing arm and the other against a flat side of the nut.

 

[SpectraSVT]

Well the axle nut reared its ugly head today. Came loose again. Gave chain enuff slack to rip off my case saver and put a hole in my case. Not very happy about that at all. Gonna call Yamaha on Monday and B*tch about it. This is just ridiculous.

 

[YZ165]

:think: I've never heard of anything like this. Keep us posted SpectraSVT. Good luck with Yamaha, YZ165

 

[darringer]

You should've been able to tighten that nut to at least 60-80lbs of torque. I'm really sorry to hear about the mishap. If the hole is close to the countershaft sprocket it can be repaired with epoxy. I have used POR-15 auto epoxy in that very same spot on my cr and it lasted 2+ years. The case would still be in service now if it weren't for the crack below the crank I had found during a rebuild a few weeks ago. Were you riding at Carnegie today?