unadilla gncc DNF due to rear axle moving

[evanchochrek]

Hopefully someone can explain to me how the chain adjuster bolts on a gasgas work. they do not thread into the swing arm like other manufacturers so 2 laps into the race I swapped the rear end pretty hard and less than a mile after that, I tossed the chain. After i got the chain back on, I noticed the slack inthe chain was way too much. It had about 4-5 inches of slack! Then I noticed the sprocket side of the axle was all the way pushed forward and the disc side was still where it was supposed to be. the odd part was the axle nut was still tight. I am positive everything was good to go for the race and nothing was left UN-tightened. After coming from a dead last start in the a-vet class to 4th in one lap, i was dissapointed, but now that I'm over that, I just want to make sure it doesn't happen again. whats the deal with the chain adjusters how they work and why is there rubber grommets on the bottom of the swing arm just below. Is it just the pressure of the axle going forward that keeps them in place? should I put some thread lock on the adjuster nut, so it doesn't move? I think that is the only reason that my axle moved. the adjuster must have rattled loose all the way forward, then when I swapped out that must have been enough force to tweak the rear end. any info for a newbie on a gasgas?

 

[Neil E.]

You must have slammed that real wheel really hard. I also think the GG adjusters are not that good. I changed my adjuster locknuts to custom nylon insert locknuts. The nylon insert keeps pressure on the thread so the nuts can't wander. I think I used 3/8-16 stainless nylon insert locknuts and rethreaded them to 10mm. Not an easy job unless you have the right tools.

You should set everything up correctly, then spin the nuts back and put a generous amount of blue locktite on the threads. Snug the nuts back in place and the loctite should hold them.

 

[nknudsen]

You must have slammed that real wheel really hard. I also think the GG adjusters are not that good. I changed my adjuster locknuts to custom nylon insert locknuts. The nylon insert keeps pressure on the thread so the nuts can't wander. I think I used 3/8-16 stainless nylon insert locknuts and rethreaded them to 10mm. Not an easy job unless you have the right tools.

You should set everything up correctly, then spin the nuts back and put a generous amount of blue locktite on the threads. Snug the nuts back in place and the loctite should hold them.

You might want to look at using a nut other than one made from stainless, it's to soft of a material. Use steel grade 8 or stronger.

After I make a chain adjustment and the axle is tight I like to tighten the adjuster nuts a hair to add some preload to them to help keep everything snug. I actually don't mind the GG setup. I worked on a buddy's KTM and his adjusters had frozen into the swing arm from moisture.

 

[evanchochrek]

Thanks guys- I figured some locktite would help. and to snug them up after the axle is tightened in place. I like how you can take the sprocket side adjuster out and put it right beside the disc side adjuster to make them exactly the same.I was never a huge fan of the little marks on the swingarm from any manufacter to align the wheel. I noticed the threaded rod also has a allen head on the end that goes inside the swingarm. Now I need to saddle up and have a good race so my KTM buddies stop razzing me. Figures, 9 straight years of finishes at Unadilla, and my first DNF is on a gasgas. Next time I'll get em!

 

[Neil E.]

You might want to look at using a nut other than one made from stainless, it's to soft of a material. Use steel grade 8 or stronger.

The adjuster nut is not under any load; it is just used to position the axle. The steel axle nut does all the work. My setup is custom, both the adjuster thread and the adjuster nut are stainless. Plenty strong enough for my needs.

 

[nknudsen]

The adjuster nut is not under any load; it is just used to position the axle. The steel axle nut does all the work. My setup is custom, both the adjuster thread and the adjuster nut are stainless. Plenty strong enough for my needs.

If the adjuster nut isn't under any load, then would you ride your bike with out the adjusters installed?? I might on a BMX bike but not a dirt bike.

 

[Fred1956]

Thanks guys- I figured some locktite would help. and to snug them up after the axle is tightened in place. I like how you can take the sprocket side adjuster out and put it right beside the disc side adjuster to make them exactly the same.I was never a huge fan of the little marks on the swingarm from any manufacter to align the wheel. I noticed the threaded rod also has a allen head on the end that goes inside the swingarm. Now I need to saddle up and have a good race so my KTM buddies stop razzing me. Figures, 9 straight years of finishes at Unadilla, and my first DNF is on a gasgas. Next time I'll get em!

The allen head is to firmly install the rod in to the adjuster collar around the axle, I personally use loctite on the threads into the collar. When I set my chain slack I then fold a shop rag in 3rds or 4ths & insert between the chain & sprocket and attempt to pull it through by rolling the wheel backwards, at this point I hold the wheel and sight down the chain to check alignment (I don't trust the marks either) if all is good I maintain the load on the chain adjusters with the rag and tighten the axle to 60 ftlbs. I have yet to have an adjuster or axle nut come loose using this method and the nut isn't locked to the threaded for the next adjustment, chain replacement, or sprocket redo.

 

[hamilton]

Thats interesting, I wouldn't think the axle could move much if torqued correct. I have had my axle nut come loose during a race, did I forget to torque it? maybe? Think I"ll install an extra nut to use as a jam nut on the adjusters.

 

[Neil E.]

If the adjuster nut isn't under any load, then would you ride your bike with out the adjusters installed?? I might on a BMX bike but not a dirt bike.

I might consider it, but I know the adjusters would stop the axle from moving FORWARD. Remember that they only sit against the aluminum swingarm anyway. It would be a good idea for the original poster to pull his entire axle/wheel assembly and inspect it. There may be something like a burr preventing the axle from clamping properly.

 

[nknudsen]

I might consider it, but I know the adjusters would stop the axle from moving FORWARD. Remember that they only sit against the aluminum swingarm anyway. It would be a good idea for the original poster to pull his entire axle/wheel assembly and inspect it. There may be something like a burr preventing the axle from clamping properly.

The torque of the engine is always trying to pull the sprocket forward with the chain, especially if the tire has a high load situation.

 

[cbutler]

If the axle is PROPERLY torqued it WILL NOT MOVE adjusters or not.

Over thinking things a little they are ADJUSTERS (to adjust chain alinement) NOT keepers

 

[2004ec200]

Double nut the adjuster nuts if you want to make sure the nuts don't move once adjusted. I would think that would be a lot easier than messing with locktite.

 

[shang]

I think with a hard enough hit in the right direction, any wheel will move. All of my previous bikes used an adjuster threaded into the swingarm, but the axle block still floated behind it. I'm not sure what the torque spec is on the gas gas, but my KX450's were around 60lb-ft. Pretty tight.

 

[desertgasser300]

Double nut the adjuster nuts if you want to make sure the nuts don't move once adjusted. I would think that would be a lot easier than messing with locktite.

+1 on the double nuts.

 

[Desert Rider]

I feel your pain. In 1981, at a hill-climb competition, I lost control and swapped so badly, that I struck the rear wheel on a YZ465, whilst going "mostly backwards".

If you hit it hard enough, it will break. I flexed the swing-arm enough to pull the threads off the axle, flat spot the wheel bearings, the swing-arm bearings, and bend the wheel.

I was 26 years old at the time. Young, dumb, and tough. Sadly, I managed to pull off the same destruction, in 2007, an a new KLX450R.

No longer young, or tough. Proudly, still dumb.

Steve

 

[GasGas]

Always snug up the adjuster nuts after you tighten your axle. Then they have load on them and should not come loose.

 

[gasgasman]

I put a wrench between the chain and top of rear sprocket, then turn the wheel backwards to force the adjuster nuts against the swingarm.

 

[eff]

Always snug up the adjuster nuts after you tighten your axle. Then they have load on them and should not come loose.

Exactly.



Sent from my iPad using Tapatalk

 

[Jakobi]

Never an issue here either. As others have said. Make sure the wheel is pushed in to load the adjusters while torquing, and make sure its done up tight. Never an issue with the back being smacked out of alignment, and if an impact was hard enough to do so I'd take it as just that. I'm sure we've all binned it and twisted the forks in the triples more than once.