Broken swingarm on 400ex

[emiliano22]

Hi guys!
I'm new here.
I broke the swingarm yesterday in a MX circuit but I think my use is not so hard :(
I broke it near to the front sproket and this is very strange for me :confused:
Do you know if this is common on 400ex?

I have heard of this happening especially on mx tracks. A friend of mine broke his and he went with a housers swingarm, kind of costly though.
Does anybody know if the newer swingarms have been beefed up any, like an '02 compared to a '99.
John

[Tommy 17]

I heard its a problem if u beat the hell outta ur quad on a mx track. theres been a few that i heard of breakin and a guy on here brokes his 250rs a few days ago, sry to hear u have to buy a new one i know brokin parts suck. welcome to the site too u will love it here.

[86atc250r]

In every broken swingarm case I've seen, pretty severe abuse was involved. You don't necessarily need to be getting big air to abuse the swingarm, it's more how you land.

That said, I've beat the crap out of mine for over 2 years now with no trouble, although I know when to say when and how to land when things start going wrong...

I have, however, broken steel swingarms on my other bikes, namely my 350X and 250R. Any OEM swingarm when abused over time is subject to cracking and breaking.

Lucklily used swingarms are very cheap, and new one's aren't bad either, as long as you plan on going a little easier on it, or buying aftermarket shocks....

Also, as far as I know, there have been no changes of swingarm design on the 400EX - the part numbers on 400EX microfiche seem to support this.

Hey 86atc250r,
What kind of landing do I need to try and avoid? I weigh 235 and concerned about snapping the swingarm. I think my back is going to keep the jumping to a minimum though due to an injury back in '94.
Thanks,
John

[86atc250r]

Try to land slightly on the back tires first unless you're landing on the downside of a double or triple (then I like to land slightly front first). Also try to land with both the back tires at the same time. Landing on one puts extreme amounts of stress on the axle and swingarm - of course it's not always possible, but try...

Another thing is to be on the gas if at all possible when landing (given the conditions). This will firm up the rear suspension and transfer torque so as to be easier on the fronts when they come down. If you are going to land sideways, be on the throttle as hard as you can - this will have the tires spinning when you land and it will be a lot less likely to grab and pitch you, and will put less stress on the machine.

One thing that's especially hard on the swingarm at the MX track is overjumping into a turn or overjumping into a rhythm section, where you have to be into the breaks before you hit the ground. Try to avoid that as best you can. The hardest landings I've ever done were over relatively small jumps where I had to be on the brakes when landing.

If you like to jump, consider the costs if you start breaking parts or crash and tear yourself up, and the cost of a good set of aftermarket shocks may not look so bad.

[papaw]

grease your factory s/arms pivot bearings when these sieze up i believe the friction may be causing thes s/arms to break.when mine broke in the same place emiliano22 my bearing on that side was siezed up.anyone with factrory s/arms should keep em' greased or pay the price!!!!!!

[86atc250r]

That may contribute, however - the one we broke was around November of 1998.... After that we knew what the abuse limit was.

Keeping the swingarm pivot bearings lubed (as well as all other bearings) is excellent advice though.

How do you like those CF beadlocks?

[emiliano22]

Really thanks guys for yours advices
The strange thing of this is this: I was riding for about 5 hours that day, after 2 hours I start to hear a little sound when I open the trottle and in the landing.
Just before leave the circuit I tried to check with a friend that sound. In that moment I discovered the broken swingarm :eek:
Maybe tomorrow I disarm the quad and post to the forum a picture of the swingarm and you could see what I'm talking about.

I'd like to see those pics emiliano, and welcome to the group.
John

[EX_RIDER]

I snapped my also yesterday man!!I was at the MX track jumping.I got the details in the post which swing arm??

[papaw]

86atc250r,
i wouldn't leave home without em' so far i've beat them pretty good.i hit a few good rocky trail sections they have some marks on them but thats it.i would recommend them to anyone in the market for a good strong rim!!!!

[400exRacerX]

sorry to hear man.......... its a very common problem with the 400ex, my friend broke his a couple of months ago and so did i......http://forums.exriders.com/showthread.php?s=&threadid=391 you can read that for some pics and advice.

NO MUFFLER DUDE?

400ex '99
Uni Filter
airbox lid holes
with out smuffler
153 main jet
ITP holeshot TC


Thats good on your bike!!! :huh :huh :huh

[emiliano22]

I wanted to say w/o arrester :D

I just finish to disarm my quad. Here are the pics of my swingarm.
It looks very bad, doesn't it?

[emiliano22]

here is a front view

[papaw]

exactly where mine broke and i'm sure there are many more around with breakage in the same spot..

[trx400ex]

i hope mine doesnt break,,, ive already broke through a set of aarms and my frame, but in the process of replcing my trashed bearing carrier and axle, i cleaned it up checked for cracks and greased that bolt good..alls well so far

[emiliano22]

Here buy a new one is too expensive.
I will try to repair it.
Take a look.

kids, not try this at home!


:huh :huh :huh :huh :huh :huh