KTM swingarm modification

[Crisis management]

I thought I would post this as it may be usefull to any KTM owners....

From another forum (ADVrider) I found this detail relating to my 990, however as the swingarms are all basically the same construction it is relevant to all the KTMs.

As the swingarm is a fabricated unit and is essentially a sealed unit except for the drilled and tapped holes in it there is no way for it to drain if it gets any moisture in it, you know, riding through puddles, rivers etc. There have been numerous (now I'm just repeating what has been stated on the other forum) cases of the chain adjuster bolts corroding and seizing in the swingarm...nasty & expensive to repair.
The recomendation is to drill a small (3 to 4mm) hole in the bottom of each arm of the swingarm as close as practical to the wheel end to allow any moisture to drain out. Strip the adjuster screws out and refit them liberally coated with an antiseize compound, I usually use coppercote as the KTMs have a variety of dis-similar metals in them and are prone to thread seizing anyway.
There were numerous posts stating they had done this modification and no one had a problem with swingarms disintegrating etc so it seems fairly safe.

For my peace of mind I checked with a couple of 990 owners I know and they recommended the modification as well, I'm convinced!

So, into the cavern and poked at the bikes to find my 990 already had a couple of holes drilled, this bike has 30,000kms on it and the swingarm ain't broke so those holes can't be hurting anything.

On to the 200 and no holes, out with the drill and 2 minutes later I had a small puddle of water forming under each side, about a 1/4 cup out of each side.

My experience tells me the rest of you probably have swingarms full of water as well, get drilling!

Iain

[Danger]

Yeah it only takes a minute to do this with a battery drill. I use a 3mm bit.
Also remove the wheel adjuster bolts and apply anti seize before refitting.
Oh I just skimmed your thread and see you mention that.

[secondfield]

Very timely advice, ive just removed the rear wheel on my kxf (to fix a flat) to find the adjusting bolts / locknuts siezed solidly. Ive got no explaination as to why they've done that.

[Reckless]

My Cr250 had one seized so bad I couldn't even move it one face of the nut to even start to work it loose.
I'm gonna check the Ktm's for the same now you've given us the inside info. I'll let you know
Cheers Iain!!

[Buddy L]

I had to get my Cr's drill out and retapped a larger size as they were fully seized in thier.
Ill have to check the RMZ to see what the deal is with the swing arm.

[barty5]

Yamaha is well ahead on this front drilled out from factory is about a 4mm hole at the bottom lower end

[warewolf]

Newer KTM models with the redesigned swingarm (last 2-3 years?) have rubber plugs covering big holes on the inside rear.

I've had the adjuster bolt seize and/or strip, despite liberal use of copperslip. Fortunately the bolt is softer than the thread in the swingarm, so it stripped. After removal the internal thread cleaned up OK.

Rather than drill extra drain holes - which I felt was like drilling a hole in the bottom of a boat - I went the other way. Drained and dried out the swingarm (yes there was plenty of water in there), sprayed liberally with DWF, allowed that to dry then sealed all the holes with RTV silicone. The other holes were for the chain guard which is absent on my bike, and also the brake line clips aren't a tight fit. Lots of copperslip into the threads on final assembly.

No more trouble since. (btw several threads on KTMTalk.com. )

Given the adjusters are problematic, if they are at all stiff I remove the axle and use a good-fitting 6-point socket on them, keeping the drive nicely lined up with the centreline of the bolt. Using the two flats of an open-ended spanner applies a side loading/bending of the bolt and probably stresses the threads more, encouraging binding etc.

[Reckless]

I drilled my two Ktm 200's just now!
I got no Moisture out of one and that's the one with the chain guard bolts missing so there is 2 x holes in the swing-arm. And just a few drops out of the other!
So not to bad.

[Crisis management]

Glad it hasn't been the end of the world as we know it!

A comment of the concept of sealing it up rather than draining it; if you can guarantee it will not leak that's fine, but I prefer to make sure anything that gets in can get out. It's easier to clear a drain hole than to remove all sealant and replace on a regular basis to ensure there is no moisture.

[Reckless]

Agreed! even if you don't put a touch of RTV in it, it will probably still get jammed up with mud anyway. So you'd need to clear it every now and then. It was good to know of the problem so we can keep an eye on it anyway Thanks for that!

[AllanB]

NO STOP DOING THIS!!!!!!

Are you guys not aware that the swingarm is water cooled - if you drain it it will over-heat and seize.


This reminds me of a 1980 Toyota I had - I was driving around a corner after a very wet week and I heard a sloshing noise - I pinpointed this to the doors. When home, I found the drain holes were rusted over and promptly drilled them out. No-bull I nearly filled a bucket with the water that came out of both doors!

[theblacksmith]

I guess that the cam type chain adjusters on my old kdx are very user friendly then?

[warewolf]

A comment of the concept of sealing it up rather than draining it; if you can guarantee it will not leak that's fine, but I prefer to make sure anything that gets in can get out. It's easier to clear a drain hole than to remove all sealant and replace on a regular basis to ensure there is no moisture.

Yep, it did cross my mind that the sealant might partially fail, which would then let water in under pressure and trap it in. Completely failing would leave me no worse off than before. So far it has been primo, including one extremely wet 3-hour cross-country race, and countless creek crossings on various rides.

But you don't need to remove the sealant to check for water; just remove the chain adjuster bolts. Pipecleaner (appropriately bent) stuck in the hole will soon show it.

One of my concerns with leaving it all exposed was that the internal portion of the chain adjuster bolt would lose its lube. With my set up, the bolt is nicely cleaned and lubed. As the chain wears and you back out the adjuster bolt, clean lubed thread is being drawn in to the swingarm's thread, rather than dry, crusty thread that's been regularly washed with muddy water and left to slowly dry. Worth a try, I thought.

[Edit]
A further thought, if you have drain holes underneath the rear, then you could squirt WD40 or similar on the threads before adjusting the chain.
[/Edit]

[B0000M]

I guess that the cam type chain adjusters on my old kdx are very user friendly then?

such a shame they are ugly though!

[clint640]

As a note for those with seized adjusters that haven't drilled the holes yet, mine were getting stiff so I gave the inside of the swingarm a good dose of CRC down through the chain guard & brakeline clip screw holes, a week later they came out no worries.

Cheers
Clint