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What is the scoop on newer KTM wheel bearings?  I know on the older RFS models that the rear wheel bearings were

a weak spot and needed to be replaced after so many hours. Is this the same on the newer bikes. I'm getting ready to

go on a 1500mile ride on my 2016 500 XC-W with about 7K miles on it and wonder if I should go ahead and replace the

bearings nowand if I do should I go with stock or Pivot Works or some other bearing kits.

 

Covered in Questions

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Hey Chris,

  I got over 10K miles on my RFS wheel bearings; replaced the rear wheel assy. only due to a crack noted in the hub. I have been a proponent of removing the bearings... cleaning and inspect them by removing the dust seals (carefully with an Exacto knife) and repacking them with a good grease such as Chevron SR1-2 grease. I'm pretty sure that your OEM bearings have been very well designed for longevity. Water, more than dust can lead to the need to inspect/clean and repack more frequently. Below is a link to one of the so-called upgrade kits for your bike.

https://www.motosport.com/all-balls-rear-wheel-bearing-upgrade-kit?mmy=ktm%3B500exc%3B2016&mmy_source=pdp

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Some mechanics have been known to inspect the wheel bearings by carefully removing the grease seals. Personally, I would check with that Kug guy; he seems to know what he is doing.  Any side to side movement?  As long as you have not exposed the wheels to water, sand or mud, you "should" be OK. What's the worst that can happen out in the middle of that 1500 miles. 

Another man with experience in Black Arts is that PMB guy. 

      :dirol:    You are welcome                   Photo taken at 5200 miles -   No wobble, but dry seal. They get greased every new tire.

 

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i-PmZF788-M.jpg

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I just replaced my rear bearings- about the same mileage. I used the Pivot Works, but I might not do so in the future. Part of their system is a set of o-rings on the wheel spacers to seal around the axle. I think that's a great theory, but the problem is in execution- first time I inserted the axle, it rolled both rings and tore one.

They give you a second set in the kit (huh- wonder why?) and I used more lube (!) the second time around.

Further- once you go to the wider bearing they offer and eliminate the circlip, you're stuck with that system- if out in, say, Blandings, Utah, you can just grab a very common industry-wide bearing that is used on many other machines in the world- the Pivot Works is fairly unique and unavailable except from them.

Here's a pro-tip: Buy a Harbor Fright bearing/seal installer kit for bout $48. I've always used a combination of a socket and the old race, until I screwed up a bearing this time. Bought the right tool, froze the bearings and heated the hub, and it's a breeze.

 

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Can't hurt to replace 'em. Did mine with stock KTM bearings at about 7k as well. It probably could have gone another 7k. About 5k now on new ones. Still good. I carry one spare rear wheel bearing. The thinking being, that in a failure, "usually" only one will go bad. And in the odd case that both go out. "maybe" the guy I'm riding with will have a second spare??? Fuzzzzy logic? The fronts? not too worried about it. So, from now on, all you guys I ride with...you have to carry one spare rear wheel bearing.

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Thanks all for the input. I think I’ll just go ahead and put in a new set of oem’s. 

 

CiD

 

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I run the stock bearing but I remove the seals, repack them and re-install the seals before I install them. The seals are easy to pop in and out so no big deal on that front.  Yes it's the same bearing that KTM used in the RFS bikes. Part of my maintenance regime is to check the rear wheel for play when it's up on the lift. So far so good. I've witnessed a guys bike destroy the rear hub when his bearing failed (on an 8 day 1200 mile trip no less) and it wasn't pretty. Personally at 7000 miles I'd be at least taking a good look at them and probably leaning towards just replacing them with nice new repacked bearings. Their cheap compared to dealing with the issue out on the trail. Not a big fan of the oversize bearing kit but that's just me:)

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17 minutes ago, Covered in Dust said:

Thanks all for the input. I think I’ll just go ahead and put in a new set of oem’s. 

 

CiD

 

Plus One!

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Personally, I have only seen two guys have rear wheel bearing failure on a current model KTM. In both cases the guys never used a torque wrench when they tightened the nut. Proper torque on that nut sets the correct preload. Not practical out on the trail but important to torque it right when ya can. Lots of other reasons they can go south, but using the torque wrench helps eliminate one of 'em.

One guy told me, "I use a really big wrench and tighten it real tight."

I told my other riding buddy, "He can't ride with us anymore."

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2 hours ago, amgems said:

Personally, I have only seen two guys have rear wheel bearing failure on a current model KTM. In both cases the guys never used a torque wrench when they tightened the nut. Proper torque on that nut sets the correct preload. Not practical out on the trail but important to torque it right when ya can. Lots of other reasons they can go south, but using the torque wrench helps eliminate one of 'em.

One guy told me, "I use a really big wrench and tighten it real tight."

I told my other riding buddy, "He can't ride with us anymore."

Ok, I don't over torque. I mean, I'm no Bagster with the labelmaker, but I'm judicious.

But it is really sensitive?

Assuming correct alignment of the bearings (inner races only) and the spacer, the tension/load clamping force is straight-through without side load on the  bearings themselves? 

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IMO the torque on the axle nut has little to do with the problem. The bearings are a little undersized from the get go. This has been an Achilles heal on ktm’s for a very long time. With a little preventative maintenance it is easily managed. 

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For those of you who have experienced the beginnings of bearings going bad, is the only indicator a wobble from wheel to axle, regardless of axle tightening? Or is there an associated sound or heat? On my last ride, I began to hear an undulating sound that didn't seem to match rpms, or gears, or tire rotations.  It seemed to undulate in sound from a slightly higher pitch to a slightly lower pitch that did correlate to the speed of the bike.  It seemed to be approx. 1.5 times the tire rotation-ish.  Since I began to pay attention to it more, as it seemed more prevalent after 30 miles of riding, I almost began to wonder if it wasn't an old, unlubed speedometer cable, but it seemed to be stronger and deeper than that, so I still wanted to default to a possible wheel bearing concern.  Is it possible to prop the bike on a stand and gently wiggle the wheel to look for play, or are there other tricks to diagnose without diving in and dismantling ?  My new to me orange 2007 525 has about 7500 miles on it.  Thanks. 

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35 minutes ago, MacDuncan said:

For those of you who have experienced the beginnings of bearings going bad, is the only indicator a wobble from wheel to axle, regardless of axle tightening? Or is there an associated sound or heat? On my last ride, I began to hear an undulating sound that didn't seem to match rpms, or gears, or tire rotations.  It seemed to undulate in sound from a slightly higher pitch to a slightly lower pitch that did correlate to the speed of the bike.  It seemed to be approx. 1.5 times the tire rotation-ish.  Since I began to pay attention to it more, as it seemed more prevalent after 30 miles of riding, I almost began to wonder if it wasn't an old, unlubed speedometer cable, but it seemed to be stronger and deeper than that, so I still wanted to default to a possible wheel bearing concern.  Is it possible to prop the bike on a stand and gently wiggle the wheel to look for play, or are there other tricks to diagnose without diving in and dismantling ?  My new to me orange 2007 525 has about 7500 miles on it.  Thanks. 

Regardless if the problem you describe is your bearings or not, I'd just replace them and play it safe. It's an inexpensive and easy process to replace them. It's well worth the piece of mind. I normally change bearings in the 7500 to 10,000 miles range as preventative maintenance. 

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5 hours ago, PbdBlue said:

IMO the torque on the axle nut has little to do with the problem. The bearings are a little undersized from the get go. This has been an Achilles heal on ktm’s for a very long time. With a little preventative maintenance it is easily managed. 

+1

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11 hours ago, MacDuncan said:

 My new to me orange 2007 525 has about 7500 miles on it.  Thanks. 

My first indication of failure was a vagueness in steering on the road. Off road it’s more difficult to tell. 

 

Especially when vague steering is one’s signature riding technique!

 

I’ve caught it before during tire changes- turn the bearings by hand- you should feel some resistance, but it should be smooth. 

 

That typed, a new-to-me 07 (great bike!) would get new rear bearings without a second thought. Changing them at home is easy, changing them in a cheap motel in Utah with a drift borrowed from a Maytag repairman is not as much. 

 

Note: The process is not made easier by drinking beer during the procedure, nor by an audience of likewise drinking companions. 

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A lot of smart riders on this thread post, so it certainly makes sense to proactively do wise maintenance on the bike even when I haven't heard the warning signs from the bike itself yet, even without a planned 1500 mile ride planned (lucky CID), so a bearings change will be done next week when I put on new rubber, new oil/air filters, tighten every nut n bolt, etc.  Local desert riding is bound to show up some day soon, even though it seems like it has been years, and having a bike ready to go is a good idea.  :)  Thanks for the insights. 

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22 hours ago, Covered in Dust said:

Thanks all for the input. I think I’ll just go ahead and put in a new set of oem’s. 

 

CiD

 

THE BEST BET !

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When an axle system is designed by very particular Austrian engineers the preload and clamping force are calculated very carefully. I know, I have worked with Austrian engineers. Too much torque and you get too much friction in the system, not enough and there not is not enough stiffness in the axle system. Too much friction you get heat, wear, bearing failure. Not enough stiffness you get play and damaged bearings and races, or the bearing housings (hubs) get damaged. Those bearings and that whole axle system take one hell of a beating.

Why not just use a torque wrench? They are cheap, easy to use and take one possible reason for failure out of the equation. 

My 2007 450 EXC had something like 13,000 miles on it when I sold it. Original wheel bearings. Torqued to spec every time. They were fine.

I don't understand why anyone would risk a failure by not using a torque wrench on such an important part of the motorcycle.

I figure if I have the opportunity to do the job correctly, I will. I will not question, second guess, or dismiss the Austrian engineers recommendations. Klaus and Hans vill not be disobeyed!!!

Bagstr, can I borrow your label maker?

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Fyi at same time I would do swing arm, and linkage if you have.

Then regrease the steering stem bearing all easy stuff and cheap maintenance 

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39 minutes ago, amgems said:

When an axle system is designed by very particular Austrian engineers the preload and clamping force are calculated very carefully. I know, I have worked with Austrian engineers. Too much torque and you get too much friction in the system, not enough and there not is not enough stiffness in the axle system. Too much friction you get heat, wear, bearing failure. Not enough stiffness you get play and damaged bearings and races, or the bearing housings (hubs) get damaged. Those bearings and that whole axle system take one hell of a beating.

Why not just use a torque wrench? They are cheap, easy to use and take one possible reason for failure out of the equation. 

My 2007 450 EXC had something like 13,000 miles on it when I sold it. Original wheel bearings. Torqued to spec every time. They were fine.

I don't understand why anyone would risk a failure by not using a torque wrench on such an important part of the motorcycle.

I figure if I have the opportunity to do the job correctly, I will. I will not question, second guess, or dismiss the Austrian engineers recommendations. Klaus and Hans vill not be disobeyed!!!

Bagstr, can I borrow your label maker?

Yeah, I get that, and am not arguing for sloppy work. 

 

And im not yet smart enough to understand how the torque specs of an aligned stack of hardened steel is critical?

The torque on the axle is linear through the assembly- it does not change the bearing preload or end play/ thrust, assuming proper assembly. 

All my training and 35+ years as a photographer can’t explain it.

 

Where are those damn Australian engineers to ‘splain it?

 

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35 minutes ago, paulmbowers said:

And im not yet smart enough to understand

Did I mis-quote you?   Hope so.    CID can you please start another Thread on Front Wheel torque and alignment.  August is dragging on and we need something to occupy our minds

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27 minutes ago, Bagstr said:

Did I mis-quote you?   Hope so.    CID can you please start another Thread on Front Wheel torque and alignment.  August is dragging on and we need something to occupy our minds

Sure what oil do you recommend?

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2 hours ago, amgems said:

When an axle system is designed by very particular Austrian engineers the preload and clamping force are calculated very carefully. I know, I have worked with Austrian engineers. Too much torque and you get too much friction in the system, not enough and there not is not enough stiffness in the axle system. Too much friction you get heat, wear, bearing failure. Not enough stiffness you get play and damaged bearings and races, or the bearing housings (hubs) get damaged. Those bearings and that whole axle system take one hell of a beating.

Motorcycle axles and wheel bearings are not designed this way.  Motorcycle wheel bearings are ball bearings, with limited ability to take thrust (they don't need to) and should have no side load on them at all when assembled, regardless of axle torque.  If axle torque is making a difference, you have other problems you need to fix.

Those of you prying the seal off a bearing and adding grease are only getting away with it because motorcycle wheel bearings are a low speed application for bearings designed and developed for high speeds.  The amount and type of lubricant that the bearing comes with is the result of a lot of ruthless testing.  My understanding is too much grease is almost as bad as no grease at all.

If you could keep a motorcycle wheel bearing free of water and dirt, it would live forever.  On dirt bikes, though, the outer seal has a hard life and gets old and hard, it starts wearing grooves into the wheel spacer, and water and dirt start working their way in.  A sealed bearing can hold this off for a while, but not forever.  It eventually goes.

If you have to replace bearings, get good bearings (like SKF) and you should replace the outer seals as well and take a good look at the spacers.  Water and dirt made their way past these two items when they shouldn't, and will again soon if you don't fix it.

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