Rear Wheel Bearing Seal (shaft seal ring) 2011 KTM 350sxf | GTAMotorcycle.com

Rear Wheel Bearing Seal (shaft seal ring) 2011 KTM 350sxf

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Recently have been doing an bit of an overhaul on my 2011 KTM 350 sx-f Cairoli dirtbike (linkage bearings replaced, wheel bearings front and rear replaced, brakes all around, clutch flush and bleed, new chain sprockets chain guide, valve shims,etc).

For my rear wheel, there was a badly rotten out wheel bearing. It was non-OEM "All balls" bearings and on my Honda I've also seen these fail pretty quickly. So replaced it with KTM OEM bearings from Italy. After going to reinstall my new bearing shaft seals, I noticed the previous owner used the same seals in the rear wheel which were from the front wheel (0760354771).
Comparing to what is in my manual that is the actual shaft seal ring for the rear wheel (0760324771) I can see why maybe he used the seals from a front wheel; the 32 in the part number I believe is the thickness (in depth) of the seal, and it doesn't seat up against the bearing leaving a 2mm gap (which can be filled with grease). If you use the seal from the front wheel it's 35 deep and fits right up to the bearing leaving almost no gap.

My question is, which is better for my rear wheel?
Use the actual rear-wheel bearing seal what is in the manual (0760324771) which has a gap between the seal and bearing?
OR
Use what the previous owner did and put the front wheel bearing seals into the rear-wheel leaving almost no gap between the bearing and seal 0760354771)?
 
The only job that seal has is to keep crud off the bearing. You could do the same thing by wrapping the area in duct tape.
If you use the seal that leaves a gap, DO NOT fill the gap with grease.

What I use for wheel bearings is a "2Z" bearing. "2Z" means 2 metal seals in the bearing, then I toss any rubber seals... you don't need them. Less weight and less drag.

I suggest you gots other problems, you seem to be eating wheel bearings. If you power wash your bike after you've playing in the dirt be sure NOT to direct the spray at the wheel hubs. The seals were never designed to seal against any real pressure (most single lip seals are designed for less than one atmosphere, some A LOT less)..

OEM bearings do not guarantee GOOD bearings. All Ball bearings are sourced from Asia, just like 99% of standard single row bearings available. The top brand names; SKF, NTN, Koyo, Fag all source their single row bearings in the east. (What brand are your "OEM" bearings from KTM? NSK?)
Point in case: I just bought a bunch of bearings to rebuild some Yamaha crankshafts. The OEM outer bearing is a nothing special NSK, it retails for about $65. I use a up-graded high precision C4 Koyo bearing, I paid $9.60.

(...but yeah... All Balls seems to have a bad reputation, I won't use them).
 
Thanks for the reply.
Think I'm okay for eating bearings, bike has 100 hours and starting the 3rd set in rear wheel (that's not bad for all rocky and wet enduro riding).
Front wheel were original OEM from when new and they were still really good (I only replaced for good measure and since had all the tools out).
I talked to the parts guy at GP and he also agreed use the front seals in the rear wheel also that will seat up against the bearing.
That's what I ended up ordering.

I don't powerwash into the axle; but the riding up north is almost non-stop water crossings hitting un-seen boulders under the water and I'm confident that's where the bearings are taking the beating.
 
Haven't read your post in great detail. The OE's spend a lot of time engineering parts for their equipment.

For deep grrove bearings. almost everyone makes it in China now. However there is a quality difference between no-name brand and bigger brands. The bigger brands also have different lines of bearings...long story short. The all balls is prob half decent quality, but mostly likely your seal has failed, which caused the bearing to fail.

Also, 2Z or ZZ bearings - have a small gap between the inner ring and the shield. Its better to get a 2RS or Sealed bearing and run a contact dust seal on the assembly as well. You will get the most sealed enclosure for those bearings.
 
The only job that seal has is to keep crud off the bearing. You could do the same thing by wrapping the area in duct tape.
If you use the seal that leaves a gap, DO NOT fill the gap with grease.

What I use for wheel bearings is a "2Z" bearing. "2Z" means 2 metal seals in the bearing, then I toss any rubber seals... you don't need them. Less weight and less drag.

I suggest you gots other problems, you seem to be eating wheel bearings. If you power wash your bike after you've playing in the dirt be sure NOT to direct the spray at the wheel hubs. The seals were never designed to seal against any real pressure (most single lip seals are designed for less than one atmosphere, some A LOT less)..

OEM bearings do not guarantee GOOD bearings. All Ball bearings are sourced from Asia, just like 99% of standard single row bearings available. The top brand names; SKF, NTN, Koyo, Fag all source their single row bearings in the east. (What brand are your "OEM" bearings from KTM? NSK?)
Point in case: I just bought a bunch of bearings to rebuild some Yamaha crankshafts. The OEM outer bearing is a nothing special NSK, it retails for about $65. I use a up-graded high precision C4 Koyo bearing, I paid $9.60.

(...but yeah... All Balls seems to have a bad reputation, I won't use them).

I would use 2RS / sealed bearings with the dust seal on the outside.

Also, a 'high precision C4 Koyo bearing' is not really a high precision, C4 refers to the internal bearing clearance....C3 what industrial people use for most low precision equipment, C4 has a greater internal clearance. The ABEC or ISO rating is what makes a bearing 'precision'....ABEC 1,3,5,7,9.. P2, P3, P4, P4A...etc. This rating is the measure of the [FONT=arial, sans-serif] amount of tolerance from the measurement indicated. Higher the ABEC, the closer to tolerance, and lower the deviation on the ring measurements., [/FONT]Grades 1 and 3 are used for commercial bearings while grades 5, 7 and 9 represent precision bearing classes.
The grading of the bearing influences the tolerance of every dimension that has an effect on the accuracy with which the bearing runs....like Bore and outer diameter, Concentricity of tracks, Parallelism of tracks, Squareness of faces,Circularity of tracks.

So the C4 bearing does not indicate its 'precision' level, but it does have a 'loose fit'. Which means it can potentially have a higher rpm...when the bearing material heats up, it will expand - which will prevent it from binding. But also if you have a greater than normal internal clearance and shock loading...it will dent the races.

So a claim cannot be made that a 'C4 KOYO' is a upgrade, when we dont know what its been rated for. Also we do don't know what the OEM is using for the bearing to deep this Koyo better or worst.
 
I would use 2RS / sealed bearings with the dust seal on the outside.

Also, a 'high precision C4 Koyo bearing' is not really a high precision, C4 refers to the internal bearing clearance....C3 what industrial people use for most low precision equipment, C4 has a greater internal clearance. The ABEC or ISO rating is what makes a bearing 'precision'....ABEC 1,3,5,7,9.. P2, P3, P4, P4A...etc. This rating is the measure of the [FONT=arial, sans-serif] amount of tolerance from the measurement indicated. Higher the ABEC, the closer to tolerance, and lower the deviation on the ring measurements., [/FONT]Grades 1 and 3 are used for commercial bearings while grades 5, 7 and 9 represent precision bearing classes.
The grading of the bearing influences the tolerance of every dimension that has an effect on the accuracy with which the bearing runs....like Bore and outer diameter, Concentricity of tracks, Parallelism of tracks, Squareness of faces,Circularity of tracks.

So the C4 bearing does not indicate its 'precision' level, but it does have a 'loose fit'. Which means it can potentially have a higher rpm...when the bearing material heats up, it will expand - which will prevent it from binding. But also if you have a greater than normal internal clearance and shock loading...it will dent the races.

So a claim cannot be made that a 'C4 KOYO' is a upgrade, when we dont know what its been rated for. Also we do don't know what the OEM is using for the bearing to deep this Koyo better or worst.

Ya gotta love the interwebs....
Who said "C4" made it a "precision" bearing?
I said I bought a "up-graded high precision C4 Koyo bearing" for a much lower cost than the standard OEM bearing. I wasn't getting all technical with the OP, I was saying I got a better bearing, cheaper, by not buying OEM. (I doubt the OP understands what C4 means, or what the ramifications are, not very many people do).
I can and will claim the bearing I bought is an "up grade", in my circumstance, from the OEM NSK bearing. I DO understand what C4 means and it's ramifications.

... anything else ya want ta learn me?

Oh and "RS" bearings are rubber sealed, as are LL and LLU, (but I am sure you already knew that) and may or may not have a thin metal backer (but I am sure you already knew that) and is not nearly as robust as a "Z" seal (but I am sure you already knew that), and the OP stated it is for an off road vehicle....
 
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Ya gotta love the interwebs....
Who said "C4" made it a "precision" bearing?
I said I bought a "up-graded high precision C4 Koyo bearing" for a much lower cost than the standard OEM bearing. I wasn't getting all technical with the OP, I was saying I got a better bearing, cheaper, by not buying OEM. (I doubt the OP understands what C4 means, or what the ramifications are, not very many people do).
I can and will claim the bearing I bought is an "up grade", in my circumstance, from the OEM NSK bearing. I DO understand what C4 means and it's ramifications.

... anything else ya want ta learn me?

Oh and "RS" bearings are rubber sealed, as are LL and LLU, (but I am sure you already knew that) and may or may not have a thin metal backer (but I am sure you already knew that) and is not nearly as robust as a "Z" seal (but I am sure you already knew that), and the OP stated it is for an off road vehicle....

"I use a up-graded high precision C4 Koyo bearing" That statement can be interpreted as 'C4' as what makes it precision, that's why I went about explaining it. But Im glad you know your bearings. :) Didnt mean to rant about it....

For this bearing application the Con's out weight using a ZZ bearing , the only thing you are gaining with a shielded bearing is lower drag but at the cost of having a non-contact seal. Why not run a sealed bearing with, external seals / wipers...gives you the most sealing properties, gives the bearing the highest chance of surviving. Yes it will give you a bit more drag...but not by much.

The shielded bearing's gap between the raceways can cause grease to wash out and pre-maturely make the bearing fail. (I see this all day in my field)
 
Thanks for all the replies guys.
Yes, C4 C3 2Z ... and all that, went completely over my head.
But from experience the all-balls weren't great, that's why I specifically paid more for the OEM KTM bearings made in Italy (STK?).
Shop confirmed use the front wheel seals in the rear like previous owner did to try and lessen gap.
Next time around maybe I'll try 2RS-sealed-bearings with the dust seal on the outside like suggested (if that's different from what I have, although the ones I have were sealed and I gently removed seals to really fill up with more grease before installing. Shaft seals were extra and I decided to use the same ones I put in the front wheel in the rear also).
 
Your KTM bearing will be a " 2 RS " bearing, it looks like this: https://www.google.ca/search?q="2r"..._AUIBigB#newwindow=1&tbm=isch&q="2rs"+bearing

A "2Z " bearing looks like this: https://www.google.ca/search?q="2z"..._jLAhXjm4MKHYhDA24Q_AUIBygB&biw=1566&bih=1049
Instead of rubber with really thin foil seals on the sides it has thicker metal seals, sealing just as well as the rubber seals (the reduction of drag comes from tossing the separate OEM one lip seal. The only down side is a "2Z" has a slighty lower limiting RPM (top speed).

DO NOT peel the seals off bearings and fill them up with grease. It really shortens the bearing's life.
Bearing lube is quite thin (about regular 30 oil with a ton of rust preventer), and there should only be enough to cover the elements, rollers and races, of the bearing, no more than 25% of the empty space.
New bearings come "pre lubed" and are ready to install. If you have to remove a bearing, you should replace it, they're cheap... but if you have to reuse a bearing; wash it in solvent and lube it with a few drops of motor oil, no grease.
 
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Your KTM bearing will be a " 2 RS " bearing, it looks like this: https://www.google.ca/search?q="2r"..._AUIBigB#newwindow=1&tbm=isch&q="2rs"+bearing

A "2Z " bearing looks like this: https://www.google.ca/search?q="2z"..._jLAhXjm4MKHYhDA24Q_AUIBygB&biw=1566&bih=1049
Instead of rubber with really thin foil seals on the sides it has thicker metal seals, sealing just as well as the rubber seals (the reduction of drag comes from tossing the separate OEM one lip seal. The only down side is a "2Z" has a slighty lower limiting RPM (top speed).

DO NOT peel the seals off bearings and fill them up with grease. It really shortens the bearing's life.
Bearing lube is quite thin (about regular 30 oil with a ton of rust preventer), and there should only be enough to cover the elements, rollers and races, of the bearing, no more than 25% of the empty space.
New bearings come "pre lubed" and are ready to install. If you have to remove a bearing, you should replace it, they're cheap... but if you have to reuse a bearing; wash it in solvent and lube it with a few drops of motor oil, no grease.

This is not true. Don't rant at my explanation as to why.....

Check out this illustration from the Koyo Catalogue...below.

The ZZ bearings (circled) will have the shield contacting the outer ring (most cases), there will be a gap between the inner ring and the shield. This is where grease will wash away, and debris will come into the bearing and contaminate it.

The 2RS (rectangles) will have a contact seal on both the inner ring and outer ring, the lip on the inner ring is usually thinner. This means the seal will contact both the rings, keeping the lubricant in and debris out better than a shielded bearing.

12967457_1159308850780614_7137515963404829073_o.png
 
Thanks for all the replies guys.
Yes, C4 C3 2Z ... and all that, went completely over my head.
But from experience the all-balls weren't great, that's why I specifically paid more for the OEM KTM bearings made in Italy (STK?).
Shop confirmed use the front wheel seals in the rear like previous owner did to try and lessen gap.
Next time around maybe I'll try 2RS-sealed-bearings with the dust seal on the outside like suggested (if that's different from what I have, although the ones I have were sealed and I gently removed seals to really fill up with more grease before installing. Shaft seals were extra and I decided to use the same ones I put in the front wheel in the rear also).


If the bearings are 'rotting' out, I suppose you mean they have been contaminated with dirt etc and failed ? Then the OEM vs. All Balls might not help, you have a sealing issue here from what I can understand. I am not sure how many hours / use the original set lasted. But this would be your third set of bearings atleast, Original, the all balls, and now this set...

The seals you are using, front wheel bearing seals for the rear wheel etc etc, if the last set has failed this will have similar life expectation.

Are the OEM seals single lip seals? or double lip seals? Dust seals are usually single lip, Oil seals can be single or double lip. If the OEM is single lip, you should change it to a double lip oil seal, gives you 2x the sealing.

Are you greasing the seals when you put the axle in? a dry seal against the spacer or axle will wear much quicker.
 
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Thanks for the further replies.
Yeah I estimated the same, on the 3rd set at 100 hours.
I imagine the first OEM set lasted a while and the All Ballz were the short-lived ones.
Might be a sealing issue, the bike is not perfect (couple dents in the rims from rocks but still true and all spokes perfect) but I budget for fresh bearings per season and I do allot of up keep (re-grease everything each ride and what not) trying to keep everything fresh for each ride.
Where we've been riding spend literally half the time almost up to the waist in water and I'm confident that's doing the most wear on the bike.
Actually my friend told me it's nice that I bought the "better" OEM replacement bearings but in our case riding in so much water and wet mud would be better off with the cheaper All Ballz not expecting to last more then a season or less anyway since any bearing no matter the quality is not expected to last long in those conditions.
 
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