Swingarm bushings
- Thread starter gbabyracing
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- bushing bushings outer reassembly steel
Bajaj's fitting of unlubed swingarm bushings was a matter of concern on the Duke forum as well. One of our members, however, discovered an exploded diagram of the swingarm assembly that showed IGUS bearings at the swingarm, two per side.
http://ktmamerica.com/part_books/2015/street/2015 BLACK DUKE 390 CHASSIS PARTS BOOK.pdf
IGUS bearings are made from an advanced industrial formulation that is said to be extremely durable and low-friction, claimed to be superior to sintered copper "Oillite" bushings. They do not require lubrication and are essentially maintenance-free (as well as inexpensive). I think we are not giving KTM credit for adopting modern, low-cost materials for the 390. Perhaps needle bearings might have been superior, but they require lubrication. One of our Duke owners, an engineer, is familiar with IGUS bearings from his work and reckons they are a good design choice. I think we can stop worrying about the swingarm bushings.
igus® - iglide® Plastic Bushings
http://ktmamerica.com/part_books/2015/street/2015 BLACK DUKE 390 CHASSIS PARTS BOOK.pdf
IGUS bearings are made from an advanced industrial formulation that is said to be extremely durable and low-friction, claimed to be superior to sintered copper "Oillite" bushings. They do not require lubrication and are essentially maintenance-free (as well as inexpensive). I think we are not giving KTM credit for adopting modern, low-cost materials for the 390. Perhaps needle bearings might have been superior, but they require lubrication. One of our Duke owners, an engineer, is familiar with IGUS bearings from his work and reckons they are a good design choice. I think we can stop worrying about the swingarm bushings.
igus® - iglide® Plastic Bushings
B7ACKTHORN
Member
Excellent. As a matter of fact, I was wondering what IGUS slide bearing was when reading the parts catalog, helps a bunch .
Cheers!
V
stevieboy
Member
And how do we know if that's what's in there? Well, if its cheap, there you go!
Rexbo
Member
Not sure I agree with saying that we're good... my swingarm bushings were already showing signs of significant wear, which is never good.Parent material should never transfer.
For wearing surfaces using special coatings or impregnated surfaces, visible wear is indicative of material failure.
For wearing surfaces using special coatings or impregnated surfaces, visible wear is indicative of material failure.
green_bread
Member
I wouldnt consider them to be maintenance free or expect them to remain "low-friction" when they are getting covered with surface rust after less than 1000 miles of usage.
If you look at section 9 of the parts manual (first link) it presents the exploded diagram of the swingarm. Part no 16 is the "IGUS slide bearing." There is an inner and outer IGUS bearing on each side of the swingarm, total four. Presumably, the IGUS bearing is what takes the rotational loads from the swingarm. Otherwise, why would it be there? In between the IGUS bearings is a metal "Bushing Sleeve" (part 17). This appears to function as a spacer rather than a load-bearing component. In any case the IGUS bearings are designed to to bear rotary loads like needle bearings or oil lite bushings. If there is rust or wear on the "bushing sleeve" that may be insignificant, as the IGUS bearings will be taking all the rotary load between the swingarm and spindle. I think this arrangement could benefit from some hands-on examination to confirm, but the use of IGUS bearings would certainly explain why Bajaj does not lube the swingarm pivot at the factory.
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Fasteddy
Member
Interesting stuff!
The igus / Iglide roller chain looks like another possible use in the motorcycle industry.
The igus / Iglide roller chain looks like another possible use in the motorcycle industry.
Treachery
Moderator
Hmm. Interesting. Thanks for the information and the discussion. Now I can't decide whether I'm glad I didn't go to the trouble of lubing the bushings when I did the shock swap, or am worried about premature wear.
Rexbo
Member
I'll have my bike apart this summer. Will investigate further.
chevaliernoir
Member
hello
when i disassembled by swingarm pivot, there was no IGUS
just the spacer already worn, and a kind of cup, on each side, to make contact with the seal.
I'm still convinced that something is wrong
when i disassembled by swingarm pivot, there was no IGUS
just the spacer already worn, and a kind of cup, on each side, to make contact with the seal.
I'm still convinced that something is wrong
ChevalierNoir, did you look at the exploded diagram of the swingarm pivot in the parts manual? The IGUS slide bearings are part no. 16: Two per side, one at each end of the spacer, just as you have described. They are not large and might resemble a "cup". Perhaps these are what you found. A photo, of course, would be useful. If in fact the IGUS bearings are not present, then that might be a cause for concern.
http://ktmamerica.com/part_books/201...RTS%20BOOK.pdf
http://ktmamerica.com/part_books/201...RTS%20BOOK.pdf
chevaliernoir
Member
What I've seen on my bike does not fit with this diagram :
I have
parts #11 & #12, on the footrest holder plate
part #13 is a gasket fixed in the swinging arm
Whay I call the "cup", is part #15.
It is directly pressed pressed between 12 and the bushing sleeve. So the cup is like fixed to the frame, and simply touch the oil seal ring.
This cup is only for sealing and not to absorbe any friction.(by the way the KTM name is "bucket for shaft seal ring"
I don't have parts#14 and #16
But total length seems OK
I should measure the total length of the bushing sleeve.
Or maybe my missing parts are located all at the same side of the bushing instead of 1 on each side ? I should check this too...
I will post a picture this evening or tomorrow..
I have
parts #11 & #12, on the footrest holder plate
part #13 is a gasket fixed in the swinging arm
Whay I call the "cup", is part #15.
It is directly pressed pressed between 12 and the bushing sleeve. So the cup is like fixed to the frame, and simply touch the oil seal ring.
This cup is only for sealing and not to absorbe any friction.(by the way the KTM name is "bucket for shaft seal ring"
I don't have parts#14 and #16
But total length seems OK
I should measure the total length of the bushing sleeve.
Or maybe my missing parts are located all at the same side of the bushing instead of 1 on each side ? I should check this too...
I will post a picture this evening or tomorrow..
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Treachery
Moderator
Not to be glib, but still under warranty? Sounds like an assembly defect.
chevaliernoir
Member
In 2 weeks I should bring back the bike for waranty. I will tell them about that too, then...
If the IGUS bearings that are part of the swingarm pivot design are in fact absent on Chevaliernoir's bike, that is truly mysterious. This would seem to make the spacer into a load-bearing bushing, not at all what we had been led to believe. Without IGUS bearings, the swingarm pivot would appear to need grease, indeed. This should be researched so we can understand how the swingarm pivot should work. Has the design been changed or is this an assembly error?
In this vein, has any 390 owner experienced a handling problem due to the swingarm bushings?
In this vein, has any 390 owner experienced a handling problem due to the swingarm bushings?
chevaliernoir
Member
I went to my KTM dealer, and discussed this topic very briefly. It seens the IGUS bearing is behind the oil seal ring. so it stays inside the swinging arm, when removing the bivot and bushing.
This would explain why I've not seen the stop disk #14 and the IGUS slide bearing #16 from the outside.
By construction, you cannot feel the "gearing mooving with your finger as there is no movement.
So it would be normal to have a (low) friction beween IGUS bearing and the sleeve.
I'm not fan at all of this low cost design and would pay to have real bearing instead of this, but it seems it is done on purpose and there is no assembly mistake behind this.
This would explain why I've not seen the stop disk #14 and the IGUS slide bearing #16 from the outside.
By construction, you cannot feel the "gearing mooving with your finger as there is no movement.
So it would be normal to have a (low) friction beween IGUS bearing and the sleeve.
I'm not fan at all of this low cost design and would pay to have real bearing instead of this, but it seems it is done on purpose and there is no assembly mistake behind this.
That is indeed a relief to know that the IGUS bearings are present but hidden in the swingarm when the spindle is removed. Therefore, the exploded diagram seems accurate and there is no design change. Grease is thus not needed.
One of the Duke forum members who is an engineer works frequently with IGUS bearings. He says they are a modern, effective, low-cost substitute for traditional bearings in many applications, and he has no problem with KTM's design choice for the swingarm. Inexpensive components, simpler assembly for the factory, lower maintenance for the rider.
One of the Duke forum members who is an engineer works frequently with IGUS bearings. He says they are a modern, effective, low-cost substitute for traditional bearings in many applications, and he has no problem with KTM's design choice for the swingarm. Inexpensive components, simpler assembly for the factory, lower maintenance for the rider.
