Damper Carrier Play

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REDTALE2000
Two wheeled terror
 
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Damper Carrier Play

Postby REDTALE2000 » Mon Mar 20, 2017 9:49 pm

Just to be clear, "Damper Carrier" is what KTM calls the inner portion of the cush drive that splines to the axle.
While installing the third drive chain on the SDR, I noticed what seemed like possibly excessive clearance between the damper carrier and the axle. I don't know what the clearance was like when new (if any) because I hadn't completely removed the chain before (pulled new chain on using old chain). With the chain on, the play seems minimal because of the radial loading by the chain.
With the chain off however, I can rock the sprocket side to side about a quarter inch and rotate it forward and backward about an eighth inch at the perimeter. The motion occurs between the axle and the carrier, not between the inner and outer parts of the cush drive.
Also, there is a small axial clearance (maybe 5 thou) between the carrier and the axle nut on that side. (There's a 1mm shim in there too. And, yes, the axle nut has been torque checked.)
So, it seems like the carrier is intended to float on its splines, i.e. it's not hard-captured between the axle nut and a shoulder on the axle. So it's going to move around a little.
But, with 60,000 pretty hard miles on the bike, I'm wondering if I've worn it enough to be about to strip the splines. There's a lot of force right there.
What I'm wondering is if any of you who have pulled the axle out can tell me
1) whether the carrier should be floating
2) whether those are big deep splines that would be happy with some play
Seems to me ABC spent some time in there during the wobbly wheel adventures.
Any advice?
Also, rather not spend $600 for new carrier, axle, bearings...
2014 1290 73K miles

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lc4
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Re: Damper Carrier Play

Postby lc4 » Mon Mar 20, 2017 11:06 pm

I`ve had mine apart a couple of times and it is all a snug fit.
I would suggest with 96000klm it is fooked.

REDTALE2000
Two wheeled terror
 
Posts: 181
Joined: Thu Apr 03, 2014 3:08 am
Location: Ojai, CA

Re: Damper Carrier Play

Postby REDTALE2000 » Tue Mar 21, 2017 11:32 pm

If for no other reason than just to add to the knowledge data base here, I though I'd update with my findings after disassembling my rear axle assembly,
As described above, initial symptom was a wobbly damper carrier.
After removing the axle, it became clear that the carrier was wobbling because the axle nut, even though it had been torqued to spec, was not actually making contact with the side of the carrier. The threads were so loaded up with hardened Loctite that the nut stopped turning before clamping down on the carrier. Net result was that the carrier was free to float in about a 5 thou gap. This caused some galling on the adjacent surfaces but not too bad.
I've not had this apart before so I'm guessing that the nut was never torqued properly when first installed and the Loctite hardened up. I did a torque check after a couple of months during the wobbly wheel adventures but the nut didn't move so I assumed all was fine.
In restrospect, I should have loosened and re-tightened it.
Also discovered that one of the 2 plastic bushings (IGUS Bearings) which fit between the damper carrier and the sprocket support was worn paper thin on its axial bearing face. This controls side to side motion of the sprocket support on the damper carrier.
This could have been caused by the motion of the carrier on the axle so hopefully it won't wear again after proper assembly.

So kids, be sure to check yer carriers fer wobble! :wink:
2014 1290 73K miles

abc
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Location: snowy mountains

Re: Damper Carrier Play

Postby abc » Fri Mar 24, 2017 11:38 am

REDTALE2000 wrote:This could have been caused by the motion of the carrier on the axle so hopefully it won't wear again after proper assembly.

Yep that sounds about right and yes sounds like you have fixed it. Sure does sound a little dodgy though, maybe it was a mistake at assembly and wasn't picked up in pre delivery check. Good find and an easy fix so well done, always satisfying to figure out a fix when everything is apart on the bench in front of you. 8)
And you're right, I certainly spent a lot of time on the rear ends on these bikes :roll:
Any modifications you undertake are your sole responsibility, I am not liable for any claims relating to modifications or suggestions posted on this forum. If you undertake any modifications you do so at your own risk.

REDTALE2000
Two wheeled terror
 
Posts: 181
Joined: Thu Apr 03, 2014 3:08 am
Location: Ojai, CA

Re: Damper Carrier Play

Postby REDTALE2000 » Fri Mar 31, 2017 10:44 pm

The saga continues... :roll:
Bought 2 IGUS bearings to replace the ones torn up during the wobbly carrier episode.
BUT, both of the new bearings are about 0.4mm larger OD than the old ones and won't fit into the sprocket carrier without MAJOR press type force.
Old bearings are a nice slip fit into the carrier.
Also the ID is about 0.5mm larger resulting in a sloppy fit on the damper carrier "axle".
Old bearings are a nice slip fit on the axle.
KTM dealer where parts were purchased knows nothing and will contact KTM North America which I expect will produce nothing of value.
SO, what I'm wondering is, if any of you (ABC??) who have mucked around in their rear wheels can tell me if your IGUS bearings were a slip fit (both inside and outside) the way my old (and possibly worn) ones are. Or whether they are supposed to be a press fit into the sprocket carrier. You'd probably have to have had your carriers apart to know this.
It is possible that the bearings are intended to be pressed in which would reduce the ID somewhat but, with an interference of almost 0.016", I'm pretty sure the bearing would be destroyed in the process.
2014 1290 73K miles

abc
Stunt rider
 
Posts: 666
Joined: Tue Dec 17, 2013 11:21 pm
Location: snowy mountains

Re: Damper Carrier Play

Postby abc » Thu Apr 06, 2017 10:50 am

sorry redtale I missed your post.
I can't rely that well on my memory but I can tell you that 0.4mm press fit will damage something and is not right. If you can find any numbers on the original bearings you can search for their exact specs (but you probably already know this) or measure everything accurately and then search by sizes.
I didn't pay much attention to the cush drive because my attention was elsewhere trying to sort the rear hub freepaly so I can't even tell you if the 0.5mm clearance on the shaft is OK but something doesn't sound right.
You are right best to check everything out again to be sure. good luck
Any modifications you undertake are your sole responsibility, I am not liable for any claims relating to modifications or suggestions posted on this forum. If you undertake any modifications you do so at your own risk.


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