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S18 Suspension Overhaul


Feynman

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17 minutes ago, Feynman said:

At least a few of the races were cracked before I pounded them out.  Not sure how they installed them.

Are you serious? Wow that is sad. Hopefully they're not pounding them in at the factory...

1 hour ago, Feynman said:

12 bearings total

Wait, why are there 12 bearings? I only see 3 pivot points, so with two different sides shouldn't there be only 6 bearings? Why are there 12? 

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14 minutes ago, BFE Duke said:

Wait, why are there 12 bearings? I only see 3 pivot points, so with two different sides shouldn't there be only 6 bearings? Why are there 12? 

Some of the points have two bearings in them.  

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5 minutes ago, Feynman said:

I'm still going to replace all the bearings since half of mine fell apart, and put a spacer between all the joints:

https://www.ebay.com/vod/FetchOrderDetails?itemid=392789577456&transid=1030126750026&ul_noapp=true

My plan is to not remove bearings just undo bolt, remove spring washers and put those spacers in.  And remove the metal block between sliders....

 

 

Edited by Duf
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Just now, Duf said:

My plan is to not remove bearings just undo bolt, remove spring washers and put those spacers in.

 

That will be easier.  Unfortunately, you still have to take the wheel almost completely apart to get to all of them. :(

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2 hours ago, BFE Duke said:

Wait, why are there 12 bearings? I only see 3 pivot points, so with two different sides shouldn't there be only 6 bearings? Why are there 12? 

Guys, I fucked up.  There are actually 14 bearings.  Sorry!  See pic... red circled pockets contained 2 bearings, green - 1 bearing.  So that's 7 x 2 = 14 total

 

 

linkage.png

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48 minutes ago, Duf said:

My plan is to not remove bearings just undo bolt, remove spring washers and put those spacers in.  And remove the metal block between sliders....

 

 

That would have worked for mine. I didn’t even have the spring washers. Don’t forget to add oil to the sliders.
I do plan on buying new bearings and having them ready for when I have a reason to take the wheel apart again. 

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19 minutes ago, Feynman said:

Guys, I fucked up.  There are actually 14 bearings.  Sorry!  See pic... red circled pockets contained 2 bearings, green - 1 bearing.  So that's 7 x 2 = 14 total

 

 

linkage.png

What on earth? :blink1: Why the hell would they put two bearings side by side? Lmao maybe it's for redundancy so that if one bearing seizes, the other one takes over :lol:

 

57 minutes ago, Duf said:

My plan is to not remove bearings just undo bolt, remove spring washers and put those spacers in.  And remove the metal block between sliders....

 

 

Please keep us updated on if the spacers alone will solve it. I've got them on order and hopefully I'll have everything I need to get up and running on day one when my S18 supposedly arrives next week. 

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I found info on this site that may be of interest. It seems like the mountain bike designers must have come across similar issues in the past, so looking at their solutions may be useful.

https://www.endurobearings.com/products/bearings/max/

My S18 is on order, but strongly considering cancelling until Kingsong makes improvements.

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On 8/25/2020 at 8:52 PM, BFE Duke said:

What on earth? :blink1: Why the hell would they put two bearings side by side? Lmao maybe it's for redundancy so that if one bearing seizes, the other one takes over :lol:

Either to a) spread the load across two bearings (seems unnecessary in this case) or b) to manage the twisting force (seems likely in this case).  Without a second bearing it may be possible for the twisting force to overload one bearing or even unseat it.

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6 hours ago, StuartL said:

Either to a) spread the load across two bearings (seems unnecessary in this case) or b) to manage the twisting force (seems likely in this case).  Without a second bearing it may be possible for the twisting force to overload one bearing or even unseat it.

Managing twisting forces with two bearings requires both bearings to be in the same housing, like in a PTO setup. With two bearings on opposite components on the same pivot point, I don't see how that would help with twisting force. If anything it would make things worse. 

Edited by BFE Duke
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6 minutes ago, BFE Duke said:

With two bearings on the same pivot, that makes twisting force even worse. 

Could you elaborate on what you mean by this?  Have I misunderstood how these bearings are installed in the suspension arms?  Surely having two bearings side-by-side (essentially making one very wide bearing) manages the shear/twisting force on the pivot significantly better than one bearing (behaving very much like the single narrow bearing)?

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On 8/27/2020 at 9:34 AM, StuartL said:

Could you elaborate on what you mean by this?  Have I misunderstood how these bearings are installed in the suspension arms?  Surely having two bearings side-by-side (essentially making one very wide bearing) manages the shear/twisting force on the pivot significantly better than one bearing (behaving very much like the single narrow bearing)?

Because they're "inline" and not "parallel", the load is not spread between the bearings, but instead placed on both bearings. I'll try to come up with an analogy...

Edit: I just realized that there are FOUR bearings in that point, meaning each pocket has two bearings. In that case, having two bearings next to each other is a perfectly good setup. However there is no need for them to have 4 bearings, and they could've eliminated 1 pocket entirely from each side. 

Edited by BFE Duke
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Okay, here's an example: 

cane_creek_thudbuster_LT-3__72133.146852

This is an example of how a load can be spread among two bearings, when one pivot is in the middle and the second pivot is designed as a clevis that surrounds the other pivot, with one bearing on each side. (they actually use bushings, but that's beside the point)

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4 minutes ago, BFE Duke said:

second pivot is designed as a clevis that surrounds the other pivot

For sure that is a better design where it's possible but I stand by my comments above.  Placing two bearings side by side does improve the situation.  It doesn't solve it, but it helps a bit.

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I got a quote for custom Delrin bushings: $70 for the set.  I'm debating whether I should bite the bullet and do it, try to find some off the shelf bronze  bushings that will fit, go with replacement bearings, or buy a lathe and make my own bushings.  I'm waiting for the spacers and replacement bearings to come in.  In the meantime, let's do a poll!  

https://www.easypolls.net/poll.html?p=5f484650e4b0065ae3b4c583   

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5 hours ago, Feynman said:

I got a quote for custom Delrin bushings: $70 for the set.  I'm debating whether I should bite the bullet and do it, try to find some off the shelf bronze  bushings that will fit, go with replacement bearings, or buy a lathe and make my own bushings.  I'm waiting for the spacers and replacement bearings to come in.  In the meantime, let's do a poll!  

https://www.easypolls.net/poll.html?p=5f484650e4b0065ae3b4c583   

LMAO looks like you just need an excuse to buy a lathe. Just a warning: The instant you buy one, you'll want a bigger one. :lol:

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6 hours ago, Feynman said:

or buy a lathe and make my own bushings

A quick Google shows at least two, if not three Makerspaces in Houston.  There will almost certainly be a lathe there which you'll be able to use for a modest membership fee, certainly much less than buying a lathe :D

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8 hours ago, BFE Duke said:

LMAO looks like you just need an excuse to buy a lathe. Just a warning: The instant you buy one, you'll want a bigger one. :lol:

Hmm... you might be correct!

6 hours ago, StuartL said:

A quick Google shows at least two, if not three Makerspaces in Houston.  There will almost certainly be a lathe there which you'll be able to use for a modest membership fee, certainly much less than buying a lathe :D

I had no idea such things existed!

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