S18 Suspension Overhaul

[Feynman]

Howdy from Texas.  I'm going to dump all my suspension updates here, and maybe some of you real engineers can tell me the right way to do this.  

I'm planning to:

1. Replace all bearings in the linkage.  They're 6088-2RS (10x19x5mm). I'm getting a quote for custom PAI or Delrin bushings - I may just go with bushings instead of bearings.  Maybe I'll test both and see which is better.  These parts don't rotate fast and get super hot, so I think bushings should be fine, and no rotating races to bind against the other side, etc

2. If I do use bearings I'll try to find some speed washers - like you use on skateboard bearings - to put the bolt force on the inner race.  I'm having a hard time finding these in the 10mm size vs the standard 8mm.

3. Add low-friction spacers between butted parts that rotate.  I ordered some of these teflon washers:  https://www.ebay.com/itm/392789577456

4. Replace the sex bolts on the linkage connections.  I measured and believe these are m8, button head, hex socket with a barrel length of 20mm.  (Please correct me if I'm wrong)

5. Cut a bit off the spacers on the shock connections and insert a low friction PTFE or Delrin bushing on all ends (4 total)

6. Replace shock with a Fox 200x57 

7. Lube everything with white lithium grease

8. Make sure everything is low friction floppy before reassembling wheel

 

Final Parts List:

1. 15mm L x M6 Cap Bolts (8 total) -- https://www.amazon.com/gp/product/B07L56Z4SY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 $6.89

2. 12mm L x M6 Button Head Bolts (4 total)  -- https://www.belmetric.com/6mm-c-563_581_584_606/sb6x10ss-button-allen-socket-head-stainless-p-3278.html $0.64

3. 20mm L x 10mm OD x M6 round coupler (4 total) -- https://www.amazon.com/gp/product/B07SQLZ568/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1   $7.99

4. 25mm L x 10mm OD x M6 round coupler (2 total) -- https://www.amazon.com/Coupling-Connector-Threaded-Adapter-Stainless/dp/B07X9W4DS1/ref=sr_1_1?dchild=1&keywords=m6+x+25+coupling&qid=1600211214&s=industrial&sr=1-1  $6.99

5. 10mm ID x 18mm OD x 5.5mm thick thrust bearings (3 total) -- https://www.amazon.com/gp/product/B07QKKWM2R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1  $6.69

6. 8mm ID x 16mm OD x 5mm thick thrust bearings (4 total) -- https://www.amazon.com/gp/product/B0192SOXN0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1  $7.29

7. M6 Stainless Flat Washers (4 total) -- https://www.amazon.com/gp/product/B009OK2AZK/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1  $9.52

8. 0.5" ID x 0.75" OD x 1/32" thick PTFE washers (6 total) -- https://www.ebay.com/itm/1-2-Washer-3-4-OD-1-32-thk-PTFE-Plastic-Insulating-Fastener-Z78070/392789577456?ssPageName=STRK%3AMEBIDX%3AIT&var=661675992196&_trksid=p2057872.m2749.l2649 $9.99

9. 0.25" ID x 0.562" OD x 0.062" thick PTFE washers (6 total) -- https://www.amazon.com/gp/product/B006GHXY90/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 $14.52

10. Custom 3D Printed Bushings -- AMIDEX Glass Fiber Reinforced Filament (1/10th roll) -- https://www.3dxtech.com/glass-fiber-reinforced-filaments/amidex-nylon-gf30/  $68.00

    a. Pocket B - internal bushing with built in spacer

    b. Pocket A - External Bushing 

    c. Pocket A - internal bushing, extends into pocket D

    d. Pocket D - internal bushing

    e. Pocket D - external bushing

    f. Pocket C - internal bushing 

    g. Pocket C - external bushing with built in spacer

11. Blue thread locker (1 tube) -- https://www.amazon.com/Loctite-Heavy-Duty-Threadlocker-Single/dp/B000I1RSNS/ref=sr_1_3?dchild=1&keywords=blue+threadlocker&qid=1600211771&sr=8-3  $6.09

Total cost not including bushings / filament or shipping (you'll have extras of every part, sorry):  $76.61

Edited September 15, 2020 by Feynman

[Feynman]

Many of the bearings were cracked and fell apart when removed.  I think this might be because of the lock washers tightened hard onto the seals, as the bearings with no lock washers seemed to be in better condition.    

[StuartL]

10 minutes ago, Feynman said:

If I do use bearings I'll try to find some speed washers - like you use on skateboard bearings - to put the bolt force on the inner race.  I'm having a hard time finding these in the 10mm size vs the standard 8mm.

M10 washers are 20mm OD as standard, however M10 shims are 16mm OD as standard.  This might be sufficiently small to fit inside the outer race, though it may still bind on the seal.

A simple approach might be to find some acetal/Delrin tube with a 10mm ID.  This could then be sliced with a chopsaw or even a handsaw to create as many spacers as you like.

[Feynman]

6 minutes ago, StuartL said:

M10 washers are 20mm OD as standard, however M10 shims are 16mm OD as standard.  This might be sufficiently small to fit inside the outer race, though it may still bind on the seal.

A simple approach might be to find some acetal/Delrin tube with a 10mm ID.  This could then be sliced with a chopsaw or even a handsaw to create as many spacers as you like.

That's a good idea.  Do you think a plastic washer would hold up here?  I found some 10mmx15mm copper washers, but not sure how well copper would hold up. 

 

Here are typical 8mm skate speed rings: https://www.amazon.com/Dime-Bag-Hardware-Skateboard-Performance/dp/B078HZN4TT/ref=sr_1_4?dchild=1&keywords=speed+washers+skateboard&qid=1598276533&sr=8-4 

Edited August 24, 2020 by Feynman
Added link

[StuartL]

6 minutes ago, Feynman said:

Do you think a plastic washer would hold up here?

I think it would need to be the right plastic.  Acetal/Delrin is a pretty strong plastic.  There may still be a possibility of cracking, especially if overtightened.  You'd definitely need a relatively low torque on the bolt which might then mean needing blue threadlock to stop it coming undone.

8 minutes ago, Feynman said:

I found some 10mmx15mm copper washers, but not sure how well copper would hold up.

Copper is a risky choice.  It's quite soft as metals go and, while it's unlikely to crack, I can't imagine it would be a particularly stable washer.  I imagine it'll crush similarly to a plastic washer.

One of the interesting things here is that (if I understand the construction correctly, I've not inspected it in person) you don't actually need anything thick.  Is this correct?

[Feynman]

1 minute ago, StuartL said:

I think it would need to be the right plastic.  Acetal/Delrin is a pretty strong plastic.  There may still be a possibility of cracking, especially if overtightened.  You'd definitely need a relatively low torque on the bolt which might then mean needing blue threadlock to stop it coming undone.

Copper is a risky choice.  It's quite soft as metals go and, while it's unlikely to crack, I can't imagine it would be a particularly stable washer.  I imagine it'll crush similarly to a plastic washer.

One of the interesting things here is that (if I understand the construction correctly, I've not inspected it in person) you don't actually need anything thick.  Is this correct?

I think that's correct.  It doesn't have to be thick.  The purpose is to transfer the force along the bolt vector to the inner race and effectively bind it to the bolt/nut while the out race is bound to the part that's rotating.

[StuartL]

What about (mad idea coming...) using a smaller washer, e.g. an M6 or M8 washer, and drilling it out to 10mm?  You'd need to make a jig to stop the washer dancing around, perhaps clamping it firmly between two pieces of wood?  Perhaps CA glue it to another piece of metal and then remove the CA glue with heat?  Or start with a metal tube/pipe and slice bits off it?

I can't imagine that this is a specialist part!

[Feynman]

1 minute ago, StuartL said:

What about (mad idea coming...) using a smaller washer, e.g. an M6 or M8 washer, and drilling it out to 10mm?  You'd need to make a jig to stop the washer dancing around, perhaps clamping it firmly between two pieces of wood?  Perhaps CA glue it to another piece of metal and then remove the CA glue with heat?  Or start with a metal tube/pipe and slice bits off it?

I can't imagine that this is a specialist part!

That's an idea.  Maybe could epoxy it down and drill it out.

Another possibility is to switch to 8x19x6 bearings, e.g. https://www.amazon.com/uxcell-698-2RS-Bearing-8x19x6mm-Bearings/dp/B07SZ7G576/ref=sr_1_4?dchild=1&keywords=8x19x6+bearing&qid=1598277527&sr=8-4

and use that standard skateboard washers.  I'm not sure if the extra 1mm of thickness  would be a problem or not.

[StuartL]

7 minutes ago, Feynman said:

I'm not sure if the extra 1mm of thickness  would be a problem or not.

You'll have 1mm x 2 for the bearings + at least 1mm extra for the shim washer.  Does the construction have enough clearance to permit an extra 1.5mm each side?  Can you get M8 bolts a good size without them hanging out either side?

[Feynman]

53 minutes ago, StuartL said:

You'll have 1mm x 2 for the bearings + at least 1mm extra for the shim washer.  Does the construction have enough clearance to permit an extra 1.5mm each side?  Can you get M8 bolts a good size without them hanging out either side?

There's not much thickness left on some of the single bearing pockets, so probably not

[Feynman]

To replace the binding post barrels and bolts, I'm going to give these a try:

https://www.belmetric.com/6mm-c-563_581_584_606/sb6x10ss-button-allen-socket-head-stainless-p-3278.html?zenid=gk1q6devagcgk3erpngqd3bla2

https://www.belmetric.com/coarse-thread-round-c-563_578_1206_1962/nround6x20ss-standoff-round-coupler-stainless-p-7047.html?zenid=gk1q6devagcgk3erpngqd3bla2

[FinRider]

I ordered me a set of these. Will probably be 6 weeks before they arrive but will test em out and see if they Fit & make a difference. 

 

€ 5,04  16％ Off | Free shipping 10pcs AXK1024 +2AS  10X24X2mm AXK series  1024 thrust needle roller bearing bearing +whosale and retail
https://a.aliexpress.com/_BTlS32

 

[Feynman]

15 minutes ago, FinRider said:

I ordered me a set of these. Will probably be 6 weeks before they arrive but will test em out and see if they Fit & make a difference. 

 

€ 5,04  16％ Off | Free shipping 10pcs AXK1024 +2AS  10X24X2mm AXK series  1024 thrust needle roller bearing bearing +whosale and retail
https://a.aliexpress.com/_BTlS32

 

I'm interested to see if the thickness will work.  I ordered some of these figuring I could combine with a spacer and use the bearing pockets to countersink them.  Not sure if I'll use them or not. 

[fbhb]

@Feynman great to see this dedicated S18 suspension topic posted here, which will no doubt be a great help for many owners.  For anyone looking to replace their bearings (especially broken bearings) with much better quality, but still relatively affordable I have tracked down a good option on Ali Express:

4Pcs S6800-2RS 10x19x5 mm ABEC-7 Stainless Steel hybrid Si3n4 ceramic bearing

Some forum members may already know that bearings are sometimes given an ABEC rating and this relates to the precision involved in the bearings manufacturing tolerances.  The ABEC rating system includes grades 1,3,5,7, and 9. The higher the ABEC rating, the tighter the tolerances are, making the bearing a more precision part. 

These RS bearings I am linking to are rated ABEC 7, with Stainless Steel construction and hybrid ceramic ball bearings.  The rest of the specs are also mentioned in the listing, but the main advantage being a High Quality bearing with very High corrosion resistance, for anyone concerned about the standard King Song bearings being susceptible to rusting and premature failure in wet conditions.

For anyone wanting to source the most ideal bearings for the S18 (read most expensive), there are a number of different designations relating to High Load & Low speed which are the most commonly used bearings for suspension pivot points on MTB's and therefore ideal for our S18 use case! 

You will need to look for bearings rated with any of the following: 6800V 2RS1 / 6800VRS1, 6800-V 2RSR / 6800VRSR, 6800 LLU MAX / 6800LU MAX, 6800 DDU MAX / 6800DU MAX, 6800EE MAX / 6800E MAX, 6800-V 2RS / 6800 2RSV MAX / 6800 2RS MAX / 6800MAX 2RS / 6800V 2RS / 68002RS MAX, 6800 VRS MAX / 6800MAX VRS / 6800RSV MAX / 6800MAX RSV / 6800RS MAX / 6800MAX RS, VF6800 2RS MAX / 6800VF / FC6800 RS / FB6800 RS

These bearings are distinguished in their construction by Not having a cage to hold the balls in place, which in turn allows for the maximum amount of balls to be fitted into the race to better spread the loads involved in suspension application.  Of course, this also makes them more costly but an option I found on Ali Express below is the cheapest I've seen so far!

6800-2RSV MAX Bearing 10*19*5mm ( 1 PC ) Full Balls Bicycle Pivot Repair Parts

I will be placing an order for a Full set of bearings in preparation for when my S18 arrives, but in the meantime would just like to confirm with you guys that have already stripped your S18 down @redfoxdude @Feynman @FinRider the Total number of bearings I will require?

 

Edited August 29, 2020 by fbhb

[BFE Duke]

Not sure I would trust ceramic bearings for an assembly that takes a lot of impact. Ceramic bearings may be harder than steel, roll better, and take heat better, but they are considerably more brittle. For this application I would actually prefer good old fashioned steel 440C stainless or 52100 chrome steel. 

[fbhb]

4 hours ago, BFE Duke said:

Not sure I would trust ceramic bearings for an assembly that takes a lot of impact. Ceramic bearings may be harder than steel, roll better, and take heat better, but they are considerably more brittle. For this application I would actually prefer good old fashioned steel 440C stainless or 52100 chrome steel. 

The bearings I have linked to are Not Full Ceramic bearings (if you are actually referring to my post above), but are constructed using Hybrid ceramic balls and indeed your preferred 440C Stainless for the races! 

The loads placed on each individual pivot point will not actually be as high as you presume, due to the load being spread between multiple points of contact, so in this application even King Songs shitty, cheap bearings would cope well enough if only they had assembled the linkage correctly with spacers instead of spring washers!

Following quote is from a trusted Bearing Resource regarding the use Ceramic Hybrid Bearings:

"Ceramic Hybrid Bearings have Steel races and Ceramic Balls. Ceramic Balls are suitable for applications where high loads, high speeds and extreme temperatures are factors. Long life and the need for minimal lubrication make this material appropriate for extreme applications. Ceramic is non-porous, non-magnetic, non corrosive and lighter than steel. In ball form, ceramic balls are also harder than steel and because ceramic balls are non-porous they are virtually frictionless and capable of spinning faster than steel balls".

Edited August 25, 2020 by fbhb

[fbhb]

After a little more research I found another Ali Express seller with a whole range of Stainless Steel shim washers in sizes that should work for the S18 bearing spacers.  They come in 5 different thickness: 0.1mm 0.2mm 0.3mm 0.5mm & 1.0mm with the 10x14x? options being the dimension that will work best as it should only clamp up against the inner race!

Thickness 1.0mm Stainless steel Flat Washer

Thickness 0.5mm Stainless steel Flat Washer

Thickness 0.3mm Stainless steel Flat Washer

Thickness 0.2mm Stainless steel Flat Washer

Thickness 0.1mm Stainless steel Flat Washer

Edited August 25, 2020 by fbhb

[slaweks82]

36 minutes ago, fbhb said:

After a little more research I found another Ali Express seller with a whole range of Stainless Steel shim washers in sizes that should work for the S18 bearing spacers.  They come in 5 different thickness: 0.1mm 0.2mm 0.3mm 0.5mm & 1.0mm with the 10x14x? options being the dimension that will work best as it should only clamp up against the inner race!

yes, and in regular shop you can just ask for DIN988 washer with 10mm ID, and according to norm, they are 10x16 and come in variations you mentioned, and also 0.25mm. I just don't know which will fix fine.

Just my 2 cents about bearings, it's not 10000RPM where you should be concerned about minimum friction and temperatures, so I will go with regular 2RS, just not the cheapest, they are sealed and filled with grease, so they will be fine.

[Duf]

I appreciate you guys doing the leg work as far as coming up with a list of quality replacement components.  I look forward to seeing what does and doesn't work/fit.  My S18 wont be here for another 3 weeks so it looks like I have some work to do when it gets here.

[Feynman]

13 hours ago, fbhb said:

I will be placing an order for a Full set of these bearings in preparation for when my S18 arrives, but in the meantime would just like to confirm with you guys that have already stripped your S18 down @redfoxdude @Feynman @FinRider the Total number of bearings I will require?

14 bearings total

Edited August 25, 2020 by Feynman
counted wrong

[FinRider]

23 minutes ago, Feynman said:

12 bearings total

I ordered 20 new ones, as well as a bunch of 4mm thrust bearings, but it will take 4-6 weeks for them to arrive..-

[BFE Duke]

1 hour ago, fbhb said:

The bearings I have linked to are Not Full Ceramic bearings (if it is that you are actually referring to my post above), but are constructed using Hybrid ceramic balls and indeed your preferred 440C Stainless for the races! 

The loads placed on each individual pivot point will not actually be as high as you presume, due to the load being spread between multiple points of contact, so in this application even King Songs shitty, cheap bearings would cope well enough if only they had assembled the linkage correctly with spacers instead of spring washers!

Following quote is from a trusted Bearing Resource regarding the use Ceramic Hybrid Bearings:

"Ceramic Hybrid Bearings have Steel races and Ceramic Balls. Ceramic Balls are suitable for applications where high loads, high speeds and extreme temperatures are factors. Long life and the need for minimal lubrication make this material appropriate for extreme applications. Ceramic is non-porous, non-magnetic, non corrosive and lighter than steel. In ball form, ceramic balls are also harder than steel and because ceramic balls are non-porous they are virtually frictionless and capable of spinning faster than steel balls".

I guess whenever anyone I've talked to mentions ceramic bearings, they pretty much imply hybrid ceramic bearings with steel races and ceramic bearings. I've never heard anyone referring to ceramic balls with ceramic races without adding the qualifier "full ceramic bearings," which might be good for like a fidget spinner or something lol. (Yes, that is a joke, I know they use them in MRI machines where they can't have anything magnetic). I did read the link, and being of questionable origin and manufacturing prowess, you'd have to take them at their word that it is actually 440C and not "Ch_440C", unless you have access to an X-Ray spectrometer. That said, if you mic- out the components and they spec out to ABEC7, then you might actually be on the safe side. The ad doesn't list any load specs at all though, which is not a good sign. In the end you might be trading one Chinesium bearing for an even worse Chinesium bearing for this particular application. Keep in mind that "high loads" and "high impact" are not necessarily the same thing. Ceramic balls are "hard" but not nearly as "tough" as steel balls, and the high speed & temperature benefits of ceramic bearings wouldn't really do anything for you in this case. 

I wouldn't say the OEM bearings are the problem. As to why his bearing races cracked during removal, you have to keep in mind that a 6800 bearing is considered a "thin section" bearing, which under no circumstances should be installed or removed with a hard tool, hammer, punch, screwdriver, or anything like that through a striking blow. It's not just Chinesium bearings that will break--even NSK's website explicitly says not to do this. Usually a press or jig is used to remove them if you want them to survive. However I will give OP the benefit of the doubt and assume that he has a shop press =). 

By the way, if you're going to go with a bushing, have you considered bronze? They're dirt cheap, though you might have to churn out an adapter to fit the 10mm ID: 

https://www.aircraftspruce.com/pages/ha/bushings/flangedbushings.php

[BFE Duke]

If you're in the states and just need spacers, perhaps these shims might help: 

https://smile.amazon.com/gp/product/B0036R4REO/

[Feynman]

3 minutes ago, BFE Duke said:

I wouldn't say the OEM bearings are the problem. As to why his bearing races cracked during removal, you have to keep in mind that a 6800 bearing is considered a "thin section" bearing, which under no circumstances should be installed or removed with a hard tool, hammer, punch, screwdriver, or anything like that through a striking blow.

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

[Feynman]

26 minutes ago, BFE Duke said:

If you're in the states and just need spacers, perhaps these shims might help: 

https://smile.amazon.com/gp/product/B0036R4REO/

Fantastic find!!  I'm definitely going to try these