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  1. #1
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    SB66c Stop Bolt Bumper - Replacement ideas?

    Hello,

    We had "lots" of rain lately in the bay area and I took this as an opportunity to service my SB66c.
    I removed the eccentric pivot/bearings and noticed that the bumper was not on the stop bolt anymore. The bumper is in a very bad shape. I donít know how long itís been like this, maybe did it fall when I took everything apart.

    SB66c Stop Bolt Bumper - Replacement ideas?-sb66c-stop-bolt-bumper.jpg

    I reached out to Yeti for a replacement and got sent to my LBS (Sports Basement in Sunnyvale) as they don't have it for direct sale. I ordered replacement bolts and bumpers 10 days ago, and today was said that Yeti does not have the bumpers in stock! I contacted Trailhead and Passion Trail and they donít have the bumpers in stock either.

    Here are the part numbers:
    300030234 - Bolt stop m12x1.25x10mm
    300030235 - Bumper stop

    So I donít know what to doÖ Are there any SB66 owners who found a replacement solution? Someone used a rubber cork (SB-66: Worn-out stop bolt - Page 3) but I donít know if that thing worked out or not.

    Do you guys have any suggestion or know of a place where I could rapidly get that piece of rubber?

    Thanks!

    Hoki

  2. #2
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    There's a bunch of kerfluffle about the bumper, and I wonder what the purpose *really* is when with the bike fully assembled the *shock* is limiting the rotation of the Switch.

    When assembling things, sure, I get it, but once assembled does it really matter?

    I just rebuild the pivots on my sb95 (new bearings and bushings) and my bumper "hat" is MIA also, but I refuse to sweat it as I don't think it can be touched. I need to de-pressure the shock though and check max-compression to be sure though.

  3. #3
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    Go to your local auto parts store and ask to see their selection of vacuum port plugs.

  4. #4
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    I have used a slightly trimmed Schrader valve cap with huge success.

  5. #5
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    This issue shouldn't happen at all but it is even worse that Yeti won't stock such a small item. They obviously have them somewhere because they continue to build frames. What's next, no replacement bearings!? Very poor customer support.

    I had an aluminum SB66 which cracked apart on my (rear triangle) and the stop was hammered by the Switch link. Yeti replaced the front and rear triangles under warranty and I sold the frame. I still love the fit and the ride and would love a SB-66C but these issues worry me because I had to wait 3 months for the replacement bearings after my first frame had the bad bearings.
    SC Tallboy C : Giant TCX SLR : Giant Propel Adv SL DA9070

  6. #6
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    I had 3 frame warrantied because of this issue. I would wear through the bumper in one ride. I absolutely love the ride and feel of the 66, but after my last warranty frame, I sold it and am waiting on a banshee spitfire. Without a doubt one of the best pedalling 6" bikes out there, but I was plagued with issues and I can stand a little less efficiency and a little more reliability. Yeti was superb to deal with though, and I can't say enough good things about their CS.

  7. #7
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    I talked to Matt from Yeti and he said that I could:

    1 - ride without the bumper.
    2 - put some super glue inside the bumper to hold it on the stop bolt.

    #1 does not work for me as I don't want to damage the eccentric. I know that some are unsure if the bumper is really useful, but I don't want to buy a new eccentric at $140 a pop. BTW, the easiest and fastest way to get a new bumper would be to order a new eccentric kit...

    I was not sure about #2 as the bumper is in a very bad shape. So I went to OSH and bought one of those rubber corks. I worked on it with a Dremel, added some Gorilla glue inside and voilŗ:

    SB66c Stop Bolt Bumper - Replacement ideas?-sb66c-homemade-stop-bolt-bumper.jpg

    It looks almost like a brand new bumper! I'm still putting my SB66c back together so I cannot tell if that really works. Hopefully it will hold up until I get the genuine bumpers I ordered from Yetifan!

  8. #8
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    O'reilleys sells different size rubber caps List: Search for 'vacuum caps' | O'Reilly Auto Parts

  9. #9
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    bringing back this topic... it's quite a shame this issue for a few reasons

    1 - yeti knows about it, doesn't deny the issue but at the same time doesn't come up with a reliable solution
    2 - the suggestion to ride without the bumper brings the question why it's even there in the first place if you don't need it? and if you don't need it why it's all trashed when it's supposedly not being used?
    3 - yeti keeps saying this is a wear part and needs replacement, but I haven't seen it mentioned in the schedule maintenance they have in the manual

    I'd expect no less than parts available for replacement, as well as a better, reliable solution so you don't have to take the bike apart every other ride to replace this rubber bumper stop.

    This makes me wonder if I should just return my brand new sb66c and get something different!

    Definitely a design flaw in terms of material that yeti needs to find a solution for! I find it very hard to accept that yeti keeps asking people to replace it or replacing frames instead of coming up with a better material that will last for at least a season of usual riding for a 6" travel bike!

  10. #10
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    For what it's worth...A Schrader valve cap has been the best solution to date for my SB66C. I make it a point to take apart the eccentric for inspection and cleaning quarterly, which I fully expect to change out the bumper condom at that time. Takes me 30 minutes from start to finish.




    Quote Originally Posted by mfa81 View Post
    bringing back this topic... it's quite a shame this issue for a few reasons

    1 - yeti knows about it, doesn't deny the issue but at the same time doesn't come up with a reliable solution
    2 - the suggestion to ride without the bumper brings the question why it's even there in the first place if you don't need it? and if you don't need it why it's all trashed when it's supposedly not being used?
    3 - yeti keeps saying this is a wear part and needs replacement, but I haven't seen it mentioned in the schedule maintenance they have in the manual

    I'd expect no less than parts available for replacement, as well as a better, reliable solution so you don't have to take the bike apart every other ride to replace this rubber bumper stop.

    This makes me wonder if I should just return my brand new sb66c and get something different!

    Definitely a design flaw in terms of material that yeti needs to find a solution for! I find it very hard to accept that yeti keeps asking people to replace it or replacing frames instead of coming up with a better material that will last for at least a season of usual riding for a 6" travel bike!

  11. #11
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    Quote Originally Posted by mfa81 View Post
    2 - the suggestion to ride without the bumper brings the question why it's even there in the first place if you don't need it? and if you don't need it why it's all trashed when it's supposedly not being used?
    I think of it as an assembly/disassembly element, guarantees the switch is properly oriented during frame assembly.

    I have the belief that you could safely run the bike w/o the stop bolt at all once assembled.

    But it's just that, a belief.

  12. #12
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    Thread revival question. Just went through my 66c and of course the bumper was shredded so I opted to ride without it. I cleaned and re greased pretty much everything on the bike and redid the shock/fork also. She rides perfect now except for a small squishy sound coming from the shock/switch area. I hear it constantly when I'm climbing but nothing on the DH. I know it's hard to diagnose noise problem but thinking the bumper not there may be causing it. Or could be the shock though I don't hear it when I press down on the bike. I guess I'll have to order one and see. Anyone running without the bumper?

    Sent from my SM-N900T using Tapatalk

  13. #13
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    Re: SB66c Stop Bolt Bumper - Replacement ideas?

    I now use a 4:1 ratio glue lined heatshrink for my bumpstop. Seems quite resilient.

    Tested on my 66a, the linkage goes over center if there is no bump stop bolt. The swingarm pops out into a non-running position.

    A poorly maintained bump stop certainly can damage the eccentric and can make a characteristic knocking noise under abrupt mid stroke compression. This may indicate peak loads that end up in the swingarm which I wouldn't be too happy about in the long term.

  14. #14
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    I've used both a plastic Shrader valve cap and a length of Tygon fuel tubing on a 95. The later worked the best and is currently going strong. Rather noisy without a bumper. The plastic shrader cap worked but was still slightly noisy.

    ^What petercarm said.

  15. #15
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    Personally I think repeatedly replacing your bumper stopper in a very short timeframe indicates a potential setup issue. Doing this isn't fixing the underlying root cause.
    Bumper stopper life is clearly proportional to the number and force of each hit.

    Ultimately there are a few very simple possibilities which are very easily tested/implemented.

    1. Run a higher rear shock pressure... say 20% sag.
    2. Speed up your rebound to prevent it packing down.


    Both 1 & 2 will clearly reduce the potential for the rear shock to max out and bash the bumper stopper on the inside of the switch link.

    I agree with the opinion that you shouldn't run without the stopper - but the real issue is the bumper stopper should only very occasionally come into play when you max out your shock anyway. The bumper stopper is a last resort for those rare one off occasions IMO not a constant use item. If your constantly bottoming your shock out your setup wrong.


    I was doing 1 and to a lesser extent 2 and was eating bumpers. 20% sag (with all my gear on) and some tweaking of the rebound stopped it totally and I've not had to replace a single stopper in over 16 months now.. checked it the other day and it's still fine with no serious wear.

    Another easy thing to try on the older RP23 (2012) is try a firmer full open setting.. Most people will set it to 0 but you could try 1 or even 2.. lift the black knob with the numbers on it and align the desired setting with the blue full open/propedal switch. On the 2012 RP23s those numbers relate to the full open mode and not the propedal mode as on older RP23s.

    If the above hadn't worked for me I'd have retuned the shock (in the UK by Mojo) to firm it up.. just tell them its bottoming out all the time.. I got them to do my 575 to try and control the blow through and wallow which is the feel I was used to so I set my 66 up similar initially. I'd say rider weight and style may be a major contributor... not sure what rider weight the stock tune is aimed at?

    It's either that or a tolerance issue with the frame/switch...

  16. #16
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    Re: SB66c Stop Bolt Bumper - Replacement ideas?

    Quote Originally Posted by RocketMagnet View Post
    Personally I think repeatedly replacing your bumper stopper in a very short timeframe indicates a potential setup issue. Doing this isn't fixing the underlying root cause.
    Bumper stopper life is clearly proportional to the number and force of each hit.

    Ultimately there are a few very simple possibilities which are very easily tested/implemented.

    1. Run a higher rear shock pressure... say 20% sag.
    2. Speed up your rebound to prevent it packing down.


    Both 1 & 2 will clearly reduce the potential for the rear shock to max out and bash the bumper stopper on the inside of the switch link.

    I agree with the opinion that you shouldn't run without the stopper - but the real issue is the bumper stopper should only very occasionally come into play when you max out your shock anyway. The bumper stopper is a last resort for those rare one off occasions IMO not a constant use item. If your constantly bottoming your shock out your setup wrong.


    I was doing 1 and to a lesser extent 2 and was eating bumpers. 20% sag (with all my gear on) and some tweaking of the rebound stopped it totally and I've not had to replace a single stopper in over 16 months now.. checked it the other day and it's still fine with no serious wear.

    Another easy thing to try on the older RP23 (2012) is try a firmer full open setting.. Most people will set it to 0 but you could try 1 or even 2.. lift the black knob with the numbers on it and align the desired setting with the blue full open/propedal switch. On the 2012 RP23s those numbers relate to the full open mode and not the propedal mode as on older RP23s.

    If the above hadn't worked for me I'd have retuned the shock (in the UK by Mojo) to firm it up.. just tell them its bottoming out all the time.. I got them to do my 575 to try and control the blow through and wallow which is the feel I was used to so I set my 66 up similar initially. I'd say rider weight and style may be a major contributor... not sure what rider weight the stock tune is aimed at?

    It's either that or a tolerance issue with the frame/switch...
    You've completely misunderstood what the bump stop does. It prevents the switch going over center at the mid stroke inflection point. It has no role to play in bottom out.

  17. #17
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    Re: SB66c Stop Bolt Bumper - Replacement ideas?

    Quote Originally Posted by petercarm View Post
    You've completely misunderstood what the bump stop does. It prevents the switch going over center at the mid stroke inflection point. It has no role to play in bottom out.
    ... so I can't explain your observations although I don't doubt your observation that the retune has alleviated some behaviours.

  18. #18
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    I suppose it's the main reason why I thought the bumper stop was end point as increasing the pressure and sorting out the rebound stopped the rapid bumper wear.

    So it contacts at the mid inflection point?... if this is the case then same thing applies as with a higher pressure and quicker rebound this reduces the number of times you actually reach and go through the inflection point. Had a closer look at it now and there are some minor marks but its pretty close to pristine.. so I don't get it as I frequently ride rocky terrain and hammer the suspension a bit...

    Your right though I clearly totally misunderstand how it works as I thought constantly hitting that bumper would be poor design.. hence the only thing that made sense to me was end of stroke... Perhaps the new Infinity link will resolve these annoying maintenance issues around the current switch?

  19. #19
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    The inflection point is actually much earlier in the travel, maybe like 1/4. I'd say it's purely a coincidence that your setup changes had an effect on bumper life. It's more about how many times the suspension cycles through the inflection point. Sounds like the bumper is easily unseated and partially comes off the bolt, which would greatly shorten it's life.

    When my bumper went bad, I would only notice the noise when going through fast chatter.

    Another tip is to wait to tighten the bolt that clamps the two half's of the eccentric axle together until the swing arm is installed. Otherwise, when torque is applied the only thing resisting it is the bumper and it can be damaged. Use the swingarm as a lever to react the tightening torque.

  20. #20
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    I did totally strip the bike down and rebuilt it when I replaced the bearings.. so rear triangle off etc and it was after this. Done it since also but don't recall the exact order.. but I think I screwed the two side together first then fitted the bumper bolt last.

    One thing I have noticed it my "long lasting" bumper stopper spins very freely on the bolt but stays put and doesn't fall off.... perhaps this rotation is helping longevity?

  21. #21
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    ok just whipped the bolt out and the bumper freely spins on the bolt but doesn't pull off easily. Looking closely at it there are signs of even wear all around it. So perhaps this is it... this bumper is spinning slightly on each hit spreading out the wear?
    May be worth seeing if they rotate ok.. if not periodically take out the bolt and rotate it by hand a bit.. its a 2 minute job...

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