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  1. #1
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    Over torque retaining bolts in upper link of TallboyC and others

    There seems to be an issue with people (such as myself) snapping their upper linkage retaining bolts.

    The first time I removed the upper link I snapped one of the M5 bolts (locking bolt with the tapered washer) when tightening to 100 in/pounds. The second time I set my wrench to 90 but I stopped at less then that. Everything ran fine for the rest of the season. Now this week I am giving the linkage it's scheduled maintenance and found that the one bolt was severely stretched and just shy of snapping. The trouble area seams to be the bolt that attaches the link to the rear triangle. The upper bolt made it to 100 in/p the first time and didn't look damaged. This time I am tightening all bolts in the upper and lower links to 60 in/p. Everything seems to move freely and is nice and snug. We'll see how it plays.

    Here's a picture of the over stressed bolt. It's hard to see but I could really feel that it was skinny in the middle.
    Attached Thumbnails Attached Thumbnails Over torque retaining bolts in upper link of TallboyC and others-screw-4.jpg  

    Last edited by Man from Utopia; 01-20-2013 at 04:51 PM.
    Help, I'm a rock!

  2. #2
    Ninja Master Powers
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    I have had the same problem with my 2012 Nomad Carbon. SC will replace the bolts but it will happen again if you use the SC spec'ed bolts.

    I've changed my bolts out to stainless, so far so good. But the proof of the fix is when you remove the bolt for maintenance then re-torque it the second time.

    My guess is it not the right material and/or bolt size for the application.

  3. #3
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    I going to look for SS at my local lomo depot.

    On a side note, I noticed once I removed the upper link and had full mobility of the swing arm with the lower link still attached that there was bit of friction. So when I cleaned, regreased and reattached the lower link and tightened the pivot axles to where there was no friction or play and then installed the tightening bolts with tapered washers and tightened down to 60 in./p that there was once again some friction in the pivot. So it seems that tightening the bolts turns the pivot axle
    Help, I'm a rock!

  4. #4
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    When I brought it in to a shop to have them drill out my snapped bolts, they put the SC replacements back in by hand to some "medium" torque without a torque wrench. So far so good.
    definite malingerer

  5. #5
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    This is a recognized problem and there are several threads on it. I've thought about converting to stainless steel but I am afraid I will get the wrong bolt specs. If anyone has sorted this out and can post up the SS sizing - see: Standard Metric Bolt Shank Dimensions (which, for all I know isn't relevant but stops me cold) - then please let us know.
    Will trade for some chicken.

  6. #6
    Ninja Master Powers
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    Quote Originally Posted by edley View Post
    This is a recognized problem and there are several threads on it. I've thought about converting to stainless steel but I am afraid I will get the wrong bolt specs. If anyone has sorted this out and can post up the SS sizing - see: Standard Metric Bolt Shank Dimensions (which, for all I know isn't relevant but stops me cold) - then please let us know.
    I took the SC bolts into Ababa Bolt in El Cajon Ca. They have any fastener you can possibly imagine in stock. They matched the bolt, the only issue is I had to buy a dozen of each size.

    You can probably also get a match from Marshals Industrial Hardware or Grangers

    One thing to keep in mind; it's not the best practice to use a SS bolt in the AL axel. I used blue loctite paste and made sure to coat the threads of the bolt completely. I also remove them to maintain the pivot every 90 days; which is probably overkill and I plan to replace the bolts and axels every 12-18 months.

  7. #7
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    I snapped my bolt in the lower axle of the upper link at at 8 nm. I now torque to 6 nm. This is way below spec but works fine as long as you check the bolt regularly. I am using the factory replacements which SC was kind enough to send me.

  8. #8
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    Stupid me...I paid $50+ for mine. I just picked up a couple SS M5s at Lowes for a buck fifty. Will try them next time.
    Help, I'm a rock!

  9. #9
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    Quote Originally Posted by Man from Utopia View Post
    Stupid me...I paid $50+ for mine. I just picked up a couple SS M5s at Lowes for a buck fifty. Will try them next time.
    Hopefully you won't need to - getting my snapped bolt out was an exercise in true patience.

  10. #10
    Ted
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    After going through the pain of extracting a broken bolt I now measure the bolt length before I use them. If they don't feel right when torquing them I take them out and measure them again. If they are stretching I throw them away and use new ones. I got the replacements from a local industrial fastener store (same size SS bolt). I don't go up to the spec torque because that will almost always stretch the bolts. I serviced my upper pivot today and had to throw away two bolts due to stretching. What a poor design. I spoke with Santa Cruz and they suggested I reduce the torque to 90 in-lb but even this is too high and will result in stretching. I now use about 70 in-lb. I wish there was a stronger bolt I could use. I am surprised there is not more discussion about this.

  11. #11
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    I just found this thread, and have had a similar experience. I was doing a full bearing replacement on a Nomad 2 for a friend and when I went to tighten that bolt with my torque wrench I got that feeling that something was not right. It's the same feeling when removing a fastener and you realize the bolt is no longer turning but stretching (usually just before it snaps).....I loosened the link bolt and tightened by hand. Since Santa Cruz recommend using loctite on the fastener, I don't see a problem with it being tightened to 50in lbs and it holding perfectly fine.

  12. #12
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    That occurs when you use santa torque specs... I went with proper 10 class screw, not s.steel, and torqued to 70% of recommended torque only. Loctite applied. Solved

    here is my case: New NOMAD alu - torque specs - BEWARE!!!

  13. #13
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    I had the same problem with the upper link bolt my aluminum Tallboy last week. Snapped the bolt around 80 psi after servicing. Called Santa Cruz tech who sent out a few complimentary replacement bolts since it is a known issue. He also said 75 inch pounds was a more appropriate torque for that upper bolt. That's interesting due to the fact that the 100 psi value is listed in their own tech guides and video on VPP. To make matters worse, my LBS can't remove the bolt and wants to drill the entire sleeve out......

  14. #14
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    Sorry to be a "me too" but.. me too. Nomad mk2 alloy, upper link top bolt. Torque wrench that was working fine on all the other bolts, but the top one snapped (and yeah, got 100i/p correct for it instead of 110 for the rest).

    However at the time I felt perhaps the wrench should have clicked by now, and should have stopped earlier. Didn't feel like it I was over torquing it though.

    Question though is on the loctite. I know that changes the torque spec, plus the stuff I've got is not the exact one they use but is the longer setting loctite. Not as fluid. So that may be a mistake also as torque perhaps is even less with that. Still, it was fine on all the other bolts. I do wonder if the torque specs factor in the loctite though.

    Interesting the SC tech guy says 75i/p.

    Trying to get the remains of the bolt out currently. Looks tricky.

    Anyway, replacement bolts from any old shop are threaded right to the head. Does that matter, as the official bolt has a smooth section before the thread starts?

    Might try SC to get a freebie, but if it's better to go with more durable bolts anyway may do that.

  15. #15
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    Breaking those bolt heads have happened to almost everyone that works on SC VPP bikes...even some of the best mechanics I know have busted them. Think of it as a right of passage.
    Contact Willie from SC and he'll take care of you. I might suggest calling SC Tech guys and just talking to them a little about what happened.

    Cheers,
    Mike

  16. #16
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    I read this thread, and a few others, before getting my first SC bike (SC 5010). I've tightened these bolts to 8nm (70in/lbs) and have not had any problems with them coming loose (with loctite 242)

  17. #17
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    Since this thread came up, I would like to mention one thing to the people that are going to go out and purchase their own bolts. Stainless steel fasteners are not automatically better than their steel counterparts. Actually stainless fasteners are a pain in the behind. They stretch, they bind up, and if you don't use anti-seize, they'll goober-up on you and you won't be able to get them out at all. As an engineer, I only use them in application where it's strictly necessary.

    Now, I know that some of you think that you need SS bolts because the bike gets wet, and they will rust and what not. But think about your car. Every fastener is steel and it lasts. Plus it sounds like y'all are doing regular maintenance so you can replace them every time you service. Steel fasteners are quite cheap. If you are worried about the corrosion, you can buy zinc plated ones that are good at resisting corrosion.

    Finally, steel fasteners are stronger then their SS counterparts. A simple look at McMaster will show that the minimum tensile strength for steel bolts is 170 ksi, while for SS its 70 ksi. If you are worried about snapping, just get the steel ones. Don't think that SS bolts will be better because SS sounds exotic.

  18. #18
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    Out of interest, looking up the part from SC's diagrams for my Nomad the part spec is...

    M5X0.8x20 SHCS 18-8SS (100in/lbs) *

    I'm guessing here, but does the 'SS' at the end indicate stainless steel?

    Have to say the bolts on mine kind of look like stainless steel. Though I thought they may even be Ti but clearly not. They look nice though, but 3rd party replacements don't look quite so good. So I'll probably try direct from SC, though I'm UK based so will have to go via Jungle Products (I believe), or otherwise book the bike in at the LBS if I can't get the bolt out anyway.


    * Though I can only find the diagrams for "Nomad 2.1". I know it's a Mk2 alloy Nomad around 2010/11ish, that's all. Didn't know there was a 2.1

  19. #19
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    Quote Originally Posted by deadkenny View Post

    M5X0.8x20 SHCS 18-8SS (100in/lbs) *

    I'm guessing here, but does the 'SS' at the end indicate stainless steel?

    [/i]
    Yes 18-8 SS is stainless. 18-8 denotes the type of stainless steel (18% chromium 8% vanadium). Pretty much all 300 series grade SS falls into this category.

    Listen, bolts are bolts. A standard bolt obtained from SC vs your local hardware are going to be exactly the same. Don't worry about appearance, worry about material. The bolt from SC will just have a massive markup.

    I can't really think of a reason why SC decided to spec out SS bolts. Even in terms of galvanic corrosion zinc steel fasteners are better than SS ones, when in contact with aluminum. If you have a carbon frame then I guess that aspect doesn't matter.

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