Results 1 to 7 of 7
  1. #1
    CTB
    CTB is offline
    mtbr member
    Reputation: CTB's Avatar
    Join Date
    Feb 2008
    Posts
    974

    Caution;  Merge;  Workers Ahead! Calling all 4-Banger Experts!

    Hi everyone. I've just gotten one of these:


    Now I'm through my bike and installing new bearings, etc. I have some questions about the main pivot on the carbon swingarm. I disassembled the bike, but now that it is apart, the inserts in that pivot don't really seem to make much sense. Maybe it's correct, but it seems odd. Here are pictures of what I have; all pictures are with the bike right-side up (i.e. it would be on its wheels):

    Pivot pieces in their locations, but pulled out of the frame:







    The main pivot pin went through these pieces, of course.

    Is this really how that pivot is suppoed to be put together? The smaller insert on the right of the bike (drive side, last picture above) seems like it was in backwards, as compared to the left side. Has anyone taken one of these babies apart and has some tips? Essentially, I just want to know how the parts should be so that I can reassemble correctly. This is vastly different from the non-Homegrown 4-Banger that I had taken apart.

    Thanks for any help/tips/info.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    4
    Here's some pics I snapped of my homegrown. I don't know if it helps at all but I can definately see that little lip on one side. The other side I can't see anything at all as the gap is very small. My intuition wants to say that the smaller pivot was in backwards looking at your pics though. I'm guessing the bearing face snugs up to these pivots right? If so it would not have a flat surface to press against on the small pivot the way it was installed.
    Attached Images Attached Images

  3. #3
    CTB
    CTB is offline
    mtbr member
    Reputation: CTB's Avatar
    Join Date
    Feb 2008
    Posts
    974
    Thanks, Kenji. You're right, it's hard to see how things are oriented in there. I'm still pretty convinced that the one spacer was backwards on my bike. I'm still working out how it'll go back together when it is time.

  4. #4
    smell my finger
    Reputation: joemamad's Avatar
    Join Date
    Oct 2004
    Posts
    289
    chris, does The tapered end of the flanged bushing fit (insert slightly) inside of the the flat end of the other bushing that had the taper against the swing arm? I'm thinking that they may have been together right and that the tapered end fits inside the other slightly to expand and center it inside of the tube before after you tighten the through-bolt, and before you tighten the pinch bolts to tighten those bushings because they are not supposed to rotate, only the pivot tube/bolt is supposed to rotate on the bearings in the swing arm. If you watch the bolt heads of the main pivot I don't think they rotate when you compress the suspension. I think that is why they have the grove cut through them. I think that the little lip that fits against the bearing on one side should be the same diameter as the end of the taper on the other so that it will fit agaist the inner race of the bearing in the swinger. As to why they aren't both flanged against the tube as the one side is, I think it has to do with insertion into the tube. They want that pivot to be pulled tight toghether as you tighten the pivot bolt, if both bushings were flanged against the tube, full tight insertion may not be gauranteed and the pivot bolt or bushings may move and wear. Just a thought as I have been looking at it. -- Joe

    It looks like the head tube angle of the 2 different generations are different. Is the Homegrown's slacker that the newer tiawanses frames? I love the homegrown's paint and frame design but do not think I'd love those pinch bolts -- seen many snapped (including a worthless parts frame I once bought), be very careful it would be a shame to tighten them 1/2 turn too tight. I think the ultimate would be the newer mag drop links and non-pinch-bolted chainstay on the stronger homegrown frame. (but I just can't get over the pinchches on the frame)

  5. #5
    CTB
    CTB is offline
    mtbr member
    Reputation: CTB's Avatar
    Join Date
    Feb 2008
    Posts
    974
    Joe, I don't believe the two inserts even contact each other when installed. They are narrower than the width of the frame opening. That's how I got the carbon arm off - I pushed the non-flanged insert farther into the frame, which allowed me ot pivot the carbon arm off the bike (after loosening the pinch bolts, of course). I'll take a look at this once I can get back to the project, but I believe the two inserts are not near each other when installed.

    According to the geometry in the catalogs, all the head angles are the same regardless of year. They claim identical geometry no matter what 4B you have; the biggest difference is the slack "real" seat angle of the Taiwan frames, though the "effective" angle is the same.

    As for the pinch bolts, I have an in-lb torque wrench and the original specs, so I should be ok. I do like those spacers that Schwinn made for the chainstay pivot bolts, tho. I wish I had those.

    Joe, you just outlined what I'm doing - I'm putting my later "light" parts onto the HG frame to see how I like it, with all-new suspension bearings. I borrowed my buddy's gram scale to weigh all the parts, too. I haven't weighed it yet, but I believe the pinch-bolt-free chainstay arm is also lighter, as it has more holes in it in than the original design. The mag dropouts are also lighter, and the SID shock took around 300g off the bike compared to the coil setup, but of course losing the head angle adjustment. That's where my uber-trick Fox setup comes in.

  6. #6
    smell my finger
    Reputation: joemamad's Avatar
    Join Date
    Oct 2004
    Posts
    289
    So how's the testing going on that adapter? Time to start marketing? That's got to be the single best upgrade to any 4-banger. The SID is OK, much better than either of the coils but a fox float -- that's the cat's A$$!

  7. #7
    CTB
    CTB is offline
    mtbr member
    Reputation: CTB's Avatar
    Join Date
    Feb 2008
    Posts
    974
    Joe, it's still working well, but upon disassembly of my bike I found a few details that need work. Sort of minor, but so far the part is holding up. Of course, I'm an engineer and am willing to sign up to less "robustness" than a manufacturer would for my own bike, but I'm not sure I'd want to sell these on the market. At least not yet.

    EDIT: BTW, I wanted to mention. Perhaps my Homegrown looks slacker in the picture because that's a 120mm fork on it. They were spec'ed with 100's, so that took some HA out of the bike with this 120mm Manitou.
    Last edited by CTB; 02-20-2009 at 08:24 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •