R80ST gets the GS Treatment

Discussion in 'Airheads' started by Airhead Wrangler, Dec 24, 2008.

  1. Readymeal

    Readymeal Been here awhile

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    i do have the copper ring thingy to adjust the bearings though... i think it only works for later GS... let me know wRanker :)
    [​IMG]
    #61
  2. lockyv7

    lockyv7 Long timer

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    There a Michelin Sirac 120 x 18 rear and a 100 x 18 rear mounted on the front. Locky.

    #62
  3. Airhead Wrangler

    Airhead Wrangler Long timer

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    Bgood, you mentioned (I think in your thread) something about flipping your rear brake over. Can anyone tell me how exactly does one go about doing that on a G/S or ST? Is it as straight forward as just pulling the arm off and flipping it over?
    #63
  4. Solo Lobo

    Solo Lobo airhead or nothing

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    I think you need to replacethe cam... don't know for sure but when I picked up my bike the rear brake didn't work for shit, and looked like this...

    [​IMG]

    Looking back, my bike was sure ugly when I got it!
    #64
  5. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Remove your rear wheel and look at your brake shoes from the left side of the bike. You'll see one half has an end in the middle and another has an end on the outside and both rest on the cam. With the lever on the bottom like normal, when you apply the brake the cam spins clockwise pushing the shoes into the drum. Notice that the cam isn't symmetrical--one part is flat, the part facing the shoes, the other part is rounded. When you flip the brake lever it will spin counterclockwise. Without modifying the cam the rounded parts would be touching the shoes and would slip--it wouldn't press the shoes into the drum. in other words:

    So, you need to do two things:

    1: modify the cam. Make the rounded sections look like mirror images of the flattened sections. The cam has 2 oil sealing o-rings on it. You'll need to drain the FD before pulling the cam. You may want to replace those o-rings while you're at it. Nathan said there's nothing at the hardware store to match them exactly(he's checked). You have to use the BMW part.

    2: flip your shoes. They pivot on a pin up forward and are held in by an e-clip. pull the e-clip, remove the springs, flip the shoes and transfer the springs to the other side so that they'll be on the outside.

    I haven't flipped mine yet but Nathan told me how to do it and showed me one that he had already done it to. I pulled mine apart hoping to be lazy and get him to do the grinding for me but the shop was too busy. I've got the luxury of having a whole box of these cams in Nathan's attic 5 miles from my front door if I screw up, but it seems pretty straightforward.

    Normally I do any grinding with a dremel but the face of the cam needs to be really straight and the dremel isn't always the best at that. I'm going to use a file(I know, I hate not using power tools) or maybe a belt sander with some 40 grit. The Ziz wheel might not be a bad option either, the cam's only about an inch across. You're removing metal from it and it's obviously under stress, don't remove more than you have too. I don't need to tell you all this. From what you've done to your bike, it's obvious you can work with your hands.

    I've got 3 midterms next week, an aunt and a dad in surgery, gobs of statistics homework and another freakin' spanish essay. If you want to wait, as soon as I get through all that I'll go through the process and post up pics on my thread.

    I may not get around to it for a few weeks though. After all these tests I've got spring break and hopefully I'll be riding this thing every day instead of pulling it apart everyday.

    Good luck!

    edit: I guess I should put some kinda 'lawyerly stuff' here saying that 'grinding on your brakes and screwing up could cause them to fail and you to die, so don't sue me since you're warned. well, go ahead and sue! can't get blood from a stone.
    #65
  6. Airhead Wrangler

    Airhead Wrangler Long timer

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    Finally. Xmas in March! My parts are here and I'm going to tear it all apart tomorrow night (and hopefully get it most of the way back together). Major mods are imminent. To use a Puttsism, I would consider myself "pissing my pants excited" right now.

    [​IMG]
    #66
  7. Infracaninophile

    Infracaninophile Finding My Way..

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    Airhead:

    What is the shiny metal welded item in the middle of your pic? Is that a new exhaust or something?

    T.
    #67
  8. bgoodsoil

    bgoodsoil Dare to be Stupid

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    is somebody getting twin discs!?

    hate ta tell ya but fender braces are fashion accessories. They really don't do anything.
    #68
  9. StephenB

    StephenB G(/)S ... what else!

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    Like so:

    [​IMG]
    #69
  10. Airhead Wrangler

    Airhead Wrangler Long timer

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    Nope. Just one disc... for a GS front end that's going on tomorrow night.

    As for the fender brace, I'm hoping it'll do SOMETHING. This big ass acerbis fender (sail?) I put on has a tendency to dance a bit above 60mph. Nothing wild, but on straight boring sections I can definitely feel it in the bars and it's a little bit annoying. Luckily it's not constant, but instead requires a bit of sidewind. I'm hoping this thing will stiffen it up at least a little.

    That's a Zach Y-pipe to replace the collector on my friend's GSPDC. Wish it was mine.


    StephenB, thanks for the visual there. I haven't put eyes on my brake shoes in awhile and couldn't recall what that cam looked like from memory. That could be kind of tough to file that thing accurately enough to get even push on both sides of the brake lining. It also doesn't look possible to grind that cam in a way that would maintain the same amount of brake travel when rotating in the other direction without adding material to parts of it.
    #70
  11. StephenB

    StephenB G(/)S ... what else!

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    You can't see it well but the two lobes or whatever you would call it are now symmetrical by removing material. I thought at first they were looking a bit flimsy after the grind but they work fine. The material is tough enough.
    #71
  12. Airhead Wrangler

    Airhead Wrangler Long timer

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    Well, the front end is on, but waiting for a brake hose from galfer which should be here on monday. In the meantime I'd like to install a racetech cartridge emulator which just arrived from 'Soy Anarchisto' today. (Thanks man!) :freaky Anyway, after reading both Anton's description and the one on gunsmoke, I'm questioning which route to pursue here. By installing it in the right leg you are adding more compression damping - adding it to the right leg where it didn't exist previously and leaving the stock compression damping in the left leg. This doesn't seem like it will reduce the harshness of fast bumps as the cartridge is meant to do as you're leaving your stock compression damping (the problem) alone and adding more compression damping to it (making it more harsh). It seems to me that the cartridge is designed to entirely replace the stock compression damping, so it would make the most sense to disable the stock compression damping in the left leg and install the racetech emulator in this leg to replace the stock compression damping entirely. Yet it seems that everyone who installs one of these installs it in the right leg. Anyone want to clear it up for me?:ear

    As for the rest of the mods, they've gone pretty well. Just a little minor tweaking necessary. I'm hoping to have this sucker on the road next week. Yes, I know I owe some photos. They're coming sometime soon.
    #72
  13. England-Kev

    England-Kev Long timer

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    Well come on then!:lurk:lurk:lurk




    :lurk
    #73
  14. Solo Lobo

    Solo Lobo airhead or nothing

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    I think the point is to make the compression damping more tunable... if you add a GV, you would also move both fork legs to different oil.

    If your compression damping is too harsh with only one leg doing the damping work, it would seem that a change of oil and perhaps spring or spring pre-load is also necessary.

    In re-reading Scot's page it does seem like he is switching beteen right and left as to where the function really lies, and Anton is very clear about this...read his first and third paragraphs.

    All I can say is that the GV made a big difference in the front end of my old R100GS!

    Anton does not that you should remove the disc from the rebound valve to allow the compression damping in the right fork leg to work best...
    #74
  15. soyanarchisto

    soyanarchisto Long timer

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    Which leg did you put your emulator in Solo?

    WRT the fender brace--I am getting ready to put one on my GS as well. Seems to me that it should add some more support if I want to mount a fender bag on there for a spare tube, no?
    #75
  16. Airhead Wrangler

    Airhead Wrangler Long timer

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    After reading it again, I realized he's saying I should bypass the rebound damping. ??:huh ?? The gold valve has no rebound damping function in it. How will I have rebound damping then? Uhhhhh...

    Those who have installed one of these:
    which leg?
    what oil weight?
    how much oil / oil height?
    how much preload on the emulator?
    how heavy are you?
    #76
  17. Solo Lobo

    Solo Lobo airhead or nothing

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    Right side as Scots say to...

    I had the alu Acerbis one on mine...
    #77
  18. Solo Lobo

    Solo Lobo airhead or nothing

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    Anton's a member.... drop him a PM and ask

    .
    #78
  19. Airhead Wrangler

    Airhead Wrangler Long timer

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    PAGING Mr. Largiader...Mr. Anton Largiader please pick up the nearest white courtesy phone...
    #79
  20. AntonLargiader

    AntonLargiader Long timer

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    I don't have one installed. I just use the 10/15 oils combo with stock or Progressive springs. But that's not because I think it's best; it's merely good enough. A local guy recently installed the Wirth springs with the 10/15 and just loves it.

    As for the GV, I'm just describing how the forks and the GV work. You can modify either as you see fit! One thing I definitely would not do is disable the stock anti-bottoming feature of the fork legs. If you disable anything, make sure you do it in such a way that you retain the anti-bottoming. Hopefully my page explains enough that you can see how that works.

    Yes, removing the valve from the right leg would reduce rebound damping. I guess I put that in there thinking that people were basically redesigning the fork anyway and would deal with that in their own way. You could put rebound internals in both legs and take it from there, if you don't like the stock compression damping.
    #80