M8000 / 9000 "End Bolt Adjustment", B-screw confusion ?- Mtbr.com
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  1. #1
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    M8000 / 9000 "End Bolt Adjustment", B-screw confusion ?

    Just installed a Shimano M8000 rear derailleur and a M8000 11-42 cassette. Sized the chain and placed the rear derailleur on the largest rear cog. With the "B" screw all the way out the upper pulley is really far from the largest cog. I figured maybe the standard 5-6mm doesn't apply for the 11spd gear. Went to the Shimano M8/9000 tech document and they call the "B" screw an "End Bolt". End bolt adjustment has you set the upper pulley to the largest cog & smallest cog clearance, On the next page they illustrate the typical 5-6mm pulley to cog clearance. A few pages before they mention a cable length adjustment using the end screw ??? So again w/ my "End adjustment screw" all they way out I have more than 1/2" gap. Advice? Thanks.

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    How does it shift as is?

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    Quote Originally Posted by dledinger View Post
    How does it shift as is?
    Didn't get that far. I would like to make sure everything is properly adjusted. I will have to lengthen the housing because the cable enters the derailleur quite rearward.

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    Regarding the cable length fuzz, I think that it is mentioned because when you adjust the B-tension screw, it will tilt the derailleur body slightly, which might affect to the required cable cover length if big adjustment is needed...


    I just installed my new 11speed XT set with 11-42 cassette and GS derailleur. I adjusted the B-tension screw so that there is ~6-8mm clearance from the biggest ring to pulley wheel and it seems to work fine with that. However, I noticed that the cage and pulley wheels are "eccentric" to the pivot point, so if you don't have chain in place, the derailleur can't move to/on the biggest cog.

    Not sure if related to this or just due to poor chain line, but seems that while on the biggest cog, pedalling backwards seems to drop the chain to lower cog and eventually sucks it between casette and derailleur, so be careful with that. On 2nd biggest cog pedalling backwards works OK...

    Otherwise the new XT set works very well, crisp and clear indexing on the trigger and lever throw/position/force is decently good level too. Maybe a bit less "ka-chingg" shifting to smaller cogs than on my previous SRAM X0 10speed setup, and lever position is slightly different and non-adjustable, but very clear shifting anyways, which hasn't been the case on some previous Shimano iterations...

    For the ref my frame is Norco Range Killer-B...

  5. #5
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    bla

    Keen, did you sort this? Ive got the same issue? With the derailleur at its longest extension - it's reaching the 2nd biggest cog and no further? Turning the end bolt screw as per the manual seems to do absolutely nothing. Im not witnessing any movement of the derailleur at all? I don't get it? If you sorted it, would appreciate a reply with what you did.

    Cheers.

  6. #6
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    I recently installed an RD-M8000-GS and run into the same issue. I filed off a little from the hanger tab - the place where the derailleur "tang" rests. This allows for the whole derailleur to rotate slightly upwards towards the cogs and then one can use the B-screw to adjust. Alternatively, you can file off a bit from the derailleur tang itself - it is quite long and allows quite a bit of material to be taken off.

    If one is to analyze what a goat link does, it is basically exactly that - allows the B-link pivot (rear bolt, the one behind the derailleur attachment bolt) to sit lower, which also optimizes the parallelogram angle for larger cassettes. Of course, the m8000 is optimized for larger cassettes, but it seems they've overdone it. So file off away and worry not, such a small mod has absolutely no negative effects on performance. Actually, if anything, it improves the situation of the design mess-up.

    My derailleur, filed the tab up to the green line: https://prikachi.com/images/176/8577176d.jpg

    My set-up: https://prikachi.com/images/736/8575736U.jpg

  7. #7
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    So I am having a somewhat similar problem. Have a 42t cassette and XT gs derailleur and I have the B screw all the way in and can't get enough space from the cassette teeth. They lightly touch each other as they pass.

    Any ideas what I am doing wrong here?

    Thanks

    Edit:
    Could having too short of a chain cause this? I put on a brand new KMC chain that was 114 links. It was about 1 link too short (if adding 2 links per shimano), but figured it would still work. If 114 can't work on a bike then what good is that size chain? I am only running a 30t up front.

    Also according to measuring a chain with the formula I need 57in of chain which should be 114 links right?

    P.S.S. Fixed it
    Last edited by yourrealdad; 01-28-2016 at 02:55 PM.

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    I"m in the same boat. Whole new setup on a GT force carbon Pro. Almost done COMPLETELY restoring it and I'm hung up on this. I'm going to head to hardware store and pick up a longer B screw and see if I can get it to work. I'm thinking that GT didn't have the insight for a 42T rear cog (or 1x11) for that matter as the bike came as a 3x9. So the hangar might be the wrong size affecting the overall length it can reach. I took the little adapter off mine XT derailleur, how about you? I'll try to get some pics up too. Me thinks others will have this problem as well trying to upgrade older bikes to 1x11 or 2x11.

  9. #9
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    I have just installed the M8000 crank with a 34t (Shimano) up front and M8000GS with a 11-42 cassette. The shifting is fine but there is a lot of noise when the chain is on 34 / 42. It does not sound good but it is working. Has anybody experienced the same? Is it the chainlink? I use a 2.5 mm spacer on the right side of the crank as said in the manual...

  10. #10
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    im a med cage m8k user 1x 32t 11-42. the tightest i can do is 5mm gap tooth to tooth.

    as for the crank side, i just used 1 bb spacer that came with the kit as bb shell is 73mm.

    been 400k on this setup and no issues so far. back pedaling at 42t drops to smaller cogs though, but im not bothered.
    Canfield Yelli Screamy

  11. #11
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    Yeah, there's not a lot of back pedal needed in those gears. I did find the solution to my problem and it was just a process thing. When I went to put my derailleur on I was just putting it through the range of motion without the chain on. I found that that the chain pulls it all forward and creates the gap for the top gear and the 42T on the cassette. Put it all together and it shifts great! The only problem is that 32/42 may not be enough!

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    in my case i have no choice but to settle for a 32t chainring as its the largest that will fit without me having to do a fix of using spindle spacers. i had to use spindle spacers on my yelli screamy when using a converted 104bcd 2x to 1x
    Canfield Yelli Screamy

  13. #13
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    Quote Originally Posted by yourrealdad View Post
    So I am having a somewhat similar problem. Have a 42t cassette and XT gs derailleur and I have the B screw all the way in and can't get enough space from the cassette teeth. They lightly touch each other as they pass.

    Any ideas what I am doing wrong here?

    Thanks

    Edit:
    Could having too short of a chain cause this? I put on a brand new KMC chain that was 114 links. It was about 1 link too short (if adding 2 links per shimano), but figured it would still work. If 114 can't work on a bike then what good is that size chain? I am only running a 30t up front.

    Also according to measuring a chain with the formula I need 57in of chain which should be 114 links right?

    P.S.S. Fixed it
    What was your fix, I have the same issue. Also, when in the smaller cog my derailleur is running into the frame, what the heck did I mess up?

  14. #14
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    Ha sounds like my issue for sure. Look on the backside of derailleur. There should be a little tab near the mounting bolt. Make sure that derailleur tab is on top of the hanger tab. Otherwise the derailleur will rotate into the frame and not allow for enough b tension movement. Hope that helps

    If you look at the dealer manual the first page of installation shows the tab if what I am talking about doesn't make sense. I totally missed it

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