Airhead Transmission cover removal (4spd)

Discussion in 'Airheads' started by RichHead, Mar 11, 2010.

  1. RichHead

    RichHead Adventurer

    Joined:
    Dec 1, 2008
    Oddometer:
    14
    Location:
    Bay Area
    [​IMG]
    I'm attempting to replace my stripped kick starter shaft (I think that what it's called:huh).
    [​IMG]



    In order to do this I need to remove the Transmission housing cover.



    I've got the 4spd tranny out.



    I got the new part from BMW Motorrad SF

    [​IMG]



    I got the tool and a new gasket from cycleworks.net

    [​IMG]


    I'm planning on doing this tomorrow. I've seen a video of a guy using the tool on a Dakar beemer, but I'm still not completely sure how the thing is supposed to work. Also, the guy in the vid had a separate tool that went in place of the clutch actuator. Does anyone here have experience with this job? Know of any other resources?

    Thanks! :freaky
    #1
  2. Caddy82rats

    Caddy82rats Long timer

    Joined:
    Mar 8, 2007
    Oddometer:
    1,228
    Location:
    South France
    Please explain more what is the question ?
    You have to grind the kick start shaft in order not to damage the hole in the cover.
    #2
  3. Wirespokes

    Wirespokes Beemerholics Anonymous

    Joined:
    Jul 26, 2002
    Oddometer:
    8,567
    Location:
    Jackson's Bottom Oregon
    I haven't done any /5s, but removing the cover shouldn't be too much different than the newer ones.

    Definitely de-burr the kick shaft!

    The newer trannys need the cover heated to 212F especially around the bearing areas to release the hold on them. Do not pry on the mating surfaces or damage could occur and leaks may result. Use a rubber mallet to gradually work it loose evenly.

    Be very careful when removing the cover as there will be thin metal shims on the ends of the three shafts. Do not mix them up or the trans will need to be re-shimmed! If it shifts badly it may need it anyway.

    There's a shaft (or something) that extends through the back cover that sometimes can fall back in - and the fix is to fasten it with a bolt. You might want to check on Duan Ausherman's or Snowbum's sites for more info.
    #3
  4. Infracaninophile

    Infracaninophile Finding My Way..

    Joined:
    Sep 27, 2001
    Oddometer:
    7,536
    Location:
    Rhode Island, USA
    Get it cowboy style with the heat.... I love this picture. A pro at work.

    [​IMG]

    Tom
    #4
  5. RichHead

    RichHead Adventurer

    Joined:
    Dec 1, 2008
    Oddometer:
    14
    Location:
    Bay Area
    Thanks for the advice.

    Yeah this is definately the case on my bike. I recently read the article on Duane's site. But about a year ago I removed this bolt from the shaft because it didn't seem like it was doing anything...:D I guess I'll try putting in a new one to pull it back out a bit.

    [​IMG]

    I'll remember to deburr the kickstart shaft, and I'll try heating up the cover.

    Here's a link to that video I was talking about. This guys got some pretty amazing videos.

    I guess my question was mostly regarding how this transmission cover puller works(see above pic). One piece seems to hold the input shaft in place and there's a pice that threads into that first piece and a bolt that threads into that second piece...



    I should also note that this transmission was attached to an R90/6. I Believe that the reason the kickstart shaft stripped is that it wasn't designed to turn over an engine that big.
    #5
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

    Joined:
    Jul 26, 2002
    Oddometer:
    8,567
    Location:
    Jackson's Bottom Oregon
    Are you talking about the last photo in post #1?

    What you see there is the tool for removing the UJoint mount from the output shaft. First off, the shaft needs to be held fast while 160 lbs of torque is applied to loosen the retaining nut. Then it's used as a puller to dislodge the mount from the shaft - it's a taper fit and really doesn't want to come off!
    #6
  7. Renner

    Renner combustophile

    Joined:
    Jul 11, 2007
    Oddometer:
    2,625
    Location:
    sunny SoCal
    where are you located?
    almost looks like San Diego County there... Mt. Palomar?
    #7
  8. kixtand

    kixtand Long timer

    Joined:
    Apr 24, 2004
    Oddometer:
    2,215
    Location:
    Lexington, KY
    The tool you got from Cyclkeworks actually serves two (well, three) purposes.

    1. With the inner/middle piece(s) removed you attach the tool to the 4 output flange bolts and get the nut securing the flange loose.

    2. You then take the part of the tool you removed in step 1 and use it as a press to pop the flange loose from the output shaft. As already noted, this is a taper fit situation, and the flange can be quite stubborn at times.

    3. The tool is used in the same manner as step 1, but this time to install hold the flange whilst you install and torque the nut to re-secure the output flange to the shaft. Be mindful that the specified torque for the output flange nut is quite high.

    After the output flange and the cover nuts are removed, you heat the rear cover and/or whole tranny and GENTLY tap the cover off. To remove the shafts from the tranny housing you first need to disconnect the shift forks from the top of the housing, and then you either heat the area around the bearings, or if you heated the whole tranny as noted above, they should pop out once the rear cover is removed asuming you move quick enough.

    If you decide to heat the whole tranny, a gas grill of sufficient size works well for this endeavor.

    Also, if you are going to the trouble of opening the tranny, then I suggest you also replace all seals and bearings, and also reshim the shafts as appropriate. In other words, if you are opening the tranny--for any reason--then go ahead and do a full rebuild while you are in there.

    Good luck--

    kix
    #8
  9. wirewrkr

    wirewrkr the thread-killer

    Joined:
    May 23, 2008
    Oddometer:
    4,295
    Location:
    HIGH desert
    I really doubt that he has the knowledge and the shim plate for a 4 speed overhaul.
    (while I have overhauled at least 10 5 speeds, I have only done 3 or 4 internal repairs on 4 speeds.)
    They are a lot more tricky than the 5 speed and I don't know of anyone making an aftermarket shim plate. Think of it this way,
    "You can lead a thirsty horse to water, but you can't make him understand the molecular structure of the water while he's drinking"
    Robert
    #9
  10. Airhead Wrangler

    Airhead Wrangler Adios Mexico

    Joined:
    Mar 4, 2008
    Oddometer:
    6,751
    Location:
    Back in Seattle, FINALLY
    #10
  11. wirewrkr

    wirewrkr the thread-killer

    Joined:
    May 23, 2008
    Oddometer:
    4,295
    Location:
    HIGH desert
    Thanks for the heads up on that one.
    You'll also need the simulation plate for adjusting the shift forks.
    Robert
    #11
  12. kixtand

    kixtand Long timer

    Joined:
    Apr 24, 2004
    Oddometer:
    2,215
    Location:
    Lexington, KY
    I agree w/ you on the comparison twixt the 4- and 5-speed trannys. I also agree on the other points you made, but felt it was prudent to throw the suggestion(s) out there anyways...

    kix
    #12
  13. kixtand

    kixtand Long timer

    Joined:
    Apr 24, 2004
    Oddometer:
    2,215
    Location:
    Lexington, KY
    Regarding the shift fork adjustment, do you set them up we/ only the output shaft installed, and then mark the nuts for reassembly, or do you make the adjustment w/ all three shafts installed so that you don't have to remove the output shaft after the adjustment is complete?
    #13
  14. RichHead

    RichHead Adventurer

    Joined:
    Dec 1, 2008
    Oddometer:
    14
    Location:
    Bay Area
    That's Mt. Diable in the Bay Area.

    So, I was able to figure the tool out thanks to your advice. What was confusing was that in the Clymer it talks about two different tools, but the one I got is a 2 in 1 tool.

    Once I got it all apart, I couldn't figure out how to take the clutch return spring off the old gear/shaft and put it on the new one. I ended up just taking it my local bike shop and paying $20 to have them do it. (I never found out how he did it either)

    I also do not have a torque wrench powerful enough to torque the nut on the output shaft. I ended up taking it to a different bike shop and they torqued it for me for free. :clap

    now I'm putting it all back together. Hopefully I'll be back on Mt. D. soon.:1drink
    #14
  15. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    3,042
    The 4-speed is very different from the 5-speed in many respects. One item is the removal of the cover; don't get it much more than warm-the rear input bearing is supposed to stay in the cover, and if you get the cover hot, it wants to stay on the shaft, complicating disassembly. There are points on the cover that are intended to be tapped with a punch and hammer to remove it.(!) It's best to set up the forks with only the output shaft in place. You'll note that there are already marks on the eccentrics put there by the man who assembled it at the factory, and these are usually very close to "as good as it gets".
    #15