shim plate and parallel rules G/S trans

Discussion in 'Airheads' started by LBourque, Jan 3, 2013.

  1. LBourque

    LBourque G/S nut

    Joined:
    Nov 2, 2010
    Oddometer:
    233
    Location:
    Northern AZ
    Before I go the internet road was wondering if any of youz might have a shim plate and parallel rules for reassemble a G/S transmission. Might be a long shot but you never know. Starting to get geared up to go in, I really miss riding this time of year in AZ.
    #1
  2. Kai Ju

    Kai Ju Long timer

    Joined:
    Jul 29, 2009
    Oddometer:
    2,171
    Location:
    Long Beach, California
    I'm in the same boat but just purchased a cracked rear cover that I'll have machined into a shim plate.
    Parallel bars would be nice as well, but I've seen folks measure the bearing seat from the gasket surface.
    If the cover is straight that should work, if.....
    Another option might be to have a glass place cut you a strip of plate glass to substitute as parallel bar. Just a thought.
    #2
  3. Airhead Wrangler

    Airhead Wrangler Long timer

    Joined:
    Mar 4, 2008
    Oddometer:
    6,821
    Location:
    Back in Seattle, FINALLY
    #3
  4. ME 109

    ME 109 Long timer

    Joined:
    Jun 25, 2009
    Oddometer:
    4,791
    Location:
    Albury Australia
    The outer edges of the cover plate is the best place to measure the pockets in my opinion.
    If the cover is warped, as mine was recently, measuring at the pockets will give a false reading.

    Tip: To get an idea of the end play required, set a micrometre @ .05mm/.002" and hold it up to the light. It ain't much.
    That is why consideration must be given to things that will vary your measurement results.

    To dismiss such analyty (is that a woid?) when setting such a close tolerance is fumbling in the dark, imo.
    #4
  5. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    IMO it's pretty tough to machine the cover plates very flat.

    The outside races rock. Even if your cover plate is flat the bearing boss floors almost never are. Personally, I think it helps to measure from the inside race to an depth average in the cover plate but there is always going to be an element of guesswork no matter how careful you are. Even experienced tuners disagree on whether to shoot for loose or tight. Personally, I think they shift better and hold up better on the tight side. Loose lets bearing walk IMO. I set them up snug enough that they might feel too tight after you install the input seal. Remember that they almost always loosen up quite a bit after a heat cycle or two. I forgot to add that if you set one up too tight be sure and rap it real hard a couple of more times before you take the cover back off. That can make all the difference!
    #5
  6. Max Headroom

    Max Headroom lost in the '70s

    Joined:
    Feb 19, 2008
    Oddometer:
    525
    Location:
    New Zealand
    #6
  7. patanga

    patanga BMWAirheadsDownunder

    Joined:
    May 10, 2009
    Oddometer:
    161
    Location:
    Australia
    #7
  8. mark1305

    mark1305 Old Enough To Know Better

    Joined:
    Feb 7, 2005
    Oddometer:
    6,296
    Location:
    Merritt Island, FL
    I don't have the link handy - its on my other computer that just died, but search for my thread "A Tale of Two Transmissions" to see the simple oversized bridge I made for my depth gauge to take the place of a shim plate. It spans the case/cover flanges sufficiently to measure each bearing at several points.

    It must have worked well, cause the box shifts like buttah since the overhaul.
    #8
  9. Rob Farmer

    Rob Farmer Long timer

    Joined:
    Aug 27, 2002
    Oddometer:
    6,730
    Location:
    Loughborough, Leicestershire. England
    #9
  10. LBourque

    LBourque G/S nut

    Joined:
    Nov 2, 2010
    Oddometer:
    233
    Location:
    Northern AZ
    Thank you for the input gentlemen, and I use the term loosely. RF has done some amazing work on these tranys and I will probably go to Cycleworks to the necessary tools. When this thing shifts like "buttah" I hope to offer the same to other inmates. Actually it already shifted like "buttah".
    Also wanted to gear up for another overhaul on another G/S I have had my eye on for about 15 years. I think it is an 1985 and a PD as well, what a huge fuel tank.
    #10
  11. Rucksta

    Rucksta SS Blowhard

    Joined:
    Oct 26, 2008
    Oddometer:
    2,724
    Location:
    Gold Coast
    Reassemble without the shims substituing a strip of solder over the bearings.
    The solder get squashed.
    Disassemble and measure the thickness of the squashed solder.
    Insert a shim stack of the same thickness less whatever clearance.
    #11
  12. ME 109

    ME 109 Long timer

    Joined:
    Jun 25, 2009
    Oddometer:
    4,791
    Location:
    Albury Australia
    I think solder will distort the cover more than the specified end play clearance. Which would give a larger shim stack than necessary.
    Resulting in a tight fit.

    Just my thoughts after dissecting the solder method.
    'Course, I might be completely wrong.:D
    #12
  13. Kai Ju

    Kai Ju Long timer

    Joined:
    Jul 29, 2009
    Oddometer:
    2,171
    Location:
    Long Beach, California
    The only way to determine that would be to do both methods, similar to the cover edge vs. bearing bore conundrum.
    #13
  14. ME 109

    ME 109 Long timer

    Joined:
    Jun 25, 2009
    Oddometer:
    4,791
    Location:
    Albury Australia
    It would certainly give an indication as to the difference between two methods.

    I found it not at all difficult to distort the cover by .002" by hand pressure.
    The fact that solder will offer 'some' resistance to crushing will distort the cover. and of course the cover cannot be 'whacked' to help crush the solder because it could well go too far.
    It all comes back to the ridiculously fine end play tolerance of .002" specified, that can be exceeded in a bowed cover, or from one side of a bearing to the other.

    It's all good fun tho'
    #14
  15. robtg

    robtg Been here awhile

    Joined:
    Jun 29, 2007
    Oddometer:
    781
    Location:
    san jose

    I agree with your findings. I always set them up at around .004".
    These things are not the precision devices some think they are. The cases as well as the cover get distorted through heat cycles and running stress over the years. The best you can do is put them together without binding with reasonable clearance. I have put hundreds of them together over the years loose rather than tight with success. Sometimes you just have to play it by ear.
    #15
  16. Kai Ju

    Kai Ju Long timer

    Joined:
    Jul 29, 2009
    Oddometer:
    2,171
    Location:
    Long Beach, California
    I have to agree with the rather a bit loose than too tight.
    My transmission had a bunch of false neutrals which I contribute not just to the loose input shaft but also to the very snug output shaft. That scenario certainly invites different shaft speeds and I found that a slight blip of the throttle improved shift smoothness tremendously. Both up and down.
    If I find the energy, I'ill try both methods just to satisfy my own curiosity......and everybody else's.
    To address SS's concern about the play in the outer race of the bearings, I usually measure the depth while preloading the opposite side and then measure again with it released. This provides two different measurements and I split the difference.
    Ditto with the cover, where I try to get more than one spot in the bore and then again average it out.
    It's a pain but it's worked well for me over the years.

    Now for something completely different. Not everybody has access to, or knows how to make, special tools.
    How about a loaner program for some of the more difficult/rare/expensive ones.
    I would think that somebody that feels confident enough to tackle a job themselves would also be considerate enough to treat the tools with the care they deserve.
    No fees, just shipping cost to and fro.
    Let me know what you guys think.
    #16
  17. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    Hopefully everyone understands that loose is better than TOO tight. I still think tight is better than loose. Yea, it can be a PITA getting there but . . . . They work fine as long as they aren't too loose. I personally think they work better tight.
    #17
  18. ME 109

    ME 109 Long timer

    Joined:
    Jun 25, 2009
    Oddometer:
    4,791
    Location:
    Albury Australia
    Got to watch those average measurements too, I found.
    With a shim plate from Cycle Works, I was able to measure up to .003" difference across one bearing :huh
    I took a shite load of measurements everywhere, spun bearings in the shim plate and re-measured to be sure.

    Also found significant difference between inner race and outer race, enough for me to disregard any measurement of inner races.
    I could set the depth gauge to the outer race and not be able to slide the gauge to the inner race without encountering a step. :huh

    The cover plate pockets (measured at pocket) also gave variations of .002"

    So, if you shoot for .002" end play, and use average measurements, one could quickly find oneself with no room to move.

    Oh yeah, a little clearance is also lost when the cover plate is tightened up.


    The concept of measuring for shims is simple.
    Factoring in the 'individual' variables is the challenge.

    My advice (as mentioned by 'real' airhead mechanics below) after servicing a total of (1) tranny :D is aim wide, go for .004" or .1mm.

    .003" might be a reasonable margin of error with all things considered, including getting a shim stack to the exact .000"

    I think yer having a lend of yesself if yer claim to have set end play at .002" or less on three shafts.:wink:

    6:00pm here, and 42 farkin degrees C. There goes another thou" :norton
    #18
  19. DiabloADV

    DiabloADV Semi-Occasional

    Joined:
    Oct 17, 2010
    Oddometer:
    2,405
    Location:
    Nor Cal, USA
    The hot cover allows the solder to squash with no resistance to speak of.
    #19
  20. DiabloADV

    DiabloADV Semi-Occasional

    Joined:
    Oct 17, 2010
    Oddometer:
    2,405
    Location:
    Nor Cal, USA
    The hot cover allows the solder to squash with no resistance to speak of.
    #20