Triumph 750 engine tear down question.

Discussion in 'Old's Cool' started by marksbonneville, Dec 18, 2011.

  1. marksbonneville

    marksbonneville Been here awhile

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    It looks like I'm going to have to order a puller, we have tried making one but the gear is being stubborn. Oh the joys of working on bikes.
    #21
  2. Mark Manley

    Mark Manley On my way

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    If you pull the crank pinion off the put the case and crank in the oven the bearing usually comes out with the crank, at least it does on mine. It helps to be unmarried before trying this procedure or it can result in serious injury and a large financial penalty.
    #22
  3. marksbonneville

    marksbonneville Been here awhile

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    OK I ordered the pinion gear puller and pretty much its a waste of $$$ as it would not fit around the case, So I heated the case and the crank popped right out, I'll take it to local machine shop on Monday and press off the gear as the pinion puller is struggling even with the clearance it needed.. I have another crankshaft lined up and I need to order new bearings etc and then I can start putting her back together.
    I appreciate all the tips and advice and other than the crank pinion its been an easy tear down.
    #23
  4. smokeeater495

    smokeeater495 Been here awhile

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    Wes White of Four Aces Cycle makes a good DVD for rebuilding Triumph Twins. It was invaluable when I rebuilt a '68 650.
    #24
  5. marksbonneville

    marksbonneville Been here awhile

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    Believe it or not I had rebuilt a couple of these but it has been many years and I forgot more than I thought. I do have my brother helping and he has done a few Norton rebuilds. Getting fresh ideas from others seems to generate some of the best help and your post reminded me I have the "building budget brits" book. which also reminds me I need to see if my VW crank gear puller will pull the right side bearing and gear off as one unit.........Thanks.
    #25
  6. marksbonneville

    marksbonneville Been here awhile

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    I have a question regarding a shim (spacer) located behind the front primary sprocket up against the main bearing. My factory parts manual does not show one, my Haynes manual list it as an oil seal, and I honestly do not remember whether or not I removed this shim during disassembly but I "think" one was there. Any help would be appreciated.
    #26
  7. concours

    concours WFO for 41 years

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    Get a proper factory workshop manual here: http://www.classicbike.biz/Triumph/Repair/Repair.htm It should explain the purpose of the shim, and how to calculate it
    #27
  8. marksbonneville

    marksbonneville Been here awhile

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    My mistake I should have added I also have the factory manual and it makes no mention of the shim. I'm actually looking for someone who has specific knowledge on the late unit twins.

    Concours thanks for the link anyhow.

    Mark
    #28
  9. FR700

    FR700 Banned

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    The shim is to align the primary drive sprocket with the clutch basket . Various thicknesses .




    .
    #29
  10. marksbonneville

    marksbonneville Been here awhile

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    I checked rechecked and checked again and with the shim polished/cleaned up a tad the primary drive and clutch basket are in line. Thanks for the help and I hope to have her back on the road soon.
    #30
  11. chaddhamilton

    chaddhamilton Just the tip

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    Do you care to explain a little more about the crankshaft on that bike?
    #31
  12. concours

    concours WFO for 41 years

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    #32
  13. marksbonneville

    marksbonneville Been here awhile

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    #33
  14. bagpiper22

    bagpiper22 Adventurer

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    Great thread. Thanks. I'm about to open the case on my 76 Bonnie, and I'm getting all the input I can before I do it. Primary drive and clutch is off, gearbox cover off, etc.

    [​IMG]

    Quick question: there were differing opinions, but no clear answer: was there a case bolt behind the inner cover, or were you able to split the cases with transmission in place? Like you, I'm trying to get the crank out, while disturbing as little else as possible.

    I'm also having a time with the pinion gear. I've read you can heat the case in an oven then remove the crank with pinion and main bearing in place. Is that what you did? I'll probably get the proper tool, but if there's something I can try in the meantime that won't hurt the engine, why not?

    [​IMG]

    Lastly, I love the T140 pedestrian slicer license on the front fender in the video. Where did you get that?

    Thanks again for the post, and everybody's replies.

    Scott
    #34
  15. concours

    concours WFO for 41 years

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    Quite sure you'll need to remove the transmission. You DO have a workshop manual on hand, right? Be careful that you truly understand the timing gears alignment, marking. MANY eff ups over the years! It's more complex than it first appears!
    #35
  16. marksbonneville

    marksbonneville Been here awhile

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    I did remove the transmission assembly but I could have removed the inner cover, removed the two bolts holding the case together and re installed the inner cover. Putting the transmission gears back was a challenge but in the end worked out ok. The other thing I learned was I did not need a crank pinion gear puller, I removed the crank and used a press, I spent a bundle on a pinion puller that did not do the job and was junk. A repair manual will be needed but you can find online copies. Hidden bolts???? hmm let me see how good my memory is.... lifter bolts inside the crank case, front stud used for the exhaust brackets, a screw is kind of hidden that hold the inner transmission cover......I may be missing something.
    I picked up the pedestrian slicer back in '88, always gave her that special look.
    After 25 years I sold the Triumph, tools, and manuals this last summer, great bike just was time to move on.
    #36
  17. bagpiper22

    bagpiper22 Adventurer

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    Yes...shop manual and exploded parts diagrams on hand. I'm not planning on removing the intake and exhaust timing gears. Just the center gear which slides right off. Everything else seems intact there. I'll be sure to line up the timing marks when I reassemble.

    My goal is the sludge trap. This bike only has 7000 miles, but sat for 30 years, so whatever is in there is hard as a rock.

    Once I get the engine back together, I can start in on the rest of the bike.

    So if I have to remove the transmission outer cover, can I get to the case bolt without disturbing the transmission too much?

    Thanks!
    #37
  18. marksbonneville

    marksbonneville Been here awhile

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    I would also leave the cams and gears alone, replace the rod bearings and check the main bearings close but they should be good. Sludge trap is pretty easy to clean but I would order a new cap bolt for it as you may mess up the current one getting it off.
    Set the engine on its left side remove the outer shifter and kick start cover (your case a kick start cover) then mark the shifter selector on the inner cover in its current position so it goes back the same. The inner cover has a phillips screw located towards the back and I believe 2 bolts on the front. Be careful and tap the cover loose so the gears don't move around and watch for a shim that may stick to the inner cover.
    Once the inner cover is off you will see a large bolt and a large nut, those are what needs to be removed to split the case. No hidden bolts inside the transmission housing itself. Hope this made sense and I'm going from memory.
    #38
  19. bagpiper22

    bagpiper22 Adventurer

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    Sounds good. I got the inner cover off easily enough and removed the nut there (top right).


    [​IMG]

    I put the cover back on for now, so I can split the cases without a hundred gears falling out. Once I have the case back together with a nice clean crank, I'll go back and remove the old gasket material and replace the case nut.

    [​IMG]

    Sound about right?
    #39
  20. marksbonneville

    marksbonneville Been here awhile

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    And remove the bottom bolt below it. If the gears come out its not the end of the world, just a few gray hairs.
    #40