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Thread: clutch removal question 1970 R75/5

  1. #1
    beemerfield
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    clutch removal question 1970 R75/5

    Trying to remove the flat head machine screws from the clutch and Haynes says use impact wrench. Tried that and it immediately snapped off the straight bit and did not budge the screw. I'm guessing not to use penetrating oil, but maybe torch?

    Any suggestions?- Now I'm going to try and find a replacement bit after no luck yesterday at 5 different places!
    beemerfield

  2. #2
    not so retired henzilla's Avatar
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    an old school impact driver works better than an air impact... use a heavy hammer as well
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    SABMWRA MOA Club#62's Flat Fixer/ current forum moderator
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  3. #3
    Administrator 20774's Avatar
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    I'm a little leary of using impact forces on these screws given how far away from the centerline of the crankshaft they are...I read some discussion about the forces that might get to the bearings. I scratched my head on that and decided to do something different.

    What I ended up doing was finding a large size screwdriver with a flat blade the fit the slot of the screw head very tight...that's important. One can also use grinding paste to help attain more grip. By holding a lot of pressure with the screwdriver, I then used an open end wrench on the shank of the screwdriver to turn the screw out. On my R69S, I had the engine out of the frame and it was sitting nose-down in a homemade stand, so I could put some body "English" on the screwdriver to keep the screwdriver in the slot. With the right tool, I think you could still do this even with the engine in the frame.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    beemerfield
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    OK- I have the "old school" impact also, but will have to find a new bit. Not sure if I can get a hammer "in there". Will try simple screwdriver also.

    Thanks so much for the quick advice! I took the day off of work to do this and got stuck first thing!
    beemerfield

  5. #5
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    heat is usually a good thing for getting out stubborn bolts and such. i like using a paint-stripping heat gun; no flame has some real advantages.
    Ride Safe, Ride Lots

  6. #6
    DaveM Dave Backmarker's Avatar
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    loosening those tight bolts

    +1 on heat. I like the idea of the heat gun because it's likely that there is BMW thread-lock you are trying to warm up. I also use thread penetrating oil like Liquid Wrench. Obviously, this can catch on fire when you add heat, so please be careful. In situations like this I like the old school hammer-driven impact wrench shown in the photo above. Use a steel hammer. Part of what you want to do is break the thread lock loose and a steel hammer will transfer a shorter and stronger impulse than a dead blow hammer.

    If the impact wrench strips the top of the bolt, I'd suggest moving on to a bolt extractor (e.g. an Easy Out). Use the same routine of Liquid Wrench, heat and absolutely the largest bolt extractor you can use and drill into the bolt with care.

    Best of luck. Please keep us updated.

    DaveM
    1975 R90S
    2000 R1100RT

  7. #7
    James.A
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    I also agree on the moderate heat of an electric heat gun. Another thing to consider; I often find it beneficial to move along after finding a bolt that is stuck and find a bolt/bolts that WILL break loose and then come back to the difficult one(s). This applies generally to any array of bolts on any machine. You might also consider the patient use of a penetrating agent such as PB Blaster or Kroil or some such product in multiple applications over the course of a few days, then put the heat to it.

    Additionally, you are fighting not only bolts that may have been in place for 40+ years, there is spring tension in play as well. Be sure to study up on how to safely release the energy stored in that compressed spring diaphragm.

  8. #8
    James.A
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    Quote Originally Posted by bikerfish1100 View Post
    heat is usually a good thing for getting out stubborn bolts and such. i like using a paint-stripping heat gun; no flame has some real advantages.
    Right!... an electric heat gun is much less likely to get hot enough to alter the hardening of the parts in the immediate proximity.

  9. #9
    beemerfield
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    OK- went to place #6 and just bought the entire impact hammer kit with tthe one bit that I broke. I tried it with no luck, so walked away before I broke something else. I was afraid to spray anything in this area fearing some type of contamination, but I like PB Blaster in these situations normally. I also have a propane torch and an electric paint stripper.

    This bike should know by now that I will not be defeated. Can't believe she still wants to fight!
    beemerfield

  10. #10
    beemerfield
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    After I get these things out, should I use something more "removeable" to replace them? Anybody used a standard bolt or anything? Maybe at least a phillips type screw?

    I don't want to have any balance issues or concerns about anything rubbing or hitting the front of the gearbox.
    beemerfield

  11. #11
    Administrator 20774's Avatar
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    I think you might be able to use something with a head on it, but the issue is going to be clearance with the webbing on the inside of the transmission bell housing. I would just use the proper fastener again, rather than resort to something different.

    You might be dealing with a PO issue...I don't think the factory used any kind of loctite on these bolts.

    Does your manual discuss how to release the pressure of the clutch pack? You can't just begin to back off the bolts/screws once you break them loose. There's a tremendous amount of pressure with the clutch spring. You need to remove every other screw and replace with a longer bolt and nut. The nut is hand tightened down to the back of the clutch pack to hold the pressure. Then you take off the remaining three screws. Finally, you back the nuts off evenly to release the pressure.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  12. #12
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    I would use kroil or pb blaster with a big dose of patience. I have seen kroil dissolve loctite after a few days. So, it should work for those screws. They can be reused afterwards with no problems.

    Another consideration that may (or may not) be obvious is that the blade needs to fit snug in the screw slot, i.e. the impact screwdriver needs a snug fitting blade. That may mean grinding a new blade from one of the other bits. The lever arm (e.g. vise grips clamped to the screwdriver shaft) approach is also a good choice if you want to re-use the screws.

    If reusing the screws is not such an issue, then heating and freezing with penetrating oil usually works. Also, a dremel tool with a cutting disk can be used to make a new screw slot in the screw heads (the mirror approach to grinding a blade). Lastly, there is getting a series of carbide drill bits and drilling out the screw heads. That destructive approach is (usually) best done using a center punch on the screw head then progressively going up in bit diameter starting with a small (~ 1/8") drill bit. I recommend starting with the simplest approach first. Good luck!
    Stan

    AH# 13238

  13. #13
    beemerfield
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    I have the bolts and nuts to release the spring tension properly. You remove 3 of these large flat head screws and substitute the nuts/bolts. Then you remove the other three screws, then back out the nuts to release the pressure. The clutch plates come off and you can access the flywheel bolts.

    I did this several years ago on my 1974 R90/6 but don't remember these flat head screws. If it was the same on that bike, I must not have had this difficulty.

    I don't think a PO did anything to this bike as it just has 27K miles and the screws look original and untouched.

    Right now, it looks like I will apply PB blaster tonight and then wait.

    I have all winter, so I'll just take my time.

    Thanks for all the input. This is a very large flat head screw and the head is at least twice as wide as any impact bit. Seems like an odd fastener here, but I'm sure it was used for a reason. It is in a location that is difficult to access with the impact driver and hammer. I may have to remove the swingarm to gain access enough.
    beemerfield

  14. #14
    Administrator 20774's Avatar
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    Quote Originally Posted by rogermansfield View Post
    This is a very large flat head screw and the head is at least twice as wide as any impact bit.
    If that is the case, I'd use something wider than the impact bit. You're asking a lot of that small bit to transfer the load to the fastener. A wider bladed screwdriver like I suggested, along with heat, PB Blaster, etc., would be my choice.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  15. #15
    Bluenoser
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    I was just in my r75/6 a couple of weeks ago and the only screws are on the oil pump housing. Everything else is a bolt, be it on the clutch or the flywheel. So I'm not sure where these screws are. On mine the flywheel bolts did have some kind of stuff on them, but there was nothing on the clutch bolts. Also use new bolts when reinstalling the clutch. You'll have to figure out a way to align it when you put it back together, so read up on that before you tighten the clutch down.

    You need to use the 3 longer bolts with nuts ( in a staggered fashion ) to safely remove the clutch. Remove three bolts, install the longer bolts with nuts, thread them in until they bottom out and then tighten the nuts down. Then you go and remove the other 3 bolts and then slowly back out the nuts on the remaining bolts a little at a time on each bolt until the clutch is free. It sounds more complicated than it is.

    In most cases an impact is a safer way to remove bolts like these without shearing them off. The vibration of the impact helps in loosening the nut. Heat is also helpful and in most cases you have to get it up to 120 degrees if there's any Loctite on the bolts.
    1971 R50/5 SWB with R75/6 drivetrain
    2013 DL650

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