R60/5 rebuild nears completion – with some puzzles. . .

Discussion in 'Airheads' started by Tin Woodman, Feb 3, 2013.

  1. Tin Woodman

    Tin Woodman Mike

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    Thanks for the kick in the butt, Plaka. I shall get on with it. Checked with a magnet tonight when I got home - yep, it's steel alright. Good advice about marking the seal with a Sharpie to check for clearance - will try that tomorrow. Checked end play with existing washer - almost imperceptible and not measurable without a dial gauge, but it's there nonetheless.

    I'm positive the inner thrust bearing is back on its pins, SS. Got it back on before I torqued or forced anything. Thing spins like a top with the flywheel back on (but without seal).

    As always, grateful for the input.
  2. Kai Ju

    Kai Ju Long timer

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    Just a couple of observations regarding the RMS installation
    When I first started as a BMW mechanic about twenty years ago, after having wrenched on Japanese bikes for the previous twenty years, I was taught to install the RMS flush with the case and bone dry on the sealing surface.
    The flywheel side seal surface is cleaned and left completely dry as well, with the explanation given that some of the Teflon on the RMS will transfer to the seal surface on the flywheel forming a Teflon to Teflon seal.
    I've never had one come back leaking, including the one I just installed a couple of months ago when I installed my lightened flywheel.
    Can anybody else confirm these instructions ? Either from anecdotal evidence or some sort of Service Bulletin or BMW training classes.

    Back to Tin Woodman's dilemma, I believe that leaving the seal sitting proud is the cause for the crank locking up, which will reveal itself with the magic marker check if I'm correct.
  3. supershaft

    supershaft because I can

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    That thrust washer is coming apart for some reason. The thing he has doesn't look like bronze because it's all been worn off somehow. I have never seen anything like it so I could only guess as to how. I bet it isn't through coming apart either. I wouldn't use it unless you don't mind a bunch of extra metal floating around in your engine. Besides, when you see one that isn't coming apart and has been worn down and worn out, you will see that it is toast. The bronze colored bearing surface of the thrust washer does not denote the size. I don't think they are color coded. Why would the inside and outside washers be color coded green and red? They are the same part. Inappropriately pinned? Don't tell that to our front main bearings! :D

    Sorry but our thrust washers are not monolithic. They ARE made out of two different metals. The one photoed above has just had one of the metals worn away. Sure, there is enough steel there for them to attract a magnet even when new but . . . .
  4. supershaft

    supershaft because I can

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    The seal's OD needs to be lightly oiled so that it can slide in without rolling rubber ridges back in this case. Just like all seal OD's made of rubber, it should be lightly oiled. It also helps to chamfer the seal boss edge as far as not rolling back the RMS's OD ridges.

    About the only rubber OD on a seal that I don't oil is oil sight glasses on oilheads and whatnot. They are looking for ANY excuse to blow out. I lubricate them with quick evaporating contact cleaner and stick them in FAST before it drys. It helps melt the rubber in tight as it evaporates!
  5. Kai Ju

    Kai Ju Long timer

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    I agree on the lubing of the outside of the seal to aid installation. But I was talking about the actual seal to flywheel contact surface, not where the seal sits in the block. I guess I should have clarified that, just didn't think I'd have to.
  6. Plaka

    Plaka Brevis illi vita est

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    You must have some clearance of there is no way for oil to get to the thrust edges of the bearing (behind that spacer). And that bearing will wear. it doesn't rotate but does take some hammering. There are longitudinal forces on the crank. Worth measuring.

    I've been trying to think of some ways around the dial indicator. most of them are elaborate and not that accurate.

    There is always dropping by a local mechanic or machine shop with the block and a cold 6 pack. The measurement only takes a moment and can be done on the counter if you hold the indicator base for the guy.

    Or just buy an indicator. $50 will get you a decent one. Fowler is a good mid quality brand. You don't need a really good one, you don't use it enough. The mag base is used for all kinds of things, like checking wheel run out (make yourself up some indicator pointers for it out of rod) . You also do things to check fork alignment and fork tube run out with the dial indicator. Other wise it is not critical for the stuff you get into. You can set your valves with it to an unbelievable level of accuracy---but you got a chain cam drive so that's moot.

    http://www.tooltopia.com/fowler-72-...tm_term=FOW72520199&utm_campaign=shopzilla_r1

    I take back what I said before, looking at your picture again. The rear bearing and both "spacers" are stationary and the crank shoulder bears on one end of the stack, the flywheel shoulder bears on the other. Babbit bearing. Replace it. It'd be worth looking at the inner one.

    Look closely at the surface of the flywheel that bears on that piece. It should be nice. if not, that must be dealt with. Numerous options, none costly.

    Assembly lube on that when you build.

    A piece of crud might have gotten in there and tore it up, or it could just be failing. usually crud in a babbit leaves long grooves. You could run it in a pinch but you have a couple of months of snow left...
  7. Plaka

    Plaka Brevis illi vita est

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    That teflon transfer would have to happen aweful quick. I always crank a fresh build with the ignition off to bring up the oil pressure before I fire it for the first time. Three 10 second bursts gets my oil light out.
  8. supershaft

    supershaft because I can

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    At first they had you soaking it in oil and then they had you install it dry. I install them dry with no problems. It says to do it that way in a service bulletin.
  9. supershaft

    supershaft because I can

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    If you are starting with a completely cleaned block, let me warn readers that it can take a lot more than 30 seconds to prime the pump. Way more than 30 seconds. I know from priming the pump before I connect the timing chain and install the top end. Sometimes it takes a lot of way faster turning than the starter will ever turn that cam to get the pump primed. BTDT many times but I prime the pump to the big end journals before I even put the top ends on. That way I can crank the engine a half turn and light the engine up with full oil pressure instantly.
  10. Kai Ju

    Kai Ju Long timer

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    There shouldn't be anything but splash lubrication near that seal. I can't imagine the seal withstanding 70 plus psi without leaking profusely. And I don't know how quickly the transfer takes place, if at all. Hence my question about anecdotal evidence or some sort of publication that is credible.
  11. Tin Woodman

    Tin Woodman Mike

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    If I could weigh in just for a moment, I have a theory about the worn thrust washer. Perhaps it was replaced during the last RMS job and it was too thick, hence no end float. Maybe that spalling we're seeing is from heat. Even though that washer attracts a magnet, I still don't exactly know its composition. Interesting that the mating surface on the flywheel is not scored - maybe it was just at the point of being damaged.

    You should have seen the rig I set up last night to measure end play (hint - involved straight edge and vernier caliper. Who was I kidding? Photos not forthcoming.)
  12. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    The thrust washer is steel, backed with "babbit", same construction as the plain bearings in the engine. Looking at the damage (deterioration) I don't see that it was caused by the flywheel.

    --Bill
  13. Plaka

    Plaka Brevis illi vita est

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    pressure oil feed to the rear crankshft bearing (it has to align with an oil passage). Oil under pressure feeds the surface and ends of the bearing. The end are against the thrust washer. by the time the oil gets to the seal though it has gone through a lot of cracks and pressure has been reduced.

    The seal lips face the pressure and they work like the piston rings. Pressurized oil inside the lips force them outward. They then press harder on the shaft. The seal has to leak just enough to establish an oil film between the lips and the shaft. If the pressure is high the lips bear down on the shaft, the lubricating oil film is lost and the seal lips wear quickly. Then they leak more, the oil film is reestablished and the wear slows down, but then you got a leaky seal.

    And then you have crank whip...

    Looks like it has been a problematic area over the years.

    If you put too much oil in an old aircooled VW engine it blows out the rear main seal every time. Don't take too much extra oil either. I always fitted mine with external oil coolers and filters which added some buffering capacity. I think the engineering screwup was not providing enough oil drainage to the sump from the seal area, so too much pressure could build up if the level in the sump was high.
  14. Plaka

    Plaka Brevis illi vita est

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    So can you turn it around and put the good face against the rotating crank and the bad face against the stationary main bearing? Checking my manual I don't see any orientation on the faces so I would suspect babbit material on both sides.
  15. Plaka

    Plaka Brevis illi vita est

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    The idea of a babbit bearing is that it is softer than the shaft that runs in it. If you go through the Machinery handbook they have lists of all sorts of babbit alloys. Anyway they will inbed particles and protect the shaft. One of my conrod bearing shells (out of 4) has a big score in it but the crank journal is perfect. I don't have my scope set up or it's go looking for the particle. Oddly I plastigauged the conrod big ends and it measured worn out of spec. After some grief I got new bearings and miked them against the shells I took out and damned if they aren't dead the same. I mean really the same. Zero wear on those shells with 100k on the bike. I'll have to comb through the serve records from the PO and see if they were ever replaced. BTW, they're magnetic as hell. Steel backers but they look the same all over.

    Using either a caliper (if it's a 4 way) or feeler gauges were some of the things I was thinking for you to do your measurement. The problem is you need a seriously ridged mount to measure from. Not easy to make. You do have a nice big flat slab of cast iron, just the thing for a magnetic base. I use my dial indicator on a mag base a lot on my saw to toe the fence and to check blade runouts, etc. My good blades are really good but the rest of the saw has to be in tune for them to work right The mag base with a simple indicator rod (1/4" rod a couple inches long) is handy as anything for reverse polish repetitive cuts where my cross cut stops are on the wrong side.

    You can maybe play another game with feeler gauges. Cut them up if you have to (they're cheap) and sand the cut edge flat or a bit low. Then put them between the flywheel and the thrust bearing. Stick them there with a dab on 90 wt or assembly lube. Torque the flywheel. Keep trying combinations until the endfloat is zero..that is the flywheel will turn (probably 1/8 turn out you'll lose the trapped blades) freely but there is no discernible end play.

    I just looked at mine. You could drill 2 holes in a piece of flat stock and bolt it across one on the jug openings with that crank journal at TDC. If the cylinder studs are in place use pipe/elec conduit to get out to the threaded nut. Then take a a piece of ground square bar (1/4" -1/2" keyway stock) and c-clamp it to the flat bar so it projects into the case and just contacts the inner side of the crank journal with the crankl fully forward. Then push the crank back and measure with feeler gauges. See what I mean about elaborate? But I bet there are other good places you can measure from. If you find one where you can use plastigauge it is the most accurate stuff you can get for cheap.

    You can play a game with a little blob of bondo. ( oil contact surfaces) Block the crank fully forward. (wood shims behind the timing chain pulley) Put a blob of bondo between the flywheel and thrust washer and torque.You may need to do two rounds so you are sure you are getting good pressure on the thrust washer.. One blob then give it a skim and repeat. maybe even a third round until the last round gets completely squished out..You will have captured the gap.
  16. supershaft

    supershaft because I can

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    No, the thrust washers only work one way.
  17. Tin Woodman

    Tin Woodman Mike

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    Came home a bit early tonight. . .

    Turns out Kai Ju is right about the teflon RMS needing to be flush with the case. Plaka's Sharpie test revealed the flywheel was binding on the seal. Reseated the seal all the way into the boss and put the flywheel back on and torqued the bolts to specification just to make sure. Crank turns freely. Made sure the thrust washer was installed prior to running these tests. Perhaps the older style seal has more latitude in placement.

    I'll pick up a new seal this week because I destroyed this one taking it off to inspect the thrust washer. I'll re-read all of your advice carefully. Looks like the manual is woefully out of date.

    Will work on the end play measurement tonight.

    This is fun again!
  18. Plaka

    Plaka Brevis illi vita est

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    if you want to know where the seal is running, put some sharpie lines on the flywheel.
  19. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Good, (this phase of) the mystery is solved. The more I ponder the more I think that this thrust washer was just made with that "irregularity" in the surface. If something caused the spalling with the washer installed we'd see all sorts of gouging and other damage. Otherwise it looks pristine. In a pinch you could get by with reusing it, but I'd feel bad doing that. Measure the thickness of this thrust washer and order the same thickness as a starting point.

    --Bill
  20. Plaka

    Plaka Brevis illi vita est

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    How about measuring the end play with the one you got and then buy the one you need. It could be the same as what you got or it could be different.

    It would be worth leaving part of the mystery a mystery. You do not need the matter settled in your mind. The flywheel looks fine so there is no obvious cause for a new washer to get torn up. So just get a new washer and leave the unfortunate history of the old one as an unknown. Save the old one and carry it in your pocket to provoke interesting campfire discussions. if you close the case now with some...ah....convenient theory, you will never really know. And that knowledge might be useful sometime. Leave it open, and unknown, and you leave open the possibility of getting a robust answer.

    In the long run developing a tolerance for some unknowns, especially if they are no hindrance, will contribute more to the enjoyment of your project, and it's success. I'm acutely aware of some of the stresses involved in these projects. I keep a weather eye on my own cognitive processes to ensure that I am doing healthy (as opposed to self defeating) stress management.