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

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

  1. supershaft

    supershaft because I can

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    I have had good luck installing them per a later service bulletin. Dry seal with no preforming. I have installed a lot of them thusly with never a problem. Lightly oil the OD.
  2. Tin Woodman

    Tin Woodman Mike

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    I knew that photo of the seal would stir up controversy - no, I didn't get it from a BMW dealership. Clearly it is old stock and I suspected as much. Definitely will get a modern one this time. I've come this far, might as well do it right.

    SS, I see what you mean about using the seal insertion tool as an extractor. Those sheet metal screws would cause damage if screwed in indiscriminately. Looks like a great tool for installation, though -

    [​IMG]

    Reinstalled valves last night before reading the last few posts - too late to un-lube the stems. It doesn't help that the shop manual insists they be lubed. BTW, the manual is often vague and ambiguous and glosses over key points. Also, it would be great if there was a glossary!
  3. Plaka

    Plaka Brevis illi vita est

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    The manual says to lube the stems because that is a pretty standard way to do it. If you follow SS's posts you will note he often has his own way of doing things and it's often at odds with the rest of the world. Not saying that's a bad thing but it's well worth being aware of.

    The guides are oil impregnated. Then they get oiled plenty from above---once the oil pressure is up. You can get guides with a teflon scraper on top intended to minimize oil leakage down the stem.

    If the seal you get has installation instructions, follow them.

    putting the rings in "dry" is one method and has it's proponents. There are a number of others. if you want to see a real Fords 'n' Chevies pissing match watch the various camps go at it. I use the "wet" method. Some oil in the combustion chamber is trivial. Do a wet compression test and you get a Lot of oil in the chamber, like a tablespoon or more. Don't hurt nutin'. Might need to clean a plug but other wise it just burns off. Some vigorous riding helps. These pistons and heads have seen multiple wet compression checks in the months before I tore it down:

    [​IMG]


    [​IMG]

    I have found, as a general rule, that when there are several camps on some issue, and the battle year after year after year about who's right, then it doesn't make a hoot bit of difference. Any of the methods will return good results. This is of course the last thing anyone in any camp wants to hear, they are invested in "rightness". So if you don't want to alienate anybody, keep your mouth shut.

    When I build a motor or gearbox I customarily use assembly lube anywhere a part gets lubrication in service.

    As far as dynamic seals, yeah, they all weep. They have to. It's also a physical impossibility to prevent it. Think about what happens when you oil a shaft before installing a seal. As you slide the seal on it wipes away all the oil it can. Any oil left between the lip and the shaft represents the gap between the seal and the shaft. if there is no gap then ALL the oil will be wiped away and you have effectively installed the seal dry---except for some oil on the inside of the seal. Gonna be a lot more oil on the inside of the seal as soon as you fill and start the motor so that's moot. I think you'll find it is quite impossible to slide a seal on an oiled shaft and have it wipe the shaft dry.

    I've tangled with some problems where I wanted a seal on a rotating shaft where these was oil on one side of the seal and thick glue on the other. No oil could pass the seal to contaminate the glue. After talking to a number of seal suppliers I was finally convinced that it could not be done. I ended up going with a sealless design.
  4. disston

    disston ShadeTreeExpert

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    I have no problem with that. The shaft or in this case the flywheel will form the seal as it is installed.
  5. Tin Woodman

    Tin Woodman Mike

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    Yes, I have seen a few dust ups on other historical threads - some of you guys are pretty passionate about your beliefs. Makes for interesting reading but more importantly, it challenges conventional wisdom and helps define best practices. Syncs up nicely with my philosophy of questioning everything until the ambiguity disappears.

    Thanks Charlie for your precision on digging up the part number on that seal - my supplier will exchange it this week. No, I was never going to hammer it in with a block of wood but I confess I thought about it.
  6. Lornce

    Lornce Lost In Place

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    Not a thing wrong with doing it that way, if you're careful enough. :dunno


    :lol3
  7. supershaft

    supershaft because I can

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    I am not talking about assembling 'an engine or transmission'. I am talking about assembling airhead engines and transmissions.

    Our bronze guides are not oil impregnated. They don't need or want oil to work. Why put oil there when hopefully you are doing your work so as to keep it out to start with? A little oil won't hurt anything but it doesn't do any good either. Personally, I think the whole start up and break in procedure works best if they are left dry. I have dozens and dozens and dozens of BMW airhead start up and break ins under my belt without one issue for it. Personally, I would hose the oil out with brake cleaner but that's just me.

    No one I know in the real world argues about following BMW's service bulletins suggesting dry cylinder assembly. I only read that on the net like a LOT of other things! I have seen a lot of BMW boxers not seat the rings. Dry start up really helps. Again, tons of experience with our engines on this topic seeing it done that way and the way I do it and most every other decent airhead mechanic I know does it.

    I have seen tons of RMS's not weeping one bit. With all that clutch dust around to prove it. On some molecular level? Why not.

    Sure there is more than one way to skin a cat. Some of them better than others.

    It looks like that head has a hammered valve and seat. Good luck!
  8. Tin Woodman

    Tin Woodman Mike

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    SS, please clarify 'hammered valve and seat'. Mine? Plaka's? And what does this mean?
  9. Plaka

    Plaka Brevis illi vita est

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    He was referring to my head. See the exhaust valve (light tan, it runs hotter so the oil on it cooks that way, just like on plugs). it seems to be sitting kinda deep in it's seat. Might be seat wear or valve wear or both--or it was cut that way. These heads have 100k (miles) on them. I think the PO had some valve work done at some point. I have to check the records.



    Pulling the exhaust valve, the seat is not too bad:

    [​IMG]

    But the valve is hammered. new valve at right.

    [​IMG]

    New heads waiting to go in. Exhaust at right. (these have the big intake):

    [​IMG]

    "hammered" kinda means badly worn in a manner similar to being reforged, ie, hammered on. You can inspect the faces and lips of your valves, the valve seats and piston crown anytime. Just look through the spark plug hole. lighting is the trick. I use a Streamlight Reach to light up the combustion chamber.

    On the old head, the valve stems/guides are very worn. There is an ample brown deposit on that side of the head on the rocker side. With it apart, you can actually rock the stem in the guide (as in you can feel it). In this condition the vale is not always hitting the seat squarely, it hits at all kinds of angles. Poor sealing at the instant of contact until it seats itself under spring pressure, and accelerated wear. Valve job time.

    I have a valve around somewhere that I saved that is much worse. The sharp lip has actually started to curl over to the piston side.
  10. Plaka

    Plaka Brevis illi vita est

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    Tough to get it started square with a shaft in the way. Without the shaft it's a breeze, use hard wood tho'. The ideal tool for the shaft situation is actually piloted on the shaft. With some time and ingenuity you can often come up with something. Even a piece of PVC that doesn't pilot on the shaft will work if it is very close to the seal bore diameter and cut dead square. Wish I had a lathe...but other people sure do. Having a piloted drift made up in acetal shouldn't cost much ($30?). I'd go 5 mil over on the ID and 5 mil under on the OD and about 1/2" longer than the shaft protrusion. Maybe a 1/16" chamfer on the ID, both ends. Nice item for a club group toolchest.
  11. Plaka

    Plaka Brevis illi vita est

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    After awhile internet bullshit kinda has a taste to it. Often the material stands up poorly on it's own so the poster does much counting of coup: listing of vast experience, daring deeds done, blah, blah. Formally it's a semantic fallacy. I believe a species of the ad hominem. Whatever.

    You'll notice people like Anton or Ted Porter do none of this. For one, their names and reputations are well known. They are not some-anonymouse-guy-on-the-net claiming this or that. And they also post little---way too busy in their shops actually doing rather than sitting around here talking.

    [​IMG]



    Speaking of which, my parts came in and I got a motor to build. Checked the bearing shells and they're dead on 26g a pair. They are also totally the wrong bearing, right down to the part numbers (which doesn't match the packing slip much less the outgoing parts or what I ordered)

    Me needs to have a word with BOBs BMW. Grrrr....
  12. Tin Woodman

    Tin Woodman Mike

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    Guys, this thing is spinning out of control. The mod will shut down this thread if the mud slinging doesn't stop. This is supposed to be light entertainment not character assassination. Take your fight outside.

    BTW, my key part just showed up yesterday. Thanks Blake - looks good!

    Let's move on.
  13. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Hate to confess, the block o'wood method is what we used to use in the pre-internet days. That, or a piece of PVC pipe or a suitable socket. And got away with it. I've since made proper flat plate press it in tool.

    To this day, I'm still uncomfortable with the dry-lips teflon rear main seal. Out of old old habit, that seems wrong, but it works.

    --Bill
  14. disston

    disston ShadeTreeExpert

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    The block of wood is still applicable if the seal is set flush in it's bore. This seal is not set flush. The original is proud of the bore by 1 or two millimeters;

    [​IMG]

    The original seal is not flush.

    The issue is the position of the contact patch on the shaft or in this case the flywheel;

    [​IMG]

    This contact patch is in an ideal spot. The new seal should be set to the same depth. Before the original seal is removed the height of the seal should be measured or at least the tool is set up with the set screws included to set the seal at this depth.

    When I did mine some years ago the contact patch was on the edge of the flywheel and the seal was set flush by a PO. I raised the seal installed depth with setting the set screws when I replaced it.

    I also have trouble with the seal being installed dry but I do understand it: It's Teflon! You know that frying pan stuff that eggs won't stick to? But I wonder if it would still be OK anyway for us old guys to wet the lip with a small amount of oil? Maybe it's wouldn't hurt?
  15. JonnyCash

    JonnyCash turd polisher

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    ^ That's funny, I have always intentionally set the seal at a different depth, when practical, than where it was before, so that it wouldn't ride in the worn spot. Probably doesn't matter. Oh, and I have never used anything but a block of wood or a socket, no problems yet! I'm not trying to shit on other people's methods. I just always get a boot out of seeing how differently we all do things, many times with the same results. I am a boatbuilder, wooden boats exclusively. If you think it gets ugly here, you should see the heated arguments between boatbuilders.
  16. Plaka

    Plaka Brevis illi vita est

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    if you want to set the seal proud, you just superglue some washers to the engine block around the seal. Your wood block then stops on the washers. Trick is, common washers are punched out of scrap and the thickness varies a lot. So you need to assemble a matched set (not hard if you have a sack of them_ or use machined washers (your head bolt washers are an example.) lot of variations on that game too. In any event, the superglue (in moderation) is weak and the washers pop off when you're done.
  17. Plaka

    Plaka Brevis illi vita est

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    That was general 'slingin'. I didn't have anyone particular in mind, exactly, or too many anyones.

    I've been working a problem with timing a dual plug high compression motor at altitude. This is one where the respected guru type have some differing opinions. it looks like Snowbum has taken more grief over his positions than he likes. He spends a Looooong page saying both everything and nothing at once. Not like him in general. So I've spent 2 days going through many, many forums looking for some sway of consensus. Grim. I need hip waders...no...chest waders. Very dispiriting. I think I exhausted my BS threshold for the next month.

    Finally I manned up to the problem and seriously thought about it. I found a way to lighten the advance weights that's reversible to stock if I want and a way to limit advance weight travel that is fully adjustable without tearing down the bean can again. So I'm happy again---except now I can't find my scale to document where I'm going. Sigh.
  18. Tin Woodman

    Tin Woodman Mike

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    Have to admit, some of the writing here is hilarious. I'll let you guys slug it out.

    And, oh, when you mentioned 'machined washers' it reminded me that the previous mechanic had torqued down one of the heads after he had lost one washer. He hadn't even bothered to use a generic substitute, just cynically torqued the nut probably with a smirk on his face. I know what happened to the washer thirty years ago. It's why I try to keep my shop clean (I take a lot of flak over my fussiness). It has to do with the immutable law governing all tiny things dropped in the workshop - you guys would know what I'm talking about.

    In the meantime, I'm going into radio silence mode for a while - I have just enough parts to keep me busy for a few days.
  19. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    And to further uber-complicate things that old, white, original lipped-seal probably has not contacted the flywheel flange in exactly the same spot as the new-design Teflon seal will. Very subtle design differences, so it may not matter if the new seal is installed proud or flush. Though I seem to recall that "the factory" sez a couple of mm proud...

    I'd suspect that the important thing is that the flywheel flange is smooth and sanitary. I'd be inclined to hit it with brake cleaner, crocus cloth and more brake cleaner.

    Enough nit-pickery. Off to work TW, and we need to hear it running next week... :deal

    --Bill
  20. Plaka

    Plaka Brevis illi vita est

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    Teflon (Polytetrafluoroethylene (PTFE) really isn't all that slippery. Compare it to UHMW-PE or even Nylon and they're all close. Teflon has very low surface energy so things don't stick to it. But again, compare it to the polyethelenes and it's close. Try sticking something to them, especially HMW-PE and UHMW-PE. Where teflon shines is it's ability to take heat. Line a frying pan with PE and it will melt all over your stir fry. But Teflon is also very soft. handle a sheet or block of it and you get a very different feeling for it than poking a frying pan. You can dent it with your fingernail. it takes abrasion just as poorly in contrast to UHMW-PE which is one of the most abrasior resistant of polymers.

    Used in a seal, Teflon will take heat, will have low intrinsic friction and will wet poorly---just as poorly with oil as with water or glue. At a microscopic level oil wets out a steel surface but beads up on a Teflon one. So what's happening at the interface of the seal lip and the shaft is quite different that what's happening with something like a Viton (another floropolymer) seal.

    I'd say the upshot is if you have a polished surface to run the seal lip on I'd use it. In general textured surfaces have lower friction, especially when coated with oil but given the softness of Teflon I'd be concerned with wear. The polished surface may give longer life.

    The Teflon may be filled with something (like graphite or Moly) and if it isn't white or light tan this is likely. Nylon is commonly filled with graphite which makes an interesting material. You would have to look at a seal under a microscope to see what's happening there. (if someone wants to send me one I'll check it out. Needs to fit an '83 R100 motor). Anyway the filler could both stiffen it and give it some abrasion resistance.

    Making a seal that can be installed dry isn't for the field people, it's for manufacturing. You can load a magazine with them and just punch them into the blocks as they come by on the line, fully automated if it's set up, and you don't have a mess or the need to accurately control lubricants automatically. So the seal salesman tells the OEM, "look at our new seal, you can install it dry!" (if the manufacturer didn't request it in the first place). What trickles down to the field is, "don't lube them".