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

[Plaka]

Originally Posted by Tin Woodman

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.

The mechanic didn't lose the washer off your bike. He lost the one off his bike. Guess where he got another one?


My view of human nature is not doing well...

[disston]

Agree Bill. The Teflon seal may not have the same profile or contact patch.

I think everybody has behaved rather well. I try, or maybe should say I don't have to try. I give it my best shot and if somebody shows me the errors of my reasoning then I learn something. I didn't see any name calling. I think in the end we all do a better job because we have looked at the problem from another's stand point. Use a socket or a block of wood or tool made from unobtainium, The next time any of us puts a rear oil seal in we will look at it with new eyes. I think that is truly priceless.

Did anybody else think Plaka's Super Glue idea was really funny? I'm afraid he may not of been joking though.

[supershaft]

Originally Posted by Plaka

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.





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....

For a googler you haven't googled much. Not that that surprises me.

I couldn't tell you how many times I am asked for the basis of my opinion and when I give it I am then accused of daring deeds blah blah. It's as if most of us can't see a bait and switch when one is right in front of us.

[supershaft]

Originally Posted by Plaka

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".

That long explanation is forgetting the fact that BMW first recommended soaking the later seal in oil for some time and preforming the seal and whatnot. Knowing that makes your explanation nonsensical.

The later seal has a completely different contact pattern on the flywheel. It contacts a much, much wider area than the typical rubber seal. That's probably the reason why they work so much better. Most of the time it will be impossible to miss a groove in the flywheel left by a rubber seal. The newer seal's contact area is too wide to miss the groove by setting the seal shallow or deep. I know it's just more blah blah but I have noticed this from installing a great deal them.

[Bill Harris]

For sure. Oil seal technology has changed so much in the past few years. And I'm accustomed to the old-school lipped seal with the garter spring and the little spiral grooves to persuade oil to go back in. This filled teflon seal is much akin to magick, but I'll have to get used ot it.

--Bill

Originally Posted by Plaka

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".

[supershaft]

Originally Posted by Bill Harris

For sure. Oil seal technology has changed so much in the past few years. And I'm accustomed to the old-school lipped seal with the garter spring and the little spiral grooves to persuade oil to go back in. This filled teflon seal is much akin to magick, but I'll have to get used ot it.

--Bill

For our airheads it's been available from BMW for 30 years now.

[bmwblake]

glad it's working out for you.

Originally Posted by Tin Woodman

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.

[Tin Woodman]

Just coming up for air and have to share this with you. Apparently I have to learn everything the hard way. Tonight I planned to install the new duplex chain and crank sprocket. Remember how paranoid I was about blocking the crank? Because if you don't and something goes wrong, the results can be nasty? Well. . .

I thought I had everything figured out - while heating the new sprocket in the oven at 280F, I practiced with the old sprocket. I slipped it onto the shaft with just enough force to center it. I tried to pull it off but it was cocked on the shaft. I tugged on it just a little too hard I guess. That's when I heard a soft 'clunk'. Uh oh.

Not fully believing the obvious, I tried gently turning the crankshaft - bad idea. Completely seized. Sh*t!!!!!!!! Next to the $3000 o-ring hazard, this is the one to avoid at all costs and I had stepped right in it.

With rising blood pressure, I scanned the manual, the web, anything that could offer hope. Finally found a short reference by Snowbum that said there is a TINY chance to get the thrust washer back on its pins by accessing through the right side of the engine case. He said it probably wouldn't work but it was worth a try. He didn't offer any details.

I'll cut to the chase. After half an hour of gentle prodding with a thick copper wire (so that I didn't scratch anything), I managed to get it back on the pins. Disaster averted.

[Bill Harris]

Ah, so the transmission and flywheel are off? Don't feel bad, I would be hard-pressed to remember to "block the crank" from the back when doing a crank pulley replacement. Good public announcement there...

Glad it went back on the pins (eventually),

--Bill

[Tin Woodman]

Some progress today - installed 'modern' rear main seal today thanks to borrowed tool (much obliged James!) Also installed oil pump with new o-ring, flywheel, camshaft, crank sprocket (very tricky) and duplex chain (trickier). Read other inmates' accounts about the tiny e-clips releasing and dropping into the oil pan. Has anyone had recent problems with these IWIS clips? Maybe it was a bad batch circa 2009.

My idea of a dental mirror -



No wonder the chain was sloppy -

[Tin Woodman]

Torqued flywheel tonight with fresh bolts - should have used the old bolts because when fully torqued, crank had set like concrete (had formerly turned freely). Pulled off flywheel and noticed spalling of outer thrust washer I hadn't seen before.



Had to have a better look. Goodbye new stretch bolts, teflon seal -



Thought for a moment it might be related to crank slipping off journals but unlikely. Here's a closeup -



Flywheel mating surfaces seem OK. Suddenly, I'm learning about crank end float. BTW, I put the flywheel back on without the main seal and everything spun effortlessly. I'm confused.

[Bill Harris]

Darn, now that is puzzling. That spalling wasn't caused by the washer slipping off of the pins, or anything I can think of offhand. And odd that the crank turns OK with the flywheel (and this thrust washer??) installed but w/o the seal. And odd also because typically a used thrust washer will have a coppery-appearance since the top layer of the bearing material will wear off. Did you have that thrust washer out for any reason? What does the other side look like-- could you have had it out and flipped it, and had a flake of grit get under the washer? No corresponding marks that I can see on the flywheel surface. Was there any "swarf" in the seal cavity?

The only other explanation is prankish spririts (poltergeists, if ya will)...

--Bill

[Tin Woodman]

I agree,Bill - kinda creepy. But to answer your questions, no, never had the thrust washer off before and, yes, crank turns freely with this thrust washer on, without the seal and fully torqued. No swarf or debris in the cavity. Here's the other side of the washer -



And, for what it's worth -

[disston]

Fortunately these are not very expensive as I remember. Since the engine wasn't run it is debatable if the bolts need to be replaced. The safe bet is to replace them.

Is it possible that any mysterious liquid got spilt onto the bearing? There are some things that eat the Bronze material a bearing is made from. Anti-Freeze comes to mind but I don't know how this or anything else got to the bearing?

Very strange indeed.

[Bill Harris]

Mysterious. That thrust washer has been in that position forever-- see the oil drain hole "shadows". The damage doesn't look recent or like an impact or gouge-- almost like a manufacturing defect. This washer may be reusable, or to be safe, order one the same thickness and another the next thickness smaller.

I be puzzled.

--Bill