ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 03-13-2013, 07:04 AM   #151
Tin Woodman OP
Mike
 
Tin Woodman's Avatar
 
Joined: Nov 2012
Location: Vancouver, BC
Oddometer: 186
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.)
__________________
One measly toaster
Tin Woodman is offline   Reply With Quote
Old 03-13-2013, 07:32 AM   #152
Bill Harris
Confirmed Curmudgeon
 
Bill Harris's Avatar
 
Joined: Sep 2008
Location: backwoods Alabama
Oddometer: 4,906
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
__________________
'73 R60/5 Toaster
Bill Harris is offline   Reply With Quote
Old 03-13-2013, 07:59 AM   #153
Plaka
Brevis illi vita est
 
Joined: Jun 2010
Oddometer: 4,449
Quote:
Originally Posted by Kai Ju View Post
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.
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.
Plaka is offline   Reply With Quote
Old 03-13-2013, 08:02 AM   #154
Plaka
Brevis illi vita est
 
Joined: Jun 2010
Oddometer: 4,449
Quote:
Originally Posted by Bill Harris View Post
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
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.
Plaka is offline   Reply With Quote
Old 03-13-2013, 08:53 AM   #155
Plaka
Brevis illi vita est
 
Joined: Jun 2010
Oddometer: 4,449
Quote:
Originally Posted by Tin Woodman View Post
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.)
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.
Plaka is offline   Reply With Quote
Old 03-13-2013, 12:08 PM   #156
supershaft
because I can
 
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 7,579
Quote:
Originally Posted by Plaka View Post
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.
No, the thrust washers only work one way.
supershaft is offline   Reply With Quote
Old 03-13-2013, 06:04 PM   #157
Tin Woodman OP
Mike
 
Tin Woodman's Avatar
 
Joined: Nov 2012
Location: Vancouver, BC
Oddometer: 186
Yippee!

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!
__________________
One measly toaster
Tin Woodman is offline   Reply With Quote
Old 03-13-2013, 07:18 PM   #158
Plaka
Brevis illi vita est
 
Joined: Jun 2010
Oddometer: 4,449
Quote:
Originally Posted by Tin Woodman View Post
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!
if you want to know where the seal is running, put some sharpie lines on the flywheel.
Plaka is offline   Reply With Quote
Old 03-13-2013, 07:31 PM   #159
Bill Harris
Confirmed Curmudgeon
 
Bill Harris's Avatar
 
Joined: Sep 2008
Location: backwoods Alabama
Oddometer: 4,906
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
__________________
'73 R60/5 Toaster
Bill Harris is offline   Reply With Quote
Old 03-13-2013, 08:02 PM   #160
Plaka
Brevis illi vita est
 
Joined: Jun 2010
Oddometer: 4,449
Quote:
Originally Posted by Bill Harris View Post
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
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.
Plaka is offline   Reply With Quote
Old 03-13-2013, 08:25 PM   #161
Tin Woodman OP
Mike
 
Tin Woodman's Avatar
 
Joined: Nov 2012
Location: Vancouver, BC
Oddometer: 186
Found what I believe is a reasonable place to measure end float - this is the only visible site I found (between the crank case and the back of the inner thrust washer.) Can see the gap open and close with soft audible clunk. Can't get my smallest feeler gauge in there - it's .008". Best guess is the float is between .005 and .006 (within limits).



Agreed, Bill - I'll pick up a couple of sizes of thrust washers. Agreed, Plaka - I'm starting to obsess. Maybe I should just fix my lawnmower.
__________________
One measly toaster
Tin Woodman is offline   Reply With Quote
Old 03-13-2013, 10:48 PM   #162
Kai Ju
Beastly Adventurer
 
Kai Ju's Avatar
 
Joined: Jul 2009
Location: So Cal
Oddometer: 1,556
Quote:
Originally Posted by Tin Woodman View Post
Found what I believe is a reasonable place to measure end float - this is the only visible site I found (between the crank case and the back of the inner thrust washer.) Can see the gap open and close with soft audible clunk. Can't get my smallest feeler gauge in there - it's .008". Best guess is the float is between .005 and .006 (within limits).


Agreed, Bill - I'll pick up a couple of sizes of thrust washers. Agreed, Plaka - I'm starting to obsess. Maybe I should just fix my lawnmower.
You need to buy a nice set of metric feeler gauges, that way you only have to buy one washer...............
Kai Ju is offline   Reply With Quote
Old 03-14-2013, 05:22 AM   #163
Bill Harris
Confirmed Curmudgeon
 
Bill Harris's Avatar
 
Joined: Sep 2008
Location: backwoods Alabama
Oddometer: 4,906
Good, you're in the ballpark. I forgot that the jugs were off, and that is one way to measure endfloat. You need a new set of feeler gauges, anyway-- the exhaust valve clearance is .008, and the intakes are at .006 (or .004 if you're nit a traditionalist....

--Bill
__________________
'73 R60/5 Toaster
Bill Harris is offline   Reply With Quote
Old 03-16-2013, 03:30 PM   #164
Tin Woodman OP
Mike
 
Tin Woodman's Avatar
 
Joined: Nov 2012
Location: Vancouver, BC
Oddometer: 186
OK, I broke down and paid the six bucks for new feeler gauges - good point, Bill, about needing thinner ones to set the valves. Isn't it strange I'm still using Imperial measurements when the bike and the country I live in are metric?

Plaka, you'll appreciate this - was having a tough time pulling out the old seal which had been driven completely into the boss - whipped up this little slide hammer in about 10 minutes. Works like a charm.



Visited my local BMW mechanic who has piles of old thrust washers - brought my micrometer and picked a washer with the same spec as the old one. Could feel some high spots on the face so I dressed it with 1500 grit paper and oil on a piece of plate glass. Final result -



Installed new RMS and torqued the flywheel on. Checked the end float and it's a little tight at, believe it or not, .002". Good enough for me - moved the party to a new location.

Getting ready to put the jugs back on. Observations - the obligatory dings in the case from the conrod. Was fully expecting this -



Dressed out the dings and moved on to the cylinder studs expecting the worse. All four studs on the left were at finger tension. Weird because each had vicegrip marks on them -



Threads on the engine case appear to be fine -



Question - should the studs be Loctited when I reinstall? On right side, appears studs have never been removed. Took this opportunity to thoroughly clean engine case where it mates with cylinder. Old aluminum base gasket was devoid of sealant and had apparently been installed dry - was that typical for the 1980s? New base gaskets are only .020" thick compared to the originals of .048" - am I asking for trouble with the higher compression?



Spent some time making sure my torque wrench was calibrated in anticipation of torquing the top ends. Back to the shop for a couple of hours. . .
__________________
One measly toaster
Tin Woodman is offline   Reply With Quote
Old 03-16-2013, 04:39 PM   #165
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 7,328
I use new base gaskets anytime I have removed them because they get bent or dinged and so don't seal. These are not expensive are they? I forget what the stock ones are. If you use a thinner base gasket you have to consider the ridge at the top of the cylinder. Is it enough of a ridge to ding the top ring if the ring now hits the ridge?

I forget what year bike? Is this one that even had base gaskets? Later bikes, you know, only get gaskets to lower compression. But I forget what year the no gaskets starts.

Use that Yamabond or Three Bond sealant. Very thin coat.

Be careful with sealant around the top cylinder studs. These have oil feed holes to send oil to the rockers.

A little on the tight side is probably perfect for the thrust washer as this measurement is supposed to be made with the bearings dry. Since they are wet they have a film of oil on them that also gets measured. 0.002 sounds good to me.

Cylinder studs can be loose in their threads. They tighten when the nuts are torqued. No Locktight.
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, privatejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 11:56 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014