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Old 10-04-2010, 05:32 PM   #1
coyotejoe OP
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awww crap did i drop my thrust washer into the engine?!

hey guys!

my name is joe and im new to this forum and wanted to say hi. ive been lurking on here for a few weeks now while getting some useful information on rear main seal replacements. anyways, i started the project today on my 1976 r75/6 and needed some advice from people who have done this before.

before i begin i wanted to note that i was following this procedure:

http://personalpages.tds.net/~nsgreear/bikes/bmw/clutch/Rear_Main_Seal_Nick.pdf

everything went fine until i hit step 5 on page 6 where it says:

5. Remove the flywheel brake and remove the crankshaft “stop” at the front of the engine and make sure the crank turns easily. If not, the rear crankshaft thrust washer may have fallen of its pin and is now crushed. If true, tear the engine apart and start over!!!!!

i noticed that wasnt the case for me. after i tightened down the flywheel bolts it didnt want to budge in either direction. however, when the flywheel bolts arent tightened it can move back and forth. now keep in mind that i definitely blocked the crankshaft using a tool that i bought from jeff trapp and also screwed down the front cover ontop of it so i dont see how the thrust washer could have fallen into the engine.

is this normal because im kinda freaking out because i just read an article that says:

If you do NOT block the crankshaft, you run the risk of the crankshaft moving forward a small amount... probably it could possibly move a bit under 1/4", and the HIDDEN thrust washer COULD move off its pegs.If that happens, the thrust washer will not align back on those pegs as you tighten the flywheel bolts, and you run the risk of MAJOR DAMAGE to the thrust washer....AND even the engine casting! You will find that the crankshaft will essentially nearly freeze up as you tighten those bolts.

any advice would be greatly appreciated
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Old 10-04-2010, 05:33 PM   #2
P B G
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So... you didn't block the crank?

Oh wait you did...

Hmm.
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Old 10-04-2010, 05:57 PM   #3
coyotejoe OP
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one thing i forgot to mention was that after i took off the flywheel i started cleaning the inside of the casing and noticed that there were some gear teeth on the topside of the casing that i think turn the flywheel? i didnt notice them after i pulled the flywheel out but noticed that something was spinning as i was cleaning it. does anyone know what that does and if that will affect my situation?

i know timing is critical because there were alot of steps that said make sure everything is still top dead center
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Old 10-04-2010, 05:58 PM   #4
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How far did you press the rear main seal in? If you used one of the tools with the three little set screws to set the seal depth, you need to make sure they were at the lowest setting, so they stuck out the least amount according to the instructions. Like one turn or something. If you leave the seal sticking too far out, it will rub on the flywheel and make it not be able to turn. DAMHIK.
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Old 10-04-2010, 05:59 PM   #5
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Quote:
Originally Posted by coyotejoe
one thing i forgot to mention was that after i took off the flywheel i started cleaning the inside of the casing and noticed that there were some gear teeth on the topside of the casing that i think turn the flywheel? i didnt notice them after i pulled the flywheel out but noticed that something was spinning as i was cleaning it. does anyone know what that does and if that will affect my situation?

i know timing is critical because there were alot of steps that said make sure everything is still top dead center
That is the starter. Don;t worry about it. If they turn that is good.
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Old 10-04-2010, 06:45 PM   #6
coyotejoe OP
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Quote:
Originally Posted by TimTowtdi
How far did you press the rear main seal in? If you used one of the tools with the three little set screws to set the seal depth, you need to make sure they were at the lowest setting, so they stuck out the least amount according to the instructions. Like one turn or something. If you leave the seal sticking too far out, it will rub on the flywheel and make it not be able to turn. DAMHIK.
i bought the tool from jeff trapp as well and i just screwed it all the way in until it was pretty much flush. ill try removing the flywheel and put the tool back on to push the seal in some more.
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Old 10-04-2010, 06:55 PM   #7
bmwrench
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It's possible to dislodge the rear thrust washer, too. Make sure it's still on the pins.
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Old 10-04-2010, 07:11 PM   #8
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I had one of the local mechanics here in Santa Rosa do that to my engine and the symptoms sure sound the same...

I would suggest that before you go any further, you pull the left jug and take a look at that internal shim to make sure that it's still on the pins. If it isn't ginched, you have dodged a huge bullet but if it is fraakked, you're going to have to pull the crank and replace that shim with a new one of the same thickness.

And no... I wouldn't even think about trying to start that engine without doing a visual inspection first.
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Old 10-05-2010, 07:47 AM   #9
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Originally Posted by mymindsok

And no... I wouldn't even think about trying to start that engine without doing a visual inspection first.
+1
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Old 10-05-2010, 09:50 AM   #10
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I think I read somewhere that you can access the shim by removing the oil pan and getting it from below. Or turn your motor upside down. I had the shim come loose on me last year. I used a piece of coat hanger and inserted it through the dowel that the shim goes onto and when the shim is in the correct position the wire would hit the crank. You could hear it when it hit. It took a while but it was better than pulling the crank.
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Old 10-05-2010, 12:49 PM   #11
ericrat
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Picture

This picture might help.

http://www.advrider.com/forums/showp...0&postcount=14
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Old 10-05-2010, 01:24 PM   #12
OldAndBusted
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Quote:
Originally Posted by coyotejoe
If you do NOT block the crankshaft, you run the risk of the crankshaft moving forward a small amount... probably it could possibly move a bit under 1/4", and the HIDDEN thrust washer COULD move off its pegs.If that happens, the thrust washer will not align back on those pegs as you tighten the flywheel bolts, and you run the risk of MAJOR DAMAGE to the thrust washer....AND even the engine casting! You will find that the crankshaft will essentially nearly freeze up as you tighten those bolts.

i did this. destroyed one of the thrust washer locating pins and of course the washer too. that was fun. took a bit of work to find a new metric solid dowel pin the right size. bmw never sold them as parts, they were just pressed into the engine case.
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Old 10-05-2010, 01:39 PM   #13
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Quote:
Originally Posted by TimTowtdi
How far did you press the rear main seal in? If you used one of the tools with the three little set screws to set the seal depth, you need to make sure they were at the lowest setting, so they stuck out the least amount according to the instructions. Like one turn or something. If you leave the seal sticking too far out, it will rub on the flywheel and make it not be able to turn. DAMHIK.
+1

Also, when you take the flywheel off rub a color dye on the rear main seal. Install the flywheel and then remove it…. transfer of the dye will indicate any contact.

An incorrect rear main seal depth will make crank rotation difficult.... ask me how I know.
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Old 10-05-2010, 02:19 PM   #14
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Quote:
Originally Posted by mymindsok
I had one of the local mechanics here in Santa Rosa do that to my engine and the symptoms sure sound the same...

I would suggest that before you go any further, you pull the left jug and take a look at that internal shim to make sure that it's still on the pins. If it isn't ginched, you have dodged a huge bullet but if it is fraakked, you're going to have to pull the crank and replace that shim with a new one of the same thickness.

And no... I wouldn't even think about trying to start that engine without doing a visual inspection first.
Actually, you need to pull the right cylinder, not left. None the less, that is the first thing I would do after removing the fkywheel and inspecting the seal and such. You should be able access the internal thrust washer w/ the right cylinder and piston removed.
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Old 10-05-2010, 06:50 PM   #15
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Quote:
Originally Posted by OldAndBusted
i did this. destroyed one of the thrust washer locating pins and of course the washer too. that was fun. took a bit of work to find a new metric solid dowel pin the right size. bmw never sold them as parts, they were just pressed into the engine case.
Just need to know where to look! 11111250156
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