Clutch Friction Plate

[Crossrodes]

I've never taken a clutch apart before and I'm not sure about the condition of my friction plate on my '79.

I suspected that the engine seal might be leaking so decided to take the clutch apart.  I haven't removed the flywheel yet but I have seen lots of black goo inside the "bell housing".  I'm not sure if it's from the spline lube that the PO put on or if it's from the engine...Anyway the friction plate is black.  It does not seem to be oily but I would guess any oil that got on the friction plate would be burned off because of the clutch action.  

The question is:  Is the clutch Friction Plate normally black or would you say it's toast?  I didn't have a problem with the clutch before but since I have things apart I'm thinking it might be a good idea to replace it if indication are that it's going to start slipping.

If you recommend replacement what company would be a good source?

  

[nhmaf]

Oil wouldn't burn off the friction plate - it would tend to aborb into the material, and make it become somewhat friction-less.  The material is fairly dark in color, though my write-upr  in the wiki is with a 1982 that uses the newer style clutch assembly, so it looks a bit different.   Someone will likely chime in soon with some pics of a 79 clutch.

The bell housing does tend to end up with alot of crud in it, but if there is an oily mess on the bottom then there is definitely either a rear main seal leak or an oil pump cover gasket leak - if you do decide to take the flywheel off BE SURE TO BLOCK THE CRANK FROM MOVING FORWARD FIRST by sticking an extender bolt into the front of the rotor, or block the rotor end from moving forward with some other means and putting the front cover back on and tightening the bolts up just enough to keep it all in place - you don't want the crank moving forward at all when you are pushing on the flywheel/bolts in the back.

I would only use BMW parts in the clutch.   You should measure the pressure plate for runout, as well as the friction plate thickness as you may need to replace more than just the friction disk, especially if high mileage engine.

[Crossrodes]

OK thanks for the tip re blocking the crank (still don't understand why the crank will move with the con rods etc. attached but I think I'll accept the general wisdom on this).  I'm thinking I'll clean everything up and re-use the friction plate but I'm still going to remove the flywheel and probably replace the engine seal.  

Question re blocking the crank...I've cut off a piece of Allen wrench and stuck it in the rotor and reinstalled the cover to put a little pressure on the crank.  Will the Allen wrench be enough?  I saw somewhere that someone welded a fender washer onto the Allen wrench.  I'm thinking that it shouldn't be necessary to weld on a washer...that the Allen wrench pressing on the cover should be enough.   Thoughts???

[Crossrodes]

OK, based on what I am reading here in other posts I'm guessing my cut off Allen key will work so I've gone ahead and removed the 5 bolts holding the flywheel.  Now the next question...

The flywheel is not coming off.  I'm guessing a tight fit on the crank.  Is there a preferred method to getting this off.  I really don't want to tap it with a hammer or mallet as I may move the crank.  I don't have a puller I could use on the clutch bolts to pull it off.  What's the usual process?

Also I've read differing advice re replacing the flywheel bolts...what's the general consensus?

[nhmaf]

The Allen key against the cover should be OK if you've got it pressing against the inside of the cover with the cover's bolts screwed in enough to keep it from moving.    There is sometimes enough slop in the whole crank assembly without the flywheel secured that it can slide forward a millimeter or two - usually connecting rods and wrist pins have this much slop as well.   If it does move forward, it can dislodge an internal thrust washer on the inside back face of the engine case, and very bad things result from that!

I'm not certain on the 78-80 bikes, on the 81-on bikes once you have all the flywheel bolts out if should come off fairly easily.      I'll have to try to look up in the manual or the online parts fiche to see any clues.

[Crossrodes]

SUCCESS!

I didn't want to pry too much with a screwdriver in case I screwed something up.  So I made up a puller consisting of a 3.5" X 7.5" steel plate with 4 holes to match the clutch bolt pattern in the flywheel and one central bolt to put pressure on the crank.  Again I didn't want to put too much pressure on this set-up so I carefully tightened up the clutch studs and without too much pressure the flywheel popped off.  I don't think (I hope) the crank moved.

The crank seal looks good but the gasket around the oil pump is leaking.  So I'll order a new one tomorrow.

Back to my question...do I have to replace the 5 flywheel bolts or not?  They appear to be in good shape.  Anyone know for sure?  

[Mike V]

Flywheel carrier bolts should be ok to re-use, the 6 clutch bolts should be replaced with new star washers. You might want to think about replacing the main seal while you're in there - your call. The oil pump cover o-ring is very easy to replace and would be a good idea while you're inside the beast. Clean all the parts well, a very light coat of moly60 on the edge of the spring plate where it contacts the flywheel is a good idea.  Just a faint amount.  Don't forget to closely inspect, clean and lube your splines.  If you have a caliper, measure the friction plate while it's out.  The minimum allowable thickness is 4.5mm per the factory manual.  Here's some picture links of my 81 R65 that may help. Not sure if we have the same applications or not.

Clutch Pack:
  http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Clutch%20Pack/

Oil Pump:
http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Oil%20Pump/

Rear Main Seal
http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Rear%20Main%20Seal/

[nhmaf]

Mike V - he has the old style flywheel/clutch assembly (1979), not the later one.   I think that he's replacing the friction disk (or at least I would after digging in that far while suspecting it, and if oil has been leaking  from the oil pump cover).   BTW - did you make your rear main seal installation tool in those pictures or did you buy it somewhere?

Crossrodes - IF you decide to replace the rear main seal, the new type seal needs to be properly seated.   There are tools out there that can help with seating it to the proper depth and getting it in there square.   I know that some people have done it without special tools, but they have good eyeballs and I think use a piece of PVC pipe with smoothed edges as a "drift".    Somewhere on this forum we had a thread with someone replacing the seal with pictures - do a search and it may help.

I think the official word on the flywheel bolts are that they can be reused if they look good.   I would clean off any surface rust and if the heads or threads were messed up even slightly just get new ones.
I think that I've seen some recommendations on just putting a drop of engine oil on the threads before installed the bols, and some have said put em in dry.    Probably whatever Robert Fleischer (Snowbum) says is the way to go, IMHO.