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Mystery 6 bolt Flywheel Help


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I’m starting a new topic because the last one was 4 pages… I’ll try to keep it short. 
 

I have a 68 1600 with a 73 block but the crank is a 6 bolt… When I removed the Transmission I discovered that it had the 200mm 1600 flywheel and clutch attached. The only reason I can think they did this was to retain the mechanical clutch. 
 

I am upgrading to a 245 5 speed and I want the 228 clutch with the new style diaphragm pressure plate… But I have the 6 bolt flywheel…

 

A friend gave me this mystery flywheel… 6 bolt but for some reason it accepts the new style 228 pressure plate. I took some measurements to compare. Wanted to get some feedback… I have no idea what this mystery flywheel came from… Take a look. 
 

The dirty flywheel is from the 1600… The clean one is the mystery…

 

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D4A14D60-7D6D-4215-B9FC-0DF5600C304A.jpeg

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Just a guess, but it's just possible that BMW made a 6 bolt flywheel that would work with either the earlier coil spring pressure plate or the later pressure plate and the earlier crankshaft.  That way they would only need one part number to cover two applications.  Other car makers did that all the time; the part was never put on cars on the production line, and only showed up later as a parts rationalization. 

 

I have an NOS Renault cylinder head that's drilled for two different manifolds so that it can be used on three different model cars--and the part number isn't in my parts books.  Perhaps BMW did the same thing.  I'll bet if you called/e-mailed the folks at Maxmillian, they could shed some light on it--or ask Paul Wegweiser--he knows all sorts of arcane mechanical things about M10 engines.

 

mike

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1 hour ago, Son of Marty said:

I guess I don't see your resistance to having your old lighter flywheel drilled to match the 225 mm clutch cover. It's really not a big deal for any good machinist.


Ya that’s next on my list. I’m waiting on the new clutch kit to arrive from rock auto. Once it arrives I’ll scurry across the street, hat in hand and see if my machinist neighbor can make something happen. If I wasn’t so cheap I could just save a bunch of time and get the JBR aluminum flywheel and be done… But alas, I can’t help but try to save a buck…

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I’m just going to save up the dough and buy the JBR… the 1600 flywheel surface looks pretty rough and rather thin as it is… It’ll probably cost me $200 or more to have it reworked… then new hardware… etc. The JBR comes with all the hardware and should just simplify my life… it’s expensive but in the end it’ll save time and stress… Hopefully… I bought one of those flywheel locking tools on Amazon in anticipation of the job… I’ve heard some horror stories about keeping the flywheel locked with a screwdriver. $13 beats a trip to the ER and some stitches any day. 

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  • 2 months later...

Your new post reminded me...that US spec 2002s up to VIN 1665200 had six bolt crankshafts and thus six bolt flywheels--that accepted the 228 mm coil spring clutch.  What I don't know is whether the coil spring pressure plate's throwout bearing is compatible with the T/O bearing fork on a 5 speed.  

 

mike

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39 minutes ago, RoccoGilroy said:

Flywheel porn… just came this week… stupid expensive but the piece of mind is worth it… as long as my wife doesn’t see the credit card bill… 🤞🤞

 

 

Does the 6 bolt flywheel and/or crankshaft have a provision for a cylindrical locating dowel?

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10 hours ago, Mike Self said:

What I don't know is whether the coil spring pressure plate's throwout bearing is compatible with the T/O bearing fork on a 5 speed.  


I don’t believe so, Mike. My ‘67 came with the 6 bolt FW and the coil spring pressure plate. I was installing a 5 speed and discovered all the things that didn’t match up. By the way... the throw out bearing for the early setup is NLA..

 

Here are some pics of the differences. 
 

Early TOB

07EE5FB1-0006-4522-BF82-DB58174FCCA2.jpeg
 

Later TOB... bearing surface would not engage the fingers, plus other things would not allow it to work. 
 

9D290350-E9DC-469E-8760-39EB6566DDA5.jpeg

I had my 6 bolt FW machined to allow the diaphragm style pressure plate and it all worked out nicely. 
 

 

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Edited by zinz
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I was going to do this to the flywheel that was on the car but it looked rough… and already very thin… judging by the weight (13.5lbs)  and the fact that if was a 200mm flywheel I assumed it was a 1600 and thus original to the car… the motor is not… it’s a 2.0L hodgepodge… I would have had to have the machine shop grind it down to the point where the original 200mm lip went away and then etch the 228 lip in… then redrill to accept the diaphragm pressure plate. Then hope that it all worked. 
 

In the end I decided to pony up the dough… Piece of mind that your using trusted, proper parts is worth the price. If I had a 228 6 bolt flywheel to start, I probably would have gone the same rout you did.   

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