Balancing Flywheel & Clutch

[RWebb]

Do I need to get the flywheel balanced together with a new clutch disk & Pressure plate?

Or do I get the Flywheel balanced by itself?

Also - I assume this is all done after I get the flywheel resurfaced...

[TimT]

PP and flywheel get balanced as an assembly, the disc does not.

Machinist will match mark the PP and flywheel so you assemble them in the same fashion that they were balanced...

you can also have the individual parts (just flywheel or pressure plate) balanced individually but to get the nTH degree balance as an assembly.

12K posts and your still havent tossed you modified flywheel and moved on?

[Zeke]

Hey Randy, since the disc can land anywhere, it should be balanced as a sole unit (if not shipped balanced perfectly, doesn't hurt to check). Last theory I heard on the FW and PP was that they could be balanced individually, but it was more important to make sure the flywheel jived with the crank. I know this sounds funny because the crank ass'y should be balanced in it's own right.

The neck bone connects to the shoulder bone, the shoulder bone connects to the backbone; the backbone connects to the thigh bone, etc.

Anyway, here is my personal experience: I get a complete motor rebuild by Andial in the 80's. The thing is perfect; you couldn't feel a thing in the seat ot at the shift lever at any RPM. Somewhere down the line, one of the flywheel bolt heads breaks and eats the FW, disc and PP ass'y. So, they take the motor out and install new parts, ostensibly all balanced. Now the thing shakes at 3 grand and only 3 K. What was once perfection is now just another VW. Might still have that car if it weren't for the crushing disappointment of seeing what would now be $12K spent end up a shaker. Have someone do it all in one place, and index it. To hell with theories that 180* boxer engines can be balanced at the individual stages and come together as one. YOU make it one by assembling it all on the machine; rod weights bolted up, flywheel and PP hooked up and disc that is known to be round in between with the best pilot bit you can find.

Then hope your CC's are spot on. We had it all once and it was sweet, smooth music until one bolt cobbed everything up.I just drive ragamuffins now; I don't care too much if I'm not getting passed at every corner.

[RWebb]

"the disc can land anywhere" - I shoulda thought of that! Makes sense.

The motor is not gonna get torn down...

Tim - I am moving on... tearing the kitchen apart has kept me a little occupied recently but have a window to F&(*& witht he car now...

THanks!

[wastintime]

How "balanced" are we talking? Cause you know while you're balancing it, you could always take off a few lbs.... lol, any race rules where you can "balance a flywheel" please they're shaving off every ounce of weight possible claiming it was necessary for balancing because no one is going to check the damn flywheel

[sabeo.m]

After starting my tear down, i realized how bad my flywheel, PP, and clutch plate really is. I've come to realize that nothing has been done to this car by the previous owner's except for basic matinance, even though i was told other wise. I guess that's why matinance records are so important when buying an older car especailly a 911. If i hadn't begun working on my car, my clutch would of only lasted about a month, give or take. The down side is i didn't include the cost for these new parts in my engine rebuild buget :0( Oh' well there's no saving these parts, so i gotta get em all new... Man this is an expensive hobby! :0)

[euro911sc]

Sabeo.m I just bought a nice used FW off fleeBay. Not a lot of $ so you may be good tehre. Decent used stuff comes up on the bbs every so often if you are not in a hury...

Anyone know of a decent balancing shop that can also machine my OEM FW into a light weight fly like the RSR ones?

Best regards,

Michael

[Quicksilver]

You can balance individual components but the balancing isn't perfect. It has a tolerance.

Here is where you get into what is called tolerance stacking. Suppose that the flywheel, pressure plate and the crank all have a 1 gram tolerance because that is the limit of accuracy of your equipment. So we install them and they happened to be installed so all the tolerances all line up with each other. You could have a potential imbalance of up to 3 grams even though all the sub components are in spec.

I could imagine that Andial would balance the clutch with the crank. They loved details and they especially loved protecting their good name.

[Buzzard95]

Related problem. Replaced my Clutch (Sachs) and flywheel (Sebro) on my 88 911, and now have a vibration/chatter at low RPM's (2000 - 2500) under load/acceleration progressively worse in higher gears. Also replaced axles (Leobro's) No problems of this type before engine drop. Ideas or links to other posts welcome.

[famoroso]

Originally Posted by Buzzard95

Related problem. Replaced my Clutch (Sachs) and flywheel (Sebro) on my 88 911, and now have a vibration/chatter at low RPM's (2000 - 2500) under load/acceleration progressively worse in higher gears. Also replaced axles (Leobro's) No problems of this type before engine drop. Ideas or links to other posts welcome.

By any chance, did you change from a rubber centered clutch disc to a 930 spring center?