355 Flywheel Grease

The "without grease" part of that spec implies that the unbalance limit of 250 g-mm is for the complete flywheel assembly (which would include differences in the various small parts and them shifting about a bit) - not just the flywheel itself (so the flywheel only should be much better).

The optimum target for the total assembly would be zero unbalance, but with the uncertainty of the location of the small parts, it's not practical to get too fussy.

 

Now THAT'S a leaking flywheel! Wow! Did the internal parts survive the loss of that much of the grease?

 

I don't know how to disassemble a 355 flywheel if it's different than a 348.

I'd be surprised if the internal parts of your flywheel have NOT turned to dust.

 

In an old thread davehelms thought the amount of grease in a 355 flywheel was raised from 150gr in the WSM to a recommended value of 220gr by FNA. Can anyone confirm this?

Doubt that it can be confirmed as it was told to me by an FNA rep. and I never saw a memo to confirm it. That is the number I have used on all the flywheel ohauls since 96. Ferrari found that a little extra grease helped with the "death rattle" upon shut down which was proving to be a PR problem for them. FNA was not pleased with the thought of me doing these rebuilds as they had no replacement parts available and are in the business of selling parts.
With that much grease in the unit dont waste a great deal of time and money balancing it to perfection. Make sure you assemble the unit with grease packed into every void and on every moving surface. You will know what I mean when you first start the engine and it shakes like the dickens until the grease flows and corrects the imbalance. This much grease that far from the center line can and does do a great job of balancing everything by itself.
Make sure you clean the housing to perfection and use wicking locktite on the rivits and the flange.

Dave

 

I have used a commercially available "Pilot bearing puller" that worked perfectly. I actually bought it at Autozone.

Jay

 

Dave, I can't remember which workshop manual I read it in (348, Mondial t or 355) but the published weight was 180-185 as I recall.

 

That rings a bell Brian. All I remember is the 220 - 230G that Amette said I should use. Seems the final weight installed is not as critical as I would believe as there are a number of techs that put near twice that weight in. It must damn near tear the motor mounts off when they start them and sure doesnt leave much room for thermo expansion.
John was having fits with customer complaints regarding the death rattle and the small increase did help a little.

Terry,
Get a stepped aluminum bearing driver and start tapping. It is a very snug fit. With this one you will be totally filthy before you are done. Make sure to replace the triple shaft seals, looks they contributed to the failure.
Fight the urge to save money and use the proper Kluber grease. Either that or have a complete anylisis done to identify all of it properties. I have had to redo many that used a grease that was far too thick and wouldnt flow until very hot. Someone saved $50 and used axel grease and it cost the next guy many hundreds for me to figure out why the engine was jumping around when cold.

Dave

 

Quite short on grease but it looks like you caught it before melt down occured.

Take the time and remove the friction surface and have it resurfaced by a machine shop. Make sure they do not touch the vertical portion of the outer tabs as they center the pressure plate. Once returned, verify the radius of the transition between friction surface and the tabs and make sure it doesnt interfere with the radius on the pressure plate (ie., plate mounting ears have a full contact with the friction surface without bolts pulling it down).

You are about 8 prs of latex gloves, 3 rolls of paper towels and a half a case of brake cleaner away from a sealed unit. Truly a filthy job.

Dave

 

My 2 cents: Don't be tempted to add more than 220g, and the next time I do it I will use 150g.

I have more than 250g in my flywheel now, thanks to an enthusiastic buddy who wanted to keep the cool can that the grease comes in. The flywheel behaves much worse, in terms of noise, damping and vibration with a lot of grease.

Thats all. But hey, how can you get mad at anybody who does the dirty work and only gets a little Ferrari tin?

Jay

 

I believe that's a misprint and those unbalance units should actually be gr-mm (not gr/mm), but more importantly, there is no physical reason why the grease would automatically distribute itself to counteract the remaining mechanical unbalance.

If all of the grease (say ~200 grams to use a round number) settled to the low side of the flywheel, it's center of mass would be at an average radius of something like ~100 mm -- so the resulting unbalance at start-up would be on the order of 20,000 gr-mm. It's this value that (potentially) gets larger if you use a larger mass of grease (when warm and rotating, the grease would be quasi-equally distributed and the running unbalance would approach the residual mechanical unbalance).

 

No, I wouldn't say this. You have the competing requirements of #1 keeping the maximum cold restart unbalance to as low a number as possible (use less grease) and the requirement #2 that the grease provides the damping function between the moving pieces so you need some to be present in the right places (use more grease). IMO, Dave Helms' comments/experience indicate the original spec of 150 grams had trouble meeting requirement #2 for any length of time -- so I'd fudge up some.

Great -- would love to see some numbers, but the bottom line number is the total assembly (without grease) being less than 250 gr-mm. For example, assuming the springs are operating out at an effective radius of ~150 mm, just a 1 gram weight difference between two springs would add 150 gr-mm of unbalance, and swapping the two spring would change the direction of the unbalance -- so swapping the small bits around might have a significant effect on the total unbalance (without grease). I don't know if all the big parts only go together one way, but if they don't, same kind of thing -- better to have any residual unbalance in the flywheel cancelling any remaining unbalance in the pressure plate rather than the two unbalances adding together in the same direction (just like on a wheel and tire assembly).

No strong comment here, but sounds like you'd also need to either make the clutch disc more parallel or get a new one.

 

The 355 flywheel is DESIGNED (according to FNA) with a .008 bevel in the maching....that is, it is dished very slightly. When machined, it will probably stay that way. My friend who machined mine, said it still kept about a .006 dish to it, even though he was machining it pefectly flat...he figures the metal is doing this from the slight heat generated during the machining process....

 

The 355 flywheels work great when they are flat (less than .010" dish) and are terrible when used in the F1 with .040" dish. "Designed" with a dish is hard to believe. I have found that once warped and then machined they tend to hold up better as they are already stress relieved to some extent.

Dave

 

Thanks for the numbers -- they did a nice job optimizing each component and beat the spec by a mile. I sort of hate to say this, but I'd wager (and your "before" values show) that, to minimize costs during the original manufacturing, that F was using (and counting on) some assembly cancellation (where they control/adjust the relative phases between the parts), and, if an assembly measured out of spec, they'd try some different random parts, and if it measured 249.9 gr-mm, it shipped