355 Flywheel Grease

I am having my 355 flywheel resurfaced and was going to get it balanced at the same time. (I had the gearbox/flywheel input shaft break and wanted to eliminate a possible source of the problem)

The WSM states the max imbalance without grease is 250 g/mm. The shop I spoke to stated that this value is quite high and he can get it much better.
With the Voith damping flywheel does it depend upon a high value for it to function correctly or is it good to get the imbalance as good as possible?

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?

Thanks
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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?

 

Still trying to separate the damper from the flywheel in order to inspect the internal parts.

I understand I need to remove this inner bearing (with red dot) to reveal a snap ring underneath. I understand a puller is required but the pullers I have will not hook into the small gap under the bearing. Not sure if I've seen a puller with such small legs that will not break.

Any ideas?
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Thanks Steve for the reply. Like you say, I will try for a better unbalance than 250 for the entire assembly without grease, then add the grease after balancing.

 

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

 

Thanks Dave for the reply and info, I will do as you suggest.

Any tips how to remove the bearing to expose the circlip underneath retaining the flywheel?

Thanks.

 

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

Jay

 

Thanks Jay.
The picture of that puller helped.
I now have the bearing and circlip removed but still cannot get the flywheel off, that's tight on the shaft. Any ideas with that one?

 

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

 

Thanks Dave for the reply.

I now have it all apart. I ended up with a little jig to put load on the flywheel then a sharp knock on the back side shocked it loose.

The last picture is what it was like when I first removed the damper cover, looks like a shortage of grease?

I did buy some of the Kluber grease, like you say not cheap but did not want to short cut for it not to not last after all this work.
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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

 

Thanks Jay.

Now the WSM quotes 150g of grease +/- 5g.

The WSM also quotes that the maximum imbalance of the flywheel/damper assembly should be less than 250 g/mm. So if the assembly was at its maximum tolerance (250) then wouldn't 150g be insufficient to balance the assembly?

 

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).

 

Steve I see your calcs so I think you are saying 150g should be plenty?

I put my flywheel and pressure plate into an aerospace approved org for facing and balancing. They will record the before and after balancing figures for me so that should be interesting. They are also going to check balance the flywheel housing.

They also rang me today to advise that the faces were not parallel and have never seen this before. I have measured my old clutch which is almost 9mm in the centre and nearly 7mm on the outer edge. I have heard that clutches wear this way, ie outer edges wear most whilst centre still has plenty of meat remaining. I cannot see a reason why these faces should not be parallel can you?
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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.

 

Thanks Steve for the detailed reply.

I will therefore go with around 220g of grease.

I pick up the parts on Thursday so will post the imbalance numbers. I recognise that the entire assembly should be balanced without grease but was hoping balancing the major parts would be adequate. Like you say though, I see now how minor weight changes in the springs etc would make a big difference to the overall assembly balance. I will therefore re-assemble everything without grease and balance again to get it right even though I did mark the alignment of all parts during disassembly.

Whilst I initially struggled to get the unit apart, it should be easier next time round. The inner flywheel bearing also had excessive play and I will replace both of those. The shop I have taken it to is a 150 mile round trip but better safe than sorry.

BTW I have a new clutch plate to hand so everything should fit nicely.

Thanks again for your advice.

 

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

 

Does anyone have a part number for the inner bearing on the flywheel? It's the one which is behind (rear) of the flywheel i.e. between the flywheel and flywheel/damper casing.

Many thanks.

 

Collected the parts after facing and balancing. Balancing figures:-

Pressure Plate
Out of balance before 302gmm, after 3 gmm

Flwheel
Out of balance before 369gmm, after 22 gmm

Damper and housing
Out of balance before 441gmm, after 2gmm

The assembly was not checked before balancing but afterwards was 34gmm

A few pics after cleaning facing and balancing. Powder coated the bellhousing exterior.

BTW the amount of grease I scooped up from the flywheel housing when I first removed it from the car was 133gr so there could not have been much left in the damper.
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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