355 clutch fix

Thats the one! Good pic of where they go. so you have that figured out and hill will sort it. did you have the newer larger diameter mount shaft? (sorry sure it has a better name than that but doesnt come to mind)
you can find the wsm here All Ferraris
you need a new clutch. That surface should be flat.

the flywheel has an almost imperceptible dish on it when new. (contrary to some opinion here I did buy one once and looked how much was 0.1/.2mm) anything over that needs sorting. I've seen too many people put a new clutch onto in a dished surface and are surprised when it doesn't last long and smells a bit. What happens is:-
a) the friction plate wears into the dish (causing burn smell) and uses a lot of the little wear tolerance up doing that before it fully grips.
b) or rips new oem material off the friction plate as you have 380hp going through the outside edge of the plate
c) or bends the friction plate as the clutch pushes the plate down into the dish.


and we still have the unidentified piece of material in there, wasnt from the bearing was it?

 

Good description of the problem with a dished surface. Makes perfect sense. Still do not know where the unidentified piece of material came from. It is hard black rubber, looks like part of a large O ring.

To address your other points, and some more questions:

1) I believe we have the later style slave cylinder. Car is a late in the production year '97 model. Is this something that you can tell from looking at a pic, or does one have to measure it? I can take a better pic of this area if needed.

2) Am I correct in assuming you can not machine the dished pressure plate? I think I have heard of folks machining pressure plates in the past, so are these cases where they are just cleaning up the surface of a still-flat plate rather than correcting any deformity?

3) I am going to check the dish of the flywheel today, using the cool hacksaw blade trick. Will post pics as I do.

 

Hill TO bearing - the carrier is your option. Replace the triple seals in the spline. Happened to me, identical symptoms. Leave the flywheel alone. Check the tech section for "how to's" on this repair. Should be more than one.

 

Its interesting everyone says whilst in there do the triple seals. yet your pic that shows through the bearing on the flywheel is bone dry, which is the place any leaking gear oil shows first.
As this is such a simple job to do, ie the whipping off the pumpkin part, and the triple seals are a not so easy job to do ie getting them into position, heating up, stretching, breaking one, and so on, my thoughts are always if it aint broke leave well alone.
if they do leak its only a matter of a new friction plate and replacement at that time. But from the look of things that is a fair way into the future.
The 4th seal - the o ring on the drive shaft is an easy replacement, and send me your address and I'll send you one as thats something that is easy to do whilst in there.

 

Update: pics of the flywheel. Appears to be dished by about 0.05 in. Thoughts?

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You can sort it or wait till new disc wears into that dish (using most of your wear limit in the process) or drive hard and tear material off a new friction disc.

 

Sorry didtn realise how much 0.05 inch was in mm.
turns out to be 1.27mm
Your limit on the flywheel is 1mm.
the wear limit on the plates is only 1.5.
so really you need a new flywheel which ever way you look at it.

 

Is this something that can be machined and "rebuilt", or are we talking about a brand new flywheel??

 

well your only meant to take a max of 1mm off in a grind according to wsm. Any more and youll put your clutch operation at risk with the bearing having to travel further forward. You could match it i suppose by adjusting the set up on the pressure plate and getting the diaphragm higher. but thats not an amateur job.

 

Ok I understand. I will say that measurement was far from precise, I just eyeballed it by placing my caliper gauge next to the straightedge. I've got a dial indicator I can get better reading with.

How much dish is supposed to be there from the factory?

 

lets hope less.
original dish is virtually nothing. 0.1 0.2 mm max.

 

Instead of eye balling with calipers, use a straight edge and feeler gauges...

 

Good tip. Will do just that and get us a true reading. Just to make sure I am measuring correctly, I should have the straight edge on the very outer edge of the disc and then measure at the very inner edge, correct?

 

Yes, because at the outer edge it will be zero.

 

At least we hope so, or the flywheel has worse problems than we originally thought!

I was just making sure the reading to be concerned with was taken at the inner edge and not in the center of the wear surface, for example.

 

Based on the WSM, it states the flatness of the flywheel must be .8mm or less. (.031"). I don't see any intentional cupping. I'd like to understand this better myself for .031" is far from flat. In my business we often purchase blanchard ground plate that is flat within .005". I hope someone with more experience will comment becuase I too wish to understand this.
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Me to Dave.

I would love to have someone visually or graphically show exactly how all clutch parts and pieces work together to activate the mechanism. Without having been in there personally yet and even looking at the Ricambi diagram, I am not clear on all of this.

An anatomy lesson please...

 

Sorry not quite right. This means you can take a maximum of 0.8mm off the flywheel when you grind it flat. As you say, you then end up with something much flatter!

 

What are you trying to understand? It is a spec just like an alignment spec. All those specs add up to the overall set-up height of the clutch pack. If you are out of spec you might have clutch no worky or short life or wonky clutch action. Each part needs to be in a range for proper function. Each part can be rebuilt to optimize as well for max longevity.

 

Andrew, thank you, that's a good point. I was reading that as the flatness specifications which would be very large. But, take a look at this, it states maximum flywheel reduction in thickness to be 1.0mm so we seem to have contradicting specifications..

So, what is the flatness specification for the flywheel?
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The flatness requirement....

Apparently, that's not specified or I can't find it. Do you understand what flatness is and how to measure it? I do and that's why I am looking for the spec. The OP posted a photo of a dished flywheel so I'm looking to understand if that's from wear or if the flywheel has a normal dish to it. IIRC, I read in another thread that it did have a dish.. This I don't understand.

 

Sorry your right here the reduction max is 1mm not 0.8. that seems to be a measurement of roughness i dont understand! I'm going to our flywheel specialists on tuesday and will ask them.

As Ive mentioned, the original dish is negligible. And obviously once reground it is flat, so in that sense it doesnt matter. A dished flywheel is certainly not the norm and the effect (of allowing a more gentle take up on new cars, according to ferrari when i asked) only lasts for a short while until the friction material wears into it.

 

Yes. You want flatness Blanchard ground not lathe cut. Bunch of reasons. Dished flywheels reused especially with normal heat check spots (hard carbide hot spots) are prone to chatter. But if not using new parts doing the repair part replacer style then people need to understand all this stuff to have a long lasting functional clutchpack.

 

Andrew, the original spec I posted had mm units and therefore it's not surface finish so I think the WSM has a mis print.