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355 F1 clutch slipping

Discussion in 'Technical Q&A' started by UConn Husky, Jun 10, 2007.

  1. UConn Husky

    UConn Husky F1 Rookie

    Nov 11, 2006
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    My current clutch has 5k miles on it, and the flywheel was replaced about 10-15k miles ago. So I took the whole thing apart and found the triples leaking, flywheel and clutch had some oil on them. Clutch disk thickness was fine, 7.0 mm (8.9 is new) so I cleaned everything up and reassembled. Unfortunately it still slips, really identical to before.

    At this point I'm guessing this is just an issue with setting the PIS (or POS I guess). Any other thoughts? Has anyone else had the same experience?

    Another peculiar thing, the ECU always says '106% clutch wear'. Back at the last clutch change that's what it said, and same for my recent PPI. Seems like something wasn't set correctly...

    Thanks!
     
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  3. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Well what is the wear limit? You have 1.9mm of wear and my WAG is that you are at that limit. Perhaps that's why the ecu says 106% wear. There is computer PIS regulation that is reset by FNA scantool. I have no idea how they work. I wonder how the ecu remembers. There is no battery in there so if you disconnect the battery I would think the PIS would reset to some factory generic point. Does anyone know how these ECU's think? I would imagine there is mechanical feedback to the ecu that tells the ecu about clutch plate wear and alters the slip for it. Then I wonder what you would do if you changed to say a kevlar plate with friction coefficients that the ecu does not expect. I'm not a 355 guy. I have lots of questions.
     
  4. No Doubt

    No Doubt Six Time F1 World Champ
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    Flash memory. It doesn't need power. Won't reset *anything* on that system by disconnecting the battery for years. You need the scan tool to set the PIS and one other thing (beats me, not my car model). The scan tool is also useful but not required to bleed the F1 hydraulic fluid lines.

    As for his slipping clutch...if he only cleaned things up but didn't replace his triple seals, then there is his problem right there. Of course, you made a good point about the wear limit. Could be that, too.

    As for Kevlar clutch or whatever...you should be able to continue to adjust the firmness of shifts via that PIS setting. I would just expect different stored PIS values for different clutch materials.
     
  5. UConn Husky

    UConn Husky F1 Rookie

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    #4 UConn Husky, Jun 10, 2007
    Last edited by a moderator: Sep 7, 2017
    In the workshop manual they say 8.9mm thickness new (8.3mm compressed), and replace at 2.0 mm uncompressed. And I'm nowhere near wearing into a rivet or anything so I'm thinking there's plenty of thickness left. Below is a side view of the clutch disk (look at top of pic to see thickness). You can see the two friction surfaces and the metal in the middle.

    No Doubt - yes, I did replace the triple seals. I've heard there is a non-SD2 technique for setting the PIS but I haven't come across that yet.

    Another thing - the wear seemed non-uniform across the clutch disk face. I was thinking this was due to the oil leaking from the inside out, so the inner region of the disk would slip from having more oil. I couldn't really measure a difference in thickness, but the wear pattern looked different.

    Thanks for the feedback!
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  6. f355spider

    f355spider F1 World Champ
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    The wear should be more on the outside of the disc, and less on the inside (progressively). Your wear looks very strange...mostly in the center? Something is not right. But the disc looks like it is ready for replacement. Strange, mine at 44k miles did not look as worn as yours at 5k.
     
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  8. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Sorry I'm not getting it. 8.9 - 2mm (wear limit) = 6.9mm You have 7mm In my book you are worn out or if you want to get technical you have 1% left on your clutch. Additionally uneven wear may put you under the limit in some locations. Clutch does not wear evenly because first 355 flywheels have a dish of something like .08" and the difference in speeds of the inside vs the outside change the wear of the material.

    And to ND...what would make you think Ferrari was so forward thinking that they would have different programs for different clutch type coefficient of friction materials? I think they woudl set up for the cheap stuff and then make you buy it!

    When figuring out how Ferrari does something you gotta think "cheap and fast" and with whatever parts might be handy.
     
  9. No Doubt

    No Doubt Six Time F1 World Champ
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    That is the cheap and fast way. The PIS doesn't care about clutch material. It just sets how much/when the clutch slips, just as a human judges how hard/when to release a clutch pedal.

    Well, set the PIS to a "2" and you are going to get a shift that is different in firmness than if you set the PIS to a "6".

    So it's up to *you* as the programmer to set the PIS value. Oh sure, the system is going to behave differently based on different clutch materials, but it is also going to behave differently based on the PIS value that you enter.

    And the best PIS value will be different for different clutch materials.

    Once set, it is my understanding that the 355's F1 system then adjusts the clutch hydraulics over time based on the detected clutch wear. This is why the PIS must be reset when you install new clutch material.
     
  10. UConn Husky

    UConn Husky F1 Rookie

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    #8 UConn Husky, Jun 11, 2007
    Last edited by a moderator: Sep 7, 2017
    I'd be happy if I were reading this wrong! Here's a snapshot from the manual. I read this as 8.9 new thickness, and min thickness as 2.0. But 2.0 is pretty thin so maybe they are saying that a 6.9 absolute thickness is the wear limit. That would be good, because then I know the next step!

    Edit - yeah after reading the posts and the manual again, sounds more like the 2 is how much can be worn away. But intuitively it just seems like there's plenty of excess friction material left on the disk, it shouldn't be toast already...
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  11. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Yup after seeing this you are toast! 2 is the wear limit not the size limit of the plate. Therfore, you are worn out at 7mm's. Before you even think of getting the dealer to set PIS you need to get everything mechanically correct which includes a clutch disc of the proper thickness uncompressed and compressed. It is critical that you follow the last sentence because if the marcel spring is too big you will get clutch drag even if the compressed limit is correct.
     
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  13. jayz

    jayz Formula 3

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    #10 jayz, Jun 12, 2007
    Last edited by a moderator: Sep 7, 2017
    Here You go. the PIS procedure is in vol. 2 of the WSM.

    from what i have read in the WSM there is only a 2 step procedure after clutch replacement:

    1. PIS self-calibration (manually set)
    2. New closed clutch value (SD1 needed)

    vol. 2 is full of f1 info.

    i'll be doing my next clutch change without an sd1, when the time comes. i'll let you guys know how it turns out. :):)
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  14. jayz

    jayz Formula 3

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    Jay, don't forget to check your pm's :)
     
  15. fatbillybob

    fatbillybob Two Time F1 World Champ
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    What is IO calibration?

    What is new closed clutch value?
     
  16. jayz

    jayz Formula 3

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    FBB, from what i understand, the new closed clutch value is the thrust bearing position, with new clutch, in closed conditions.

    according to the wsm, io calibration is not needed when replacing a clutch, it is used when the gearbox ecu is replaced.

    it's all in vol.2. section D
    the clutch control strategies are described in section D :):)
     
  17. UConn Husky

    UConn Husky F1 Rookie

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    #14 UConn Husky, Jun 14, 2007
    Last edited by a moderator: Sep 7, 2017
    ok rec'd a new clutch disk and pressure plate today. I remeasured the old one, found 6.9mm at the outer edge and 7.5mm closer to the ID. New one is 8.9mm all over just as specified in the WSM. I've seen clutches still grabbing that were well into the rivets, it just seems strange to me that I'm slipping from losing 1.5 - 2mm from the friction surface. And that's on the whole disk, so it's about 0.75 - 1mm per side! Maybe this is why F1 clutches go so fast? Are the non-F1 cars able to grab beyond this thickness?

    Also note it does seem like there are wear bars on the disk, and mine are just gone at the outer edge and still barely visible near the inside. Are these in fact wear bars to show when the disk needs replacing?

    Edit - damn, just noticed I reversed it in my sticky note on the pic! The 6.9mm should be at the outer edge, 7.5mm at the inner...
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  18. FERRARI-TECH

    FERRARI-TECH Formula 3

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    Holy Crap,
    That clutch plate is shagged.
    I don't care what the computer tells you, (because if it is not reset when the new clutch is installed its readings are worthless), your clutch is slipping because it is only "gripping" on about 50% of the friction surface. Figure out why that is (warped flywheel/driven disk etc) and you will correct you fault. I assume you fixed your seals.
     
  19. UConn Husky

    UConn Husky F1 Rookie

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    Thanks for the feedback! This is the strange thing, the earlier pic in this post seems to show it contacting mostly on the inside. But that area measures thicker...which ok, makes sense but how did the outside wear first but isn't contacting much now? Anything related to the oil leaking? (I did fix the seals). Car has 37k miles, flywheel was replaced at 26k miles along with the bearing by a dealer. The clutch was replaced again at 32k miles...
     
  20. f355spider

    f355spider F1 World Champ
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    I will have a buddy of mine post pics of my clutch disk with 44k miles...it has a similar wear pattern, but I am uncertain of the thickness. He is busy, but will try and post on Monday. It was working perfectly up until the release bearing failed and I lost all the hydraulic fluid. ;)

    Oh, and my car is a 6 speed manual.
     
  21. UConn Husky

    UConn Husky F1 Rookie

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    New clutch and pressure plate installed today. Did the self calibration of PIS and IO per the manual. Reverse and 1st grab real quick now! Before had to rev to 4k to get reverse to move, and 1st launch was at least 2k. Now seemed to grab instantly. But without using the SD1 to put in the new clutch thickness, what are the potential risks? Just faster clutch wear? Would gear shifts be affected (2-3, 3-4, etc), as if the friction isn't fully released? Hopefully the PIS calibration took care of that. Thanks...
     
  22. UConn Husky

    UConn Husky F1 Rookie

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    Fantastico! Drives perfect as far as I can tell, great launches and shifts. Now need to figure out what's up with sport mode, I flip the switch and nothing happens (been like this since I rec'd the car). Not sure if the light doesn't work or maybe the switch...anyway for now time to drive!
     
  23. jayz

    jayz Formula 3

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    Jay, good to here everything worked out :)
     
  24. fatbillybob

    fatbillybob Two Time F1 World Champ
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    So if you can adjust the pis who needs the sd1? Can a similar pis calibration be done with the 360?
     
  25. ernie

    ernie Two Time F1 World Champ
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    ROCK ON jayz!!! Thanks for posting that. This will help a lot of people.
     

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