Ernie's diff....iculties | Page 3 | FerrariChat
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Ernie's diff....iculties

Discussion in 'Technical Q&A' started by fatbillybob, Apr 21, 2006.

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  1. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #51 PAP 348, May 6, 2006
    You maybe correct there FF. As you know with conventional LSD diff centres,with both wheels off the ground,you can turn one wheel and the opposite wheel turns in the same direction. My 348,both wheels off the ground,spin one wheel and the other wheel spins in the other direction
    That inidcates to me that it is a open diff centre. Or.........a really worn LSD diff centre? :(
     
  2. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #52 PAP 348, May 6, 2006
    What model 348 did you have there Phil that had a preloaded diff? What year and month please and how many km's on the clock?
     
  3. ferrarifixer

    ferrarifixer F1 Veteran
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    #53 ferrarifixer, May 6, 2006
    Chassis 88022. A 1990 TS. 25000km

    It had a clutch too, as it had done heaps of circle work in a used car yard.
     
  4. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #54 PAP 348, May 7, 2006

    Are you sure that when you checked the car for diff preload that it didnt have a sticking brake caliper?? Maybe thats what gave you the feel of pre-load on the diff FF? lol :D :D Ive exhausted all avenues looking into this crap.:confused: My manual tells me that the 348's use a "Lamellar Self-locking differential" Ive have never personally come across this setup. This is my wild explanation,i could be way off here......Does the self locking mean that the diff centre acts as an open wheeler under normal driving conditions,until........the car loses traction and then it "self-locks" the diff centre and it becomes LSD to help regain traction? Sort of makes sense to me in theory,but i cant mentally picture this as ive never seen the internal setup of one. My manual doesnt show an exploded view of the differential,only the gearbox. But...........Ive looked back at ernie's pics and it actually looks like a conventional clutch pack LSD unit. :confused: Argghhhhhhhhhhh!!
     
  5. No Doubt

    No Doubt Seven Time F1 World Champ

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    #55 No Doubt, May 7, 2006
    348's all have the ZF self-locking, limited slip differential, yes?!
     
  6. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #56 PAP 348, May 7, 2006

    Are you asking me or telling me???? :confused: Is the ZF the same as the Lamellar is it?? Or are you telling me porkies? :)
     
  7. No Doubt

    No Doubt Seven Time F1 World Champ

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    #57 No Doubt, May 7, 2006
    Last edited by a moderator: Sep 7, 2017
    Oy Vey!
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  8. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #58 PAP 348, May 7, 2006

    Lol. Well........seeing as you think you are the big man on campus,can you please explain to me how the ZF/Lamellar self-locking diff works please? Id appreciate it ;)
     
  9. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #59 fatbillybob, May 7, 2006
    From what I have been able to gather from looking close at other explosed difff diagrams the ZF unit in our cars is very simple and I believe it works as FF has first thought. I do not know if static slip (not pre-load please us the right terms) is a different torque value for different differentials but it appears that 348's have non-existent static slip in the you can turm them with 1 finger kind of range.

    I do know that I can light up my tires and make 2 black marks so at some point the diff locks. I also know that my car has more of a tendency to understeer that oversteer powering out at apex to track out which would be a quality of a working LSD. I need to be very bad and going really fast to snap the rear around.

    This makes me think the LSD 1 finger static slip is normal in 348's. I also have a late 90' manufacture car. On the otehr hand my Z06 vette with 3kmiles has a static slip of 67 ft/lbs! This is significantly more than FF's 40-50 ft lbs for a racey 348.

    The obvious cheap fix / learning tool is to open a 348 lsd and shim it up for more static slip and see what happens.

    The 348 lsd is a simple ZF unit. I bet the universal Alfa Romeo LSD's using ZF diffs have the same internals and thus available parts. Someone in the USA must sell these clutch plates and or star spacers. I would rather use "more" clutch plates which in my line of thinking would increase torque and decrease overall wear. I would think that shimming exisiting clutch plates would increase torque fine but would wear rapidly and taking the lsd out all the time is a pain in the rear.

    I think I need to buy some of thee plates.
     
  10. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #60 PAP 348, May 7, 2006
    You may be on the right path there FBB. Pull it apart and add more LSD plates if they will fit. And shim it up from there if need be. Im not tooo worried about it then. I thought it looked like a normal type LSD unit from your pics. :) Ill leave it be then. Cheers.
     
  11. No Doubt

    No Doubt Seven Time F1 World Champ

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    #61 No Doubt, May 7, 2006
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    Is it safe to say that the gear dampers (part #40 in the pic below) have nothing to do with static slip because we're doing this test in Neutral?
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  12. No Doubt

    No Doubt Seven Time F1 World Champ

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    #62 No Doubt, May 7, 2006
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  13. ferrarifixer

    ferrarifixer F1 Veteran
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    #63 ferrarifixer, May 7, 2006
    errr, yes. They have nothing to do with anything in any gear..... they're just rubber mounts.
     
  14. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #64 PAP 348, May 7, 2006

    Hahaha,you just beat me to it FF. I was just mixing the spaghetti :D
     
  15. ernie

    ernie Two Time F1 World Champ
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    #65 ernie, May 7, 2006
    What Phil said. All those do is hold the bolt that runs through them, which attaches the trany to the subframe.
     
  16. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #66 fatbillybob, May 7, 2006
    Well Ernie is taking his time with his gearbox. I'm mostly looking over his shoulder as he struggles with it. I sit on my hands with it in my garage. I want to just put it together. I think he has learned alot but he is getting tired of it. He really wants to just get his gearbox together and he is about 1 weekend away from being done. But..... Perhaps we can all convince Ernie to take his diff back out and shim his differential to see what happens? It would cost nearly nothing. I propose to use brass shim stock hand cut between the non-moving star plates. Precision is not real important just pressure on the exisiting clutch plates. I have never seen new plates so I do not know how worn these are. They fell like your wife's fine emerybords for doing fingernails. Does anyone want to voluteer some clutch plates or have a POS alfa differential around? Clutch plates would be ideal but home depot shim stock can work too. Come on Ernie lets do it and post the results here! That would end all speculation and solve another piece of Ferrari black art. What say you guys? Ernie needs some convincing...
     
  17. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #67 PAP 348, May 7, 2006

    I think it will be hard to convince him FBB... I waited around 2 months to get a clutch kit for my car and once i had it all there,it was straight in and i was back on the road. :) I had the biggest smile for a week because i just missed driving the car. :D Ernie maybe is in the same boat,he wants the car back on the road? :)
     
  18. ernie

    ernie Two Time F1 World Champ
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    #68 ernie, May 7, 2006
    Hardy har har, oh your just a funny guy aren't you.

    Some convincing, HA.

    Okay fatboy, we'll take it out again next time I'm over. However I'm not gonna shim it, I'm gonna take it with me to my budy's shop and ask him what he thinks. But more than likely I'm just gonna stagger the clutch rings, or whatever they are called. So it will go cup, clutch ring, cross plate, clutch ring, cross plate. This way I'm making contact with three sides of the cross plates and the back of the cup, instead of just two sides of the cross plate.

    Then when we're done with mine lets' pull your tranny and do the same thing. Or are you CHICKEN?!
     
  19. ernie

    ernie Two Time F1 World Champ
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    #69 ernie, May 7, 2006
    That is for sure! I have had this car off the road for MONTHS!
     
  20. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #70 fatbillybob, May 7, 2006
    First, I don't thik stagger will increase static slip much. You need pressure.

    Second, "take it with me to my budy's shop"? Are you chicken to experiment and do you really want to get this gearbox back in the car? That's just another week down the tubes! If you really want to take it to Larry's do you want me to take it out of the case and have you pick it up at my work in Torrance on Monday? Lets get this thing going man...

    Third, YOU calling me "chicken!" L-a-z-y is more like it. I don't want to take my box out of the car unless I have to. But I'm doing engine out service in June and I can do it then. I'll probably get me engine out and back in before you get your box done. I want you to increase the static slip dump it in your car and tell us how it feels diving into corners and powering out. You should drive Bruce's car first then yours and see if you got more hook up and understeer.

    Fourth I don't think FFixer will tell us anymore so let experiment and share with the brotherhood.
     
  21. fatbillybob

    fatbillybob Two Time F1 World Champ
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    #71 fatbillybob, May 7, 2006
    Also, why take it to larry? Have him look at the pics right here. Do some research on Diff guts. This one is overly simple and I am sure he can give you a quick opinion just from the pics and description of our lack of static slip. I really think we need more lock-up and this is just another classic Ferrari using the cheapest parts thing and us dumb owners not knowing any difference especially on the street.
     
  22. ferrarifixer

    ferrarifixer F1 Veteran
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    #72 ferrarifixer, May 7, 2006
    1) You're right about the stagger. Typically just changes it ~10% tighter if you stagger both sides that were previously stacked.

    4) Why's that... what else do you want... I've told you what I do and have done many times (but not on 348).... I've done everything from Daytona and BB to 308/355/360...
     
  23. ernie

    ernie Two Time F1 World Champ
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    #73 ernie, May 7, 2006
    Well even if it's only 10%, it will be an improvement over were it's at now. Besides I'm planning on driving it on the street more than on the track, and there are these little things called curbs that I have to worry about. ;)

    But what I still don't get is why I, and the others, can turn it by hand with no real affort?
     
  24. ferrarifixer

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    #74 ferrarifixer, May 7, 2006
    Gotta admit, there seems to be more 348 with open static slip than would seem "normal" if they're supposed to have prelaoded static.....

    Have you tried other Ferrari model you have access to?

    I don't have a 348 or 355 in at the moment, but apart from the 246, all others are preloaded (365BB, 550x2, GT4x3, 360, F50, Trossa,)
     
  25. ernie

    ernie Two Time F1 World Champ
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    #75 ernie, May 7, 2006
    Yeah I was wondering if the 355's did the same thing? I'm gonna guess that they do.
     
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