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Installing my new Diff

Discussion in 'Boxers/TR/M' started by qwazipsycho, May 17, 2013.

  1. qwazipsycho

    qwazipsycho Formula 3

    Oct 30, 2004
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    I have to disagree Romano. I think it's the coast side. We'll find out today. I'm going to move the pinion aft.

    You think the drive side pattern was getting better. I also disagree. The pattern is almost non existent on the drive side and way heeled out on the coast side. In fact the coast side is much worse than original.

    Give me a few hours. I honestly think I've got this beat now. If I'm wrong, it's time to start parting out the F'ing F car....no, not really.
     
  2. qwazipsycho

    qwazipsycho Formula 3

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    If you read about the different ways they machine gears, there is face milling and face hobbing. Each way causes the gear pattern setup to be in reverse of the other. If you have the pattern that I have, you would move the pinion forward for one mfg process and move it the other way for the other mfg process.

    I have no idea which way these gears were made so all I can do is try.
     
  3. qwazipsycho

    qwazipsycho Formula 3

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    Definitely not the first bizarre thing to find with the manual and/or parts catalog. To work at someplace like Ricambi or Trutlands, you really better know your 5h1t or you're going to send people the wrong stuff!
     
  4. turbo-joe

    turbo-joe F1 Veteran

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    I´m really confused now scott :( and I think you are right with the coast side
    may be I now need the white coatet men? :( :(

    when I have a look at your post 293 the top picture shows the coast side, not the drive side
    also on post no. 280 the upper 2 pictures shows the coast side and only the buttom picture the drive side. if it is really so as I think now then the pinion has to move to the back. but until now I always thaugth the WSM shows the drive side

    when I now have again a look at the WSM then I think that those drawings from looking to the CP is from under the car. the crown is on the left side of the car showing the teeth to the right side. the pinion is located to the teeth of the crown. so it could only be the coast side.

    so really sorry scott that I gave you wrong info, but i have been convinced from my telling to you. also I must say that all other specialists here have not known this problem, otherwise they had immediately told that something is wrong.

    but it makes no sense what F was doing to show the coast side and not the drive side :(
     
  5. qwazipsycho

    qwazipsycho Formula 3

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    LOL!!! Romano, no you don't need to be locked up yet. You and everyone else said the pinion should go to the front.

    Now both of us have learned something and we're better off for it.

    I'll post what I hope to be a good pattern shortly.
     
  6. turbo-joe

    turbo-joe F1 Veteran

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    yes, because everybody confused drive side and coast side

    I'm excited :) :)
     
  7. qwazipsycho

    qwazipsycho Formula 3

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    #307 qwazipsycho, Jul 15, 2013
    Last edited by a moderator: Sep 7, 2017
    :( maddening...absolutely maddening...but I think, once again, I have an answer.

    By moving the pinion aft, I'm getting the exact same effect as I did moving it forward, only reversed.

    The drive side doesn't move and the coast side starts to move more centered but takes on that same narrow "knife blade" marking effect. Pics of this below.

    My only conclusion is that Ferrari meant to set it up the way it was originally because it gives the widest and deepest overall gear to gear contact between both drive and coast sides. Even though it's way out on the ends of the teeth, it's still the best available pattern.

    When looking at that original pattern, viewing the crown gear looking straight down between the peaks of two teeth, the pattern is somewhat of an oblong bow-tie across both coast and drive. Where they meet in the valley is a little off center favoring the coast side but it's the largest overall pattern I can get. Each side of the pattern meets nicely in the valley for the "knot of the bow tie". I wish I could explain it better than that but I have yet to master the Vulcan mind meld.

    The car was quiet and drove fine before the diff blew. I don't WANT to use the original pattern but short of busting out another $5K for a new gear set, it's my only choice.

    Below are the pics from the last movement of the pinion aft. Note the drive side hasn't moved but the coast side moved and got weird.
    Image Unavailable, Please Login
    Image Unavailable, Please Login
     
  8. qwazipsycho

    qwazipsycho Formula 3

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    #308 qwazipsycho, Jul 15, 2013
    Last edited by a moderator: Sep 7, 2017
  9. turbo-joe

    turbo-joe F1 Veteran

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    this your are going for now scott ( red ring on the picture ) seems acceptable but not ok in my eyes.
    try to go for one of the top pictures. important is that the pattern is not ending at the edge of the teeth like the middle and the bottom pictures.

    could you please make a picture of the pattern at the pinion, drive and coast side.
     
  10. turbo-joe

    turbo-joe F1 Veteran

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    #310 turbo-joe, Jul 16, 2013
    Last edited by a moderator: Sep 7, 2017
  11. qwazipsycho

    qwazipsycho Formula 3

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    Yeah, that's not going to happen. It just won't line up that way no matter what.
     
  12. godabitibi

    godabitibi F1 Veteran

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    Those last pictures are of the coast side. The drive side is always the convex side of the gear. Concave is the coast.

    Qwasipsycho what is your backlash? A wider backlash will move the pattern toward the heel on the drive side.
     
  13. BigTex

    BigTex Seven Time F1 World Champ
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    I tend to agree there's something wrong in the surface mating with you gear set, maybe just one, or the other, but that's not right, something is 'off' in the way they were machined???

    You have run into a 25 year old QC issue, IMO.
    It does explain the original set up but its not much comfort.....
     
  14. vincent355

    vincent355 F1 Veteran
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    subscribing. Read the entire thread and I love the dedication, don't give up now.
     
  15. qwazipsycho

    qwazipsycho Formula 3

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    #315 qwazipsycho, Jul 17, 2013
    Last edited by a moderator: Sep 7, 2017
  16. qwazipsycho

    qwazipsycho Formula 3

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    So you may be looking at that pattern and saying, "that's still not right." Well guess what, Ferrari disagree's with you. This pattern is dead on.

    Balderdash you say??? Well, you aren't here to see it so you'll have to believe me. I have cleaned up that ring gear once again and done some polishing and looking at it under a magnifying glass. The pattern you see in the pics above are IDENTICAL to the wear pattern on the gear. There is no doubt in my mind.

    I put the pinion shaft back to the stock depth using the 2.7mm shim. The Capristo LHS cover bearing hole is too deep by 0.7mm so I added that much to the original shim, compensated the equal amount on the other side and voila! I get the pattern you see above. The SAME pattern I've been fighting to correct all this time. It wasn't wrong in the first place.

    The backlash is a little out of spec at about .00075" or .019mm. The manual calls for a max of .016mm but I have to consider the wear of 38,000 miles on those gears.

    So what's the deal with the heel/toe pattern you ask?? Every single gear shop I spoke with said the same thing. Heel and toe don't matter as long as the pattern isn't slipping off the edge and as long as it covers at least 50-60% of the tooth or more.

    I can't believe I've beat myself up so much over this. Oh well,the knowledge I gained was immense! I can tell you exactly what a wrong pattern looks like because I've created them all. I moved the pinion back and forth and the diff in and out all to extremes.

    It was also worth it in the sense that I have a shiny clean gearbox with no debris inside and it won't leak anymore!! Hooray!

    There is light at the end of the tunnel...
     
  17. vincent355

    vincent355 F1 Veteran
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    subscribed just in time! :)

    Very cool.
     
  18. turbo-joe

    turbo-joe F1 Veteran

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    you are right. because of the translation german-english I was wrong and confused the drive and the coast side :(

    that is why I have written here in post no. 309 :

     
  19. qwazipsycho

    qwazipsycho Formula 3

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    So what do you think Romano? Did I finally get it to look acceptable??
     
  20. turbo-joe

    turbo-joe F1 Veteran

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    the drive side seems to be too much to the inside ( center ) of the diff. so the pattern ends at the end of the teeth, not on the teeth. that makes me thinking. would be better to have the pattern not ended with the teeth.

    the coast side seems to be ok for me
     
  21. davehelms

    davehelms F1 Rookie

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    It looks quite close to me, the drive side pattern will move towards the heal when under load. Because of this I usually shoot for a slightly toe heavy set up pattern that stops short of running off the tooth.

    Given these gears are already worn in to a slightly different wear pattern, you will never get text book patterns.... but this isnt short of that now.

    How's that warm fuzzy feeling feel now?
     
  22. qwazipsycho

    qwazipsycho Formula 3

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    Like my old blankie thank you very much! :D
     
  23. Melvok

    Melvok F1 World Champ
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    Please Scott ... find a gb builder to help you out .... if all this work of you ends in one year from now, it would really be sad !
     
  24. qwazipsycho

    qwazipsycho Formula 3

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    I just got it figured out Mel...Why would I do that now? No one is going to be able to make it any better than what I have here. The only way to do that is purchase new gears.

    The pattern I now have is EXACTLY what it was before the diff failed. I have no doubt that it's as perfect as it's going to get.

    I've talked to gearbox builders, diff builders, and read every piece of info I can get my hands on. This pattern is very much acceptable.
     
  25. Melvok

    Melvok F1 World Champ
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    Kee, then you are right ; keep your fingers crossed and GOOD LUCK :) !
     

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