96 F355 and Hill Bearing Surprise | FerrariChat

96 F355 and Hill Bearing Surprise

Discussion in '348/355' started by yelcab, Dec 13, 2010.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    #1 yelcab, Dec 13, 2010
    Last edited: Dec 13, 2010
    So I took out the engine in my 96 355 for a major service and general cleaning up. Using my four post lift, the engine came out pretty easily. Ordered from Ricambi new Hill bearings, timing belts, a bunch of necessary gaskets, and a few other nick-nacks.

    Hm, orignial bearings were date coded 96, so they have never been changed. They still worked fine, but it's better to replace them with the best Hill bearing anyway. New bearings in hand, I saw the warning label about the 94-95 model. Well, does not apply to my 96.

    So, belts went in, bearings went it, rigged up a tool to turn the bearing, set the 2.5mm gaps, tightened everything, turned by hand a few revolutions, no problem. Degreed the cams, the marks on the back were right on. Bank 2 exhaust cam was off by a degree or two but certainly very close. Cleaned the engine, the transmission, the subframe, the engine bay, painted the frame where needed, tig welded the Alt bearing brackt, mig welded a new frame bracket for the underbody panel, and in went the engine. Connected up everything in a couple of days. Filled her up with fluids, double checked everything against the notes. OK, charged the battery, and fired her up.

    She came to life, and squealed like a stuck pig. Shut her down. Remove all accessory belts, started her back on and she squealed like two stuck pigs. WTF?

    Engine came back out last weekend. Opened up the cam belt covers and I found ... both Hill bearings were rubbing against their brackets ... even on a 96 model which is not supposed to be the case. Does anybody want to guess that Ferrari AG had some left over 95 bearings and brackets and they used them all on the 96 model year before they switched over?

    Lesson learned: With Ferrari AG, assume nothing. Don't trust, just verify.

    Silver lining:
    1. At least the belts did not break and grenade the engine
    2. I get to do the cam timing twice.
    3. Dropping the engine using a 4 post lift is now second nature.
    4. Here is my chance to fix that messed up engine mount hole in the frame with a helicoil.
    5. While the engine was steaming off the water vapor after it was fired up, I noticed some steam coming off cylinder 5 sample port on the bank 2 header. Ah, it is now time remove it and have it welded. Yes, I am buying time, but we are all just buying time on this earth.
    6. I finally had a chance to do some R&D for Daniel at Ricambi. They now can change the warning label to include 94-96 models

    Finally a question: what makes the 328 timing belt $21 and the 355 timing belt $125?
     
  2. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    17,913
    USA
    Hi Mitchell, sorry to hear of your troubles, what is the build date on your car?
     
  3. greyboxer

    greyboxer F1 World Champ

    Dec 8, 2004
    12,282
    South East
    Full Name:
    Jimmie
    Who are 'Ferrari AG' ?
     
  4. ronrob

    ronrob Formula Junior

    Jan 15, 2007
    395
    Var, S.E. France
    Full Name:
    Ronald Brown
    Mitchel - I admire your positive attitude!
     
  5. mad dog

    mad dog Formula Junior

    Jan 5, 2006
    875
    suffolk uk
    Full Name:
    andrew
    #5 mad dog, Dec 14, 2010
    Last edited: Dec 14, 2010
    Tough one, still whats a few more days in the garage.....

    So being in exactly the same position here with engine near ready to go back in a 96 car and hills bearings fitted, couldn't we tell if the bearings are wrong before starting engine? I did look and turn them etc when fitting and all seemed well. But is there a better check I can do now, do you know? Would obviously be very helpful!
     
  6. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    The thicker tensioner arms extended well into 96 from what I have found.

    Once Ferrari "clearanced" the arms in mid 96's they left a very sharp corner in their machining of the flat area where it transitions to the tensioner contact point. I have never seen one break at this point but if ever there was a poster child for a stress riser... that is it. Some of the replacement arm forgings are so thin (and expensive) I just cant get myself to use them and instead choose to machine the originals. I grind and polish a radius into this machined area on most all of the arms, just cause.

    328 timing belt $21 and the 355 timing belt $125

    Kevlar and a far more complex and stout design. I'm sure it has nothing to do with the 'modern Ferrari' surcharge theory.
     
  7. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    Kevlar, wow this belt must be bullet proof then. No wonder it did not break.
     
  8. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,292
    socal
    Not being a 355 guy can't the rubbing bearing bee heard on hand turnover of engine or felt when you assemble the bearing and spin it by hand? Just askin...
     
  9. mad dog

    mad dog Formula Junior

    Jan 5, 2006
    875
    suffolk uk
    Full Name:
    andrew
    well my point exactly bb. They presumably dont move that much sideways once fitted. And I certainly tested mine by hand as ok, but this experience raises concerns of course. would be a good idea to have a build chassis no from when they were ok.
    anyone?
     
  10. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    #10 davehelms, Dec 15, 2010
    Last edited: Dec 15, 2010
    Nearly impossible because of spare parts variances. I have seen some through 97 that were too close for my comfort and I machined and clearanced those. The replacement parts went the other way and are quite a bit thinner in cross section and varied a great deal one to the next but as I stated above, have not proven problematic. Some of the replacement arms come bare with no teflon bushings, no sleeve, no pin boss... Some come with sleeves and boss in the same part number box. Add up all the prices and its just too expensive with too many variables for my taste when I have an overly stout one sitting on the bench.

    When I see a forged arm such as this with a sharp right angle bend in it there is always a concern in my eyes, too many years building race cars and having to predict failure points. It appears a common method to make bearing roller clearance now is to take them to a bench grinder which then puts deep gouges and a near zero radius running right at the base of the 90 degree bend. If ever a crack would appear this is the perfect storm. Right back to the question I have been asking... What's included in a "Major Service?"

    Worry not, the 355 is not the only model that has this problem, we dealt with another having .15mm clearance just the other day and this is not just a problem with the Hill Bearings, OEM has the same issues. How much deflection will the bearing show as it ages? Fatso, I have found there is a very slight clearance when it is assembled by hand and the bolt snugged while setting tensioner clearance. That little gap goes away when a final torque is put on the bolt but then you have the chatter of the new belt making too much noise to hear the contact. A very easy mistake to make if you dont know what to look for.
     
  11. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    I have found these belts split into three narrow belts, belts with multiple holes through them from debris stuck in the gears and some ripped to shreads from fence failures and all still doing their job fine. As these engines are aging I see the later becoming the next challenge to deal with and is why I am now stitch welding all of the fences on all of the models.

    This belt design is really quite nice. The extra groove in the tooth aids in allowing the belt to flex as it goes around the small drive gear. The tooth also splays out a slight amount when in contact with the gear thus taking up side clearances between it and the gear, holding tighter timing. This is really quite a nice setup and a vast improvement over the old 308 design.

    Gear rust and fence failures, those are the challenges we are researching and trying to deal with now.
     
  12. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,292
    socal
    The OEM new tnesioner to the bearing has what installed and torqued clearance? Are we looking for 0.25mm min or maybe even a full 1mm?
     
  13. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    There is no clearance spec given by Ferrari. On the last one that came apart... zero, there was significant contact. What should it be? Great question, how much deflection does an aged bearing have?
     
  14. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    I finally got home from a trip and had time to tear into the engine again.

    One Hill bearing is toast. The heat from the belt rubbing on it was so great that it left an indent on the bearing surface that I can feel with my finger. The other Hill bearing is a little shiny on one side but fine otherwise.

    It is a testament to the kevlar design of the belts that they still survive. In fact, they don't look stretched or burnt or damaged at all. The lettering printed on the back of the belts are gone but they all do that once run in. I am almost tempted to re-use them.

    Here is the mystery. The old factory bearing and the new Hill bearing are of the same size. The brackets on the engine already show signs of machining (like the factory took a boring bit and thinned down the spots a bit ... leaving a sharp corner as Dave Helms pointed out above.

    So, why the interference ???
     
  15. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
    Austin TX
    Full Name:
    Brian Crall
    The bearing can physically be rotated either CW or CCW to tension the belt. It will often hit the bracket when turned one way and not the other.
     
  16. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,292
    socal
    I would not reuse the belts and fyi I have belts going the full 3 year distance and the writing on the back is still clearly visible.
     
  17. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    I said "almost" but not quite.
     
  18. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    Most every arm was machined by the factory, just not enough for the Hill (and in many cases OEM) bearings to fit on the earliest series of arms. The latest replacement arms are so thin no machining was required as I remember.
     
  19. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    The $****ty thing is I happen to have a picture of the old bearing sitting on the arm. When I put the Hill bearing on the arm, matching the angle of how the old bearing sat on the arm, the Hill bearing rubs.

    There must be some tiny difference in the recess surface of the bearings from the edge, between the two bearings that is. That and the zero clearance coming off the factory adds up to this mess.

    I am at work now, but I will check when I am at home.
     
  20. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    Yup.
     
  21. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    Ok, to close out this thread.

    The Hill bearing is 0.010" more recessed than the "stock" ones and eats up all the clearance with the bracket. I had the brackets machined to remove 0.030" and after installation, a feeler gauge of 0.040 fits underneath the bank 2 hill bearing and bracket, while a 0.050" gauge fits underneath the bank 1 bearing and bracket.

    So, if this does not work and it squeals again, I am pitching the whole thing and going back to stock... but it should be fine.

    And, during this mess, the exhaust cam on 5-8 skipped one tooth !!!

    Just for the records, this car has all the timing marks front and back spot on after degreeing the cams to specs. I am still unclear as to how the factory manual suggests that a "catch" (the pin inserted into the tensioner) could slide free while maintaining a 2.5mm gap but that puzzle is for another day. I am done with this one.
     
  22. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    Oh, one more thing.

    TDC center for number 1 cylinder, plus 90 crank degrees is exactly TDC for number 5 as well. Confirmed with dial indicator. No need to find it again.
     
  23. plugzit

    plugzit F1 Veteran
    Silver Subscribed

    Dec 1, 2004
    7,667
    Redondo Beach, CA
    Full Name:
    Bruce Bogart
    Good job! Priceless experience!
     
  24. UConn Husky

    UConn Husky F1 Rookie

    Nov 11, 2006
    4,422
    CT
    Full Name:
    Jay
    Dave, forgive my ignorance, what's the 'fence' you're referring to?
     
  25. 348paul

    348paul Formula 3

    Dec 27, 2002
    1,098
    Kent - UK
    Full Name:
    Paul Hill
    I would like to post this information to clear a few things up. The dimensions from the back face of the shell/outer race to the mounting face on a selection of 355 bearings we have are as follows:

    SKF OEM 355 Bearing Sample (Early design)
    #1 - 3.62mm
    #2 - 3.55mm

    The latter bearing design had a slight change in dimension and the samples we have are as follows:

    SKF OEM 355 Bearing Sample (Later style)
    #1 - 4.02mm
    #2 - 4.13mm
    #3 - 4.04mm
    #4 - 4.07mm

    The Hill PT355 bearing dimensions are based on the latter SKF design and here are the dimensions of four units taken from stock:

    Hill Bearing sample
    #1 - 4.03mm
    #2 - 4.11mm
    #3 - 4.08mm
    #4 - 4.01mm

    We also have several other unknown origin bearings that have been sent to us over the years and out of interest we have measured these as well.

    Unbranded 355 Bearings
    #1 - 4.09mm
    #2 - 4.02mm
    #3 - 4.08mm
    #4 - 4.14mm

    We already know that the OP had the early SKF bearings on his car that had approx 0.5mm more clearance than the latter SKF bearings and unfortunately this problem could have quite easily also been a problem if the OEM SKF bearings had of been used or even any of the unbranded bearings that are out there in the supply chain.

    I think the most important thing to remember is to check bracket clearance regardless of what bearing is being used - I know we put warning labels on our packaging to make the installer aware of possible clearance problems on 94/95 cars but I have already made alterations to the wording so that bracket clearance should be checked at all times.

    Paul
     
    Qavion likes this.

Share This Page