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575m timing gear replacement

Discussion in '456/550/575' started by Dan575M, Oct 11, 2019.

  1. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
    Full Name:
    Dan Luke Halfhill
    Hi all! I have a 575m making noise from cam belt area. After tearing it down I found driver side lower cam drive gear loose. After removing the gear I found the woodruff key to be badly worn and the slot on the shaft also badly worn. So, looks like I need to pull the gear cover and replace the pinion gear (70000876) and maybe the bearings also. Any tips on doing this job? Nightmare? Many thanks in advance!


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  3. Soren

    Soren Karting

    Jul 13, 2011
    68
    Atlanta, Georgia
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    Bryce Anderson
    #3 Soren, Oct 17, 2019
    Last edited: Oct 17, 2019
    Hi, Dan, I am sorry this happened to your car- reading your post brought back some bad memories for me, as it sounds eerily similar to what happened to my old 550. It’s a significant amount of work to fix correctly. One complicating factor is that the lower drive gear isn’t (or at the time, wasn’t) available separately, and obtaining one required purchasing the entire front cover gearset. The front cover will need to be removed, and in doing so, I would strongly recommend replacing both bearings in the front cover as well as the bearings in the block that support the aft ends of the drive gears. Also, be certain to ensure that the locking nut on both driven cogs seats properly. It requires a fair amount of torque to install, and one of the theories of failure by some pro wrenches is that the locking nut reaches the specced torque before seating. This leaves a small amount of space that allows the driven cog to undergo motion and subsequently loosen. Compounding this may be installing the timing belts too tight, which applies a moment acting around the base of the driven cog and exacerbating the cog’s movement, especially as the entire engine heats up and expands dimensionally. As always, if there are any pros here who would like to opine on this and offer you guidance, I hope they will do so. Meanwhile, if you want to discuss it in more detail, send me a PM or email. I hope the repair goes well.
     
  4. Cribbj

    Cribbj Formula 3
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    Good to see you back Bryce!
     
  5. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
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    Dan Luke Halfhill
    Thanks for the reply! I did manage to get the cover removed but I can’t say it just fell off onto my lap. No, it was hours and hours of small gentle taps with a soft mallet. The oil drive gear reluctantly creeping ever so slowly towards the end of the crank-shaft.
    The pinion gears used to be sold as a set (70000876). However they can be purchased individually (168701 for the 2 cam gears and 168702 for the crank).
    And yes, new bearings it will have to be.
    Just really glad the great bearing crisis got sorted! Or did it??


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  7. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
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    Dan Luke Halfhill
    Anyone have a thought about installing the timing cover with the gilmer gears pressed into the cover. Or, better to have the gilmer gears installed on the block first and fitting the cover second? It seems it would be nice having the oil pump chain all fastened up prior to installing the cover but those gears don’t exactly slide into front cover bearings easily. Hmmm....


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  8. Cribbj

    Cribbj Formula 3
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    I've had my timing cover off/on several times tinkering with different things, and IIRC, the best way to put it on is with the timing gear shafts already installed in it, then tapping it ever so gently into place so as not to bugger up the main gear on the crankshaft.
     
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  9. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
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    Brian Crall
    Like John I have done it many times. I install the front cover fully assembled.

    As far as why it happened we certainly saw that in 355 transmissions. The ring nut torque by itself was not sufficient to draw the gears totally in place so there was no clamping pressure. Don't know if that can happen here. In my experience they are not that tight a fit but maybe some are? In any event when putting together assemblies of that type I never count on the nut to seat anything. It gets fully seated prior to installing the nuts.

    Factory instruction for timing the 575 are hard to understand for some. It is awkwardly worded.

    These are the latest and greatest instructions. A friend with the factory just gave them to me to be sure I had the correct stuff.
     

    Attached Files:

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  10. dodici

    dodici Karting

    Mar 24, 2007
    82
    Bay Area, CA.
    Full Name:
    Dale
    Very nice Brian. Any chance they have the same kind of instructions for the F133A version (550)?
     
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  12. Rifledriver

    Rifledriver Two Time F1 World Champ

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    Yup. In the book. Its much easier on 550.
     
  13. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
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    socal
    Dan,

    where the gears hard to source or did you repair the woodruff slot? I think the biggest problem in the future are lack of parts.
     
  14. Dan575M

    Dan575M Rookie

    May 17, 2018
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    Dan Luke Halfhill
    Nice! Thank you for that info!
    This particular issue was with the left cog, a loose ring nut that resulted in noise and most likely retarded cam timing on the left bank. I’m going to press the new gears in place and install as a unit. Do you suggest sealant on said gear shafts before I press them?


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  15. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
    Full Name:
    Dan Luke Halfhill
    I contemplated repairing the woodruff slot, if I could get away with keeping the cover, bearings and gears intact. But, as high heat would be used, those bearings would be toasted. So, I opted to replace everything.
    The gears were not readily found here in the states. I called a contact in the UK who had a pair of nos gears on my doorstep in 2 weeks. It’s nice to have peeps!
    Bearings from Hill.
    Glad to get involved with this job after the great bearing debacle a few years back!
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  16. Rifledriver

    Rifledriver Two Time F1 World Champ

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    I'll ask you the same question I always ask myself or employees......Why?
     
  17. Rifledriver

    Rifledriver Two Time F1 World Champ

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    That has been said for a very long time and yet here we are still driving 166's and 212's. Fact is parts are easier to replicate than ever and existing parts are easier to find than ever. We are regularly fixing things that once we threw away or parted out. If that shaft and gear were simply not available I have 2 phone numbers of people who will make you one better quality than the original and I am not even in that part of the business.
     
  18. Dan575M

    Dan575M Rookie

    May 17, 2018
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    Dan Luke Halfhill
    Because .0100”


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  19. Rifledriver

    Rifledriver Two Time F1 World Champ

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    I have reread the entire thread and have zero idea what you are talking about. I don't do guessing games.
     
  20. Dan575M

    Dan575M Rookie

    May 17, 2018
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    Dan Luke Halfhill
    Oops, I think I prematurely sent the reply without finishing.
    The tolerance between the id of the timing cover bearing and the od of the new gilmer gear shaft is around .0100 “.
    So, I’d would seem that “gap” would be a source of oil leakage. Hence my question about using a sealant when pressing the gears into the cover.


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  21. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    Nowhere in the world is .010 a manufacturing tolerance. You have the wrong parts. It should be a pretty snug interference fit. It is a very long way from that.

    They are such a tight fit I once broke a housing pressing a gear out of the bearing.


    By the way. Your circlips are improperly installed.
     
  22. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
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    Dan Luke Halfhill
    Not the wrong parts, my Mitutoyo vernier’s are reading all over the place. Sigh. Oh well, they served me well for many years.

    I was not about to risk cracking the housing on a press. The Draper worked amazingly well.

    Circlips incorrect?



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  23. Cribbj

    Cribbj Formula 3
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    The edges opposite the open ends are not seated in the grooves.
     
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  24. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
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    Dan Luke Halfhill
    Oh wow. How embarrassing, I can’t believe I didn’t catch that. You’d think after 30 years of wrenching
    those mistakes wouldn’t happen...but they still do,from time to time. Thanks all!


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  25. Cribbj

    Cribbj Formula 3
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    Freeze the gears before installing if you don't want to risk using the press. As Brian said, they're a very snug interference fit at room temperature, but freezing helps them slip in without a press.
     
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  26. Dan575M

    Dan575M Rookie

    May 17, 2018
    34
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    Dan Luke Halfhill
    That’s a good tip, thanks.
    I pressed them both last night without issue.
    I just can’t understand how the cover can be installed when the gears are already in the engine block? Must be a tool that helps draw the gears through the cover as you install it.
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  27. Cribbj

    Cribbj Formula 3
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    I did it once with a block of wood across the thread bosses then gently tapped the cover on. I had frozen the gears so they slipped into the inner bearings without a problem, and they were still cold enough that the cover went on without any issues.

    But doing it with the gearshafts already in the cover is definitely the better way.
     
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