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  1. #1
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
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    1,522

    Default Facing used Toyota flywheel

    My 80s Toyota MR2 clutch had been on the way out for a while, this weekend I whipped it out and got to repairing it. I figured what I learned about heavily heated cast iron might be useful to others.

    I put it on my surface plate friction surface up with some 123 blocks underneath the centre bolt circle and found it had a bad uneven surface all over the central band of heat discolouration (+-.009") but was otherwise good.

    It is important to measure any shoulder height (mine was .017") as this will need to be re machined in the new face

    I then grabbed it on the inner cast flange at the back but also used a allthread through the spindle with a big flanged nut and aluminium collars at the back of the spindle and in the flywheel.

    Then an hour or so of dialing in the face and OD on the unworn sections and I started cuts, I have no compound and had to shuffle the tool back in the holder but the CVA can just take 12" and this was slightly under.

    I found the cast cut well but as soon as I hit the heated areas the insert I was using chipped. Even at just .002" doc. (46 rpm) I then swapped to a larger insert nose radius and raised the speed to 112 rpm and .004" doc. This improved things but the chips were coming off red and discoloured when I hit the glassy stuff.

    Finally I upped it to 360rpm and .004" and slowed the feed rate to .002" per rev and got a beautiful smooth finish.

    It's nice to be able to use a machine to its full capacity.

    Final face concavity was .0003 across the friction which I was very happy with the only thing is I'm concerned my surface finish may be too good.

    Sent from my Nokia 8 Sirocco using Tapatalk

  2. #2
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,942

    Default

    Any better finish and you'll be able to use it as a mirror and shave with it.
    Thanks for the how to, might come in very handy, one day.
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,436

    Default

    The secret to machining cast iron is to take a cut deep enough to get under the hard surface !

    Nice work anyway Thanks for the pictures.
    Best Regards:
    Baron J.

  4. #4
    Join Date
    Dec 2007
    Location
    Sydney
    Posts
    395

    Default

    [QUOTE=BaronJ;1945724]The secret to machining cast iron is to take a cut deep enough to get under the hard surface !

    I understood this for unmachined stuff straight from the foundry but I guess the heat from use had created the same surface chilling as from a mould.
    H.
    Jimcracks for the rich and/or wealthy. (aka GKB '88)

  5. #5
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    Have you put it on a surface plate and blued it up?

    I did a truck flywheel, or tried to, the surface finish was fine but the hard spots were all high .

    I had to grind the hard spots down manually with a die grinder using a flap wheel.

    20121218_153057 (Custom).jpg
    Gold, the colour of choice for the discerning person.

  6. #6
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    I didn't blue it up but I did indicate over the high spots and I was all good but it's still off so I'll give it a blue. Thanks for the tip

    Sent from my Nokia 8 Sirocco using Tapatalk

  7. #7
    Join Date
    Dec 2005
    Location
    South Australia
    Posts
    1,656

    Default

    I am no expert although I believe you should stone the surface to remove the glaze

  8. #8
    Join Date
    Jul 2016
    Location
    Melbourne
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    35
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    1,522

    Default

    Thanks everyone, I blued it up and the heat affected areas came up high but my indicators were only showing sub one thou. I just stoned them down until it all blued up no problem.

    Great advice.

    Sent from my Nokia 8 Sirocco using Tapatalk

  9. #9
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

    Default

    Thanks for posting a great practical project, complete with challenges and solutions.

    Just pondering how important it is to re-machine the shoulder to the same height as original. Guessing it would reduce the clamping force slightly if you didn't, but in practical terms the change due to thickness reduction of the friction plate in its lifetime would be many times greater than the 0.017" shoulder.

    Steve

  10. #10
    Join Date
    Jul 2016
    Location
    Melbourne
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    35
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    Default

    Yeah I dont really think a .017" difference in effective plate thickness would have a massive effect on overall life, maybe something like 10% at most. That mounting face did have some dings in from people levering the clutch housing of the alignment dowels in the past though so nice to get rid of them. I would be curious to know whats happening structurally in those hard spots to make them so awfully hard though.

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