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If anyone is interested in how a 1997 F1 Gearbox works.....

Discussion in 'Motoring Related Discussion' started by Capra, May 31, 2019.

  1. Capra

    Capra Senior Member

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    here is Youtube vid. Not sure what they are like in the modern era, but maybe the principle is the same. I'm not car techie but I found it an interesting watch.

     
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  2. Blobcat

    Blobcat Moderator

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    Interesting, he could do with some ratchet spanners :D

    5th & 6th look worn (or the oil is sat on the teeth so it looks like the teeth are worn)
     
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  3. LostKiwi

    LostKiwi Senior Member

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    Modern F1 is very different and has more in common with automatic gearboxes (with high dependency on hydraulics) than that one.
    Interestingly it bears quite a close resemblance to the gearbox used in Smarts:
    IMG_20150815_170841.jpg IMG_20150815_170953.jpg

    The large silver drum is the selector drum which drives the selectors engaging gears sequentially as it's turned - in this case by an electric stepper motor.

    Note the helical gears for noise reduction as opposed to the straight cut gears (which are better for power transfer).
    Also note the two speed differential on the Smart (which is actually a 3 speed box with a 2 speed diff). The lowest selector on the lower photo selects hi/lo diff ratios.
     
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  4. Blobcat

    Blobcat Moderator

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    I'm sure my smart cdi has straight cut gears to handle the immense power :p:cool: none of that helical noise reduction nonsense for me :rolleyes::D
     
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  5. LostKiwi

    LostKiwi Senior Member

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    I had straight cut gears in my old competition mini. Everyone knew that (you could hear them whining louder than a plane load of Aussies returning home from a holiday in Bali).
     
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  6. OP
    Capra

    Capra Senior Member

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    Cool, appreciate you taking the smart's gearbox apart to help me understand the gearbox setup.
     
  7. EmilysDad

    EmilysDad Senior Member

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    Which is where Andy Citroen got his badge :)
     
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  8. LostKiwi

    LostKiwi Senior Member

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    No probs. Only took 2 minutes :)

    Actually it was out as I had a suspected fault with it, funnily enough a very pronounced whine on overrun.
    Whilst apart found a bearing had been spinning in the housing:
    IMG_20150815_171918.jpg

    I replaced the box with a low mileage used one. That didn't fix it. Between putting in the new box and pulling it apart again we drove to the South of France in it and two days after returning there was a loud bang and clatter....
    Stripped it and found the drive plate the flywheel mounts to had shattered. This had cracked and was loading the input shaft hence why the box was whining.
     
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  9. LostKiwi

    LostKiwi Senior Member

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    Correct - he used Herringbone cut gears (effectively two opposing angle helical gears in one).
    Helical gears generate high side loadings causing friction. Straight cut and herringbone gears get around this. Herringbone gears are very expensive to make so not used in many applications.
     
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  10. EmilysDad

    EmilysDad Senior Member

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    That would have been 'fixed' at work with a series of centre pop marks in the housing and a smear of Loctite :rolleyes:
     
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  11. ajlsl600

    ajlsl600 Senior Member

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    thats very motorbike type selector drum , and i was a bit surprised to see the straight cut gears as its been my understanding that helical cut are able to stand transmitting more power ? more contact area.and quieter ? the side effect more side thrust,heat .that needs control. (thrust washers) tighter end float control. and likely oil cooling .
     
  12. ajlsl600

    ajlsl600 Senior Member

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    slightly off subject ,did you see the latest joke posts the aussi bbq made me howl, esp as i could see it happen at an auss barby......
     
  13. LostKiwi

    LostKiwi Senior Member

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    Straight cut transmit power better (less tooth to tooth friction, no side loadings) but are not as strong as helical/herringbone as power is transferred through a smaller contact patch is by fewer teeth at any one instant.
    The transfer of power from tooth to tooth is very noisy compared to helical (where at any given time there are typically 3-4 teeth in mesh compared to 1-2 for straight cut).

    Whilst my S/C box was noisy a mate also had straight cut drop gears and diff. That was seriously loud to the point of hearing the transmission before anything else when he was on full chat.
     
  14. ajlsl600

    ajlsl600 Senior Member

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    basically ,not wrong then.
     

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