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Thread: double clutching?

  1. #1
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    double clutching?

    I've got a 87' volvo 740 turbo intercooler. Now of course the car has syncros so double clutching isn't required. But I just wanted to do it for the experence and to fool around, But it just doesn't seem to work. As far as I've understood it is when you pop the clutch quick between gears so that the gear box can turn with the rpms of the engine, and it can let you do dynamic shifting from say 4th to 2nd. so I wanted to try it out, I pop out of 4th let the clutch out, then push it back in then try to go into 2nd, but just like always it won't let me get in there. I think I'm doing somthing wrong, I haven't been driving stick to long but I can heel and toe ok but this double clutching has me stuck.

  2. #2
    And then I was mod. Tidder's Avatar
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    I think you are doing something wrong. I think you're missing a step...

    Say you're in 4th at 2700 rpm. Now you wanna jump to 2nd. You push in the clutch, pop it out of gear, pop the clutch, rev up to where 2nd would be for your current speed, for me it's probably around 4800rpm or so. Push back in the clutch, put it in 2nd then release the clutch again, feeding it the proper gas. You shouldn't feel ANY jerk, if you do, you did it wrong.

    Basically, when you're trying to mash it into 2nd from 4th, your tranny isn't gaining the rpm it needs to get into second. When it won't go into gear, it may be a sign that you're going too fast to get into that gear properly anyway... be careful.

    If you haven't been driving stick too long, then I would not get into double-clutching just yet. Get a feel for your car, know where each gear's RPM is compared to the current gear and RPM. It'll take time, but in the end, your car will thank you.
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  3. #3
    Constant Bitrate monger's Avatar
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    It wont let you into second because the driveshaft is trying to spin up the clutch to match its speed in second. Meaning you are going too fast for the clutch to easily get up to speed through the syncro. If you apply pressure long enough it will pop into second, but it will make the syncro's wear out faster.
    Monger
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    UPDATE: I moved farther north. Now its even too cold for the deer; only moose now

  4. #4
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    ah much thanks.

    maybe you can help me with anther question,

    the tranny has been replaced once before (the car has 190,000 on it but the engine is still perfect, compression and everything go volvo!) though it wasn't a factory volvo replacement, it was a expesive custom job (can't rember why we couldn't get a basic volvo tranny). the gear design isn't normal. Reverse is all the way left and up and then the normal H is to the left of the reverse (keep in mind that left is the driver side, so the gears look somthing like this:

    R..1..3
    |..|...|
    ------
    ...|...|
    ...2...4

    what keeps you from accedently going to reverse is that it requires a ring around the stick to be lifted to move over that far. Not sure why they came up with this design but it screws me because I doupt I could get a shortshifter with the same kind of setup. but the prob I find is

    When I go from 1st to 2nd i get stuck. I understand that running across the left wall i can expect some trouble because of the degisn for the reverse. But it still feels bad when i try to go into second it just doesn't get there. It feels like when i'm going from 3rd to 2nd with out reving. where it just a block in the way. Though after about .75 secs it's open and i can pop in. when I just sit and idle i can go back and forth just fine, but if i accelerat quickly in first or slowly start up in 1st it still hit that block and it really slows down my acceleration. I think it has somthing to do with the servos and was one of the resons why I wanted to try double clutching. but even with double clutching I still have this problem.

    I'm I just a moron and is missing somthing completely obvious?

  5. #5
    Constant Bitrate
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    Quote Originally Posted by Tidder
    I think you are doing something wrong. I think you're missing a step...

    Say you're in 4th at 2700 rpm. Now you wanna jump to 2nd. You push in the clutch, pop it out of gear, pop the clutch, rev up to where 2nd would be for your current speed, for me it's probably around 4800rpm or so. Push back in the clutch, put it in 2nd then release the clutch again, feeding it the proper gas. You shouldn't feel ANY jerk, if you do, you did it wrong.
    You are in 4th at 2700rpm. Clutch pedal in (optional for old cars like mine where I can slip it out of gear w/o the clutch). Put the gearbox in neutral. Clutch pedal out. 'Blip' the gas while in neutral to about 4800rpm. Clutch pedal in and put the gearbox into second. Clutch pedal out. Feed gas.

    To upshift is easier. You need to just put it in neutral. Clutch pedal out in neutral and wait a second or two for the rpms to drop down to match your higher gear. Then shift normally into the next higher gear. If done right, you get a smooth ride running up through the gears on cranky gearboxes.

    Ask somebody who drives old beaters with tempermental gearboxes.

    Edit: Tidder's description is correct. I got confused reading the clutch descriptions. Have edited my description to make it clearer as well.

  6. #6
    Constant Bitrate monger's Avatar
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    Quote Originally Posted by Maver
    ah much thanks.

    maybe you can help me with anther question,

    the tranny has been replaced once before (the car has 190,000 on it but the engine is still perfect, compression and everything go volvo!) though it wasn't a factory volvo replacement, it was a expesive custom job (can't rember why we couldn't get a basic volvo tranny). the gear design isn't normal. Reverse is all the way left and up and then the normal H is to the left of the reverse (keep in mind that left is the driver side, so the gears look somthing like this:

    R..1..3
    |..|...|
    ------
    ...|...|
    ...2...4

    This is a standard shift pattern for Volvo's. At least all the ones from the 80's that I have played with.....


    EDIT:

    I just read the rest of your post, and it sounds like the syncro's are already worn out for second gear.
    Monger
    ICQ-7207702
    UPDATE: I moved farther north. Now its even too cold for the deer; only moose now

  7. #7
    And then I was mod. Tidder's Avatar
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    Quote Originally Posted by piabu
    Edit: Tidder's description is correct. I got confused reading the clutch descriptions. Have edited my description to make it clearer as well.
    I confused myself as well after reading what I just typed... but I just said to myself "f*&k it". I can't do it any better...

    I own a '95 btw, and I can still pop in and out of gear without the clutch... is that bad? You say old beaters... does mine count?
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  8. #8
    FLAC alti's Avatar
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    Quote Originally Posted by piabu
    Ask somebody who drives old beaters with tempermental gearboxes.
    ha my first car was a 83' Trans Am with a manual clutch. Man you dont know what a difference the hydrolic makes unless you have experienced a manual. It did not help the situation that my clutch fork was bent either It got so bad at one point that i actually broke the shifter tring to get it into gear!!! yes you read that correct... the 1/2 or 3/4 inch peice of round steal actually gave to metal fatigue from my efforts to get the ***** in gear.

    I did do a tranny overhaul after that
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  9. #9
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    so syncros arn't just 1 part? it's a part for each gear?

  10. #10
    Raw Wave Rob Withey's Avatar
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    Quote Originally Posted by Maver
    so syncros arn't just 1 part? it's a part for each gear?
    correct. often they leave out the synchromesh on reverse.
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