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Synchros

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Old Jan 7, 2005 | 04:26 PM
  #1  
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Default Synchros

Alright, so on most cars there is a lock on first gear, so you cannot (accidentally or intentionally) downshift into first gear at a speed to high for the engine at that given ratio. The lock, as I'll call it, continues on my car down till almost 4mph, I almost need to come to a dead stop untill it lets me easily shift into 1st. I don't think this is an actual locking mechanism however, it's simply the synchros on the gear box don't synchronize the transmission untill your car slows to that speed.

But the other day I was told that if I blipped the throttle rather high (sort of like in heel toe) it would let me into first gear at higher speed - and it worked! I use this method often now, but I truley don't understand it. If the clutch is in this whole time, how can revving the engine effect the synchros? I thought the clutch disconnected the engine from the tranny, so they could operate independantly. Thanks guru's.
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Old Jan 10, 2005 | 07:23 AM
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Right, it's not an actual 'lock', it's the synchro doesn't let you into 1st when the revs are too far off.

What you're doing is double-clutching, but it isn't supposed to work unless you engage the clutch for a moment while the revs are up. Maybe your clutch is dragging & that's why it works??
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Old Jan 10, 2005 | 08:19 PM
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just out of curiosity why are you trying to put it in first while revving? for acceleration? I would think it's not good to use 1st to downshift
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Old Jan 10, 2005 | 09:39 PM
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It definitely isn't good if you have to rev to get into any gear. That will considerably shorten the life of your tranny. I recommend against it since if it wanted you to shift into it, it would let you without you having to rev. Also, there is no need to downshift to first unless at a dead stop since first is such a short gear anyways.
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Old Jan 11, 2005 | 06:18 AM
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Originally Posted by Shmoo
I recommend against it since if it wanted you to shift into it, it would let you without you having to rev.
Originally Posted by kill_kill_kill
I would think it's not good to use 1st to downshift
All is probably true, good advice

But still, why does revving the engine effect the synchros? Nobody has been able to answer it. It might just be the clutch rubbing, but it happens on two of my friends cars as well.
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Old Jan 12, 2005 | 04:48 PM
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Yeah when I come to a stop sign I just drop it into 2nd instead of first.
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Old Jan 12, 2005 | 09:20 PM
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Originally Posted by beier
All is probably true, good advice

But still, why does revving the engine effect the synchros? Nobody has been able to answer it. It might just be the clutch rubbing, but it happens on two of my friends cars as well.
It would suggest to me that first gear doesn't have syncros. I am not sure because when I look at the illustrated picture of the tranny in my service manual, it displays a synchro for 1st gear. You are rev matching to get it into gear which is only done on a non-synchronized transmission, so it is strange. I don't know why they would put a syncro on 1st gear since it isn't like you are shifting into it from any other gear while moving anyways. :dunno:
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Old Jan 15, 2005 | 06:15 AM
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Originally Posted by beier
But the other day I was told that if I blipped the throttle rather high (sort of like in heel toe) it would let me into first gear at higher speed - and it worked! I use this method often now, but I truley don't understand it. If the clutch is in this whole time, how can revving the engine effect the synchros? I thought the clutch disconnected the engine from the tranny, so they could operate independantly. Thanks guru's.
I had this exact same prob on my box in my Civic VTi and within about 3 weeks of reving before poping it into gear the synchros totally jammed up!! So my advise would be get it sorted now before you totally wreck your gearbox.
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