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Old 01-06-2011, 12:48 PM   #51
Rick@RKT56
 
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Drives: Corvette
Join Date: Jan 2011
Location: Maryland
Posts: 106
Quote:
Originally Posted by RipperFox View Post
I have been having the same issues as all of you.

1. Grinds 1st to 2nd at higher RPM's
2. Tried a new shifter (Hurst), got no better, maybe worse. Probably cause it shifts even faster.
3. Change the fluild to Mobile Syn. No improvement.
4. Noticed that is happens alot more when tranny temp is colder. Above 75-80F, nearly goes away.
5. I can get it to do in the garage too.

In the garage, I notice that if I go from neutral ALMOST into 1st. (just to the point of resistance) and hold it there. Then pull back into second really quick it will grind. No clutch involved at all. Pedal to the floor, car at idle.
Now, let me say that again. I get the exact same grind, from 1st to 2nd, if I push the clutch tothe floor, just nearly push it into 1st, hold or a couple of seconds, and pull back into 2nd (as if speed shifting), and it will grind. Car is at 500-700 RPM the whole time, clutch is on the floor, the whole time. Give it a little gas (say 2-3K RPM) and it will grind like speed shifting at 6K.

Someone else try this and see what results you get. PM me or post here.

This is why I know it is the syncro's: RPM, clutch are not involved in this test. Syncro's are not match gear speeds quick enough for these gears. That is why slowing down your shift fixes the situation. I do believe that the tappered syncro's could be the cure for this.

I think what is happening in the garage is: The syncro's are matching speed to first gear (just at the edge of the entry gate), and when you are pulling into 2nd really quick, there is not enough time for the 2nd gear syncro to make gear speed.

The temperature thing: The viscosity of the tranny fluild is lower thus allowing the bearings and thus the gears to react faster.
Are you saying you have the engine running, clutch pedal to the floor and shifting from 1st to 2nd WHILE you have the clutch pedal to the floor and it grinds? While the vehicle is stationary? If this is what you're stating, then it's your clutch and not the transmission. When you have the clutch pedal to the floor, the input shaft of the transmission should be stopped (unless the clutch is dragging) so all the internal parts of the transmission should NOT be turning. If you hear it grinding that mean the internal parts are STILL moving.
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