Manual Transmission T56 | T5 | MN12 | Clutches | Hydraulics | Shifters

grinding gears

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Old Sep 9, 2014 | 11:35 AM
  #1  
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Default grinding gears

my 2nd, 3rd and 4th gears grind under fast shifting, especially the 2nd gear. If I shift slow then there is no problem at all. Is it the synchroes and. I need a rebuild or maybe the clutch doesnt disengage quick enough?
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Old Sep 9, 2014 | 01:25 PM
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It would help a lot to know what you are driving, what mods you have, and how fast you consider "fast." (speed of shift as well as RPM at which you are shifting)

Here is how I make sure the clutch is fully disengaging.. press clutch in all the way, put shift lever in 4th gear to stop all rotation. Then put it back in neutral with clutch still pressed all the way in. Rev to 1000RPM or so for 10 seconds and then gently sneak the stick into reverse(keep clutch pressed in the WHOLE TIME). If it goes right in, you are good. If you hear any grinding or noise and it doesn't go in, your clutch is dragging or pilot bearing/bushing or similar might be binding a bit. Once you have eliminated clutch adjustment as an issue, then look at transmission.

When was the last time you checked/changed your transmission fluid? This can have a large effect on shifting, especially at high RPMs. Make sure you use GOOD stuff and the appropriate friction modifier(s) if applicable. IMO, newer transmissions use fluids that like to be changed more often. Used to be the thick, sludgy gear oil would last almost forever in older transmissions.

Beyond that, you may have worn synchros.

Good luck.
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Old Sep 9, 2014 | 01:41 PM
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Originally Posted by Mercier
When was the last time you checked/changed your transmission fluid? This can have a large effect on shifting, especially at high RPMs. Make sure you use GOOD stuff and the appropriate friction modifier(s) if applicable.
I wouldn't worry about buying "GOOD" stuff, I asked 2 different people from TICK Performance what the best transmission fluid is to use in a T56, I was told to use any DEX 3 non synthetic ATF, they really stressed the non synthetic part. When I asked the exact brand used in their shop I was told they use the store brand from the local parts store.

Also if the problem persist get it rebuild ASAP, continuing to drive it will tare up more parts and it can get really expensive when that happens.

Also almost forgot this isn't a internal engine question, there is a manual transmission forum for these questions.

Last edited by Fry_; Sep 9, 2014 at 01:47 PM.
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Old Sep 9, 2014 | 02:49 PM
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Originally Posted by Mercier
It would help a lot to know what you are driving, what mods you have, and how fast you consider "fast." (speed of shift as well as RPM at which you are shifting)

Here is how I make sure the clutch is fully disengaging.. press clutch in all the way, put shift lever in 4th gear to stop all rotation. Then put it back in neutral with clutch still pressed all the way in. Rev to 1000RPM or so for 10 seconds and then gently sneak the stick into reverse(keep clutch pressed in the WHOLE TIME). If it goes right in, you are good. If you hear any grinding or noise and it doesn't go in, your clutch is dragging or pilot bearing/bushing or similar might be binding a bit. Once you have eliminated clutch adjustment as an issue, then look at transmission.

When was the last time you checked/changed your transmission fluid? This can have a large effect on shifting, especially at high RPMs. Make sure you use GOOD stuff and the appropriate friction modifier(s) if applicable. IMO, newer transmissions use fluids that like to be changed more often. Used to be the thick, sludgy gear oil would last almost forever in older transmissions.

Beyond that, you may have worn synchros.

Good luck.
It happens at any rpm really as long as I shift really quick, im not sure how to be more specific. but just think of as fastpossible, when I shift slow it doesnt grind at all. its a 99 v8 firebird btw. Well the clutch fluid is low and is almost black so I need to change that. any advice about what kind to use? as well as the tranny fluid.
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Old Sep 9, 2014 | 06:38 PM
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YES folks, another one. Vlad, this is the INTERNAL ENGINE section, not the manual transmission section.

Take it over here guys: https://ls1tech.com/forums/manual-transmission-14/
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Old Sep 9, 2014 | 10:08 PM
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Originally Posted by vlad1995
Well the clutch fluid is low and is almost black so I need to change that. any advice about what kind to use? as well as the tranny fluid.
I asked Joey at TICK Performance about the clutch MC also, was told any brand non-synthetic DOT 3 brake fluid.
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Old May 4, 2016 | 08:47 PM
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Austin6969 welcome to LS1tech!

I've moved this into the manual trans section.

Austin, have a look here: https://ls1tech.com/forums/generatio...g-threads.html
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Old May 5, 2016 | 11:10 AM
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I just bought a 96 chevy s10 with the 4 cyle. It grinds in all gears it shifts just fine but its grind all the time wile driving like it grind when someone would grind the gears when shifting can help me figure this out
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