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4th gear grinding!!

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Old May 28, 2010 | 06:34 PM
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Default 4th gear grinding!!

I'll try and expalin this a clear as I can.

I have a issue where fourth gear grinds when I shift. No, its not my driving

1. Only happens during high RPM shifts, hard shifts. If I shift at high rpms but shift slow(let it hang in neutral for a split second)it may or may not do it.

2. Only fourth gear does this.

3. Tranny fluid has been changed. Made no difference.

4. Only happens on upshifts. I can downshift fine.

5. Even with the grinding, the transmission has never failed to go into gear. Ever. It drives perfectly fine.

FYI car is a 97 coupe. Roughly 64000 miles.
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Old May 28, 2010 | 06:48 PM
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Worn synchros, possible bent shift fork.
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Old May 28, 2010 | 09:06 PM
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Originally Posted by ctusser
Worn synchros, possible bent shift fork.
Is there any way to confirm any of these without getting into the tranny??
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Old May 29, 2010 | 12:32 AM
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Originally Posted by Gicantor
Is there any way to confirm any of these without getting into the tranny??
The symtoms you are having is a 99% chance its bad syncros or paper blocker rings. I had the same exact thing on mine. Grinded 4th only at highrpms. My paper blocker rings were torn up which also led to worn syncs. Another good indication is that if you shift at low rpms fine, its bad syncs. Syncs are used for highrpm shifts to help the gears "syncronize" at high speed.

You can just replace the bad parts in the trans. I decided to get a built trans to make it bullet proof with a Spec 3 Plus clutch and ECS adjustable master... It feels good to shift at highrpm with confidence again

Last edited by Ikester; May 29, 2010 at 12:36 AM.
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Old May 29, 2010 | 01:10 AM
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Originally Posted by Ikester
The symtoms you are having is a 99% chance its bad syncros or paper blocker rings. I had the same exact thing on mine. Grinded 4th only at highrpms. My paper blocker rings were torn up which also led to worn syncs. Another good indication is that if you shift at low rpms fine, its bad syncs. Syncs are used for highrpm shifts to help the gears "syncronize" at high speed.

You can just replace the bad parts in the trans. I decided to get a built trans to make it bullet proof with a Spec 3 Plus clutch and ECS adjustable master... It feels good to shift at highrpm with confidence again
Thanks. I don't need a built trans as the car is pretty well stock, so i'll just replace the parts. Probably next year when i do the clutch.
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Old May 29, 2010 | 02:06 PM
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Originally Posted by Gicantor
Thanks. I don't need a built trans as the car is pretty well stock, so i'll just replace the parts. Probably next year when i do the clutch.
BTW, You didnt use synthetic trans fluids did you? Only Dexron III for your car.
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Old May 29, 2010 | 02:34 PM
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Originally Posted by Ikester
BTW, You didnt use synthetic trans fluids did you? Only Dexron III for your car.
I used Dex 6. That's ok right? the Tech at the dealership said it was

Last edited by Gicantor; May 29, 2010 at 02:37 PM.
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Old May 29, 2010 | 09:16 PM
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Originally Posted by Gicantor
I used Dex 6. That's ok right? the Tech at the dealership said it was
Good question, im not sure on that. I used synthetic on mine back in 2006 and that was the cause of my blocker rings being ruined. Back then the info i had was 97-99 had paper rings. That was incorrect. 2000 models had paper blockers also which is the year of my car.

Very expensive mistake on my part! i should have just used Dex III

Last edited by Ikester; May 29, 2010 at 09:19 PM.
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Old May 29, 2010 | 09:51 PM
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Originally Posted by Ikester
Good question, im not sure on that. I used synthetic on mine back in 2006 and that was the cause of my blocker rings being ruined. Back then the info i had was 97-99 had paper rings. That was incorrect. 2000 models had paper blockers also which is the year of my car.

Very expensive mistake on my part! i should have just used Dex III
How fast did it kill them? I've had dex6 in for about 2 years now, but the problem started before the fluid change.

From my research dex6 is a synthetic blend and is compatible with anything that used dex3 . Who knows i can't find a definite answer anywhere.
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Old May 30, 2010 | 12:57 AM
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Originally Posted by Gicantor
How fast did it kill them? I've had dex6 in for about 2 years now, but the problem started before the fluid change.

From my research dex6 is a synthetic blend and is compatible with anything that used dex3 . Who knows i can't find a definite answer anywhere.
It took about 3 years to wipe them out completely. Although my car is not a daily driver; only weekends.

FYI- any "synthetic" type fluid is not compatible with 97-2000 manual transmissions.

For starters Id switch back to Dex III before any more damage occurs.
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Old May 30, 2010 | 01:09 PM
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Originally Posted by Ikester
It took about 3 years to wipe them out completely. Although my car is not a daily driver; only weekends.

FYI- any "synthetic" type fluid is not compatible with 97-2000 manual transmissions.

For starters Id switch back to Dex III before any more damage occurs.
Will do. Thanks.
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Old May 31, 2010 | 07:09 PM
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I doubt it's a bent shift fork. I would say a blocking ring or just worn 3-4 synchro/engagement tooth. The 4th gear is the input shaft by the way. I know this is your daily driver but the weak parts inside do break over time. Look here why.

Use GM part # 88861800 for the fluid. The Dex III isn't produced anymore and the Dex VI isn't recommended for T56's.
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