4th Gear Grinds...WTF?
Thread Starter
Racer
Joined: Apr 2003
Posts: 272
Likes: 0
From: Podunk IL
4th Gear Grinds...WTF?
My forth gear always grinds going into gear when I shift even remotely quick. When I lazily shift, it doesn't do it. No idea what is going on... Is this just an adjustment problem or do I need a new tranny? The tranny is fairly new, it's a Rondney M6 I had put in about 30k miles ago, car has 65k on it total (there was nothing wrong with my original tranny, it was misdiagnosed by a shop and I ended up buying a new tranny that I didn't need).
The car is not raced or anything, and only has about 330 rwhp, so I know it can't be caused by a lot of power or anything like that.
Please help!
The car is not raced or anything, and only has about 330 rwhp, so I know it can't be caused by a lot of power or anything like that.
Please help!
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
Originally Posted by Jimmy Smits
My forth gear always grinds going into gear when I shift even remotely quick. When I lazily shift, it doesn't do it. No idea what is going on... Is this just an adjustment problem or do I need a new tranny? The tranny is fairly new, it's a Rondney M6 I had put in about 30k miles ago, car has 65k on it total (there was nothing wrong with my original tranny, it was misdiagnosed by a shop and I ended up buying a new tranny that I didn't need).
The car is not raced or anything, and only has about 330 rwhp, so I know it can't be caused by a lot of power or anything like that.
Please help!
The car is not raced or anything, and only has about 330 rwhp, so I know it can't be caused by a lot of power or anything like that.
Please help!
Ranger
Racer
Joined: Nov 2002
Posts: 397
Likes: 0
From: Auburn AL
It's a common problem with the M6. You probably have a bent shift fork or a screwed syncro. Had my MM12 replaced at 14,000 due to stupid previous owners. If you continue to shift your tranny hard it will eventually lock in 4th like mine did. Get it checked out.
Burning Brakes
Joined: Jan 2004
Posts: 896
Likes: 1
From: Overland Park KS
Originally Posted by electronbluec5
It's a common problem with the M6. You probably have a bent shift fork or a screwed syncro. Had my MM12 replaced at 14,000 due to stupid previous owners. If you continue to shift your tranny hard it will eventually lock in 4th like mine did. Get it checked out.
Been there done that. Fortunately, I had warranty coverage at the time. 
Here's the TSB covering the problem (and related conditions): http://www.corvetteactioncenter.com/....php?qstId=533
Pro
Joined: Dec 2001
Posts: 555
Likes: 44
From: Gilbert AZ
The guys at RPM told me this is a function of the factory paper blocking rings when I was down there last week having my transmission rebuilt. They put compressed carbon rings in their tranny's now and it eliminates the grinding. The only downside is that it wears faster than the paper.
Team Owner
Joined: Aug 2006
Posts: 24,680
Likes: 1,180
From: Raleigh
My 01 Z does thesame thing. Replaced the tranny fluid with Amsoil and no change. I am assuming I have a slighly bent shift fork or a synchro is weak. I can still drive it hard just have to be mindful not to slam 4th.
Melting Slicks
Joined: Oct 2006
Posts: 2,228
Likes: 5
From: Gainesville Georgia
My old 98' Ram Air used to grind 3rd gear, that was because I was shifting the gears to hard. I eventually had to replace the transmission. Grinding=Bad news. Maybe It's fixable though.
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Racer
Joined: Mar 2006
Posts: 464
Likes: 0
From: silverdale washington
Alot of it is due to the freakin skip shift crap. First eliminate that. Then change tranny fluid. There was a guy on here last week saying he used some german castor oil and his tranny stopped doing it!!! Try doing a search on it. Also if you have a 97-early 2000, slave cylinders also contribute to this.
Burning Brakes
Joined: Aug 2000
Posts: 889
Likes: 0
From: DFW tx
I have a '98 with the 02 z06 master / slave and the drill mod. I have an aluminum flywheel and LUK clutch combo. Skip shift is programmed out.
I am also getting the 4th gear grind on quick 3-4 shifts. I am running redline ATF in the tranny. The problem does not happen at higher RPM's, only at lower RPM's when I shift too quick. At higher RPM's I sometimes have problems going from 2-3. Frustrating.
I was thinking about trying some non-synthetic ATF to see if it helps. Don't feel like spending the cash to rebuild the tranny at this point.
If anyone has had similar problems, let me know what you did to fix it.
I am also getting the 4th gear grind on quick 3-4 shifts. I am running redline ATF in the tranny. The problem does not happen at higher RPM's, only at lower RPM's when I shift too quick. At higher RPM's I sometimes have problems going from 2-3. Frustrating.
I was thinking about trying some non-synthetic ATF to see if it helps. Don't feel like spending the cash to rebuild the tranny at this point.
If anyone has had similar problems, let me know what you did to fix it.
