M7 transmission grinds from 1-2
06-29-2018, 04:45 PM
#81
Safety Car
06-30-2018, 01:03 PM
#82
Advanced
Good dealer, good Tech. Surprised they are touching the Trans! Have a friend with a shop that was mostly fixing transmissions for the large Chevy, Caddy Dealer etc in town as there were not enough failures for the dealers to keep a trained Tech who had and could maintain the skill!
He has expanded his 6 Service bay shop activities to other service as too few Trans repairs from dealers. He does those mostly directly for customers older cars.The C7 has triple syncros in 2nd but they just fit together.
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JerryU (06-30-2018)
06-30-2018, 01:21 PM
#83
E-Ray, 3LZ, ZER, LIFT
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^^^
If you haven't watched, this is my favorite synchro video. Even as a gearhead from a teenager I have to watch it several times. Very knowledgeable guy! I even bought his book! Fun to watch, as you go without your car for the week!
He'll show a double synchro toward the end, the C7 just adds one more!
If you haven't watched, this is my favorite synchro video. Even as a gearhead from a teenager I have to watch it several times. Very knowledgeable guy! I even bought his book! Fun to watch, as you go without your car for the week!
He'll show a double synchro toward the end, the C7 just adds one more!
Last edited by JerryU; 06-30-2018 at 01:22 PM.
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9779 (07-01-2018)
07-01-2018, 09:31 AM
#84
Racer
I’m not sure if my experience is applicable to the M7, but on a C6 Z06 M6 I had the same exact symptoms being described here.
An excellent Corvette dealership service manager in Hammond, Louisiana explained to me that the shifting forks on Corvette transmissions had plastic “slippers” on each side of the shifting forks where they rode (and moved) the gear itself when shifting. The plastic slippers would become deformed (especially with hard shifts).
He replaced the shifting fork slippers under warranty but actually ordered brass slippers (I paid the $80 upcharge) and installed them. The Z06 I had back then shifted flawlessly from that point forward.
He also told me one of the reasons the plastic slippers became deformed was dirty clutch fluid which caused the clutch not to totally disengage during fast/hard shifts. He suggested I vacuum out the clutch fluid and change it every 3 (or so) engine oil change.
I’ve stuck to his suggestions since (as do my friends) and have had no problems since.
Hope that’s helpful with your situation.
An excellent Corvette dealership service manager in Hammond, Louisiana explained to me that the shifting forks on Corvette transmissions had plastic “slippers” on each side of the shifting forks where they rode (and moved) the gear itself when shifting. The plastic slippers would become deformed (especially with hard shifts).
He replaced the shifting fork slippers under warranty but actually ordered brass slippers (I paid the $80 upcharge) and installed them. The Z06 I had back then shifted flawlessly from that point forward.
He also told me one of the reasons the plastic slippers became deformed was dirty clutch fluid which caused the clutch not to totally disengage during fast/hard shifts. He suggested I vacuum out the clutch fluid and change it every 3 (or so) engine oil change.
I’ve stuck to his suggestions since (as do my friends) and have had no problems since.
Hope that’s helpful with your situation.
07-01-2018, 10:27 AM
#85
Drifting
Mine never grinds and mine has 17,500 miles on it !! The only time it grinds is when I don't push in the clutch pedal far enough to engage the next gear !!! My fault !!! And I should know better because I have had 7 other manual transmission cars with my 2014 Corvette being the 8th car !!!! Your car sounds like it needs an adjustment !!! Wayne
07-01-2018, 10:28 AM
#86
Team Owner
Mine never grinds and mine has 17,500 miles on it !! The only time it grinds is when I don't push in the clutch pedal far enough to engage the next gear !!! My fault !!! And I should know better because I have had 7 other manual transmission cars with my 2014 Corvette being the 8th car !!!! Your car sounds like it needs an adjustment !!! Wayne
!!!! wow !!! crazy!!!!
07-01-2018, 12:39 PM
#87
Melting Slicks
How do you vacuum out the clutch fluid without introducing air into the system? I understand the bleeder valve is hard to access and requires some disassembly. I've been using the Ranger method every month or so, about 6X in the past year. Fluid looks relatively clean now, but I would like to bleed it fully every so often if it isn't a huge PITA.
Last edited by iclick; 07-01-2018 at 12:39 PM.
07-01-2018, 01:46 PM
#88
Racer
How do you vacuum out the clutch fluid without introducing air into the system? I understand the bleeder valve is hard to access and requires some disassembly. I've been using the Ranger method every month or so, about 6X in the past year. Fluid looks relatively clean now, but I would like to bleed it fully every so often if it isn't a huge PITA.
Probably not as good as a complete flush and bleed, but it works just fine.
07-09-2018, 06:46 PM
#89
Advanced
07-10-2018, 09:21 AM
#92
E-Ray, 3LZ, ZER, LIFT
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So got the car back today after a two week stay at the dealer. Tech took the transmission out, found both 1st and 2nd gears worn. He replaced both gears along with new syncros and blocking rings. He also installed a CAGS for me. The transmission seems to shift much better now.
1st and 2nd are the gears that manage the highest torque loads.
Last edited by JerryU; 07-10-2018 at 09:22 AM.
07-10-2018, 08:06 PM
#93
Melting Slicks
I've got a small vacuum device and I suck about 90% of the fluid out of the reservoir. I refill with clean fluid, put the cap on, and then depress the clutch (back and forth) a couple of dozen times. Then vacuum out 90% of the fluid again. I repeat these steps (maybe 3-4 times) until the fluid stays clean after I've pumped the clutch.
Probably not as good as a complete flush and bleed, but it works just fine.
Probably not as good as a complete flush and bleed, but it works just fine.
07-11-2018, 07:20 AM
#94
Race Director
Mine is balky on the 1>2 shift when cold that sometimes extends into warm operation. Although it is not an audible grind it is felt in the shift lever. .................................. The M7 performs fine otherwise and I consider this a quirk rather than a fault, although Tremec might call it a "feature."
After six weeks with my new 2019, my experiences as well. My 01Z T56, 06Z T56, and 2011 ZR1 T6060 trannies were not near this bad.
07-11-2018, 07:25 AM
#95
07-11-2018, 07:29 AM
#96
Holding firm leftward pressure, and slow-motion shifting when cold has completely eliminated the 1-2 "notchiness" for me. Once the box warms up, it's a non-issue, but my technique includes firm leftward pressure on all 1-2 shifts. One shouldn't be doing spirited driving anyway on a cold powertrain.
And once again, what folks are feeling is not gears "grinding." It's the 1-2 synchronizers doing a very difficult job of managing the transition between 2 very large gears in the only remaining manual transmission capable of handing LT engine levels of torque.
And once again, what folks are feeling is not gears "grinding." It's the 1-2 synchronizers doing a very difficult job of managing the transition between 2 very large gears in the only remaining manual transmission capable of handing LT engine levels of torque.
Last edited by Foosh; 07-11-2018 at 08:20 AM.
07-11-2018, 09:41 AM
#97
Team Owner
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St. Jude Donor '05
Your trans is defective, this is not normal. Manual boxes either work right or they need fixing, dont accept a "breaking in" explanation.
Only going to get worse over time.
I hear hondas have the same issue