Early T-56 1st gear issue solution?
Thread Starter
Pro
Joined: Jan 2009
Posts: 727
Likes: 11
From: Springfield Ohio
Early T-56 1st gear issue solution?
I posted this in general but no good answers.
So, the early manual C6’s have the issue of being hard to shift into 1st and 2nd.
Like what is talked about here.
https://www.corvetteforum.com/forums...post1562288138
Was a solution ever found?
There has to be some solution better than a complete rebuild or replacement of the entire transmission, right?
So, the early manual C6’s have the issue of being hard to shift into 1st and 2nd.
Like what is talked about here.
https://www.corvetteforum.com/forums...post1562288138
Was a solution ever found?
There has to be some solution better than a complete rebuild or replacement of the entire transmission, right?
Retired & lovin' it!
Joined: Mar 2005
Posts: 4,475
Likes: 549
From: Jackson NJ
A TSB (pasted below) was issued in 2005, but there was never a recall. I've owned an '05 MN6 since new & have learned to live with the issue. From a full stop, if 1st is blocked, I do a quick pump on the clutch which rotate the gear synchro off the flat spot. In my case it happens "occasionally" & as noted before, I've learned to live with it. If the condition in your case is really bad, you'll have to spring for the cost of repair yourself.
Document ID# 1690618
--------------------------------------------------------------------------------
Intermittent Block Out of First Gear from a Stop - keywords hard no shift shifter stop #PIP3513 - (Aug 5, 2005)
Intermittent Block Out of First Gear from a Stop
2005 Cadillac CTS-V
2005 Chevrolet Corvette and SSR
2005 Pontiac GTO
Equipped with Manual 6 Speed (RPO - MM6, M10, M12 or MZ6) Transmission
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Intermittent block out of first gear at a stop. Driver may have the vehicle in neutral while stopped in traffic and when depressing the clutch pedal to engage first gear, the shift is blocked.
Recommendation/Instructions:
If this condition occurs less than 5 percent of the time, it would be considered normal. This condition occurring more than 5 percent of the time should be repaired. A clutching tooth improvement has been made to the first speed gear. Replace the first speed gear in the transmission. Check the gap between the vertical faces of the blocking ring teeth and the speed gear as per Document ID # 588712.
Transmission
Application
Part Number
MM6
Corvette
12455013
MZ6, M12
Corvette
88894089
M12
CTS-V
88894089
M12
GTO
88894089
M10
SSR
89059976
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
Document ID# 1690618
--------------------------------------------------------------------------------
Intermittent Block Out of First Gear from a Stop - keywords hard no shift shifter stop #PIP3513 - (Aug 5, 2005)
Intermittent Block Out of First Gear from a Stop
2005 Cadillac CTS-V
2005 Chevrolet Corvette and SSR
2005 Pontiac GTO
Equipped with Manual 6 Speed (RPO - MM6, M10, M12 or MZ6) Transmission
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Intermittent block out of first gear at a stop. Driver may have the vehicle in neutral while stopped in traffic and when depressing the clutch pedal to engage first gear, the shift is blocked.
Recommendation/Instructions:
If this condition occurs less than 5 percent of the time, it would be considered normal. This condition occurring more than 5 percent of the time should be repaired. A clutching tooth improvement has been made to the first speed gear. Replace the first speed gear in the transmission. Check the gap between the vertical faces of the blocking ring teeth and the speed gear as per Document ID # 588712.
Transmission
Application
Part Number
MM6
Corvette
12455013
MZ6, M12
Corvette
88894089
M12
CTS-V
88894089
M12
GTO
88894089
M10
SSR
89059976
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
Drifting
Joined: Sep 2014
Posts: 1,924
Likes: 392
From: Atlanta - - - - - Save the manuals
I have a 05 and had this problem myself. I recommend Venom Mod (one ring), AMSOil Dexron III rated, and pump the clutch twice before starting or double clutch the first shift into second and normal after that. I usually do the latter.
Using this method I now have the problem about once a year.
Using this method I now have the problem about once a year.
