05Z51C6

05 Z51 manual 6

Here are the current issues:

When sitting in neutral, the car will not allow me to shift into first without it grinding or blocking me. To shift into first, I have to go into second then first. Sometimes when attempting to go into second, it blocks me, but then lets me go into first. When going at highway speeds for 5-10 miles, if try to downshift into second (at even a slow speed) it grinds. I can slow down all the way to 10 MPH and it still grinds. It has gotten to the point now where downshifting to second is not an option.

The clutch pedal feels good no matter when romping on it or normal driving. Gears 3,4,5,6, and reverse never give me any trouble. No issues at this point of the shifter popping out of gear or anything like that. Once the car is in first or second, it feels strong. Any ideas or someone that has had this issue?

Boomer111

Syncros. Sp? Not sure if cars have clutch brakes like big rigs but when this goes out the same symptoms occurs.

Slave cylinder too can be going out, assuming the car has one? But this would cause trouble in all gears.

I'm sure another will nail it down for you.

Gary '09 C6

shifter-linkage adjustment ?

05Z51C6

I fear you may be correct. Any more possibilities?

HorsePower Junkie

How many miles on the car?

05Z51C6

47,xxx

HorsePower Junkie

Depress the clutch pedal several times, and then try to put it in first or second. If it is better, visually check the clutch fluid to see if it is dirty and no longer a clear gold color. Do a search for clutch fluid replacement and change out the fluid. As I remember it is called the Ranger Method of changing out the clutch fluid, and is probably found in the FAQ section. Cloudy dark dirty fluid can make it have the symptoms you describe.

Let us know what you find.

RicK T

What you are describing is the well known T56 "first gear blockout" due to the design of the gear teeth. The issue was corrected with the T6060 in '08. Check this:

http://forums.corvetteforum.com/1562288138-post3.html

05Z51C6

What are the ways to correct the first gear blockout?

05Z51C6

Anyone else experience the things I mentioned?

05Z51C6

Will replacing the synchros cure the first gear blockout?

Thrill6

I have a 2007 with the T56 and have NEVER experienced these symptoms. I don't think this is OP's issue.

05Z51C6

So anybody have their car repaired successfully for the first gear block out? Will synchro replacement take care of this...or does the gear have to be replaced as well? Would be very helpful to hear some success stories on how this was corrected so I can work with the shop to fix correctly.

Thanks for any feedback here.

Bill Dearborn

I don't think you have gear blockout. I had it on both my 97 and 03 and although it was similar to the description of your problem it wasn't the same. Gear blockout can be overridden easily by the driver to the point it becomes second nature and although I kept both cars for 6 years each I never bothered seeing if it could be fixed.

You could have the clutch fluid issue and it wouldn't hurt to use the ranger method to see if the problem decreases as it is very low cost. The better way to flush the clutch hydraulics is to pull the exhaust and the tunnel plate and do a clutch bleed using the bleeder valve located on the slave inside the bell housing. That will cost a little more if you can't do that yourself. If that doesn't fix it then you are probably looking at a synchro issue or a slave cylinder issue. Either one means dropping the drive train and the repairs will be expensive. Clutch replacement will run at least $1500 including labor and trans repair will be more.

Bill

05Z51C6

One thing I notice...the car never grinds once I am in first. The only time second gear grinds is either if I am in neutral and try to shift into second while decelerating, or when coming from gears 3 or 4 decelerating. Second gear has no problems when shifting from first. From driving it a bit more kind of testing when the problem happens....it is NEVER when shifting from 1-2.

EDinPA

Do you mean while stopped and in neutral then trying to get into first? That would sound like a clutch dragging issue.

Have you had any service done to it? Has the trans fluid been changed? A lower cost first attempt at a fix may be to replace the trans fluid with a high quality fluid. There are synchronizing clutches on the gears that require just the right amount of friction to allow proper shifting.

05Z51C6

Thanks for the input Ed. Yes, first gear problems are while sitting in neutral mainly. Currently while sitting still, I shift into 3rd and then into 1st. It goes right into gear if I do that.

EDinPA

Car off clutch in and in neutral start the car and keep the clutch in. If the clutch is not dragging then the input shaft on the transmission should not be moving. Work the shifter into first then go up and down the gears 1 through 6 and then 6 through 1. If it shifts ok then the clutch is not dragging and the gears are remaining lined up. It should shift the same as it would with the car off.

Next, car running but not moving with the parking brake set and in neutral let the clutch out. This will allow the input shaft to spin in the transmission at engine speed. rev the engine to bring up the speed on the transmission input shaft. Push in the clutch and quickly try to shift into first from neutral. Repeat for second. If it is difficult to shift, the synchronizers are not doing their job. I would try a high quality (not store brand) transmission fluid change to see if that would make the synchronizers job just a little easier for them. If not it is likely going to need service.

beaversstonehaven

The first thing I would try is the Ranger clutch fluid flush. It could make a difference if the fluid is really nasty. It would not hurt to give it a whirl.

truckplay

you should really try flushing the clutch fluid really good before condeming the rest of the system.