Warning to c6 6-speed owners

dbakke

dbakke

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Jan 26, 2009
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I found this info about c6 tranny's. Here is the quote!

The factory rubber bushing tend to tear easily and get really sloppy. If you are experiencing problems like with missing shifts, difficulty in shifting or grinding, take a look at the rubber shifter mount bushings.
 
dbakke said:
I found this info about c6 tranny's. Here is the quote!

The factory rubber bushing tend to tear easily and get really sloppy. If you are experiencing problems like with missing shifts, difficulty in shifting or grinding, take a look at the rubber shifter mount bushings.
Click to expand...

Not only that , but the syncros are made of plastic and can wear very easily making it hard to shift. If you experience grinding between shifts and still have warranty get it looked after right away .

Thx
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if i'm not mistaken there are some other issues with the Chev version of the T-56:

1. The aluminum shift forks were prone to bending under hard service. This also causes issues with the plastic synchro's obviously and causing gears to grind. Interestingly, Chrysler ordered the steel shift forks for their Viper service.

2. There are teflon wear pads used on a few surfaces and over time, they wear and loose their ability to provide a resistance-free surface.

In addition to the carbon synchro's i also had to upgrade the shift forks and remove the teflon pads and replace with brass/bronze... I can't remember now the details... it's been a while since i had all the work done.

I also had to replace a number of the actual gears due to the damage caused by the bent 3-4 and 5-6 shift forks...
The full tranny upgrade with the clutch was ~5000 including labor if I remember correctly but it was probably a bit more LOL
 
I couldn't even guess Riley but its hard to say if they cheaped out or not. Ironically, if you upgrade the blockers, shift forks and some other very small items, they become almost indestructable.

A guy I know from the shop that did mine is running the same trans and with over 500 RWHP, he's made over 500 full runs at the track with drag slicks and never had an issue since. I'm sure that you'd need the stouter RPM tranny if you had much more power but even most of those other tranny (from my research) have the same basic upgrades. It isn't until you start wanted treated gears etc for ultra high out put engines that the upgrades are whole lot more substantial.

I actually think that GM did go potentially to steel shift forks later on but I couldn't verify. Also, a lot of C5 guys want the z06 gear ratios which is another reason for the popularity of getting an upgraded trans.

Have I rambled yet?? Lol
[mob][/mob]
 
HLN A55 said:
if i'm not mistaken there are some other issues with the Chev version of the T-56:

1. The aluminum shift forks were prone to bending under hard service. This also causes issues with the plastic synchro's obviously and causing gears to grind. Interestingly, Chrysler ordered the steel shift forks for their Viper service.

2. There are teflon wear pads used on a few surfaces and over time, they wear and loose their ability to provide a resistance-free surface.

In addition to the carbon synchro's i also had to upgrade the shift forks and remove the teflon pads and replace with brass/bronze... I can't remember now the details... it's been a while since i had all the work done.

I also had to replace a number of the actual gears due to the damage caused by the bent 3-4 and 5-6 shift forks...
The full tranny upgrade with the clutch was ~5000 including labor if I remember correctly but it was probably a bit more LOL
Click to expand...

I had to do that to my T56 also, except left orginal gears in it. I bought a $700 heavy duty rebuild kit on line and took it over to a friends garage that had rebuilt a 4 speed before, slaped it together with him and hoped for the best..... still holding together a year later but 5th is getting hard to get in now though
 
Talking about cheaping out...they decided to finally cover cooling lines under warranty ($900-$1000) but took away warranty on around $10k worth of computers and other stuff...way to go GM!
 
I believe the issue is actually with the 08s and up, which is the T6060 transmission.

All I know is that with my 2006 (T56) I never had ANY shifting issues, but with my 08, I do sometimes miss shifts and sometimes get the grinding and I KNOW it is NOT my driving. Good news is my dealer has said it is likely the synchros and they are covered under warranty, just haven't had the time to do it yet.
 
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I have a 2008 C6 manual which I bought new. It has 73,000 km on it with no shifting issues so far. I sure hope it stays that way.
 
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It will. You have a TR6060 not a T-56. The TR6060 was introduced in the Corvette in 2008 and doesn't share any parts with the T-56. Sintered bronze synchros in all gears except 2nd. where carbon fiber is used. No T-56 ever used plastic for synchro material.
 
GMJim said:
It will. You have a TR6060 not a T-56. The TR6060 was introduced in the Corvette in 2008 and doesn't share any parts with the T-56. Sintered bronze synchros in all gears except 2nd. where carbon fiber is used. No T-56 ever used plastic for synchro material.
Click to expand...
Sorry GMJim, when you say "It will" do you mean it should stay problem free or that I will likely have problems?
 
Sorry for the long delay answering your question, I've been away from my computer. The T56 is a great transmission but the TR6060 is a much more robust transmission and like the aftermarket Magnum will handle big torque. It was developed for the coming horsepower increases planned for the C6 ZR1 and the TR6070 for the C7. The ONLY complaint I hear about is what's called the 3rd gear nibble. This so called nibble (Tremec's lead engineer coined the phrase) usually occurs when the trans is cold. When going from second to third the synchro will sometimes feel like a very slight bump (not a grind) and usually will go away as it warms up. In the early days of this transmission when I was involved with Hurst Driveline (formerly Classic Motorsports group) I had several people very concerned about this and it lead me to visit Tremec in Michigan where at a training session they talked about this and it was considered normal and not to be a concern. The TR6060 and it's cousin the aftermarket Magnum are in my opinion the best 6 speed transmissions you can buy.
 
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GMJim said:
Sorry for the long delay answering your question, I've been away from my computer. The T56 is a great transmission but the TR6060 is a much more robust transmission and like the aftermarket Magnum will handle big torque. It was developed for the coming horsepower increases planned for the C6 ZR1 and the TR6070 for the C7. The ONLY complaint I hear about is what's called the 3rd gear nibble. This so called nibble (Tremec's lead engineer coined the phrase) usually occurs when the trans is cold. When going from second to third the synchro will sometimes feel like a very slight bump (not a grind) and usually will go away as it warms up. In the early days of this transmission when I was involved with Hurst Driveline (formerly Classic Motorsports group) I had several people very concerned about this and it lead me to visit Tremec in Michigan where at a training session they talked about this and it was considered normal and not to be a concern. The TR6060 and it's cousin the aftermarket Magnum are in my opinion the best 6 speed transmissions you can buy.
Click to expand...
GMJim said:
Sorry for the long delay answering your question, I've been away from my computer. The T56 is a great transmission but the TR6060 is a much more robust transmission and like the aftermarket Magnum will handle big torque. It was developed for the coming horsepower increases planned for the C6 ZR1 and the TR6070 for the C7. The ONLY complaint I hear about is what's called the 3rd gear nibble. This so called nibble (Tremec's lead engineer coined the phrase) usually occurs when the trans is cold. When going from second to third the synchro will sometimes feel like a very slight bump (not a grind) and usually will go away as it warms up. In the early days of this transmission when I was involved with Hurst Driveline (formerly Classic Motorsports group) I had several people very concerned about this and it lead me to visit Tremec in Michigan where at a training session they talked about this and it was considered normal and not to be a concern. The TR6060 and it's cousin the aftermarket Magnum are in my opinion the best 6 speed transmissions you can buy.
Click to expand...
That's great and welcome news, thank you!
 
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