[Z06] Is There a Major Issue with C5 Z06 Transmission?
08-21-2012, 11:27 PM
#41
Burning Brakes
Your post bro made me think that I should forget about the C5 Z and wait 8 more months and then get the C6 Z 
I would love to have a C5 Z now, but I don’t want to spend lots of money on it because I have no plans for keeping it more than 1 year. 2013 will be the year to get a 09+ C6 Z for me!
However, I am thinking now to skip the C5 Z and wait 8 months and then get the C6 Z. What is your thought on that idea guys..?
I would love to have a C5 Z now, but I don’t want to spend lots of money on it because I have no plans for keeping it more than 1 year. 2013 will be the year to get a 09+ C6 Z for me!
However, I am thinking now to skip the C5 Z and wait 8 months and then get the C6 Z. What is your thought on that idea guys..?
08-21-2012, 11:30 PM
#42
Burning Brakes
I'm sure I'll get some flaming for this but I think a lot of these issues are driver error. Power shifting, to hard of a launch, lack of fluid changes or just not shifting properly. I understand they do have their weak links and they weren’t built for all out drag racing. But I think can hold up to a certain amount of hard use if maintained and shifted properly. Then when they do need a rebuild beef up the weak links. Just my opinion.
08-21-2012, 11:49 PM
#43
Race Director
I've been road racing this car since 04, (its an 02)started around 8500 miles and still road race it. It now has 71000 miles on it and I had the 3-4 shift forks replaced along with some billet parts from ECS put it. It wasn't built to powershift/drag race. I think its pretty stout, I don't abuse it, but I certaintly drive it hard.
08-22-2012, 07:25 AM
#44
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Unfortunately they get drag raced and street/drag raced. This car was never really intended to be a drag racer. It's a road racer. I've had 2 of them and several friends have them. The only ones with trouble drag race them.
Also if it is just rough shifting and low miles. Probably still has stock fluid. Dump it and put in a good synthetic like RP Synchromax. Smooths up the shifts and last much longer.
Also if it is just rough shifting and low miles. Probably still has stock fluid. Dump it and put in a good synthetic like RP Synchromax. Smooths up the shifts and last much longer.
Change the fluids to a good synthtic and maybe a minor adjustment to the shifter shaft to slide in and out of the gears.
08-22-2012, 08:30 PM
#45
Premium Supporting Vendor
I don't think there is a major issue with the tranny. I've been racing mine since 03, and though I have done a few preventative rebuilds over the years, I've never had a failure.
I use the AMSOIL Torque-Drive Synthetic Transmission Fluid (Product Code ATD1G)
Forum Vendor RKT Performance has a good webpage on the weak parts of the T56 and how a relatively simple upgrade can make the T56 much more robust: http://rktperformance.com/why-upgrade/
I use the AMSOIL Torque-Drive Synthetic Transmission Fluid (Product Code ATD1G)
Forum Vendor RKT Performance has a good webpage on the weak parts of the T56 and how a relatively simple upgrade can make the T56 much more robust: http://rktperformance.com/why-upgrade/
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dbs1vette (05-27-2016)
08-23-2012, 11:52 AM
#46
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My take:
The stock trans is good at reasonable power levels, but not bulletproof. You have to take care of it.
There IS an issue with the stock hydraulic setup in that you have to keep your fluid clean.
I ended up having to rebuild my trans and replace all the hydraulics at 20,000 miles due to a hydraulics issue at high speed / high RPM.
The stock trans is good at reasonable power levels, but not bulletproof. You have to take care of it.
There IS an issue with the stock hydraulic setup in that you have to keep your fluid clean.
I ended up having to rebuild my trans and replace all the hydraulics at 20,000 miles due to a hydraulics issue at high speed / high RPM.
08-23-2012, 12:05 PM
#47
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I've been on these forums almost 10 years and owned a C5Z for 5 and I don't think there's an issue with the trannys.
Like any mechanical part, if you abuse it, it will eventually fail.
I drive my Z hard put do not powershift or drop the clutch. Still on the stock clutch and tranny.
However, they do sometimes leak from the diff\tranny, and the valve springs might need to be looked at depending on the year.
C5Z is in my opinion, the current best bang for the buck corvette.
Still lots cheaper than an LS3 and LS7, provides more feedback from the road as well, and you don't have to worry about "should I tune it or not?!" because of the fragile LS7 motor...like someone else said, do your homework on the LS7 before you decide to dive into one...
Like any mechanical part, if you abuse it, it will eventually fail.
I drive my Z hard put do not powershift or drop the clutch. Still on the stock clutch and tranny.
However, they do sometimes leak from the diff\tranny, and the valve springs might need to be looked at depending on the year.
C5Z is in my opinion, the current best bang for the buck corvette.
Still lots cheaper than an LS3 and LS7, provides more feedback from the road as well, and you don't have to worry about "should I tune it or not?!" because of the fragile LS7 motor...like someone else said, do your homework on the LS7 before you decide to dive into one...
08-23-2012, 01:44 PM
#48
Tech Contributor
My 04 Z06 tranny would grind going into 4th, 25% of the time. Only had about 18K miles on the car at the time. I tried new fluid, and still had issues. I had it rebuilt locally with all RPM hardware. Spent about 1700-1800 on the local rebuild by someone that constantly rebuilds the Corvette 6 speeds. One of the syncro's went I was told. Smooth shifting now. No issues since.
Toque
Toque
08-23-2012, 02:43 PM
#49
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I haven't heard of any recurring problems with the C5 Z06 tranny - could be those cars have been driven pretty hard. That said I would keep looking. And I'd you can wait, I'd go for the '09 Z06 if that will be in your price range.
08-24-2012, 05:16 PM
#50
Race Director
Mine was a POS. Rebuilt 7 times by the chevy dealer under warranty. Last time it bit it, I sent it to RPM in Indiana and went Level V on it and its been perfect since, even better than new!!!
08-24-2012, 07:57 PM
#51
Melting Slicks
Strange...well over 100 1/4 mile passes on my old c5z, many of them being pretty respectable times. Road course duty and lots of spirited runs and never an issue. Bought the car with 50,xxx miles and put over 10k miles on it. I am a believer that it's not bad trans...power level was bolt ons. Clutch was stock. Fluids changed twice in my ownership.
08-24-2012, 08:50 PM
#52
Melting Slicks
So in a nutshell, those who haven't had problems with them think they are great, and those who've had to rebuild think they suck in stock form. But reading through the thread, the number of tranny failures per number of posts is rather high; and lots of them failing with low miles; mine went at ~16K miles.
Remember, you count the failures to get failure rates, and the failure rate is very high. It's easy for the guys who haven't been down the road fixing the tranny to be dismissive of problems with a, "It didn't happen to me so there must not be a problem," attitude. But on a different note there are lots of guys still running on the original valve springs who haven't had a problem, and we know there is a problem there and it's become accepted as a must fix for anyone who is still running the OEM springs.
Remember, you count the failures to get failure rates, and the failure rate is very high. It's easy for the guys who haven't been down the road fixing the tranny to be dismissive of problems with a, "It didn't happen to me so there must not be a problem," attitude. But on a different note there are lots of guys still running on the original valve springs who haven't had a problem, and we know there is a problem there and it's become accepted as a must fix for anyone who is still running the OEM springs.
Last edited by ctusser; 08-25-2012 at 10:06 AM.
08-24-2012, 09:24 PM
#53
Tech Contributor
I'd say honestly that in the group of C5's I hang with 50% have had a 6 speed rebuild.
Two guys at work have had theirs rebuilt too (C5 and C5Z). I only know 2 guys at my work with C5's.
I don't know a lot about it but I hear something about the syncro's being aluminum and they bend rather easily...? Something like that anyways.
Toque
Two guys at work have had theirs rebuilt too (C5 and C5Z). I only know 2 guys at my work with C5's.
I don't know a lot about it but I hear something about the syncro's being aluminum and they bend rather easily...? Something like that anyways.
Toque
08-26-2012, 02:32 AM
#54
Melting Slicks
Frankly...these trannies have a lot of flaws that can easily fail and require a full rebuild to repair.... I spent $3200 to rebuild/upgrade the tranny... Personally I think these trannies are junk...they cost a lot to repair and will likely break again. If you even remotely drive these cars the way you would expect a performance car to be driven, the trannies break in no time..
08-26-2012, 01:40 PM
#55
Team Owner
The T56 was used in a zillion cars as a cost-effective, semi-performance transmission. It is hardly bullet-proof, but the folks calling it fragile or worthless are IMO hyperbolic.
07-02-2016, 11:30 PM
#56
4th Gear
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C5 trans
Hello. My c5 is having a late shift into 2nd. If i let off the gas it will change to 2nd like stick shift. ANd if im running 70ish and smash the gas the car will pull then redline when it downshifts to gain speed. But if i push the gas slowly it will pull strong and gain all speed without redlining..
07-04-2016, 07:00 AM
#58
Melting Slicks
IMO many folks experiencing transmission trouble, especially synchro trouble, is due to poor clutch hydraulic maintenance. You can tear up a set of synchros in no time if you don't have a good working clutch.
07-04-2016, 12:20 PM
#59
Moderator
Mine has been perfect. 2004 with 70,000 miles. I do have a MGW shifter. Not sure if that matters. Love it.
07-06-2016, 04:41 PM
#60
at stock power levels they are fine.. at around 450 rwhp they fail even on the street.. went through 2 transmissions already. My '03 Z will be my LAST manual trans. New automatics have NONE of these issues and shift faster
Last edited by Dave02C5; 07-06-2016 at 04:42 PM.
