My tranny has always performed flawlessly up to recently where it has ground for a split second as I come hard into 2nd gear. I have royal purple atf in there now which is what the car came with in it, I know everyone seems to use different brand atf's with vastly varrying results so Im not gonna ask what to run so much as even if I do change the fluid since it already has started to grind slightly will anything short of a rebuild fix it?

 

My car does the same thing when shiftting from 1 to 2 it makes a soft grinding
noise it feels like something is keeping it from shifting hard, i have had it in to the dealers 3 times and they cant fix it, pisses me off i have a PP3 and have the shift fimness at 100% and it will not chirp from 1 to 2.

 

lol oops I forgot to mention its a T56

 

yeah pull it apart and put syncros in it. But if you go that far you might as well but new bearings in it too.

Chris

 

damn the car only has 85k miles on it and has never been seriously raced, what the hell happened... what could cause it to happen so early?

 

The times it has been romped on, there are always those times when speed shifting you may slightly kiss the synchros when shifting. You can't feel these through the shifter, but only hear them. 1-2 for some reason is the shift I tend to do that on occassion as well. I don't know if the LT1 cars are like this, but the 98 and 99's have a subpar master cylinder which is the bottleneck of the hydraulics and can sometimes cause slow clutch disengagement. This can cause those little times when you kiss the synchros as well. Annoying, you bet it is, but it's why I may start practicing launches to kill my worn stock clutch and replace it with the better slave cylinder and Z06 clutch.

Jason

 

hmmmm so it could very well be that the clutch isnt dissengaging as fast as Im trying to shift? Ide like to hear some others responses and see what they have done as well. Thank you very much for the info, gave me something to look into Also is there any reason why it woudl be only at high rpms? Im going to do it at 3k rpm and see if it does it to make sure but IVe never noticed it when shifting fast at sub 5k rpms...

 

My car just started a grinding noise and vibration in the stick when I shift quickly from 1st to 2nd. If I shift slow between 1st and 2nd, no noise or vibration. It doesn't matter what RPM. I have 166K mi on the transmission and 4K on my second clutch.

Question: It sounds like I need a rebuild (unless someone has a better idea?). Any tips on what I should ask the mechanic to do?

 

lol could it be the fluid Im using in the tranny thats doing it because I figure its not the clutch if it doesnt grind in any other shift. My tranny has 85k on it

 

Well the factory puts ATF in the M6's. Sounds as if you both need new syncro sets atleast. You're both experiencing the beginning of the syncro failure. Funny part is when you get them out they look fine...but they're not. It happens with driving and the way you drive the car....You could baby the snot out of it, or drive it like you stole it. There may be air in both of your hydraulic setups as well. That would cause a slow engagement/disengagement issue. Check to make sure they're not leaking anywhere. Joe, you said you only have 4K miles on your clutch so it may have just been the abuse of a worn clutch that caused your issues...Is this only the second clutch in the car??? And lt4, are you the original owner of the car?? If so, I hate to say it but it could be your driving...I'm not trying to be a dick, but if you don't disengage the clutch Completely, you'll wear out your syncros. My daily kinda falls into gear because my clutch has 90K+ on it and I don't always go to the floor (full disengagement on my car). It happens to everyone.

Chris

 

no im the 3rd owner
I remember my friend trying to shift without the clutch for a long time and not being any good. once he had it sitting and got the car moving by shoving real hard trying to put it in first without the clutch and eventually it crept foreward enough to get into gear ****ing idiot ... Im glad I have a spare tranny in the garage. I forgot about all that and I do drive it well, always have the clutch on the floor I rarely slam it or anything but meh well see how the new one takes it if it gets worse.

 

I am the original owner. I got good milage out of the first clutch (160K mi). I drive mostly highway, so that is part of the story. I changed the clutch because I had the engine rebuilt, not because it was failing. It was used up though. By the way, it is also sometimes difficult getting it into 1st gear, but the problem going into 2nd is pretty new. So will I do damage to my M6 if I nurse it for a while or should I just rebuild it now? If I rebuild it, what should I do to make it stronger, like the Viper M6? My motor is putting out over 300 RWHP and I expect 350+ RWHP after more tuning. I would like the M6 to be set up for better than 450 RWHP (I hope to get there).

 

Ok LT4, Looks like we found out where yours originated from. A manual is supposed to be shifted while using the clutch, if you don't you're making the syncros try to stop the next gear whilt the engine is trying to spin the shaft the gears are on. Needless to say, trying to slow gears down against and engine isn't going to work really well, therefore chewing the syncros, causing a grinding while trying to shift. I would drive it if you have another one, until it gets really bad or you need a new clutch.

Joe, you can nurse it for awhile. It'll eventually get worse to the point where you either can't get it into gear, or you're really forcing it (I've seen guys try to use two hands to shift, funny, but not good). As for beefing up the t-56 they sell carbon syncros, Steel shift forks from the viper, as well as a viper output shaft, but that would require a custom driveshaft with the Viper slip yoke. I would talk to the guys at G-Force or FLP (Flp2win.com). I heard somewhere someone was working on a set of Billet gears, but that's a little overkill for your setup. I think the upgraded syncros, and shift forks should be just fine and handle the abuse you're looking to put through it. Either of the two aforemntioned will be able to build you something for a reasonable price (if you consider T-56 rebuilds reasonable)...The kicker is it is a 6 speed and they aren't cheap. And typically limping it for a while won't hurt it as long as you don't try to race it and start really banging gears. If you really start to grind them, then it's time to get it out so you don't destroy the teeth on the gears, because then you're looking for some good $$ to rebuild it.

Good Luck guys
Chris

 

yeah mine has a while to go before anything bad happens, it only makes a grinding noise at very high rpms when shifted very hard and only does it for a split second. Thanks for the advice

 

no problem, take good car of it, and you may want to change the fluid as it may help it last a little longer. It takes straight ATF, nothing special...don't use synthetic either, it'll just chew stuff up faster.

Chris