2 Sweet Posted September 10, 2009 Report Share Posted September 10, 2009 I'm pretty sure I know the answer, but I want some opinions... '98 Z28, T56. New clutch, master, and slave. The car shifts smoothly and flawlessly in every gear. Except... A little bit ago I was messing around on the freeway (out in the middle of nowhere, nobody else around). In 4th gear, RPM's climbing, I did a fast 4-5 shift. It had a quick grind right when it went into 5th. It stayed in gear and didn't pop out or continue to grind once in gear. I slowed down, sped back up again, same thing happened. Only grinds right when the shifter hits 5th. I tried a 3rd time, but this time as I got close to redline in 4th and prepared to shift, I took it easy and shifted slower and more casually into 5th, and it didn't grind going in. Under normal driving conditions, it doesn't grind 5th (or any gear). Also, it downshifts from 6th to 5th easily without trouble. I'm assuming this is a syncro problem, although 5th doesn't seem like a common issue. Will the grinding eventually get worse? I never noticed before because I haven't tried to speed shift into 5th, because when 4th tops out I'm usually around 115mph or so and don't feel the need to keep going. I know if the grinding continues it will only do more damage (and cost more when the time comes for a rebuild) but it only happens during a quick 4-5 shift at high RPM's. Syncro problem? Should I be worried? Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted September 10, 2009 Report Share Posted September 10, 2009 shift timing issue.. and im going to recommend not beating on a over drive gear.... Quote Link to comment Share on other sites More sharing options...
2 Sweet Posted September 10, 2009 Author Report Share Posted September 10, 2009 (edited) shift timing issue.. and im going to recommend not beating on a over drive gear.... Shift timing issue? Care to elaborate? And yes, thats good advice lol Also, I'd like to add that I don't really beat on the car, I'm just wondering if this is a sign that the syncro is showing signs of failure and if I should expect it to get worse. RIGHT before the slave and master cyl were replaced, 2nd and 5th would occasionally grind very slightly while going into gear, but only when the car was cold (and it only happened a couple times). This was during normal street granny driving. It hasn't done it since the new parts though. Edited September 10, 2009 by 2 Sweet Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted September 10, 2009 Report Share Posted September 10, 2009 was you shifting fast when this happened? and it doesnt do it under normal shifting? you could also be looking at a shift fork issue as well. but hard to say. Quote Link to comment Share on other sites More sharing options...
ohsolow Posted September 10, 2009 Report Share Posted September 10, 2009 More than likely it has broken keys on the sycronizer. That is the normal culprit in those tranmissions. The stock ones are stamped steel and always break. The other thing it could be is the friction material worn/ broke off the blocker rings. This is also a common problem. My typical fix is add billet keys, bronze fork pads and carbon fiber blocker rings. and while you are in there the Viper steel 3-4 for is also a good upgrade. If you keep driving it, and grinding gears you run the chance of messing up that gear. One of my buddies kept driving his and eventually broke the shift fork and messed up some gears. I would have it checked out now since it is just starting, it will be a lot cheaper to fix. If you have any questions get a hold of me I have been rebuilding these for a couple years now. Quote Link to comment Share on other sites More sharing options...
AJ Posted September 10, 2009 Report Share Posted September 10, 2009 try and change the fluid to Amsoil Torque Drive ATF. dirty fluid can cause a problem sometimes, if its too bad then you'll need a rebuild but its worth a shot to try the fluid. Quote Link to comment Share on other sites More sharing options...
2 Sweet Posted September 10, 2009 Author Report Share Posted September 10, 2009 was you shifting fast when this happened? and it doesnt do it under normal shifting? Correct. Only when shifting fast, and only during the 4-5 shift, and only at high RPMs More than likely it has broken keys on the sycronizer. That is the normal culprit in those tranmissions. The stock ones are stamped steel and always break. The other thing it could be is the friction material worn/ broke off the blocker rings. This is also a common problem. My typical fix is add billet keys, bronze fork pads and carbon fiber blocker rings. and while you are in there the Viper steel 3-4 for is also a good upgrade. If you keep driving it, and grinding gears you run the chance of messing up that gear. One of my buddies kept driving his and eventually broke the shift fork and messed up some gears. I would have it checked out now since it is just starting, it will be a lot cheaper to fix. If you have any questions get a hold of me I have been rebuilding these for a couple years now. Good info, thanks and I'll keep that in mind try and change the fluid to Amsoil Torque Drive ATF. dirty fluid can cause a problem sometimes, if its too bad then you'll need a rebuild but its worth a shot to try the fluid. Thanks, I'll probably give that a shot Quote Link to comment Share on other sites More sharing options...
99ta Posted September 10, 2009 Report Share Posted September 10, 2009 its telling you not to shift into 5th! thats just asking for trouble..... Quote Link to comment Share on other sites More sharing options...
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