6 speed - 4th gear grind
Advanced
Joined: Feb 2015
Posts: 82
Likes: 38
The 4th gear in the T56 is your 1:1 gear (locks the input and output shafts together). Unfortunately, it's pretty common that they get damaged and you experience 4th gear grinding. If you get to it early, it could be a simple blocker ring replacement. If it's really bad, may require the synchro and the possibly even the input shaft ($$$$).
However, you're low miles, could just simply be your master cylinder not depressing the clutch enough to fully disengage it. Tick master cylinders may help with this.
However, you're low miles, could just simply be your master cylinder not depressing the clutch enough to fully disengage it. Tick master cylinders may help with this.
Melting Slicks
Joined: Jun 2013
Posts: 3,473
Likes: 691
From: West Virginia
Before you do anything, change the fluid. I changed mine out at around 65k and could not believe how much better it shifted afterwards - I had been seeing "balking" on a 1-2 shift and grinding if I tried to rush a 4th or 6th shift. The book says it does not need changing, but IMO it does. I used regular non synthetic Valvoline Dex/Merc (Walmart by the gallon jug), labelled for older GM and Ford vehicles - which means it meets the correct Dex III spec that was the original specification for C5's. Do NOT use the new Dex VI - GM sent out a warning to it's dealers that it could trash a manual transmission.
Advanced
Joined: Feb 2015
Posts: 82
Likes: 38
You're right. Newer Dex will eat the paper-lined blocker rings. If you have to open the trans, I would suggest replacing all blocker rings with carbon-lined rings. Better shifter feel and you can run synthetics if you so wish. About $500 worth of parts for the carbon-lined rings.
But I always laugh if a manual actually suggests never to change fluid. Such a bad idea on every level...
But I always laugh if a manual actually suggests never to change fluid. Such a bad idea on every level...
Thread Starter
2nd Gear
Joined: Apr 2017
Posts: 2
Likes: 0
6 Speed - 4th gear grind
The 4th gear in the T56 is your 1:1 gear (locks the input and output shafts together). Unfortunately, it's pretty common that they get damaged and you experience 4th gear grinding. If you get to it early, it could be a simple blocker ring replacement. If it's really bad, may require the synchro and the possibly even the input shaft ($$$$).
However, you're low miles, could just simply be your master cylinder not depressing the clutch enough to fully disengage it. Tick master cylinders may help with this.
However, you're low miles, could just simply be your master cylinder not depressing the clutch enough to fully disengage it. Tick master cylinders may help with this.
