Tranny shift problem
Thread Starter
Cruising
Joined: May 2011
Posts: 11
Likes: 0
Tranny shift problem
95 6 speed w/LT1
At 46K miles I drained the transmission, refilled with Penzoil Synchromesh Fluid, drove this 100 miles and drained hot, refilled with RedLine Synthetic Syncro.
Often times, (and at my age I am a very conservative driver, do not power-shift), I cannot shift from 1st to second, this is sparatic but I get totally locked-out of the shift from 1-2, other gear selections are OK, downshift is OK, reverse is OK.
Changed the hydraulic clutch to DOT3/4 synthetic,...think I did a fair job bleeding the air out.
When I experience this lockup between 1st to second, double clutching allows the shift to complete but that's a pain.
Question: Obviously synchro tranny oil has conditioners that allow the synchronizers to slow down & line up, and wondering if, IF, the RedLine oil might be the problem. Hate to dump it, it was not cheap, but....gotta do what I gotta do.
Appreciate objective analysis, and thanks.
At 46K miles I drained the transmission, refilled with Penzoil Synchromesh Fluid, drove this 100 miles and drained hot, refilled with RedLine Synthetic Syncro.
Often times, (and at my age I am a very conservative driver, do not power-shift), I cannot shift from 1st to second, this is sparatic but I get totally locked-out of the shift from 1-2, other gear selections are OK, downshift is OK, reverse is OK.
Changed the hydraulic clutch to DOT3/4 synthetic,...think I did a fair job bleeding the air out.
When I experience this lockup between 1st to second, double clutching allows the shift to complete but that's a pain.
Question: Obviously synchro tranny oil has conditioners that allow the synchronizers to slow down & line up, and wondering if, IF, the RedLine oil might be the problem. Hate to dump it, it was not cheap, but....gotta do what I gotta do.
Appreciate objective analysis, and thanks.
Team Owner
Joined: Feb 2006
Posts: 23,115
Likes: 117
From: San Antonio Texas
Dump the REDLINE it's no good for the synchros in a ZF6. I tryed it in my old GT Mustang and I might as well have filled it with Dr. Pepper. It was the worst stuff I've ever used and a total waste of my money. Glad I never put it in my ZF!
I first tryed the Castrol they recommended from the BMW store and it was OK but not that great. Then I finally listened to a friend and cheched out the AmsOil website and read up on their Manual Synchromesh Fluid. I put some in (2 1/3 bottles I think) and it was like having a freshly rebuilt transmission. No joke, Like a rebuild in a bottle!
It has an additive that is especially made for the brass synchros in a ZF, and after a few miles you can really tell the tranny loves that stuff! Shifts smooth as butter even with my stiff short throw B&M shifter. I won't use anything else now. Yes, it's a little expensive, but not nearly as much as your ZF transmission. It's well worth it.
I first tryed the Castrol they recommended from the BMW store and it was OK but not that great. Then I finally listened to a friend and cheched out the AmsOil website and read up on their Manual Synchromesh Fluid. I put some in (2 1/3 bottles I think) and it was like having a freshly rebuilt transmission. No joke, Like a rebuild in a bottle!
It has an additive that is especially made for the brass synchros in a ZF, and after a few miles you can really tell the tranny loves that stuff! Shifts smooth as butter even with my stiff short throw B&M shifter. I won't use anything else now. Yes, it's a little expensive, but not nearly as much as your ZF transmission. It's well worth it.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
I used Redline Synthetic Lightweight Shockproof Gear Oil in my ZF on a recommendation. I cannot complain one bit and it WILL protect my transmission under the conditions I run it. I have NO issues shifting in any gear.
Le Mans Master
Joined: Jan 2008
Posts: 7,030
Likes: 10
From: Edmonton, Alberta
You are probably experiencing the 1 to 4 lockout which is normal when certain criteria is met. You should see the "One To Four" light up on your dash which will lock out second and third gears
Team Owner
Joined: Feb 2006
Posts: 23,115
Likes: 117
From: San Antonio Texas
If it shifts OK when you accelerate a bit more agressively, but has the 2nd gear problem when you are light on the throttle and just doing a relaxed move away from a stop, then it could very well be the 'skip shift' feature. GM put that into the manual cars to increase the Corporate Average Fuel Economy and keep the Corvette out of the gas guzzler tax bracket. It forces the transmission to shift from 1st to 4th under light throttle accelleration. Most people have disabled that aggravating feature, but your car could have escaped modification and still have it plugged in.
Le Mans Master
Joined: Jan 2008
Posts: 7,030
Likes: 10
From: Edmonton, Alberta
DOH! I didn't even think of that, but you may have located his problem.
If it shifts OK when you accelerate a bit more agressively, but has the 2nd gear problem when you are light on the throttle and just doing a relaxed move away from a stop, then it could very well be the 'skip shift' feature. GM put that into the manual cars to increase the Corporate Average Fuel Economy and keep the Corvette out of the gas guzzler tax bracket. It forces the transmission to shift from 1st to 4th under light throttle accelleration. Most people have disabled that aggravating feature, but your car could have escaped modification and still have it plugged in.
If it shifts OK when you accelerate a bit more agressively, but has the 2nd gear problem when you are light on the throttle and just doing a relaxed move away from a stop, then it could very well be the 'skip shift' feature. GM put that into the manual cars to increase the Corporate Average Fuel Economy and keep the Corvette out of the gas guzzler tax bracket. It forces the transmission to shift from 1st to 4th under light throttle accelleration. Most people have disabled that aggravating feature, but your car could have escaped modification and still have it plugged in.
