another TC lock-up question
Thread Starter
Racer
Joined: Oct 2002
Posts: 416
Likes: 2
From: Westfield MA
another TC lock-up question
My last post was about finding a 700R4 shop in the CT./Ma. area. I am going to remove the transmission and take it to Gran Trans. in CT. this winter. But, just for my own curiousity, I have a question about oil temp. vs. TC lock-up.
Now that the weather has turned colder, the TC lock-up will work properly for the first five or ten minutes of driving when I leave work. I can tap the brake pedal and the tach jumps up about 300 rpm (at 55 mph). After driving about 10 miles, it will not lock-up again after tapping the brake pedal. I'm assuming the converter clutch valve is working with the higher pressure of the "cold" fluid and then hangs up when the fluid warms up and the pressure decreases a bit. Anybody else ever experience this? Thanks
Now that the weather has turned colder, the TC lock-up will work properly for the first five or ten minutes of driving when I leave work. I can tap the brake pedal and the tach jumps up about 300 rpm (at 55 mph). After driving about 10 miles, it will not lock-up again after tapping the brake pedal. I'm assuming the converter clutch valve is working with the higher pressure of the "cold" fluid and then hangs up when the fluid warms up and the pressure decreases a bit. Anybody else ever experience this? Thanks
Team Owner
Joined: Apr 2000
Posts: 27,818
Likes: 8
From: CT
another TC lock-up question
My last post was about finding a 700R4 shop in the CT./Ma. area. I am going to remove the transmission and take it to Gran Trans. in CT. this winter. But, just for my own curiousity, I have a question about oil temp. vs. TC lock-up.
Now that the weather has turned colder, the TC lock-up will work properly for the first five or ten minutes of driving when I leave work. I can tap the brake pedal and the tach jumps up about 300 rpm (at 55 mph). After driving about 10 miles, it will not lock-up again after tapping the brake pedal. I'm assuming the converter clutch valve is working with the higher pressure of the "cold" fluid and then hangs up when the fluid warms up and the pressure decreases a bit. Anybody else ever experience this? Thanks
Now that the weather has turned colder, the TC lock-up will work properly for the first five or ten minutes of driving when I leave work. I can tap the brake pedal and the tach jumps up about 300 rpm (at 55 mph). After driving about 10 miles, it will not lock-up again after tapping the brake pedal. I'm assuming the converter clutch valve is working with the higher pressure of the "cold" fluid and then hangs up when the fluid warms up and the pressure decreases a bit. Anybody else ever experience this? Thanks
Regarding your convertor lock up. As far as I remember, mine waits for a certain temperature, then goes to lock. If you tap the brakes, it will unlock...then it should go back in shortly after.
Let us know how you made out,and tell Grant Jay said Hi :)
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: another TC lock-up question (SS409 425HP)
Jay's explanation of TC lockup sounds right, but I'm not sure how long the ECM holds off on the lockup command after you have tapped the brake pedal.
You can easily check to see if the ECM is holding off on the lockup command by hooking a DMM or test light across ALDL pins A & F. The light will be On (or you will read a + voltage) whenever the ECM is NOT sending the TC lockup command.
I also agree with Jay about Grant Transmission's work; you should be pleased with the work done.
BTW, are you having the tranny rebuilt, installing a shift kit or new TC, etc.?
You can easily check to see if the ECM is holding off on the lockup command by hooking a DMM or test light across ALDL pins A & F. The light will be On (or you will read a + voltage) whenever the ECM is NOT sending the TC lockup command.
I also agree with Jay about Grant Transmission's work; you should be pleased with the work done.
BTW, are you having the tranny rebuilt, installing a shift kit or new TC, etc.?
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Re: another TC lock-up question (SS409 425HP)
Your theory on the converter valve is spot-on. Had to have my 4L60E repaired (thank God for GMPP) after similar symptoms (but brake pedal had no effect). It would lockup when cold but not when hot. They replaced the pump and pump cover I think.
[Modified by Lone Ranger, 5:30 PM 11/19/2002]
[Modified by Lone Ranger, 5:30 PM 11/19/2002]
Thread Starter
Racer
Joined: Oct 2002
Posts: 416
Likes: 2
From: Westfield MA
Re: another TC lock-up question (65Z01)
I figure if I'm going to remove it myself, I may as well do it all. I spoke with Grant on the phone about a complete rebuild, shift kit, and a new converter. I was suspicious about the pump pressure (hot vs. cold) and the replies I received here on the forum confirmed it. I will mention this to Grant. My task will be easier now that there is a nice, yellow powder coated Kwiklift sitting in my garage waiting to be put together. They're running a Christmas special on the shipping charges and I took advantage of it. No more wobbly jack stands!!! Thanks to all for your replies.
