: 4T80E hard shift



remmans
01-18-05, 02:05 PM
I just bought a car with the 4T80E trans in that needs the motor replaced (cracked block) when I did start it and put the shifter in Reverse or Drive it his very very hard (bang). The Lady aslso told me it will no longer shift into drive because somebody tried to steal the car. The Trans shop told he it was just a cable and the tranny is fine. Since I am going to have the motor and trans out of the car should be there be certain parts that I should replace (don't want to due full rebuild) before re-installing that motor and trans back into the car. I have read maybe PCM, TFP but I was looking for somebody with more knowledge like Bbobynski to give me some ideas

danbuc
01-18-05, 02:16 PM
I would make sure to put new tranny and engine mounts in when you re-install them back into the car. I've got nothin' on the tranny problem though. Good Luck. :thumbsup:

BeelzeBob
01-18-05, 02:21 PM
I just bought a car with the 4T80E trans in that needs the motor replaced (cracked block) when I did start it and put the shifter in Reverse or Drive it his very very hard (bang). The Lady aslso told me it will no longer shift into drive because somebody tried to steal the car. The Trans shop told he it was just a cable and the tranny is fine. Since I am going to have the motor and trans out of the car should be there be certain parts that I should replace (don't want to due full rebuild) before re-installing that motor and trans back into the car. I have read maybe PCM, TFP but I was looking for somebody with more knowledge like Bbobynski to give me some ideas


Is all this second hand info?? If the trans will not shift into drive because of the cable how did you shfit into drive or reverse and get the bang??

If the trans is failing, the engine mounts are bad, the drive axles damaged, etc...could all cause a bang when going into gear. Nothing specific on the trans to cause that necessarily. It will take some diagnosis when you have it apart.

How is the block "cracked"...??? Where is the crack at?? Rare for Northstars to crack blocks unless they freeze due to water in them instead of coolant.

remmans
01-18-05, 02:40 PM
The block did crack from Freezing (car was moved up from Arizona) I drained about 15+ quarts of Milk from block. I was still able to start the car (Did not run very well) and when I shifted into drive and reverse and hit very very hard even though the RPM was not high. So it went into drive when I shifted into drive but I was not able to take the car for a test drive on the road.

BeelzeBob
01-18-05, 03:03 PM
If the engine power is down then the trans will shift hard as it is shifting for a certain anticipated power or torque level and if the engine is weak it will seem hard.

If it was a known freezing problem then take some pics of the cracks and post them if you can when the engine is out for reference. Some cracks have been posted that are suspected freezing damage but it is always speculation after the fact. It would be good to see a known freezing damaged block for reference.

BeelzeBob
01-18-05, 03:11 PM
If the trans is going to be out and on the ground it might be a good idea to replace the TCC/VCC apply solenoid that is under the side cover of the trans as well as the input speed sensor. Failures of both of those are reported occasionally on higher mileage older 4T80E transmissions so it would be a preventive maintenance item on the trans if it is out and easy to remove the side cover....much harder to do those with the trans in the car. Also, that would give you an opportunity to inspect the trans line pressure control solenoid to see if there is a problem with it as that could be stuck on max line for some reason. In any case, remove the side cover and replace the filter that is in there. The actual trans filter is rarely serviced as it is inside the side cover so now would be the time. The lower pan has pickup screens that can be cleaned in the car but those are only the scavenge pump pickups which deliver the oil to the dry sump'ed side cover for pickup by the main pressure pump. If the lower pan is off to do the screens then drop the valve body off and replace the shift solenoids that also fail occasionally at high miles. These can be done later in the car but it is easier now that you can roll the trans over and attack it out in the open.

remmans
01-18-05, 04:12 PM
Thanks for the advice it is much appreciated. I will purchase some parts and swap them out when they are a little easier to work on (Out of car) You might have saved me many hours of labor!

Thanks Again,
Rory Emmans
:)

remmans
02-15-05, 04:31 PM
Updateon my project. I just put a motor and tranny back in the car. I had bought the car from a lady with a cracked block (froze) so I had to replace the motor. She had also told me that it would not shift into 3rd gear because somebody that tried to steal the car did something to it. When she took it to a transmission shop they told her it was the shifter cable? When I had the transmission out I replaced the shift solenoids, speed sensor and the TCC. When flooring the gas on the car the car shifts at 6000 no problem 1, 2 and 3rd. When I am driving it normal the shift normal sometimes with no check engine light. When I take off from a stop sign the next time it will not really shift from 2 to 3rd unless I accelerate 4000 to 4500 RPM )then let off the gas then when hit the gas again it will down shift again into 2nd gear and the check engine light will come on. The light will come on then go off depending if the tranny is working or not. Any ideas? I heard maybe modulator? Anybody know where that is located? Is ther a tpS kick down cable? OR anybody have a idea on what sensors could control this? Thanks in advance for any help you might be able to provide?