overdrive vibration
Thread Starter
|
New User
Joined: Mar 2006
Posts: 2
Likes: 0
overdrive vibration
Hey guys I'm new to trucks and to this forum,I have a 1996 F-150 with a automatic trans,straight 6 ,4.9 liter engine.Truck runs good except it seems to shift to overdrive too early approx 30-35 mph.Runs smooth through 1st. 2nd.3rd,then vibrates badly when in 4th. So the guestions are why the vibrations? And can I keep it out of 4th gear until it reaches a higher speed?
Postmaster
Joined: Mar 2001
Posts: 4,968
Likes: 3
From: So Cal
Sounds like it might be torque converter shudder.
This happens when the lockup clutch starts to slip as it wears. Usually you feel it when under light acceleration in 4th usually above 45mph, and sometimes 3rd I have read. It kind of feels like driving on California rain grooves or small road markers(Bot's Dots). It goes away under hard acceleration or coasting.
Another symptom that may show up is intermittant harsh shifting. This is a sign that there has been some damage and the computer is boosting pressure to compensate. I had this problem and the Check tranny(flashing OD) light never came on.
But yours does it at a much lower speed, so wild guess(I am NOT a tranny expert) is that your tranny might be shifting too soon for the speed and acceleration you are doing and the clutch is slipping because it is too soon to be in that gear and locked up.
Good Luck,
Jim henderson
This happens when the lockup clutch starts to slip as it wears. Usually you feel it when under light acceleration in 4th usually above 45mph, and sometimes 3rd I have read. It kind of feels like driving on California rain grooves or small road markers(Bot's Dots). It goes away under hard acceleration or coasting.
Another symptom that may show up is intermittant harsh shifting. This is a sign that there has been some damage and the computer is boosting pressure to compensate. I had this problem and the Check tranny(flashing OD) light never came on.
But yours does it at a much lower speed, so wild guess(I am NOT a tranny expert) is that your tranny might be shifting too soon for the speed and acceleration you are doing and the clutch is slipping because it is too soon to be in that gear and locked up.
Good Luck,
Jim henderson
Last edited by jim henderson; Mar 24, 2006 at 03:16 PM.
Thread Starter
|
New User
Joined: Mar 2006
Posts: 2
Likes: 0
Hey Jim,what you said about the shifting too soon ,I really think you're on to something.Can I adjust the shift points? The truck shifts fine 1st.2nd.3rd.I've heard about adjusting the vacume modulater (spelling),to change the shifting.Thank you for the advice.
