4+3 Specific Question re gthe Overdrive
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Melting Slicks
Joined: Nov 2016
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From: So Cal
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4+3 Specific Question re gthe Overdrive
My first post under this username, but I've been here for years under another name, but forget the login.
My 1985's Overdrive has developed a specific quirk. I'm hoping someone that's had one apart, and understands what's in there can help me understand what is actually happening. I've owned this car since new, I know how it is supposed to behave, and the light comes on when I push the button, so the control circuit is working. It's not electrical.
After the coolant warms up, it shifts into overdrive normally. After its been driven awhile, perhaps 1/2 hour or so at highway speed, I push the button, the light comes on, it comes out of direct, but does not engage overdrive. It just kind of "freewheels", if I add throttle, the revs increase to direct speed, and the sprag engages. If I just coast along for 5-10 seconds, maybe reving it gently to 1500 or so, it will eventually engage overdrive with a terrific BANG, then its fine until the next engagement, or the next day.
The way I read the diagram, the piston engages overdrive, then continues on to disengage direct. So I'm baffled as to how direct is disengaged first. Any ideas welcomed. Thank you.
My 1985's Overdrive has developed a specific quirk. I'm hoping someone that's had one apart, and understands what's in there can help me understand what is actually happening. I've owned this car since new, I know how it is supposed to behave, and the light comes on when I push the button, so the control circuit is working. It's not electrical.
After the coolant warms up, it shifts into overdrive normally. After its been driven awhile, perhaps 1/2 hour or so at highway speed, I push the button, the light comes on, it comes out of direct, but does not engage overdrive. It just kind of "freewheels", if I add throttle, the revs increase to direct speed, and the sprag engages. If I just coast along for 5-10 seconds, maybe reving it gently to 1500 or so, it will eventually engage overdrive with a terrific BANG, then its fine until the next engagement, or the next day.
The way I read the diagram, the piston engages overdrive, then continues on to disengage direct. So I'm baffled as to how direct is disengaged first. Any ideas welcomed. Thank you.
Last edited by IHBD; Nov 17, 2024 at 02:02 AM.
Racer
Joined: Dec 2003
Posts: 277
Likes: 3
My first post under this username, but I've been here for years under another name, but forget the login.
My 1985's Overdrive has developed a specific quirk. I'm hoping someone that's had one apart, and understands what's in there can help me understand what is actually happening. I've owned this car since new, I know how it is supposed to behave, and the light comes on when I push the button, so the control circuit is working. It's not electrical.
After the coolant warms up, it shifts into overdrive normally. After its been driven awhile, perhaps 1/2 hour or so at highway speed, I push the button, the light comes on, it comes out of direct, but does not engage overdrive. It just kind of "freewheels", if I add throttle, the revs increase to direct speed, and the sprag engages. If I just coast along for 5-10 seconds, maybe reving it gently to 1500 or so, it will eventually engage overdrive with a terrific BANG, then its fine until the next engagement, or the next day.
The way I read the diagram, the piston engages overdrive, then continues on to disengage direct. So I'm baffled as to how direct is disengaged first. Any ideas welcomed. Thank you.
My 1985's Overdrive has developed a specific quirk. I'm hoping someone that's had one apart, and understands what's in there can help me understand what is actually happening. I've owned this car since new, I know how it is supposed to behave, and the light comes on when I push the button, so the control circuit is working. It's not electrical.
After the coolant warms up, it shifts into overdrive normally. After its been driven awhile, perhaps 1/2 hour or so at highway speed, I push the button, the light comes on, it comes out of direct, but does not engage overdrive. It just kind of "freewheels", if I add throttle, the revs increase to direct speed, and the sprag engages. If I just coast along for 5-10 seconds, maybe reving it gently to 1500 or so, it will eventually engage overdrive with a terrific BANG, then its fine until the next engagement, or the next day.
The way I read the diagram, the piston engages overdrive, then continues on to disengage direct. So I'm baffled as to how direct is disengaged first. Any ideas welcomed. Thank you.
Hopefully I'm all wrong.
Racer
Joined: Dec 2003
Posts: 277
Likes: 3
Thank You.
I've read about the thrust washer. I'll study the refrence material I have and understand this washer better. The way you describe it, the tangs have to 'slide' in the grooves in the case to allow overdrive to engage?
This unit was redone under the 36,000 mile, 3 year powertrain warranty when the car was 2 years old, and had 17,000 miles on it. The carrier bearing began making noise. A few years back, I looked at the paperwork, and most of the updated parts were installed at that time. It's been fine for 29 years, although it doesn't get driven a lot. It just turned 50,000 this summer.
The 85 has a TV cable. I was hoping it had something to do with the TV system, but I know it doesn't if it tries to shift, but doesn't engage at all. When the thing had a TV issue, it would slip in overdrive.
Something (thrust washer) hanging up makes perfect sense to me, and fits the symptoms. I've never seen the insides, you have. You helped me understand. I guess it has to come out and apart.
Thanks again.
I've read about the thrust washer. I'll study the refrence material I have and understand this washer better. The way you describe it, the tangs have to 'slide' in the grooves in the case to allow overdrive to engage?
This unit was redone under the 36,000 mile, 3 year powertrain warranty when the car was 2 years old, and had 17,000 miles on it. The carrier bearing began making noise. A few years back, I looked at the paperwork, and most of the updated parts were installed at that time. It's been fine for 29 years, although it doesn't get driven a lot. It just turned 50,000 this summer.
The 85 has a TV cable. I was hoping it had something to do with the TV system, but I know it doesn't if it tries to shift, but doesn't engage at all. When the thing had a TV issue, it would slip in overdrive.
Something (thrust washer) hanging up makes perfect sense to me, and fits the symptoms. I've never seen the insides, you have. You helped me understand. I guess it has to come out and apart.
Thanks again.
