Automatic shifting hard when cold
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From: Arizona
Automatic shifting hard when cold
I have a 1989 F-150 XLT Lariat 4x4 with an 4.9 and an Automatic Transmission. I am experiencing hard shifts when initially shifting into Reverse or Drive when the engine is cold. For example, in the morning I start the truck and let the motor run for a few minutes. When I put it in Reverse, it shifts hard as I back out of the garage. It also shifts hard when I put it in Drive. After that, the transmission shifts beautifully. If I drive it for a while, shut it down and start it back up, it also shifts fine. It's only when the vehicle is cold.
I should note that my driveline is in great shape. I just installed new u-joints on the rear shaft.
I suspect something vacuum related, but I not sure where to look first.
Any ideas?
Thanks!
-Richie
I should note that my driveline is in great shape. I just installed new u-joints on the rear shaft.
I suspect something vacuum related, but I not sure where to look first.
Any ideas?
Thanks!
-Richie
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From: South Dakota
I see you live in AZ, so I'm assuming you're not dealing with really cold temps like we have here in SD (-9 bellow now). So I would look at the tranny fluid, if it is a darker color to brown it is time for a flush and fill. If has been a while since it has had a filter, but the fluid looks good, you could just replace the filter and fluid you drain from the pan. When you say it shifts hard do you mean it bangs into gear or it takes a couple of seconds to go into drive? If it is soft shifting it could also be vacuum related, bad hose or one that has popped off, or even the modulator.
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From: Arizona
Originally posted by 68torino
I see you live in AZ, so I'm assuming you're not dealing with really cold temps like we have here in SD (-9 bellow now). So I would look at the tranny fluid, if it is a darker color to brown it is time for a flush and fill. If has been a while since it has had a filter, but the fluid looks good, you could just replace the filter and fluid you drain from the pan. When you say it shifts hard do you mean it bangs into gear or it takes a couple of seconds to go into drive? If it is soft shifting it could also be vacuum related, bad hose or one that has popped off, or even the modulator.
I see you live in AZ, so I'm assuming you're not dealing with really cold temps like we have here in SD (-9 bellow now). So I would look at the tranny fluid, if it is a darker color to brown it is time for a flush and fill. If has been a while since it has had a filter, but the fluid looks good, you could just replace the filter and fluid you drain from the pan. When you say it shifts hard do you mean it bangs into gear or it takes a couple of seconds to go into drive? If it is soft shifting it could also be vacuum related, bad hose or one that has popped off, or even the modulator.
I will take a look at all of these things and report my findings. I appreciate you taking the time to answer my post.
-Richie
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From: South Dakota
You are quite welcome. Also a nehibor has a F150 with AOD which had been rebuilt but the TV cable had never been adjusted correctly. Talk about a bad shifting tranny. You have to take it up to 30-35 to get it out of first. I told them what was wrong but it never was taken back that I kow of. That's why I like manual transmissions they are less finicky than a slushbox.
Last edited by 68torino; Jan 5, 2004 at 11:48 AM.
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From: Arizona
Originally posted by 68torino
You are quite welcome. Also a nehibor has a F150 with AOD which had been rebuilt but the TV cable had never been adjusted correctly. Talk about a bad shifting tranny. You have to take it up to 30-35 to get it out of first. I told them what was wrong but it never was taken back that I kow of. That's why I like manual transmissions they are less finicky than a slushbox.
You are quite welcome. Also a nehibor has a F150 with AOD which had been rebuilt but the TV cable had never been adjusted correctly. Talk about a bad shifting tranny. You have to take it up to 30-35 to get it out of first. I told them what was wrong but it never was taken back that I kow of. That's why I like manual transmissions they are less finicky than a slushbox.
I have verified that I have a C-6 Tranny. The fluid looks very clean and it's full. I didn't see any vacuum hoses disconnected. That leaves the modulator. What does the modulator do? Would a bad modulator cause the tranny to shift hard when it's cold?
-Richie
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From: hickory
i have the same problem with my 91 4x4 ranger 4.0 literw/4 spd overdrive trans. when its cold and i dont mean the air outside i mean the engine has not been run in several hours (overnight) when i first crank it up then put it into reverse it bangs into gear the same if putting it into drive "bang". It shifts through the other gears ok. After the trucks warmed up 10 or 15 min it quits doing it and works fine. i have new atf in mine so its not old fluid. wish i knew what to do!
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From: Arizona
Originally posted by 68torino
You are quite welcome. Also a nehibor has a F150 with AOD which had been rebuilt but the TV cable had never been adjusted correctly. Talk about a bad shifting tranny. You have to take it up to 30-35 to get it out of first. I told them what was wrong but it never was taken back that I kow of. That's why I like manual transmissions they are less finicky than a slushbox.
You are quite welcome. Also a nehibor has a F150 with AOD which had been rebuilt but the TV cable had never been adjusted correctly. Talk about a bad shifting tranny. You have to take it up to 30-35 to get it out of first. I told them what was wrong but it never was taken back that I kow of. That's why I like manual transmissions they are less finicky than a slushbox.
The problem was a bad vacuum modulator. I pulled the vacuum hose off and found fluid. I replaced the modulator and it now shifts like it should. Thanks for the good advice.
For anyone else who has this problem with the C-6 tranny. THe part was about 25 dollars. The R&R took about 10 minutes. Make sure you have a pan to catch the fluid that will pour out after removing the modulator. You will only need a 1/2" wrench or socket and a funnel to add fluid that was lost during the R&R.
-Richie
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