auto trans shift
Thread Starter
Racer
Joined: Nov 2015
Posts: 452
Likes: 159
From: Port Charlotte Florida
auto trans shift
Need help with a auto trans concern.
While on the freeway going a steady 75/80 mph, the trans did a erratic downshift to third gear. I could not find fourth all the way way home. Had several stops and all other gears performed as normal. A week ago I dropped the pan to repair a leaky pan gasket and the fluid still looked clear red and the pan was mostly clean. Cannot detect any slippage in any other gear. Any thoughts would be appreciated. Vehicle has always be taken care of and has 103k.
While on the freeway going a steady 75/80 mph, the trans did a erratic downshift to third gear. I could not find fourth all the way way home. Had several stops and all other gears performed as normal. A week ago I dropped the pan to repair a leaky pan gasket and the fluid still looked clear red and the pan was mostly clean. Cannot detect any slippage in any other gear. Any thoughts would be appreciated. Vehicle has always be taken care of and has 103k.
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Might have a transmission tune to change the shift points.
Racer
Joined: Oct 2021
Posts: 324
Likes: 157
From: Maine
Here is a strange idea, lets say your shift cable is going bad and as it's eating it's self to a point that it has move into 3 gear at the transmission when in drive.
Or you have a new cable that was not installed correctly and when its in Drive at the transmission its in-between Drive and 3rd.
from what I understand when in 3rd the car will downshift/upshift like normal with 3rd as the top gear.
Or you have a new cable that was not installed correctly and when its in Drive at the transmission its in-between Drive and 3rd.
from what I understand when in 3rd the car will downshift/upshift like normal with 3rd as the top gear.
Racer
Joined: Oct 2021
Posts: 324
Likes: 157
From: Maine
Well good it's acting normal again, it could have been a fluke.
Do you know if the cable has ever been replaced, I saw a few posts about it being a problem so I changed mine when I changed the rear diff from 2.73 to 3.15
Another thing to consider old dirty filter and slightly low fluid level. until it happens again keep driving it.
side note: A new GM shift cable is 70.99 at rockauto you could get one and toss it in the trunk, when they break it's never near an auto part store and most places will have to order it.
Do you know if the cable has ever been replaced, I saw a few posts about it being a problem so I changed mine when I changed the rear diff from 2.73 to 3.15
Another thing to consider old dirty filter and slightly low fluid level. until it happens again keep driving it.
side note: A new GM shift cable is 70.99 at rockauto you could get one and toss it in the trunk, when they break it's never near an auto part store and most places will have to order it.
Pro
Joined: Jun 2022
Posts: 691
Likes: 317
From: NW OH
agree to check the fluid level, it needs to be done at a specific temperature on the dash and with the engine running so look up the specific procedure.
It probably heated enough on the highway to open the tstat and either there was air in the cooler because it was not filled properly or (unlikely) the cooler has a leak.
It probably heated enough on the highway to open the tstat and either there was air in the cooler because it was not filled properly or (unlikely) the cooler has a leak.
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Thread Starter
Racer
Joined: Nov 2015
Posts: 452
Likes: 159
From: Port Charlotte Florida
Well trans shifts as intended to and from work. Gonna visit a local trusted tranny shop to get the fluid level checked and maybe a pressure check. Kinda lost confidence till I find the cause. Don't want to get stuck somewhere.
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Thread Starter
Racer
Joined: Nov 2015
Posts: 452
Likes: 159
From: Port Charlotte Florida
that was my first thought, but 3-4 clutch is also for 3rd and 3rd gear is fine. Also when pan was pulled, fluid clear and bottom of pan was clean with no wear or metal residue. Trouble is now there are no shift concerns for the last two days of driving.
Thread Starter
Racer
Joined: Nov 2015
Posts: 452
Likes: 159
From: Port Charlotte Florida
Here is a strange idea, lets say your shift cable is going bad and as it's eating it's self to a point that it has move into 3 gear at the transmission when in drive.
Or you have a new cable that was not installed correctly and when its in Drive at the transmission its in-between Drive and 3rd.
from what I understand when in 3rd the car will downshift/upshift like normal with 3rd as the top gear.
Or you have a new cable that was not installed correctly and when its in Drive at the transmission its in-between Drive and 3rd.
from what I understand when in 3rd the car will downshift/upshift like normal with 3rd as the top gear.
Drifting
Joined: May 2020
Posts: 1,663
Likes: 702
From: Baton Rouge, Louisiana, metro area
Well sir I believe you hit the nail on the head. Yesterday I had a hard time finding reverse. The gear shift is very sloppy. I ordered a new cable to correct the probably worn out bushings. But today I found that C@S Corvettes offer replacement cable bushings for 30 bucks. Gonna go that route. Don't have to pull exhaust, belly pan etc. That's the way to go. Thanks for your thoughts, I owe you!
I visited Lyle at C&S when I was in the Tampa area on a business trip last year. He is very knowledgeable, helpful, and very friendly. He warned me my shift cable bushings would be failing soon on my 76,000 mile 99. I picked up a set from him while I was there and tossed them in the glove box - thought no more about it.
About a month later, the lower bushing disintegrated and left me at my office. Fortunately, I was able to jack up the car, zip tie the lower cable to the shifter well enough to make two shifts: In reverse, then drive. I was able to drive it home where I changed the lower bushing the next day. Still trying to find time to change the upper one.
I know, I know….