Auto transmission shifting woes
11-16-2015, 03:54 PM
#16
Rennlist Member
Thread Starter
From the transmission doc I linked above:
HARSH ENGAGEMENT WHEN SELECTING "D" OR "R"
Idle speed too high. Check pressure receiving (pick-up) piston in valve body for ease of operation and correct installation. Replace valve body (if necessary).
NOTE: Pressure pick-up requires a running period of approximately 2 seconds. Harsh engagement may occur during repeated shifts between "N" and "D". If harshness takes place within 2 seconds, condition is considered normal.
You can give Seafoam Trans Tune Additive first, and see if that loosens up piston movement.
HARSH ENGAGEMENT WHEN SELECTING "D" OR "R"
Idle speed too high. Check pressure receiving (pick-up) piston in valve body for ease of operation and correct installation. Replace valve body (if necessary).
NOTE: Pressure pick-up requires a running period of approximately 2 seconds. Harsh engagement may occur during repeated shifts between "N" and "D". If harshness takes place within 2 seconds, condition is considered normal.
You can give Seafoam Trans Tune Additive first, and see if that loosens up piston movement.
11-16-2015, 03:55 PM
#17
Rennlist Member
Thread Starter
Also before making any vacuum adjustment, I'd check the cables for proper adjustment first.
And like others have said see if the vacuum line that goes to the trans (located at the firewall) will hold vacuum, you may have a break in the line, if it doesn't hold then trace it back to the modulator, testing the modulator last.
If you don't know when the fluid was last changed, change it, and don't forget to hold on the brakes when shifting gears w/ the wheels off the ground as you can damage the trans.
And like others have said see if the vacuum line that goes to the trans (located at the firewall) will hold vacuum, you may have a break in the line, if it doesn't hold then trace it back to the modulator, testing the modulator last.
If you don't know when the fluid was last changed, change it, and don't forget to hold on the brakes when shifting gears w/ the wheels off the ground as you can damage the trans.
Last edited by Andre The Giant; 11-16-2015 at 03:57 PM. Reason: Typo.
11-16-2015, 03:59 PM
#18
Rennlist Member
Thread Starter
This group never ceases to amaze me by the willingness to help other rennlisters.
A big thank you everyone for getting me on my way for next spring. It's going to be a long winter, unless I keep busy between renovations and ATV'ing.
A big thank you everyone for getting me on my way for next spring. It's going to be a long winter, unless I keep busy between renovations and ATV'ing.
11-16-2015, 04:00 PM
#19
Nordschleife Master
Dave's reference to cable adjustment is for the Control Pressure Control Cable (commonly known as the transmission Bowden Cable) for your shift adjustment issue when driving. Very important this is tensioned correctly. It is easy to get right. Search, and you will find many posts on doing it right.
11-16-2015, 04:01 PM
#20
Rennlist Member
Thread Starter
Dave's reference to cable adjustment is for the Control Pressure Control Cable (commonly known as the transmission Bowden Cable) for your shift adjustment issue when driving. Very important this is tensioned correctly. It is easy to get right. Search, and you will find many posts on doing it right.
11-16-2015, 04:02 PM
#21
Nordschleife Master
It is the Golden Rule thing.
Amongst men, it is always important.
11-16-2015, 04:03 PM
#22
Nordschleife Master
11-16-2015, 11:14 PM
#23
Former Sponsor
Keep in mind that the first thing to wear out in these transmission is usually the reverse clutches. As the clutches wear thinner and thinner, the "run up" of the reverse piston is longer and longer. And the longer the "run up" the harder the shift into reverse will be.
A transmission filter and fluid change is always one of the first things to do. Look carefully on the top of the filter for band material....it collects here. If there is band material on the top of the filter, take the time to cut open the filter (it's a pain in the butt) and inspect the inside for more band material.
Doubtful that you have a modulator pressure problem....there would be other symptoms besides reverse.
However, check for vacuum at the modulator and make sure you check to make sure the modulator holds vacuum also. There's a little rubber cap on the modulator that cracks and will leak vacuum.....very common.
A transmission filter and fluid change is always one of the first things to do. Look carefully on the top of the filter for band material....it collects here. If there is band material on the top of the filter, take the time to cut open the filter (it's a pain in the butt) and inspect the inside for more band material.
Doubtful that you have a modulator pressure problem....there would be other symptoms besides reverse.
However, check for vacuum at the modulator and make sure you check to make sure the modulator holds vacuum also. There's a little rubber cap on the modulator that cracks and will leak vacuum.....very common.
11-17-2015, 08:42 AM
#24
Rennlist Member
Thread Starter
Keep in mind that the first thing to wear out in these transmission is usually the reverse clutches. As the clutches wear thinner and thinner, the "run up" of the reverse piston is longer and longer. And the longer the "run up" the harder the shift into reverse will be.
A transmission filter and fluid change is always one of the first things to do. Look carefully on the top of the filter for band material....it collects here. If there is band material on the top of the filter, take the time to cut open the filter (it's a pain in the butt) and inspect the inside for more band material.
Doubtful that you have a modulator pressure problem....there would be other symptoms besides reverse.
However, check for vacuum at the modulator and make sure you check to make sure the modulator holds vacuum also. There's a little rubber cap on the modulator that cracks and will leak vacuum.....very common.
A transmission filter and fluid change is always one of the first things to do. Look carefully on the top of the filter for band material....it collects here. If there is band material on the top of the filter, take the time to cut open the filter (it's a pain in the butt) and inspect the inside for more band material.
Doubtful that you have a modulator pressure problem....there would be other symptoms besides reverse.
However, check for vacuum at the modulator and make sure you check to make sure the modulator holds vacuum also. There's a little rubber cap on the modulator that cracks and will leak vacuum.....very common.
