Rebuilt tranny shifts hard
#1
04-15-2014, 06:00 AM
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Rebuilt tranny shifts hard
I just had my tranny rebilt it doesn't shift hard all the time but it does from time to time going from 2nd -3rd and 3rd -4th I thought being new it may need to soak up some fluid so the bands can swell so I ask the shop that rebuilt it that question he said they soaked them as they rebuilt it so they should be swollen already then he proceeded to tell me it was electrical is he telling me the truth because the ck engine light isn't showing any faults and if it was electric shouldn't that have been fixed in the shop while it was being rebuilt if it was interior electronic? thx
#2
04-15-2014, 10:53 AM
The Electric pressure control valve controls fluid pressure applied at shifts by being modulated by the PCM.
If it were sticking, a code would be set and the Trans shifter light might flash and set a code.
.
The fluid is directed toward each shifts channel by the other solenoids after the fluid is gated where a servo, disc clutch and or band clutch is activated, for that gear sets.
.
HOWEVER, when a solenoid is opened a valve body spring controls the speed of engagement against a shuttle valve and spring tensions are set to be smooth for engagement.
These springs are often replaced in performance applications to cause more positive shift engagements.
An increase in fluid pressure will do the same for all gears equally.
If a spring for any gear is broken, the shift can get harsh or intermittent.
.
Since you listed 2 to 3 and 3 to OD that seems to rule out a spring issue .
I would first be looking at the EPC solenoid or something in the valve body such as control ***** etc that may be sticking .
The only way is for the shop to take the valve body down and inspect for some issue. A mistake made etc.
It's likely not bands or clutches.
You may note if reverse is also harsh. If yes, there is no solenoid involved except the EPC and would lead to a conclusion of what is not the problem because reverse does not use a control solenoid to engage reverse because it's mechanical from the shift lever linkage and there is no up or down shifting from reverse as there is in forward speed changes..
.
If the shop won't back up their job after noting the harsh shifting, you have a problem in addition to the transmission.
Good luck.
If it were sticking, a code would be set and the Trans shifter light might flash and set a code.
.
The fluid is directed toward each shifts channel by the other solenoids after the fluid is gated where a servo, disc clutch and or band clutch is activated, for that gear sets.
.
HOWEVER, when a solenoid is opened a valve body spring controls the speed of engagement against a shuttle valve and spring tensions are set to be smooth for engagement.
These springs are often replaced in performance applications to cause more positive shift engagements.
An increase in fluid pressure will do the same for all gears equally.
If a spring for any gear is broken, the shift can get harsh or intermittent.
.
Since you listed 2 to 3 and 3 to OD that seems to rule out a spring issue .
I would first be looking at the EPC solenoid or something in the valve body such as control ***** etc that may be sticking .
The only way is for the shop to take the valve body down and inspect for some issue. A mistake made etc.
It's likely not bands or clutches.
You may note if reverse is also harsh. If yes, there is no solenoid involved except the EPC and would lead to a conclusion of what is not the problem because reverse does not use a control solenoid to engage reverse because it's mechanical from the shift lever linkage and there is no up or down shifting from reverse as there is in forward speed changes..
.
If the shop won't back up their job after noting the harsh shifting, you have a problem in addition to the transmission.
Good luck.
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