Built 4l80e, no 4th gear
11-13-2011, 07:44 PM
#1
Built 4l80e, no 4th gear
I originally had this problem back in January when I lost 4th gear, so I sent the trans back to performabuilt since it was still under warranty. They said they fixed it and its been sitting in a corner since then until now. It is still doing the same thing except now its out of warranty and I havent had a chance to use it until now.
Gears 1-3 are fine and shift normally, when it goes to shift to 4th it doesnt engage and the engine just revs. I can command 4th with the scanner but it doesnt do anything, and the converter does not lock up as well. Since its out of warranty I would rather have someone local fix it since I dont want to pay freight charges to send it back to PB in addition to whatever it costs to fix it. Needless to say I am very irritated.
Gears 1-3 are fine and shift normally, when it goes to shift to 4th it doesnt engage and the engine just revs. I can command 4th with the scanner but it doesnt do anything, and the converter does not lock up as well. Since its out of warranty I would rather have someone local fix it since I dont want to pay freight charges to send it back to PB in addition to whatever it costs to fix it. Needless to say I am very irritated.
11-14-2011, 12:59 AM
#6
Picture is worth a 1000 words, right?
Kinda tells the whole story, I labeled the shifts on the bottom section. This is what happens when I apply and hold a constant throttle position (20%) in this case. The green line in the bottom section is torque converter slip. The red line of the top section is engine RPM. Notice how when it shifts to 4th the engine rpm dips down for a fraction of a second then shoots up.
Kinda tells the whole story, I labeled the shifts on the bottom section. This is what happens when I apply and hold a constant throttle position (20%) in this case. The green line in the bottom section is torque converter slip. The red line of the top section is engine RPM. Notice how when it shifts to 4th the engine rpm dips down for a fraction of a second then shoots up.
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11-14-2011, 06:23 AM
#8
I honestly do not know what all those squiggly lines mean.
However I kind of see what your saying. Didn't you have another 80 in this truck while this one was out? If so did you have this issue with the other one? I think this is a VB issue if I had to guess and I remember reading about this complaint in one of my tech manuals. I believe it relates to one of the shift valve springs IIRC. I'll look into it to see if I can find it for you. HTH Vince
However I kind of see what your saying. Didn't you have another 80 in this truck while this one was out? If so did you have this issue with the other one? I think this is a VB issue if I had to guess and I remember reading about this complaint in one of my tech manuals. I believe it relates to one of the shift valve springs IIRC. I'll look into it to see if I can find it for you. HTH Vince
11-14-2011, 07:24 AM
#9
Interesting, the log reports an excess of converter slip rather than trans slip on the 3-4 shift... I have had a similar issue where two snap rings were swapped out and the beveled edge on one allowed it to pop out of the case lugs so there was no pressure applied to the OD clutches. So it looked like that log, all it would do is rev up.
11-14-2011, 07:35 AM
#10
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In an 80E in overdrive all 4 clutch packs are applied... Overdrive, Direct, Forward and Intermediate. The Sprag and one way rollers are overrunning (not applied).
So, for it to not have 4th but have all 3 forward gears, and I presume it has reverse... then I would suspect a problem in the valve body like Vince stated or a problem in the overdrive clutch area. But that's kinda speaking the obvious....
What is the fluid condition? Is it the exact same condition as before? When you originally installed the transmission was it operating properly or was this issue apparent immediately?
Have you contacted Frank to see what he says?
If you go the local shop route, then you need someone who is familiar with performance 80E's.
g
So, for it to not have 4th but have all 3 forward gears, and I presume it has reverse... then I would suspect a problem in the valve body like Vince stated or a problem in the overdrive clutch area. But that's kinda speaking the obvious....
What is the fluid condition? Is it the exact same condition as before? When you originally installed the transmission was it operating properly or was this issue apparent immediately?
Have you contacted Frank to see what he says?
If you go the local shop route, then you need someone who is familiar with performance 80E's.
g
Last edited by Gilbert@Ace Racing; 11-14-2011 at 07:41 AM.