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Stupid Tranny Question

J

jiangtao

Guest
I just got a 1990 with 45k on it and auto transmission. My question is how many shifts/changes should you feel from a normal take off from a stop to overdrive? I am feeling 3 shifts [one a little different from the others] until I hit 41/42 and go into O.D. I also seem to get a type of shift when I let the car coast from overdrive. I am asking because I am used to my '86 and this one is acting different. Thanks in advance!!
 
Joined
Jan 15, 2004
Messages
2,240
Location
Northern Indiana
Corvette
1987 Z52 Black Convertible
Well in my 87 You can feel the shift from 1-2, then from 2-3, then from 3-4. And then the converter locking up around 43ish, also kind of feels like it shifting, but not really. The only thing I can think is something might be wrong with your converter locking up. You sure the fluid in it is full, and has good color, not to old?
 
J

jiangtao

Guest
The fluid looked good and was full. The "mystery" shift I was talking about earlier is different from the others. With a normal shift you get that little "crouch down and jump forward" feeling. The one I am in question about [the 3rd one] is more of a "forward moving" feeling [if that makes sense?] Also, I have the G92 option if that helps? Now that I think about it the shift in question feels like a drawn out version of the downshift into first gear you get when the car isn't in overdrive after decelleration [at about 18 mph] but it still goes into overdrive afterward. Strange!!
 

c4cruiser

Well-known member
Joined
Feb 22, 2002
Messages
971
Location
Lacey, WA USA
Corvette
87 Gold Z52 Coupe 02 EB Z51 Supercharged Coupe
What position was the shifter in? 3 or OD? Probably what you are feeling is the torque converter locking/unlocking and that's typical at the low 40's MPH speed you mentioned.

My 92 A4 would feel like it's "shifting" when in OD when I lightly applied the brakes with my foot off the throttle at speeds below 25. That's a normal operation and feel in the later automatics.

As long as the 1-2 and 2-3 upshifts are firm when you apply medium throttle, you should be fine. T/C lockup will occur once speeds hit a certain point or when speed and engine RPM stabilizes (cruise).
 
Joined
Aug 30, 2002
Messages
1,533
Location
Colorado Springs, CO USA
Corvette
84 Z51 auto R.I.P. 89 black roadster SOLD
What you're probably feeling when you let it "coast" is the TCC unlocking when you take your foot off the throttle (don't ask me why GM does this). It'll lock back up when you get back on the throttle (lightly). At least that's how the earlier years work.

It's not surprising that the '90 feels a little different, the transmission innards are a little different than what's in the 86.

Bill
 
Joined
Jan 15, 2004
Messages
2,240
Location
Northern Indiana
Corvette
1987 Z52 Black Convertible
What you're probably feeling when you let it "coast" is the TCC unlocking when you take your foot off the throttle (don't ask me why GM does this). It'll lock back up when you get back on the throttle (lightly). At least that's how the earlier years work.


Mine doesn't do that as long as I am above like 40 mph. But if I hit the break or go below that speed then it does unlock.
 
J

jiangtao

Guest
It sure doesn't feel like my '86 did, but I am thinking that it might be when, before going into full overdrive, the idle goes down a little [on my other cars]. It is doing it after what should be the shift into 3rd at around 26-30 mph.
 

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