Pietro Bisanti

Hi guys, as specified in the title...
The transmission seems to be working just fine, but it won't shift to overdrive when full throttle, it just remains stuck a 6,000 r.p.m until I release the throttle then it shifts...
Any idea? The TV cable?

bjankuski

Once it shifts if you floor it will it stay in forth or downshift back to third? This will help use determine if it is a valve body issue or a governor issue.

Pietro Bisanti

Thank you,
I'll test it soon and I'll let you know.
I have just bought it.
Could it be related to the fact the the exhaust system is all open and custom-made and so I have the check engine light always turned on in the control panel?

Soon2Bcammed

I was under the impression regular vettes with the 2.59 rear end will NOT shift overdrive at WOT. If the car has G92 axle with 3.07 gears, it will shift 4th at full throttle.

cv67

I thought none of them were supposed to shift WOT to 4th.

Soon2Bcammed

The 3.07 geared cars do, at least my '94 does but I know thats the 1st year of the electronic controlled trannies

ggrassmid

I had read somewhere here that all corvettes would shift into OD at WOT, but standard vehicles did not. I think this was talked about on someone's tranny rebuild thread. People had suggested to watch out who rebuilds as shops have taken the corvette vavle body out and replaced with a non corvette valve body that does not allow the 3-4 shift at WOT. My 85 stays in OD when WOT with a 2.73 gear

cv67

Id think they do that so the trans doesnt hurt itself.
02 Silverado does the same thing (4l60E)

Pietro Bisanti

Well
I had a 91 previous to this, and I can remember it shifted to OD at WOD.
Could it be the TV cable, as the transmission is not perfectly aligned to the right letter "N, D" etc..
In fact, the reverse lights don't turn on when I shift into reverse, but only if I move the shift up to N

Flame Red

Before I blew up my 700R4, it would not shift into 4th at WOT. That was great. Then I made the mistake of putting in a race built 700R4, but the core was not from a Vette. Now I have the opposite problem, the tranny shifts early into OD and won't kick down with WOT. Found out later that Vette trannys have quite a few special parts and never ever install a non-vete tranny. Rebuild your original!

I kind of wish this tranny would die so I would have an excuse to get-r-done right again.

GibDTD

My fathers 92 LT1 has a similar issue, it seems like it always wants to shift to the next gear. We have taken road racing a few times and it seems like it always wants to go to overdrive and then doesn't really want to kick down when you get on the go pedal. When it actually does down shift (at low speeds, 45-60 MPH), there is a hard shift. If we manually shift the car, its fine and accelerates well, but its annoying to manually shift an auto car.

I'm not sure if the tranny has been rebuilt or if its original, but the original owner claimed that the engine was making 400+ HP. He did tell us that he had been hit in the left rear quarter, and the car was rebuilt.

Does anyone know of a physical fix for this or a special tune that can fix the issue?

Rodney_Gold

The vettes and some Camaro z28's with their original 700r4's and 4l60e's will all shift to OD at wot if speed is high enough , there is something wrong if it wont.

stevie1dr

I'm stuck with the same problem in my 89 700R4. I posted here regarding the problem, and have had the car back to the trans builder twice. He still hasn't found an answer. I did question him about the Vette only parts in the trans and he says he was aware and did not swap out any non Vette parts on the build. He did drill a tiny hole in a large flat plate (that i don't know what function it has,) but he said that the original hole could be made larger to help the shift. (we're talking a hole only about .060 thousandths in diameter). It still goes all the way over 6000 rpms in 3rd w/o shifting unless I let off and then ease the pedal down. I'm all ears for a cure!

Steve

cv67

Thats the way its supposed to work!!

6000 rpm on a TPI?!

87 vette 81 big girl

Your original C4 valvebody is likely long gone.

Truck valvebody or similar in place now.

87 vette 81 big girl

All C4 700R4 transmissions original since 1984 upshifted 3-4 WOT stock Ron.

Seems most C4 owners current are missing the special valvebody & special steel separator plate.