Z's r Best

Just got new (rebuilt) 700r4 and shift cable put in 86 IROC (305 TPI. During road tests the 1-2 and 2-3 upshifts seemed to occur at "normal" rpms vs. gas pedal pressure (around 1800 to 2000 rpm when smoothly accelerating from a stop). However, the 3-4 up shift will not occur until the car is up around 55 mph and around 2400 to 2500 rpm. The torque convertor (also new) isn't locking up till the 700r4 goes to overdrive whereas it used to lock up (I'd see about a 200 rpm drop) at a different point than the 3-4 upshift. Once the torque convertor locks up it will stay locked up (and the tranny stays in OD right on back down to the 40 mph range, but it won't shift into OD that low. Does the throttle cable valve adjustment affect all shifts, or just the 3-4 upshift?
Thanks for any help.

Z's r Best

Well, the cable is adjusted by the book and no change. The transmission did not come out of an F-body as I had to remove the tailshaft housing from my old 700r4, put a new rear seal in it, change over the speedo gears and install the old tailshaft housing on the rebuilt 700r4. Does anyone know if truck/van 700r4's are set up to upshift to OD with torque convertor lockup at a higher speed than F-body 700r4's? If I can't figure this one out I'm going to use a lot more gas running around at 45 mph in 3rd without TC lockup than I did in OD with TC lockup.

gearhead0384

iTrader: (7)

I have a similar problem with my newly rebuilt tranny. I dont know if it is exactly what you are talking about, but are you getting a 3-4 shift flare up? Do the RPMs flare up a couple hundred RPMs then shift in to 4th?

Kevin

Z's r Best

No. No rpm jump as it shift to OD. However, I did a little test yesterday. I put the gear selector in 3rd and ran it up to 65 mph and the torque convertor clutch would not lock up. It will not lock up till the transmission shifts into OD and that does not occur till 55 mph. I've driven down the road for a couple of miles at 45 to 50 mph and it stays in 3rd gear till I get to 55 mph and then the shift to OD occurs at the same time the torque convertor clutch locks up. I noticed today that their is another difference depending on the shift lever position (3rd or 4th). In 4th (OD) prior to torque convertor lockup the rpm will drop from 2200 to 12 or 13 hundred when letting off the gas at 45 mph. When the gear selector is in 3rd and you let off the gas a 45 mph the rpm only drops to about 1800 instead of going all the way down to 1200. Looks like I'll be rebuilding (or getting it rebuilt) the original 700r4 to put back in my IROC. Running around town at 2200 rpm with no torque convertor lockup at 45 mph is gonna drink up the gas compared to running around at 1500 rpm with the torque convertor locked up.

Fast355

iTrader: (2)

Sounds like you have a transmission calibrated for a truck. Trucks can't pull OD very good around town unless the speed is up a little so the converter locks only in 4th and the OD shift occurs late.

Z's r Best

Thanks for the reply. I didn't bother to get the numbers off the transmission before I put it in and don't know if I can read them now. We'll see how it goes.

miacamaro305

you can try adjusting the cable.i can adjust it to shift as early or as late as i want.also the later i shift the more line pressure for me.

Precision Trans

"Z"

Your problem can be easily solved by installing the valve body and internal wiring harness from your original transmission. If there is a shift programming kit in your new trans, the parts and mods can be transferred to the old valve body before installation. Also, don't forget to use the separator plate that goes with the valve body.

Don

Vader

...And the TCC valve.

You should be able to solve all the problems from the pan, and not have to remove the trans again. Even the pressure control and TCC valve are accessible from there.

IROC212

iTrader: (1)

I had a similar problem,tried all kinds of stuff in the valve body. Turned out I set the 2-4 band too loose. I used a trans-go kit with the washers, my friend took out the servo and set it up tighter, and now it works perfect. just my experience.

IrS89IROC

mine is doing the exact same thing except my torque converter is locking up in 3rd gear around 43 mph where it used to shift into overdrive