To all 700R4 gurus out there.
I have an 88 GTA with a 700 R4 which I disassembled circa 3 years ago simply to change all the internal and external seals using a CARGO K77900C. Transmission works fine, going through all the gears albeit having a very harsh 1-2 and 2-1 shifts which are becoming tedious to endure.
When I had the transmission open, I figured someone had fiddled around with it at some point as I didn't have the springs in the 1-2 and 3-4 accumulators. Instead, I had sleeves which prohibit the accumulator piston to move and from what I could find, its something which normally B&M shift kits recommend for street use.
Unfortunately I only took a few pictures of the valve body and valves which I am attaching below.

So my questions:
Can someone figure out from the pictures if it actually has a modified valve body? From the transmission code it should be an 1988 model.
Can I simply install springs at least in the 1-2 accumulator to smoothen out the shifts? If so what color springs should I use? Maybe I should get a pinless accumulator from Sonnax?
If I were to use a proper kit like a Transgo kit, will it be safe without knowing if it was already tempered with?
Ideally I do not end up dropping the transmission again

Any thoughts?

 

Definately been messed with. There should be springs in the accumulators. Solid spacers is for race use only. The throttle valve also looks to be a different color than all the others, probably been upgraded as well.

 

I wouldn’t think that the color of the throttle valve is related. Maybe it’s the camera.

When I disassembled it, everything matched the ATRA Rebuild book. The only differences I could notice are those accumulator spacers but I didn’t check if there were any passages blocked or enlarged.

Would it make sense to simply introduce back the springs in the 1-2 accumulator and leave the rest alone?

 

Installing the accumulator springs will definitely soften the 1-2 and 3-4 shifts. However, it looks like your 3-4 accumulator piston is turned upside down. It doesn't match the pictures of my previous Level-2 transmission.

 

Yes it might be the case that it is turned upside down however I ready that even GM changed the orientation between years.
Still 3-4 also has the sleeve so it cant move and I wont be touching 3-4 as I cant complain on those shifts.

Do you have any idea on spring colors? Looks like there are various colors based on stiffness and I am not targeting going fully stock/soft shifts.

 

No, don't remember the colors. I did a manual VB swap and tossed the springs & pistons. Someone else may be able to help with that.

 

Will wait to get some info from fellow members on here. I would like to avoid having to remove also the separator plate but if needed I am willing to do this right. Perhaps people will tell me that I also need to touch the 3-4 accumulator, this will require the removal of the valve body altogether.

 

I can see the separator plate has the 2nd feed hole way to big. Bring it down to .076" - .086" max with a stock diameter torque converter. 3rd feed at .110" - .116". 4th feed at .155" and install the spring first, then the piston on the 4th accumulator in the case. I would add the TransGo Junior here, to go along with the above suggestions. A .471" or .500" main boost valve. A .282" or .296" intermediate/reverse boost valve. Use the Corvette servo with this setup, and setup the band clearance at a minimum. The TransGo Junior will help with a lot of what you want here. Smooth part throttle shifts and firm WOT shifts.

 

Wow thats quite a prescription!!
I would be willing to change to a new separator plate and perhaps enlarge the areas that you indicated. Installing the transgo Jr kit it also something i can do but when it comes to the main boost valve and corvette servo, I think that would involve removing the trans from the car and honestly I would like to avoid that if at all possible.

Would I benefit by replacing the separator plate and use valves and springs from the transgo Jr kit?

 

Hi again
I carefully studied what @ Probuilt is suggesting and it looks like I was wrong assuming that I need to take the trans out. Apparently all of your suggestions can be done with the transmission in the car. I have a car lift so it should make things easier.

I live outside the US and for me it’s important to get all the necessary parts before starting the job or else it will put me months behind.

So I did a list of parts which I think I would need to follow your recommendations and would like to double check then with you.
Separator plate feed hole adjustments:
- I need TransGo 700P and then see how I can get small drills to enlarge to the area you are recommending.
- Will also need ACDELCO 8689949 for gaskets
- TransGo SK700JR. This includes the springs that I have missing on the 1-2 and 3-4 accumulators and also shims to adjust the servo band clearance amongst other valve springs
- TransGo 72P. This includes the internals of the corvette servo and the necessary o rings
- TransGo 7500. This includes the .500 Main valve
I am not sure about the Intermediate/Reverse valve. Would the TransGo 7300 be fine? Couldnt find the size of such valve.

As you might have noticed I am trying to source from RockAuto as they have decent shipping prices and they always delivered. Cant tell you how many sticker I have

Would appreciate your feedback on the above.
Thanks again!

 

If you have a 1988 or later V8 700R4, it will have the .282" intermediate/reverse boost valve. If you have under 400 FWHP, this valve with work fine. This valve gives firmer 1-2 manual shifts.

 

"Front Wheel Horse Power"?...

 

I think the best way forward here is to disassemble the valve body before ordering any parts to see what is currently in there. The previous owner might already have replaced the main and intermediate valves and it would be pointless getting them again.

Will keep this thread alive but it will be some weeks from now as I had an accident while cycling yesterday and surely won’t be going under the car this week..

Thanks for your help.

 

Flywheel Horsepower