I'm at the end of my rope. I've searched all over and am making myself crazy.
I have a 700r4 I built a few years ago with about 5k miles on it. I have a vette servo in it, 10 vane pump, 2800 stall lockup converter with a .500 tv valve, and I believe a .296 boost valve. I also installed a full Transgo kit in it. It is behind a 355 with heads cam and intake mods. The trans shifts firm and on time at part throttle thru 1-3. 3-4 upshift happens pretty late usually around 55-65mph, and will drop back into third below 50-52 mph depending on throttle angle.

I have two problems...
First is how late the 4th shift is. I was wondering if I put the wront spring in the 3-4 valve maybe delaying the shift. (the car has 3.27 gear)

Second is at WOT the shifts are soft, almost seems to slip on 1-2 and 2-3 upshifts.

The line pressure measured from the port above the shift linkage is

Idle TV connected............Full TV...........TV disconnected
(P) 115.............................180..................75
(R) 170.............................160.................115
(N) 110.............................180..................75
(OD) 110...........................150..................75
(D) 110.............................150..................75
(2) 170.............................150..................150
(1) 150.............................140..................130

Fluid is clean, no noise from front pump, no shavings or excessive clutch material in pan..I'm stumped.
Any help is greatly appreciated!!

 

The 3-4 shift being late is because you changed the 3-4 shift spring when you added the kit. Put in the original spring and that will fix it. I do not know why Transgo has that "orange" spring in that kit still, as it will always do this. I remove it from my modified Shift kits so that this will not happen. I don't know why the line pressures are low, but at 2,000 rpm and higher in manual 1 or 2 it should be over 210 psi., and reverse should be 220 - 250 psi. Try the readings again at a higher rpm and "see" what happens. Drive around and get the readings. Are the shifts ok?

 

Thanks for the reply Dana,
The shifts are good at part throttle, full throttle the shifts are slow and soft.
I'll get the gauge on it tonight after work and post the results. I'll have to look in the box for the original 3-4 spring.

 

Well I checked it on the road, and at 2000 rpm with TV closed and full. The pressure never went above 185ish. Front pump?
Thanks again for the input

 

I'm thinking about pulling the trans and checking out or replacing the front pump. I have a feeling the low line pressure may have hurt the 3-4 clutches, maybe the band.
Maybe its a good time to upgrade to the z-pac clutches, the input drum reinforcement, and the beast or hardened sun shell while I have it apart.

 

Call me on this. 909 795-1876 Dana