Hello everyone, I'm new to the forum. I have a '91 RS, 350 with a mild cam, Holley with the correct TV cable adapter, and 700R4. Installed a Transgo 700-2-3 shift kit, the shifts were firm under light throttle and very slow, actually slipping, at WOT. Once in the next gear there was no slippage. I upgraded to the .500 main & .296 reverse boost valves, and the Vette Servo; I had these installed by a shop so they could adjust the band by shimming the servo shaft. The shifts are now firmer and faster as expected, but half and WOT shifts are still lazy. Lets me explain, under light throttle, 1-2 and 2-3 shifts will jerk your head back; under WOT these shifts feel like those of a stock transmission. The shifts are the same when shifting manually as well. The TV cable was adjusted at the shop, I tightened it three clicks as I wanted the shifts points slightly higher. I have moved it back to where the shop had it set as well as upto six clicks looser and tighter. It is now back to 3 clicks tighter than the shop had it. I can say that none of these adjustments had any effect on the WOT shifts. Now something I've noticed, if I accelerate slowly, not more than 1/3 throttle, and manually shift at 4500 RPM, the shifts are as I would expect. I need to try doing the same thing, but going to WOT just before shifting to see how it reacts. My concern is that I have a failing pump or torque convertor and the line pressure is low unless I let it build as I described above. The torque convertor is the stock unit and appears to have about a 1700 stall behind the 350; I think it was about 1500 behind the 305. Regardless high enough not to be impacted by the cam and higher idle. Heat is not an issue either as I did install a good high thermal range external cooler. The only other thing I can think to tell you is that the fluid is cherry red and smells like it just came out of the jug. Oh, and the shop did tell me that the pan and filter were clean when they replaced the boost valves.

I would appreciate hearing your thoughts on what this problem could be or suggestions for further troubleshooting.

Thanks

 

Welcome to TGO

There's a spring shim inside the clutch packs which still softens the application of the clutches. A high performance transmission rebuild will remove that spring shim and install enough steel plates or disks to take up the clearance.

All the shift kit does is reprograms the hydraulic flow and pressure. It can't change the mechanical components. If the transmission has never been stripped down for a complete rebuild, it's possible the clutches are simply worn out.

 

This is my sons car and I'm finishing the work he started. It was originally going to be a restoration project for us until he experienced torque and mayhem; now its destined to be a weekend warrior which is turning me into a weekend worrier. Back to the transmission though.

The transmission had about 15,000 on a rebuild when the 305 was replaced with a 350 and the shift kit was installed. Truthfully, it was an off the shelf transmission from a transmission parts outlet. Not a salvage yard, they sold parts to transmission shops in the area. I don't know anything about the internals and they are now out of business so I can't find out. I just drove it again, and put my foot in it. This is the first time I've driven it in two weeks and its not that bad. It doesn't slip while shifting, my test of letting it build pressure and stabbing the throttle just before shifting didn't change anything. I had an epiphany as I was pulling back into the driveway, I'm comparing the performance of this transmission to a C4 I built back in the day. It was in a Mustang II behind a 300HP 302 with a 2500 stall convertor and backup up by a 3.55 geared posi. This car might have 275HP, with a 1700 stall, and the killer; it still has the stock one-wheel-wonder 2.73 gear. Given this, I'm probably getting everything out of transmission I can expect; a lower gear and posi in this car would make a world of difference. So I've decided to drive it like it is, the all that can happen is I'll have to rebuild it and install a higher stall convertor; worse case - well barring an explosion - is I'll have to replace to cooler and flush the lines as well.