Finally got around to doing some line pressure checks. Found out a few things that with a little input, I could hopefully cure. I've noticed my 2-3 shift has always been a little soft at WOT. With that said, here are the pressures.

Idle 120 psi
Reverse 240 psi WOT
1st 230 psi WOT
1-2 shift 230 psi WOT
2nd 230 psi WOT
2-3 shift psi drops just before the shift to 120 psi and recovers to 150 psi after the shift WOT. During normal driving in 3rd, rolling into the throttle, psi follows the throttle to 220 psi WOT. My best guess is some sort of a problem in area of the 2-4 servo. Tranny has a Transgo HD2 kit and a vaccum modulator. Experts please chime in.

Mec

 

Why would you suspect the 2-4 servo? Kind of confusing… pressures running 120-150 after shift recovery then you go on to say 220 wot. Help me to understand, running pressure will drop as you get into the gear, then will hop to 220 wide open throttle? Every time it shifts you’ll have pressure drop especially in 3rd gear, you’ll notice that it doesn’t drop quiet as much in 4th and the recovery time is faster. Back to your problem, from what you’re telling us these seem to be good pressures, I don’t see extreme pressure lose; there are many factors to a good firm 2-3. Clutch clearance is a major issue on shift firmness, feed hole size (sometimes bigger isn’t better), as well as accumulator circuit just to mention a few. In short I don’t see pressure being your problem. Hope this helps Dave

 

Sorry Dave, I needed to be a little clearer. When the 2-3 shift occurs under hard acceleration (WOT) there is a pressure drop. It happens just before you can actually "feel" the shift. The drop does not happen at the same moment of the shift (compared to the 1-2 shift when the slight drop happens pretty much at the same instant as the shift). You can almost get a "one" count between the drop and the actual shift. Its probably just me but I dont remember seeing such a lag. As far as the pressures, let me try again. When the 2-3 shift psi drop occurs its not just a "bump and recover" kind of thing. At the top of second with approx. 220 psi, picture the pressure drop to 120 psi and just hanging there for about a "one" count before the actual shift and recovering to 150 psi after the shift. (Sorry to ramble but its kinda hard to paint a mental picture of the situation) Now, picture a normal 2-3 shift under normal acceleration. After 3rd gear is established, I roll into the throttle the line psi will rise just over 200. Solid and normal. The 3-4 clutch pack clearance was .038 and I drilled the feed hole to .135. When I mentioned the 2-4 servo area I was kinda grasping at straws, thinking maybe the 3rd accum. check ball might be leaking. I replaced and leak checked it during the build (but trash could be stuck in it kind of thing). Turbine shaft and stator seals were also replaced and air checked thru the pump to make sure there were no cross leaks. Just thinking a 100 psi drop is a little much. Building is a hobby for me and I'm just trying to get a better understanding. Inform the uninformed.

Mec

 

Can anyone add anything? Dave? Dana? Vince? Chris? If you think I'm crazy and the only problem is me just trying to create a problem and there really isn't one, please say so. Maybe it's me that needs diagnosed! lol

Mec

 

we typically don't see 100psi pressure drop on a shift,which would lead me to belive your leaking in the servo area , or past the third accumlator circuit, having said that it could be anywhere in this circuit ...the most we typically see is like 80 psi....but I suppose 100 could be okay ..kinda in between here, as long as your recovery is an okay pressure... Get out of drive and put it in over drive...this is where you should be testing...when your in third you've gotta deal with the coast clutch ...this circuit could be leaking off as well ...get into 4Th to eliminate this troublsome circuit...See what it's doing there..Hope this helps.... Dave