no WOT lockup

[bad V6]

2004r with a 3600 stall Precision Industries multi disc L/U, chip controls the lockup. On the street the transmission and converter do perfect, with very firm shifts and solid lockup at 55 MPH. At the track, 1-2 & 2-3 shifts are at 5750 RPM, and WOT lockup is set for 3rd gear @ 5700 RPM as well (106 MPH), and the datalogs show the converter locking at that time, however it doesn't stay locked. The RPMs pull down to 5300, then the RPM climbs back to 5750 within a few frames on the Power Logger, and RPMs are at 5900 going thru the traps. Anyone have an idea as to why the converter will not stay locked?

 

[GN87Mike]

Mine does the same thing. I had Precision rebuild the clutches and it made no difference. My pump pressure is 260 and I have good oil flow through the cooler. It just about locks on the first run but initially locks then slips just like Patrick's above.

Mike

 

[chris718]

Verify the o ring on the input shaft is good and that the o ring end of the shaft fits into the converter tight so you know the o ring is sealing inside the converter.I had a guy fighting this issue and we had him install our .555 boost valve and pr spring and it fixed it.Using the large boost valve has shown me that converter flow and pressure unlocked and locked up is almost the same,something we have never seen with the stock GN .470 or the updated.500.Removing the ball check in the input shaft also helps get the oil out of the converter during apply of clutch.Oil is fed in to the converter from the converter neck or pump side after the lock up valve has upshifted and the shaft is used to exhaust the oil.If the converter is locked why does it still need to be full?Because we still need lubrication oil and if we didnt when the clutch unlocked the engine rpm would spike until the converter filled again.

 

[TurboDave]

Chris makes good points. My builder made sure all that stuff was right, when he installed my vigilante 7 disc years ago. Although, with that said, If memory serves they put in a .500 boost valve way back then (early 90's). Even after all these years this thing still bangs the kidney's when it locks, even at WOT (mine set to 90 mph wot).

 

[bad V6]

Thanks Chris, I'll get the tranny back out soon and check these items, unfortunately the track is closed now.

My pump pressure is at 275 psi with the .500 boost valve and the check ball has been removed.

Mike, hopefully one of us can figure this thing out.

 

[GN87Mike]

Thanks Chris. I'll check the o-ring and install the larger boost valve. I think I have the .500 now. I hope that does it.

Mike

 

[TurboTnZ06]

I have the same problem, did you guys get it fixed? Just want to know before pulling the unit out again.

Thanks!

 

[GN87Mike]

Mine is fixed. I changed three things that may have corrected it - installed a .550 boost valve - replaced the TCC solenoid - replaced my billet turbine shaft. The reason I replaced the turbine shaft was I discovered the plug that blocks the oil hole through the center of the shaft into two circuits had moved. At BG the converter locked fine on every run.

Thanks - Mike

 

[bad V6]

That's great to hear, Mike. I abandoned the LU converters and went to a PTC.

 

[TurboTnZ06]

Thanks for the info and glad it is fixed.