9 second wall and advice to help bust through............

Big Blue24 said:

If you run the 48re stator seal, converter pressure will closely follow line pressure and 200+ psi will balloon the converter which can wipe out the pump, crank thrust bearings, or cause other general mayhem in both the converter function and other portions of the transmission itself. Simple fix, remove the 48re stator seal when running 200+ psi. Without the seal you'll have a little less line pressure but the converter will be much happier.

The torque converter switch valve serves a dual purpose as a torque converter pressure regulator when not in lockup. When you stage the truck and have over 150 psi line pressure, the converter pressure usually exceeds the regulation target psi and the regulation function starts to kick in.... unfortunately this causes the lockup clutches to drag. There are a few "proprietary fixes" that have been developed to prevent this problem. I won't go into detail on an open forum, for respect to the craft of building high HP diesel race transmissions but if you call-in, we'd be more than happy to help you privately understand what needs to happen with your valve body to fix the problem. The dragging lockup clutches are most likely making the debris plugging your filter.

Third, with a mechanical injection Cummins engine with fixed timing, you generally need much higher stall speed to get big chargers lit than an electronically controlled variable timing engine. This means you're going to be using stall speeds not commonly used for a Common Rail so you might not get the correct help if your tranny VB Builder has little to no experience with high rpm stall speed setups and the myriad of weird tranny issues that come up with these setups. We've found that even if the regulation function of the converter lockup switch valve is defeated or altered, once staging RPM exceeds 2800, a "proprietary" converter dump valve is necessary to keep the lockup clutches from dragging. Basically, to hold a big nasty launch on a race truck, you typically need more than 150 psi line pressure to keep the tranny from slipping at the the starting line when stalled up against the converter. When the converter is fed higher line pressure, at 2800+ RPM, the lockup clutches start dragging. Some builders are focusing on regulating the converter feed, others are simply telling their customers to get a lower stall and spray it to light the chargers. We came up with a trick dump valve setup... We literally spent hundreds of hours on this problem and burned up several converters in the process before we developed a reliable fix. We went as far as putting a transbrake in the Junker so we could test 60+ psi boosted launches (way more than the rear brakes could hold without transbrake assistance) to replicate the forces we were seeing with the triple GTX55 charger 6.8L UCC engine setup.

One final bit of advice, once you get your trans working properly, you will probably pick up some trap speed/power to the track. However, if you're not trapping 138MPH or so after the trans fix, you're still a little short of a reliable 9 second setup. No sense killing it every launch and hurting parts if it continues to see sub 138 MPH trap speed. Obviously most of your time is made up the first part of the track so suspension mods that produce reliable and repeatable 60' and 330' times will be key for reliable 9 second times and reliability in the transmission hard parts. My truck only runs 10.50's and 60's at 134 to 135 MPH, but rather than kill it chasing 10.2's or 3's, I'm spending time upgrading the suspension and power so I can easily get into the 9's without bouncing from wicked hard glory pass launches that may or may not hook. I knew my suspension was not ready for "big power" so focusing on getting reliable tune-able suspension now!

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T-MAN said:

Kinda don't know how to reply to this one.....your referenced pressures and my staging habits fall right in line with what's going on with my trans... Old valvebody and new...looks like a phone call is in order, Thank you for the reply... and thank you to everybody else who jumped in. next up is the power to hit the 9s.. I know jeff :nos: lol you kill me everybody is doing it...

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Mudn_1 said:

Yes, Torque Converter clutch is dragging. I had this same issue last season. I dont know the technical term, but when I built boost on the line it would blow a valve open in the VB that fed the lockup circuit causing the converter to drag... sending gravel material into my coolers and filter.

once you get this cured, you will need to flush your coolers with a hotflush machine.

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Mudn_1 said:

Yes, Torque Converter clutch is dragging. I had this same issue last season. I dont know the technical term, but when I built boost on the line it would blow a valve open in the VB that fed the lockup circuit causing the converter to drag... sending gravel material into my coolers and filter.

once you get this cured, you will need to flush your coolers with a hotflush machine.

Click to expand...

Big Blue24 said:

If you run the 48re stator seal, converter pressure will closely follow line pressure and 200+ psi will balloon the converter which can wipe out the pump, crank thrust bearings, or cause other general mayhem in both the converter function and other portions of the transmission itself. Simple fix, remove the 48re stator seal when running 200+ psi. Without the seal you'll have a little less line pressure but the converter will be much happier.

The torque converter switch valve serves a dual purpose as a torque converter pressure regulator when not in lockup. When you stage the truck and have over 150 psi line pressure, the converter pressure usually exceeds the regulation target psi and the regulation function starts to kick in.... unfortunately this causes the lockup clutches to drag. There are a few "proprietary fixes" that have been developed to prevent this problem. I won't go into detail on an open forum, for respect to the craft of building high HP diesel race transmissions but if you call-in, we'd be more than happy to help you privately understand what needs to happen with your valve body to fix the problem. The dragging lockup clutches are most likely making the debris plugging your filter.

Third, with a mechanical injection Cummins engine with fixed timing, you generally need much higher stall speed to get big chargers lit than an electronically controlled variable timing engine. This means you're going to be using stall speeds not commonly used for a Common Rail so you might not get the correct help if your tranny VB Builder has little to no experience with high rpm stall speed setups and the myriad of weird tranny issues that come up with these setups. We've found that even if the regulation function of the converter lockup switch valve is defeated or altered, once staging RPM exceeds 2800, a "proprietary" converter dump valve is necessary to keep the lockup clutches from dragging. Basically, to hold a big nasty launch on a race truck, you typically need more than 150 psi line pressure to keep the tranny from slipping at the the starting line when stalled up against the converter. When the converter is fed higher line pressure, at 2800+ RPM, the lockup clutches start dragging. Some builders are focusing on regulating the converter feed, others are simply telling their customers to get a lower stall and spray it to light the chargers. We came up with a trick dump valve setup... We literally spent hundreds of hours on this problem and burned up several converters in the process before we developed a reliable fix. We went as far as putting a transbrake in the Junker so we could test 60+ psi boosted launches (way more than the rear brakes could hold without transbrake assistance) to replicate the forces we were seeing with the triple GTX55 charger 6.8L UCC engine setup.

One final bit of advice, once you get your trans working properly, you will probably pick up some trap speed/power to the track. However, if you're not trapping 138MPH or so after the trans fix, you're still a little short of a reliable 9 second setup. No sense killing it every launch and hurting parts if it continues to see sub 138 MPH trap speed. Obviously most of your time is made up the first part of the track so suspension mods that produce reliable and repeatable 60' and 330' times will be key for reliable 9 second times and reliability in the transmission hard parts. My truck only runs 10.50's and 60's at 134 to 135 MPH, but rather than kill it chasing 10.2's or 3's, I'm spending time upgrading the suspension and power so I can easily get into the 9's without bouncing from wicked hard glory pass launches that may or may not hook. I knew my suspension was not ready for "big power" so focusing on getting reliable tune-able suspension now!

Click to expand...

RacinDuallie said:

Sorry 2 part question on your statement, who's valve body you running?

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Mudn_1 said:

Lavon/ Firepunk. they are pretty familiar with this issue. but I can tell you... I also went from a DPC Slut Converter to a 2800 Stall. Completely different truck.

if you shift into 2nd at idle and hit lockup, the converter wont lock....but if I tap the throttle it will engage and die.

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Timbeaux38 said:

DON'T YOU CALL HER A SLUT!!!! SHE IS JUST TRYING TO FIGURE OUT LIFE!



You just liked hotflushing.

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9 LIVES said:

Wow awesome info ! First class guys there at PDD

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T-MAN said:

I spoke with Will, he fought this issue last year with his truck,,, burned up quite a few converters and a ton of time to find a fix that works. Actually he has 3 ways to fix this problem and was nice enough to share them with me. Im going to test the simple method this Friday and report back. Out of respect for Will im not going to post them on an open forum. Im going to say that Will is a great guy, good at what he does, has a ton of knowledge and doesn't mind helping a fellow racer... Thank you again for your time Will . I will report back this weekend, Thanks for all the replies guys.....

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RacinDuallie said:

Going Friday?? :tree:

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T-MAN said:

im hoping, just waiting on nitrous express....*nx*

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