6.7L Cummins Forum

Just had my 68rfe rebuilt, 107xxx miles. Long story short, my od clutches burnt. I change my tranny oil every 50,000 miles and have a Mag-Hytec deep pan on tranny. I had the trans repair shop put on a Sonnax Line Pressure Booster. It has definitely firmed up the shifting, especially with heavier throttle use, under light throttle though, you can hardly tell. Its not enough that a passanger would notice, but a driver should be able to tell the difference.


Repair shop said most trannys nowdays for econmy reasons shift up to higher gears at to low of an rpm. Best thing is to manually keep truck in lower gears when in town and use higher rpms, it will safe the clutches. The od actually acts like a splitter on the 3 gears in the 68rfe to give the 6 speeds.

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If you bad mouth farmers just make sure your mouth is empty
07.5 2500 quad, sb, auto,4x4, Big Horn. wheel to wheel nerf bars, amp bumper step
08 Jazz 36' 5er, 12,000lbs
28' PJ gooseneck,22,400 gvw

Looks like I've been treating my tranny right but for different reasons.........the DPF. Anyway, I went ahead and ordered mine. For less then $40 and just a plug and drive install you really can't beat the price for the insurance. Thanks!

68RFE Electric Line Pressure Boost 68RFE Transmission Pressure Booster Sonnax 44957-LB1 I've included the install PDF down below.

Attached Files

44957-LB1_LB2-IN.pdf (126.7 KB, 13 views)

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2007.5 Dodge Ram 3500 HD,QC, 6.7L Cummins, 6speed Auto, 4X4, Bighorn Edition.
Click for installs: Carr Steps PML Diff Cover Edge Juice with Attitude Volant Intake Hankook ATM RF10

FYI After hooking up you will notice the most improvement after a day or 2 of driving. It seems it takes awhile for the TCM to learn and reprogram itself to adjust for the Sonnax.

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If you bad mouth farmers just make sure your mouth is empty
07.5 2500 quad, sb, auto,4x4, Big Horn. wheel to wheel nerf bars, amp bumper step
08 Jazz 36' 5er, 12,000lbs
28' PJ gooseneck,22,400 gvw

I installed one maybe a year ago I do like it.

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CUMMINZ NC
2007.5 CTD, QC-DRW 3500 BFT Laramie, Smarty S-67, AMSOil Dual-Gard Bypass, Custom Line-X 4x4, 4.10LS, 988s, 68rfe, MBRP 5", Mobil Delvac. Yukon free spin, 19.5x245 G647 Goodyear's - 2006 - 37RLTSD Cedar Creek-Day Dreamer
My 2007.5 DRW Truck at www.CumminZ.com

I've had one the Sonnax boosters installed since the spring. It is an improvement but not as much as I would like. TransGo now has a shift improver kit for the 68RE. I'm going to install one of these with the updated throttle body.

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2007 Ram 2500 QC 4x4 SLT TRX4-Offroad 6.7L Automatic. '08 Jeep WK 3.0L diesel-wife's DD.
1998 Jeep ZJ 4.0L Automatic Selectrac-project for our son. '98 Jeep XJ-my wife's former DD.
1965 Dodge Polara 880 Convertible 383 Automatic.