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Reviewed in the United States on January 21, 2025
I actually didn’t have a lot of faith before ordering. Crazy enough I actually monitored the line pressure for the transmission while driving before and after the install and all I can say is I’m blown away. It actually increases the line pressure quite a bit and made the shifts feel wayyy more solid which helped me a lot towing
Rob 2289
Reviewed in the United States on August 4, 2024
Boosted pressure under towing. Easy to install could feel a better shift. Quick and not sluggish but not harsh.
James E. Arens, Jr.
Reviewed in the United States on October 2, 2024
I have a "low mileage" 2011 RAM 1500 with the 4.7l engine and 545rfe transmission. Current mileage around 99,000. At around 95,000 with very little in the way of hard driving, I developed a shudder in the 3-4 shift @ ~42mph. I saw links to doing a transmission relearn, and found scan tools capable of doing one at home was hundreds of dollars. Then I saw the reference to the Sonnax Line Booster product. Being a guy who watches YouTube videos of a mechanical nature (wristwatch servicing, motorcycle restorations, etc.), I happen subscribe to "Richard at Precision Transmission." I remember how he promotes Sonnax products, so I knew it would be worth a try. I was correct! Even without installing the spring, the shudder is gone and the shift points are different in a way that I like. Whole installation including finding a sheet of cardboard to lay on and washing up after was less than 30 min.
Zach
Reviewed in the United States on January 23, 2024
A good cheap upgrade for your 45 or 545. It's been working great for a couple of thousand miles now. Doesn't firm your shift, just makes it faster. Which I love. Less annoying in between as it goes between gears.
Mario
Reviewed in the United States on November 9, 2022
I drive a 2015 Ram 2500 with the 6.4L engine with a stock, rebuilt, 66RFE transmission. I purchased this hoping it would fix my occasional transmission shuddering problem and it did for only the first drive cycle. I was disappointed the second I opened the package to find the part looks nothing like what Sonnax advertises on their website, one side was even missing one of the red locking tabs, but I held onto my judgement until I at least put it to the test. I know to reset and relearn the transmission, but figured I would try it first just by putting it in and seeing what happens. RAN GREAT! One time, the first time, drove around and felt much better than the transmission has ever felt. Then the second start up the check engine light came on and drove much worse than it ever has. Ok I figure time to relearn it. I did a quick and dirty battery cable disconnect and left them off for about 2 hours. Money light did turn off and ran ok till it warmed up, and then started shuttering like the first time. Unplugged it, went back to factory harness connection and no check engine light like usual but I still have my same issues. Figure it wasn't even worth going through a proper trans relearn procedure with a fancy scan tool.TLDR: Ran good once, not official looking part, gave me more problems than I had, returned to sender
fe
Reviewed in the United States on May 30, 2021
Bought this pressure booster to try and help out some shifting issues and put it in when I did a filter kit on the Trans along with a new shift solenoid pack....short of, this booster caused codes to trigger and put the truck in limp mode....removed this booster, did the quick learn procedure again and no problems since.
Joshua Prewitt
Reviewed in the United States on September 16, 2019
Does as advertised, purchase this and save over BD Diesels same product.
Darrell C.
Reviewed in the United States on November 16, 2019
This is a great product. I put it on my 2018 Ram 3500 6.4 Hemi. It has the 66RFE . With a little work it has lots of power. I will be Procharging it next. The Trans liked to lag between gears or not fully engage. Not sure which. Checked on line. I seen the RFE trans all have this problem, it seemed. After installing your product. It does not seem to lag much if at all. Its so easy to install. Will see in time if it throws a code. As for now it works great. Thanks
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