#37AP – 4L60E 3-4 factory accumulator piston. You will replace a spring or springs in this bore so replace this! This is a very cheap part and should most defiantly be replaced. This will result in fluid loss, delayed engagement, slipping, burned clutches and/or band. Very common for the factory plastic piston to wear or crack. This piston goes in the valve body and cushions the shock when shifting from reverse to drive. #37AP2 – 4L60E Billet Forward Accumulator. Instead of drilling the factory sleeve with the drill bit supplied in the shift kit, you will just replace factory ones with these. 470" and the larger diameter valve will yield a 10% to 15% higher line pressure. This will not remedy the weak 3-4 clutch pack 60E's are known to have but will obviously help (which is the point of this whole write-up) #3 – 4L60E high performance overdrive 4th servo : Made by Sonnax and has a 40% more holding power (fluid apply area) than the factory 4th.
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There is thought you will get a better 2-3 shift from the Superior and Sonnax, but for the money the Corvette is by far the best bang for the buck. I have ran both the Corvette and Superior 2nd in different transmissions and in my opinion one isn’t any better than the other as far as applying. Other options are the Superior and Sonnax 2nds. It has a greater fluid apply surface area which in turn will apply or "grab" the 2-4 band more efficiently.
![4l60e shift kit for towing 4l60e shift kit for towing](https://shiftritetransmissions.com/wp-content/uploads/2015/07/IMG_0054_001-300x289.jpg)
#2 – 4L60E Corvette 2nd Intermediate Servo : This is the servo that comes in high performance Corvettes and Camaros. I will have the part number first, part name, and a little description as to what it is and why to use it. They should be in descending order through the web page. First off, you can easily find 90% of these parts on this website You might have to hunt around a little on the site for the parts but you will find them. I am not at all saying the other parts on the market are inferior such as Trans-Go as many run their product with good luck, but I have not heard anything as far as negative feedback with these. The parts listed below are parts that I have used and have had good experience with. There are a good handful of parts and pieces out there to choose from when it comes to this upgrade. With all that happens inside a transmission it’s hard to tell what’s going to break first with all the variables for a failure. This will not correct breaking of input/output shafts, pinion failure, reaction sun shell breaking, etc. Again this is a process to help the longevity of the stock 60E due to the issues above.
4l60e shift kit for towing mods#
Now for those who ask "will my transmission hold up by doing this for so and so mods / horsepower?" There is not answer to that. This firms or quickens shifts by releasing and applying circuits more efficiently and reducing "overlap".
4l60e shift kit for towing install#
When you install a "shift kit" and servo upgrade you are positively modifying the valve bodies ability to apply and/or direct fluid to the clutch or band apply circuit. As well as glazing/polishing the clutches, steels, drums, band, etc. This generates heat and removes clutch and band lining at a greater rate. This is also happens on a downshift as well.
![4l60e shift kit for towing 4l60e shift kit for towing](https://www.monstertransmission.com/assets/images/4L60E-2PC-Side2.jpg)
So for the short time the transmission is in two gears at once they are essentially "slipping" as one or the other has not fully engaged. When your transmission is shifting into a higher gear, the lower gear has not fully released all the way. For example, when you ride your brakes while driving the pads will fail and wear a lot sooner and generate heat right? Take that and convert it over to what happens in a transmission. On a bone stock transmission, overlap is referring to the softness between upshifts (1-2, 2-3, 3-4) and also downshifts. The best way to describe this (at least that I can describe) is to use the word "overlap". What is the point of a shift kit/servo upgrade? But if you do your research, read carefully, take your time, keep things organized, clean, and double check your work it can be accomplished. Transmissions can be intimidating due to all the small parts and the amount of parts internally. Personally if you are mechanically inclined and have basic hand tools YOU CAN DO THIS. For all you guys wanting or wondering about how and what it takes to upgrade your 4L60E and 4L65E transmissions, this will give you an idea of what you will be getting into.