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 4L60E 3-4 clutchpack upgrades FYI

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sherlock9c1



Posts : 2089
Join date : 2009-05-28
Location : Huntsville, AL

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PostSubject: 4L60E 3-4 clutchpack upgrades FYI   4L60E 3-4 clutchpack upgrades FYI Icon_minitimeThu Dec 14, 2017 10:32 am

Hey everybody,

As most of you probably know, 3-4 clutchpack failure is a common occurrence in these cars. I've paid attention to this problem for literally years and I think it's finally properly understood and licked. In the early days most thought it was the clutchpack itself that was inferior. Thanks to a lot of detective work by the good folks at Sonnax (and probably others) the real culprits have been properly identified as valvebody wear and clutchpack distortion due to the design of the retainer plate.

Now with such great tools as Youtube and the availability of new Sonnax parts, the average DIY car owner can successfully replace the 3-4 clutchpack, upgrade the retainer plate and the valvebody with NO special tools.

A few years ago Sonnax introduced the "Smart Tech Input Housing" for the 4L60E which eliminates clutchpack distortion but it's overkill for anybody whose powertrain is nearly stock. I do know they were testing that in a boosted AWD Trailblazer SS that was consistently running 11s in the 1/4 mile, just to give you a sense of why YOU probably don't need that part, plus you'd need a lot of special tools and seal installers.

A cheaper and easier option is the Heavy Duty 3-4 Clutch Backing Plate Kit . The next 4L60E I'm in, I'd seriously consider installing this in, along with the specified clutchpack.

I'd also recommend installing every Sonnax valvebody upgrade valve available for the 3-4 clutchpack circuit to minimize leaks and keep pressure up in that circuit. Some may require reamers and other expensive tools; you may want to see if a local transmission shop has them and is willing to install those valves for you. Otherwise you can rEbay them when you're done.

Also, if you have snap ring pliers, I'd highly recommend installing the Smart Shell sunshell. It is by far the best designed aftermarket sunshell on the market.

Add that stuff and a 4L60E-HP-01 kit and you'll have yourself a very reliable 4L60E.
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sherlock9c1



Posts : 2089
Join date : 2009-05-28
Location : Huntsville, AL

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PostSubject: Re: 4L60E 3-4 clutchpack upgrades FYI   4L60E 3-4 clutchpack upgrades FYI Icon_minitimeWed Jul 11, 2018 1:39 pm

Another great article from Sonnax here..

There's no excuse for a rebuilder not to have the 3-4 clutchpack problems licked, whether it's a national chain (I've had great success with Jasper transmissions) or a local mom and pop (show them this article!).
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Brandt51

Brandt51

Posts : 112
Join date : 2017-08-14
Location : Las Vegas Nevada

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PostSubject: Re: 4L60E 3-4 clutchpack upgrades FYI   4L60E 3-4 clutchpack upgrades FYI Icon_minitimeWed Jan 30, 2019 12:31 am

What about the Z-Pack with a valve body upgrade?
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sherlock9c1



Posts : 2089
Join date : 2009-05-28
Location : Huntsville, AL

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PostSubject: Re: 4L60E 3-4 clutchpack upgrades FYI   4L60E 3-4 clutchpack upgrades FYI Icon_minitimeWed Jan 30, 2019 12:51 am

I've used the Zpack before (I had it in my 9C1 for years) and it works, but it doesn't solve the real issue which is flexing and coning of the whole clutch assembly.  If you do a lot of full throttle 2-3 upshifts you may wear it out sooner. That said, I put all the goodies in my 9C1's transmission and it ran perfectly every time, including over 100 quarter mile passes and some road racing (albeit stock motor, stock torque converter and street tires).

See this video.  

Looks like the Zpack is around $60 on ebay right now. The Sonnax 74140 heavy duty backing plate is around $100 as I write this, and new GM 3-4 clutchpack isn't very expensive at all. Doing this would be fine for a nearly stock B-Body.  If it was me I'd buy the Sonnax plates and a new GM high energy 3-4 clutchpack setup (per the Sonnax instructions, as GM has several different 3-4 steel plate thicknesses available, FYI).

If your future HP/Torque level is over 450, I'd strongly suggest the heavy duty input drum. It alone is $500, but you'll never ever have to worry about a 3-4 clutchpack ever regardless of power level. One shop visit can cost that much. I will be putting one of these in an upcoming build.
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PostSubject: Re: 4L60E 3-4 clutchpack upgrades FYI   4L60E 3-4 clutchpack upgrades FYI Icon_minitime

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