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There have been a lot of failures with late model input sprags on newer ’07 – ’08 vehicles and some design changes. I heard recently of a plastic cage design. At this point I am not sure which one is failing but I do have some preferences I will share. The key to making a sprag live is keeping the inner and outer race concentric. Once they are off center from each other the life is short. For this automotive application it is the sprag end caps that keep the two races concentric. Of the more common 4L60E designs there was the SKF with stamped (rounded) end caps and the BW with machined (squared off) end caps ( I think I have the names correct). Anyway, I prefer the style wiith machined (squared off) end caps as I feel this gives better support to the races and keeps them on center with each other. Also, you may want to consider the Sonnax 2-3 shift valve 77754-41. This brings the over run clutch on in D3 (1st & 2nd ) gears will add durability top the input sprag, forward and over run clutches. I D3 it makes the 4L60E work like the older 700-R4.

Hope this helps,
Gregg Nader
Sonnax Tech
 

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I prefer running high energy in the o-run, but have not been able to find them new, only good used. I believe GM went across the board with HE then backed off and went back to paper in the non-shifting clutches to save money. I have devised a way to potentially get 50% more friction into the o-run, but this would require some expensive custom clutches and I have just not heard that many looking for it.

As for other stuff for the 4L60E, we have a lot, just check the performance section of the Sonnax website. All 4L60E parts are categorized into valve body, pump, servo, other/internal etc. making finding parts easier than before. More new stuff is on the way too. Notable parts are a Teflon rear stator bushing, input housing reinforcement sleeve and a billet aluminum forward piston.

Gregg
 

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Gregg, what's wrong with the stamped steel forward piston set that you made a billet forward piston?

The Sonnax input housing reinforcement sleeve can only be used with an aluminum o-run piston. Aluminum o-run piston should only be used with aluminum forward, not stamped steel. OE aluminum forward breaks, thus our billet forward brings max durability.

Gregg
 
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