I am getting ready to rebuild my 4l60E what are some mods I can do while I'm in there this will be for my towing vehicle. I remember seeing something about drilling the valve body plate but can't find it anywhere.....

Thanks Mark

 

What are you driving (vehicle, horsepower, etc)?

Is this strictly daily driver with some towing or will it also see a track?

What's your budget, and does that include getting a new torque converter?

Have you rebuilt a transmission before?

 

This is a stock 2003 Yukon XL I have rebuilt several 4l60 and 4l60e but I have never done any mods other then drilling the drain hole behind the pump seal .... I just got this vehicle and I was originally led to believe that this was a 4l80e then once I picked it up I found it was a 4l60e ... This will be used to tow a camper and boat....

 

I'm sure others will chime in, but beyond the usual things to do during a rebuild of a stock unit (like a shift kit and new clutch packs) I'd say both the Sonnax 2nd and 4th servos, heavy duty 2-3 shift valve, transmission cooler, and a wide band.

 

Quote:

Originally Posted by markhodges78

I am getting ready to rebuild my 4l60E what are some mods I can do while I'm in there this will be for my towing vehicle. I remember seeing something about drilling the valve body plate but can't find it anywhere.....

Thanks Mark

There is no constant really for plate hole sizes for a towing application too. I spent a lot of time looking and some people really open up the holes a lot while others recommend only minimal increases.
I saved a few quotes from different forums that talked about the holes for truck / towing applications. I didnt save the complete post so I cant tell you who's the author, sorry.

Quote:

With the stock diameter torque converter, the 2nd gear feed hole in the separator plate (this is with the Corvette servo) should be .076" with .086" maximum. The part throttle shift will get too firm with anything larger than this, and will be very hard on the splines on everything in the gear train.

Quote:

A .093" orifice will give you a nice, firm 2-3 shift with the 3-4 clutch setup listed above and a Corvette (or better) 2nd servo set up at about .070-.080" servo travel. I use a .110" in many street rod setups. A .125" orifice will work well with a very loose converter, but would be pretty abusive in a truck application.

I used .082 for the 2nd feed and .093 for 3 and 4. I am not an expert but in this case the shift feel is firm but not too bad for 3-4. I think I would have gone with the .076 for the 2nd feed if I had to do it again. I put in a superior shift kit and a Sonnax .490 boost valve in at the same time, so they had something to do with the change in feel too.

For other parts just for a quick list Sonnax's HD build list is an easy link.
http://www.sonnax.com/tech_resources...charts#pickups

They just released the #74140-01K last week.