I have 120,000 miles on my stock 2001 5.3 and 4l60e and I'm wanting to add a mild cam, headers, and a custom tune. Will this kill my transmission, and if so, what are some things I need to do to beef it up? This is my DD so I really don't need the trans to die on me. Eventually, (maybe next year) I'd like to a 6.0 and 4l80e swap.

 

There really isn't a cut and dry answer. Honestly man at 120k miles it could give out on you right now in stock form.

The 4l60e from the factory is pretty weak. It's not bad behind a 3300 pound car, but behind a 5000 pound truck it's a ticking time bomb behind anything over 300 rwhp.

 

Even in stock form, it's almost like i'm just waiting for it to go out, because I know it will at some point. I've seen a couple of rare occasions in trucks where they actually went over 200,000 miles and I've seen some in stock trucks only last 30 or 40,000 miles.

 

I'm kinda having the same thought as you, although I only have 83K on mine, and mine's not my DD, but I'd like the tranny to hold up for a few more years.

I plan on getting a TransGo shift kit, servos, and change the fluid to synthetic for a cooling running tranny and just hope it hangs in there.

 

Running synthetic doesn't seem to do much from what I've read. There's guys pushing over 500 rwhp in their 4l60es running the cheap Autozone brand Dexron III

 

You're probably right, but I believe heat is the killer for the 4l60's and keeping it cooler couldn't hurt...

 

From what I've read mostly here, synthetic trans fluid is not recommended in the 60E, I believe that both FLT and Performabuilt recommend against it.

As far as trans life goes, I just smoked my stock trans at 59,6XX miles, with mods in sig. The truck has had the cam and has been tuned since about 37K, with no torque management...so I got about 23K of abuse out of it before it puked. I believe that the torque converter clutch let go and sent debris throughout the trans. Trans was never overheated btw, and currently has a 17k PermaCool trans cooler on it...

 

True, but instead you may want to look into a larger transmission cooler. I have a 30k and the stock on mine.

 

Thanks for the info. Yeah, I read no sytnetic for the rear end, too. Makes things cheaper, that's for sure.

Ok, done stealing the thread!

 

If it's a G80 you want synthetic with no additive, if it's a TruTrac you want dino (not sure about the additive but I believe none), as for an Eaton LSD, I'm not sure...