These transmissions are incredibly reliable with stock to mild engine power levels. That's why GM started using them in the 80's under the name 700R4 and continued on for decades afterwards. They simply work. Over the years they saw many subtle improvements and were rebranded as 4l60 and later the 4l60E. Add superchargers like I see on your truck or other big power items, they aren't gonna last as long. The Corvette servo only helps raise the pressure on the 2-4 band, meaning only 2nd and 4th see a benefit. It doesn't correct the other weak links inside the transmission such as the sun shell. There are kits out there that replace those so they hold up under more power. The reason they get a bad name is because of people who don't read the owners manual and try towing in OD. These are designed to be placed in 3rd under heavy load, otherwise they can potentially destroy themselves in mere minutes. If towing in this manner, they will operate as intended for years. Please note, the fluid and filter should be changed at regular intervals regardless of power levels(15-100k miles depending on the year). My personal recommendation is 50k maximum between changes, even in the Dexron 6 era, particularly if the vehicle is driven hard. Also, not all 4L60's were designed for the relatively slippery, synthetic dexron 6. Adding dex. 6 to a 4l60 that was meant for Dexron 2 or 3 is going to lead to more clutch pack wear. You wont even notice it's happening until your next fluid change interval and you see how dark the fluid has become and how much excess debris has stuck to the magnet compared to previous fluid changes. If you don't believe me and still want to change from earlier non-synthetic dexrons to the newer Synthetic Dexron 6, then you'd want to do a full flush to clear out the old fluid. The pan/filter swap only replaces(IIRC) 4 quarts but the torque converter, valve body, oil pump, clutch packs, case, etc combined all hold just as much. Plan on buying 12-14 quarts for a thorough flush because its a process of dilution to remove the old fluid, rather than a straight drain and refill. This ends up costing more than $60 and is tricky to do without shop equipment, though not impossible.
I’ve had great success with my current set up for many years of abuse on multiple different boosted applications around that 500hp range. Even when towing in 4th gear. Much over 500hp and the reliability definitely goes down. Raising the line pressure is key. Personally I would NEVER run a dexron 2 or 3 ATF. Dexron 6 only! It provides better fluid performance and doesn’t break down with higher temperatures as quickly. It’s just a better quality fluid all around. Fluid technology has came a long way over the past 20 years. Why use a fluid that’s extremely outdated?
You did yourself a favor with the corvette servo and I agree fluid pressure is key. But most 4l60's don't have that and with stock fluid pressures under heavy loads, 4th gear is not ideal or intended for towing. Especially in trucks models that, stock, don't even have enough line pressure for 4th gear WOT upshifts. Theres a reason GM used beefier transmissions in it's towing rigs. As for Earlier Dexron's vs 6, I'll share a personal anecdote. In 2010 I bought a 1990 Firebird with a 5.7L and 700R4 with only 30k miles. I promptly did a filter change and flushed the 20 year old fluid out with new Dexron 6. At 60k miles I did a filter change. The fluid was black with a red hue. Debris almost half the size of a golfball had accumulated on the magnet. The transmission still operates properly but I expect it to have a shorter lifespan. I went back to Dexron IIE after that discovery because that's what those clutch packs and those line pressures are designed for. Dexron 6 is a thinner fluid with different frictional properties and materials compatibility. Maybe not all transmissions will suffer as much as my 1990 model did, but the change is not without risk and I just wanted to caution the viewers with my own experience before they made the choice. Some builders actually recommend decades old Ford Type F in 4l60's for its increased friction, but I've never been bold enough to try it when doing 4l60 rebuilds. I'm glad its worked out well for you, and I'd add your truck is pretty dang nice from top to bottom. I'll close by saying: if you're ever towing and the trans is frequently upshifting and downshifting between 3rd-4th, save yourself a potential headache, and put it in 3rd. @@JT2JZ
It's best to change the boost valve to a .500 snd a Vette servo swap..a transgo kit also helps tremendously. Im running 600 dyno hp on a 383 Chevy with this combo. Its stsyed together 7 years and counting.
I saw somebody else's video and they did the Corvette servo but they also change some valve thing with Springs like a cylinder about the size of your finger. They call it a mod two, cheers Graham
I rewatched other video and it's .500 boost valve. What do you think about installing one of those valves? They said it increases pressure through the whole system. So about $60 AUD, cheers Graham
No in stock form behind a stock LS those transmissions are good for 2500,000 Mi plus. The problem is with minor bolt-ons you can easily send the power will passed its rating. Attuned 4.8 with mild Cam and good headers will hit 450 horse 420 torque, a 5.3 easily goes 500. And since the 4L80 and the 6l80 are so much larger and they don't fit well behind some of the smaller transmission tunnels in a retrofit you pair of 6.o with minor bolt ons and a 4l60 and full send you get transmission salad.
Nice video, great info..the info on the line preasure is great, what kind of supercharger? And how much did u give for it? And it be a cool video on install of one, with part numbers...thank you
It’s a very old supercharger that has been discontinued now ( magnason mp112 ) it’s a 1.9L displacement. I bought it used for very cheap back in the day. New kits are $10,000 if not more.
I love the stance on your truck. Looks close to stock which is what I wanted to maintain. What suspension do have, or did you have at the time of recording?
Is that literally all you have done to the transmission? My truck has 215k, bone stock right now and plan on throwing boost at it eventually. Wasn’t sure if I should just go ahead and build it out.
Yup. Transmission has never been removed from vehicle. Just a vette 2-4 servo and raised line pressure with efi live tunning. The truck has ran a 13.6 in the 1/4 mile and I’ve never had a single issue. Been running the set up for many many years.
The servo has a larger surface area for the fluid pressure to push on. This will give you more holding / clamping force in 2nd and 4th gear. The added pressure amplifies the corvette servo effectiveness. Raising the pressure without the servo will still help but the servo was literally $41 so it would be silly not to install one at that price.
Do u get belt slip and if so how do u eliminate that . I went with an rpm belt and changed out the top pulley with a griptec supercharger pulley it was supposed to bite on the belt better but I still get belt slip ? Any tips???
I have been lucky and don’t get any belt slip. Make sure your belt tensioner is working correctly. You can also try a bigger blower pulley ( more surface area to prevent slip ) but your boost pressure will go down. Put an overdrive crank pulley on instead to up boost pressure.
Correct. Nothing wrong if you want to add a shift kit as well but I have had great success with my current setup. Just raised line pressure with an efi live tune and the 2-4 corvette servo! ( the 2-4 servo is extremely important! ) It’s held the power of my supercharged LQ9 6L for many many years and the fluid still looks brand new.
