4L60E Complete Rebuild

[vlad01]

Yeah I have seen this a lot with LS specifically which seems to an issue with LS mainly, because it happens with manuals too under a heavy clutch on them.

I'd say the V6 is pretty safe from the tear downs I have done with decently heavy clutches and zero evidence of wear, but a clutch isn't pushing 24/7 when driving and more intermittent, so I agree with The1 to be cautious of that thrust bearing.

[immortality]

Something else I'm not sure about is the relationship between line pressure and converter charge pressure.

[The1]

Not sure. One other thing the PCM on our models does poorly to is apply rate and release rate, i think factory is about 30% pressure, so it's real slow apply and release rate which isn't good, i think from memory i upped mine to 80% or so playing with it by feel so it engaged quick but without a bad feel, rather than slowly engaging which would cause wear and heat.

[V8fan]

I was talking about the thrust bearing on the engine crank shaft. Excess line pressure in the converter pushes the converter forward into the crank and conversely the crank thrust bearing takes a beating.

Seen a few US guys killing thrust bearings with high line pressures (not specifically with our V6 motors but can't hurt to be careful).

There is one thing
When ur converter is balooning and start pushing crank - it cant do it by jedi power
It needs to some anchor point to apply force
And this 'ground" is tranny pump rotor
I doubt that powder metal (rotor was made) can withstand such force and even not damaging aluminum pump case
Even so - proper gap between converter and flex is the key
And no matter how big is ur engine
Tranny works at same pressure under same rpm no matter what engine
With shift kit and bigger boost valve line pressure at WOT will be at least 16 bar (230PSI) -I measured
I personally drove with sonnax limiter and with blocked valve -have zero traces inside pump case
Maybe if I add washers to make gap between flex and converter close to 2-3mm as many suggested to provide full length contact between converter and pump ...
But I have it 4 or 5 mm (dont remember exact number)

[immortality]

I don't disagree, the converter has to push back against the transmission. But does it push back against the pump? If the converter is spaced out correctly it shouldn't. I have seen one racer who had problems with the trans when the converter wasn't spaced correctly and it pushed back against the pump bottoming out.

But I've seen videos of the high dollar engines with damaged cranks from this problem. So much so they fit rollerised thrust bearings (torrington bearings) to prevent it from happening.

On the latest GM engines they only have the thrust bearings on one half of the bearing.

[V8fan]

Maybe with race engines that goes over 7k it is a problem
But for daily driving street car with big gap (mine from factory was 7 mm ) its not a problem to block TCC valve
I changed TCC to lock from 60kmh to whatever it can
If I pushed throttle hard -it downshifts to 3rd or 2nd and unlocks it immediately
But I dont need it unlocked at 4th at all

[immortality]

Ohh definitely, turbo cars that require lots of revs and spend ages sitting on trans brakes to build boost on the starting line is hard on everything.

I'm locking the converter as soon as possible on mine, drives much better. I'd be happier if I could lock it in 2nd.