clutch not disengaging (lm7 + hm290)

[Sprocket454ss]

My clutch is not disengaging when I press the pedal in. I did the nfw1050 flywheel and luke 4-201 clutch kit. I can row through all the gears when the truck is sitting still, pressing in the clutch helps a little bit with this. If I fire it up in first gear with the clutch pressed in (I may be imagining things) but I think I can feel the clutch starting to disengage. The slave cylinder is pushing the fork so I don't think that's the issue. Now let's get to the part where **** got half-assed, I am using the stock oil pan on my 5.3. I'm not sure if it's just the hm290's that have this problem or if the nv3500's do too. The external slave cylinder hole on the tranny is placed too close to the bottom of the pan so the cylinder hits it. I shaved away a little bit of the pan to make it sit more "flush" instead of buying an ls swap pan. I also can not remember if I put a new throwout bearing in my tranny when I did the swap (still the sbc throwout bearing) could there really be that big of a difference between the sbc and a ls throwout bearing that it would no longer allow the clutch to disengage?

 

[Erik the Awful]

The throwout bearing is not the issue. It will likely make rumbling noises long before it seizes. If it does seize up, it spins around and wrecks everything inside the bellhousing.

Fix the slave cylinder fitment. "More flush" /= flush, and you need it flush without rubbing on the pan, at all.

If the pilot bearing is bad, the crankshaft keeps the transmission input shaft spinning, making it hard to shift. If fixing the slave cylinder doesn't solve your problem. I would suspect it.

 

[Sprocket454ss]

The throwout bearing is not the issue. It will likely make rumbling noises long before it seizes. If it does seize up, it spins around and wrecks everything inside the bellhousing.

Fix the slave cylinder fitment. "More flush" /= flush, and you need it flush without rubbing on the pan, at all.

If the pilot bearing is bad, the crankshaft keeps the transmission input shaft spinning, making it hard to shift. If fixing the slave cylinder doesn't solve your problem. I would suspect it.

Ok, That'll be the first thing I do, its also the easiest, But my throwout bearing isn't making any noise. When you put an nv3500 behind an ls you need this specific type of throwout bearing is what another source told me. But when I press my pedal down all the way it doesn't even go to the floor, there is some weird stuff going on.

 

[Erik the Awful]

I'm a big fan of doing things on the cheap, but if there's a reason they're recommending special parts for the swap, it's time to start working some overtime to buy the parts. It might be a throwout bearing issue if the throwout bearing can't move far enough to completely disengage the clutch.

 

[Dropped88]

I'm not much help with external but my experience with internal slave nv3500 was I needed a later model slave cylinder with throw out bearing because it was different from the sbc so research if you may need a different throw out bearing cause it is a possibility