Nv3500 to 5.3 pedal feel

[Bluebell]

I recently put a 5.3 in my 97, replacing the vortec 350 (previous owner swapped the 4.3 out).
The transmission is a nv3500.

It seems the general consensus was use a 4.8/6.0 flywheel, pilot bearing, clutch kit and it will work with the sbc slave cylinder.

After doing part number cross references. Seem the truck slave was same as camaro and s10. So felt no need replace, previous owner said they replaced it and it worked fine past 2 yrs for me and visually I could tell it was a newer unit.

So to the point, after bolting the trans to the 5.3, I had someone push on the truck, so I could make sure the clutch was disengaging.
It did but initial thoughts. The pedal feels incredibly soft as compared to before.

I guess my question, before thinking somethings wrong, is were the nbs trucks pressure plates, designed differently, allowing a more softer pedal feel?

Cause my initial thought, in regards to the 4.8 pressure plate was clamping force. Not so much whether I should have used the 4.8 slave. As before the pedal feel was much stiffer, which I'm more accustomed to in pre 2000 fullsize trucks, all makes. Now it feels like a pedal I'd expect in an s10 or ranger, even a car.

Just thinking out loud in print. I'll go with it for now, still need finish up the wiring before maiden run but that pedal feel caught me off guard and has me wondering.

 

[0xDEADBEEF]

I never drove a manual NBS, so I can't answer that, but I do have a 5.3 mated to an NV3500.

If you are using the same master and slave as before, I wouldn't have expected that to feel different. Did you get air in the system somehow? Any fluid leaks?

FWIW, I am using a newer slave that doesn't have the line built in. I think it was '04 +. Not sure the exact year. Only reason for that is because this is installed into an old truck with old style master cylinder.

 

[Bluebell]

I left the hydraulics intact. During the swap.
The 97 hydraulic components are same as the 4.8/6.0, in that the master and slave are seperate, connected with a braided flex line.
Interestingly enough, the slave cylinders, didn't cross reference. Across the SBC and LS years. Although visually they appear much alike.
Tried figure out why they are separate part numbers but no luck.
So I thought maybe that was the reason. I dunno.
May end up bleeding the line but if it needs bleeding. Then somethings wrong. And it needs replaced.

What year truck did you swap?

 

[Erik the Awful]

When in doubt, bleed it, bleed it, bleed it.

You might have a weak point in the line somewhere that opened up during the transfer and then closed back up when bolted in place. How old is it?

 

[Bluebell]

Just noticed you replied.
Finally test drove the truck today.
Clutch master was full. I've never put any fluid in it. So no leaks.
Had trouble getting it into reverse. But forward gears were fine.
Pedal is still crazy soft as compared to before.
I stopped on a hill put it in first. Engine off. Push pedal and it definitely disengaged. Truck rolled. Didn't hear any disc rubbing against flywheel.
So I guess pedal feel is what it is.
Wondering if the pilot bearing is too tight causing it to want grind into reverse. Maybe it'll loosen up. Lol. Probably wishful thinking.

Course with a new swap, I have hundred things that need tweaked or addressed and anything trans related falls way down that list right now.

 

[DerekTheGreat]

If you had trouble getting it into reverse, the clutch isn't disengaging all the way. Another way to test this is to put the vehicle on flat ground with the engine running. Press and hold the clutch to the floor and go into first gear. There should be the typical resistance & delay of the synchros stopping the input shaft so you can get into gear without clash. From there, you should be able to pull back out into neutral and go back for first without any delay, especially after a few seconds. If you feel resistance or delay after going back to neutral, the clutch isn't completely disengaging as it should be.

 

[Erik the Awful]

Pedal is still crazy soft as compared to before.

There's your problem. Bleed, bleed, bleed your clutch.

 

[Bluebell]

How would it get air in it? I didn't touch the hydraulics. I unbolted trans and slide it back enough to switch engines,.
Won't hurt to bleed it but seems like being untouched, thst variable shouldn't have changed.

 

[0xDEADBEEF]

To my knowledge pedal "feel" is determined by the ratio of the pedal pivot and push rod attachment and also by the master bore diameter to the slave bore diameter. None of those changed.

I'm kinda stumped. Possibly the slave is just shorter than the NBS slave? So, there's more air gap. I don't know.

 

[Bluebell]

Hold up there, dont get too technical my brain is still on dial up. Lol. Yeah I get what your saying.
Today it shift into reverse fine. No hint of grinding. And the truck had sat for over a day, so if it was going bleed down. It had plenty time do it.
But pedal feel is still easy compared before.
Just for hell of it, I'll bleed it, see what happens. It may have had a lil air in there but not enough notice, till I switched pressure plates.
Seems I need fuel pump too, trucks nosing over at moderate rpm, and upon testing. The pressure does drop when I give it a little throttle. Idling, pressure is good. When I remove vac line from regulator the pressure does go up to where it should be. So that seems me like pump just can't keep up, that and when I turn engine off the pressure drops zero instantly.