Slave: Internal or External? Which is better?

[SalahHH83]

So I picked up an NV4500 (5.61 1st gear) to swap into my C1500 2WD. It’s a Jasper rebuild that was put into a fleet vehicle about 3 years ago. About 1000 miles after being swapped in, the starter died and they just left the truck sitting. I picked the thing up for $450 and it looks immaculate. It came complete with the bell housing and internal slave cylinder (had previously been bolted up to a Chevy 350).

So my 88 C1500 has an external slave with the NV3500 that’s in it now. This NV4500 has an internal slave. I like the simplicity of the internal slave/throwout bearing combo, but don’t like that if it goes bad or needs to be bled, it’s trapped inside the housing. Still, it gets rid of a lever system and seems to be a direct “push on the pressure plate” design.

My question is which is a better design? Does either have problems I should know of? Also, will my MC work with the internal slave? That is, is its fluid output matched to the internal slave so all I would have to do is run the hydraulic line to the internal slave?

Thanks in advance!

 

[heavychevy98]

I can't say for sure on the fluid output the way your doing it but it works the other way around. My truck was originally internal 3500 and I swapped in an external slave nv4500 and just ran the line. Apparently the master cylinder end is the same on both style lines because I just got a line for a 95 and it all went together like it was meant to be

 

[SalahHH83]

Thanks that's helpful. Any reason you went with an external slave over the internal?

 

[heavychevy98]

Not really. Found a good deal on one just happened to be a 95 with an external slave. Makes the clutch a little stiffer but if my slave goes out I don't have to pull the transmission.

 

[someotherguy]

Internal can be bled right there through the access hole on the bellhousing where the line goes through. You don't have to take anything apart.

I like the internal better because there's less moving parts. No wear on the fork or pivot ball since they don't exist.

Richard

 

[SalahHH83]

Thanks again Richard! I agree with you on that so I think I'll stick with the internal slave/bearing combo. I'm going to a 454 pressure plate on my 350 (350 flywheel of course), so I would think the all hydraulic setup should make for an easier clutch than an external slave with a fork and pivot

Btw, I followed your advice and found myself a C2500 at the junkyard to scavenge the upper control arms and spindles/calipers. I'm going to get some new bearings, rotors and pads and get the 8 lug set up done on the front. I took some measurements and I think the C2500 spindles should give me a little bit of lift up front as well which will be good since I'm going 2500 HD springs in the back on top of the 14 bolt. You've been a huge help with all your knowledge

 

[SalahHH83]

One more question, does anyone know if the internal slave uses the same release bearing as the external slave set up?

 

[someotherguy]

Nope, different part #'s; not surprising considering the drastic difference in release mechanisms. Easy enough to check stuff like this by just looking up the same parts for different years, on Rockauto, NAPAonline, etc. By the way most of the internal style slaves will come with a release bearing already, if you buy it new.

Richard

 

[SalahHH83]

Thanks Richard. I am currently trying to sort out how to use my stock clutch MC with the internal slave. My MC (for external slave) has a threaded -AN fitting whereas the internal slave has GM's attachment. I am searching for an adapter that would help me avoid having to buy the expensive newer clutch master cylinder. My MC has a 17.8mm bore whereas the newer MC has an 18mm bore. It's a 1% difference, so as long as I can physically connect them, I'm thinking it should work fine

 

[heavychevy98]

Mine had the oring/roll-pin set up on both ends so I'm at a loss. Aftermarket MC?