mhuppertz

Anyone know if the throwout bearing on an NV4500 is continuously running or on demand like the older trucks were?

KATOOM

All hydraulic clutch systems will have the TO bearing spinning at engine RPM simply because its always in contact with the pressure plate fingers. That doesnt mean its always under "pressure" either but that it cant back away otherwise the hydraulic master/slave wont work properly. The same principle as hydraulic brakes.

mhuppertz

Thanks for the info. Exactly what I wanted to know.
Was thinking about putting a helper spring in the fork to reduce the pressure plate load on my clutch pedal, but I don't want to burn up the throwout bearing.
I cut the clutch master cylinder rod and cut a longer piece off my old one and welded them together using square tube to splice.
Of course I made it too long so the pedal is way out and bottoms out way before the floor, so I have to grind off my welds and shorten it a bit. Afraid I will push master through the firewall.

gorms

Would take one honking spring to help overcome a ~3k lb pressure plate. Buy extra throwout bearings.

mhuppertz

I'm not going to do it, was just a thought.

KATOOM

Both Southbend and Valair have HD adjustable master/slave hydraulics which let you adjust the peddle height. Stronger and better than OEM systems.

mhuppertz

Got to thinking about your reply, my truck does not have a hydraulic throwout bearing, it just have a hydraulic ram that replaces mechanical linkage, so it might have a conventional style throwout bearing that only engages when the ram presses on the fork and engages the bearing... Hmmmmm

KATOOM

Sorry about that..... I didnt mean to confuse the situation but just to be clear the bearing is just a bearing. All throwout bearings are the same (similar). None are "hydraulic". The hydraulic part is the master/slave cylinders, whereas the other types of clutch systems are lever or cable.

So what I was trying to explain in regards to the hydraulic clutch systems is..... because the master and slave are hydraulic, the TO bearing cant pull away from the pressure plate fingers otherwise the master/slave would have to move it that much further with no force before they would have to apply the ample pressure required to move the fork. In doing so, this would cause the clutch pedal to move considerably before doing any real force was applied.

Again, the best comparison is your hydraulic disc brakes. If you've ever replaced the pads on them by spreading the calipers..... To get the calipers to reset in place the brake pedal has to move all the way to the floor a few times until the calipers position the pads right up against the rotors. Same thing would happen to your clutch pedal if you tried to pull the TO bearing away from the pressure plate fingers.

mhuppertz

They do actually make hydraulic throwout bearings, that's why I was confused.

https://m.summitracing.com/parts/mcl-1429?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-mcleod-racing&gclid=Cj0KEQiAuonGBRCaotXoycysvIMBEiQAcxV0n GTssRheqh7T57lZy9-CAnDELPCjLm7_SYZTDoE0PoMaAkRf8P8HAQ

KATOOM

Gotcha..... I guess I just called those the same "bearing", but still works with a hydraulic function because basically all a hydraulic TO bearing consists of is a slave system incorporated and sitting directly behind the bearing itself. There's no need to run a fork or lever with that kind of setup.....