KATOOM

On a positive note for you, I've experienced a sticky clutch pedal two times. The story I just told was the second time. The first time was with the stock clutch and the OEM hydraulics. The clutch pedal felt like rubber shoe sole sliding across a smooth surface. That time it was the clutch master cylinder and I didnt want to spend money on replacement hydros. So what I did was kind of difficult to explain but here goes..... I had someone assist me by sitting in the drivers seat while I was laying on the floorboard in front of them. They pressed the clutch pedal about half way and I pulled back the clutch safety switch with my hand. Then I took a can of PB blaster and using the spray straw, I poked the straw in along next to the cylinder shaft and sprayed a douse of PB blaster directly into the master cylinder piston. I love PB blaster as the stuff really does wonders for rubber components. (plug over) Then waiting about 30 seconds I had my helper press the pedal all the way to the floor and then let them release the clutch. Yes, some PB oozed out so I had a rag handy to mop up the mess. But now for the good news, my clutch pedal regained its smoothness and lasted that way for a couple more years until I replaced the clutch and replaced the hydraulics for a new SB set. I'm not telling you what to try but merely sharing what worked for me.....

I ran into this very same "sticky" clutch pedal feel about 5000 miles after installing my SB clutch. I did everything as I've always done on any clutch job, and was feeling like the problem was the hydraulics. But.....the strange part was the clutch pedal movement was smooth when the engine was not running. Strange..... So after pulling the hydraulics and finding that they were fine, I reluctantly pulled the tranny back and found that the throwout bearing was hanging up on the input shaft sleeve. Upon the clutches initial installation I lightly greased the input shaft sleeve, but I think what happened was that the clutch dust was incompatible with the grease I used and eventually turned that grease into sticky crud instead of lubricating. Kind of the same thing as what happens with molly grease. I cleaned the sleeve off and bought a new throwout bearing (just because I was in there). This time I used no grease aside from what was pre-lubed in the new throwout bearing. And after putting it all back together, the clutch pedal has never felt so smooth..... It even feels lighter and the clutch engages better. In point, it appears that the throwout bearings sticky movement on the shaft was causing more issues than just a jerky clutch pedal. If you find that hydraulics arent the problem, you might be experiencing the same issue I was.

Thanks tonyjsan..... Thats what we like to hear. These forums are valuable tools for not only the members but.....the vendors as well.

"Friends".....or....."acquaintances”. Most people misunderstand the difference. I have a couple true friends but I have a butt load of acquaintances.

That couldnt be farther from accurate as South Bend will go over and beyond to help their customers. As so will Valair. But what you're potentially dealing with is a shop who doesnt want to absorb a cost burben which is on them. Maybe they're claming that SB wont help. I'd give SB a call and personally talk to Peter and give him the scoop.

The stock clutch is good to about 65-85 hp over stock. Any more than that and the odds of slippage under load is significant. I dont know what opinion I can offer you in regards to a manufacture since I've heard good and bad for both Valair and SB. But generally far more good feedback for both. These companies have to address not only the variables of off chance mechanical failures of the components but they also have to address driving conditions and installations. Lots of room for errors which can easily be blamed on a company who shouldnt be. Thats not to say this is your situation either..... Did SB completely blow you off or was there more to this story?

Factory manuals will usually state things like "lifetime" fluids for various driveline components but in reality the service life of a lubricating fluid is based completely on the temperature that fluid runs at. Meaning, if you tow often and/or drive in triple digit weather often, or live in mountains, then you may consider that the fluid has probably gotten hotter than the desired maximum temps a time or two. Or if there's a small leak and the fluid level drops to a point where heat becomes a problem due to lubrication issues. If the driveline components never get overly hot, are never subject to water intrusion, and run under mild temps forever then eccentially the fluid should last forever. At least 100,000 miles easy. That obviously excludes the engine though..... Point being is that there are reasons why you'd always want to keep an eye on the driveline component fluids. That doesnt mean they need to be changed every "X" amount of miles but that you should and can assess how often you need to maintain something based on the driving conditions and how the vehicle is used. Taking the approach that if you mess with it then something will go wrong simply means that you should have someone else perform the task. Or should I say.....someone who knows what they're doing and doesnt mess things up.

Well let everyone know what happened when you get everything pulled apart.

Nothings bulletproof..... But yes, generally the 5600 is a safe bet. The only common issues that I can think of off the top of my head with that tranny is, they do better when overfilled for better bearing lubrication. And making sure the correct fluid type is used. There's quite of bit of discussion on this very topic too.....

Just coming into this thread so sorry if its been discussed already..... Has the fluid ever been changed in this tranny? If so, what fluid brand? If not then it sounds like thats the next step. Knowing that a DD clutch is going to be flinging a lot more mass then a single disc, I could see going into the more difficult gears being a problem. That said, you must have an adjustable hydraulic system so have you tried to adjust it out some so the pressure plate is opening farther?

Strangely though, Cummins is not the only engine to use the VP44. Lots of people work on the VP but the true understanding of what’s going on inside it seems to be some highly guarded secret no one will divulge.

Hmmm…..viable. The way it was explained to me some years ago was that the VP has three levels of pressure within itself. High, middle, and low. I know “middle” isn’t the correct terminology but let’s not split the hairs just yet. So the diaphragm is situated on the low pressure side of the VP but yet because of the rotor design, the mid pressure pulses are allowed to travel back through the low pressure side. The only thing to stop or offset those mid level fluid pulses from traveling back through the low pressure side is the pressure from the fuel pump. And when the fuel pump pressure is too low then the mid pressure pulses are the stronger of the two and the constant wave of mid to low, mid to low, pressure signals felt by the diaphragm are what causes it to “flex” and eventually fail. Apparently it seems were not sure what the actual failure is or if the failure is what we think it is as this diaphragm seems pretty stout. But nonetheless….. Sometimes I feel like the VP holds mysterious secrets like the pyramids of Egypt. You’d think after 16 years SOMEONE would have an accurate understanding about the mystical VP diaphragm.

No, what I meant by "outer plastic" was that its a steel disc covered in plastic. To the best of my understanding its always been plastic but the upgraded version became plastic over steel. So that said, is the "plastic" serving as some sort of sealer? Something about the diaphragm must be sealing because when the diaphragm fails, proper fuel timing is no longer achieved at the timing piston.

Or better yet..... Is the "crack" even a problem or is it just merely the outer plastic. Or.....does the plastic form some kinda diaphragm seal which whereby the "crack" is allowing fuel to bypass under pressure, thus the reason why when the diaphragm cracks the timing piston is soon to follow because of it beating itself up from improper fuel timing?

Good to know. Thanks.

Mike I'm curious to know what you've found with your new gauge readings in comparison to your old gauge readings. Are they all the same? My main curiosity is your EGT's too. I remember reading you mentioning that you can achieve something like 500* EGT while driving down the highway. The lowest normal EGT's I can reach is around 600*. Even driving down a slight grade my EGT's are just above 500*. So I'm wondering if your old pyrometer was reading as accurately as you'd hoped it was.

Why did you change gauges?

Sounds like thats what happened.

The pictures a great example of what a JIC thread and connection type is but the reason JIC fittings are superior to banjo fittings is because JIC fittings have wide open curved bends. Banjo fittings work in a strange setup whereby having all the fuel flow into the line head and cram around the main bolt to find a hole which leads down a hollow center of the bolt and then into the source. JIC fittings flow like any wide open flare fitting.

I have JIC fittings and 1/2" lines from the tank to the VP. The only fitting which is otherwise is the OEM supply line quick connect fitting on the fuel module. I opted not to install the drawstraw since there was way too many issues being posted with the drawstraw. I know they've supposedly solved most if not all of the drawstraw problems but I dont think I'll ever bother getting one. My fuel psi is OK with the minimal fueling I have.

I havent had time to drive it with the fuel pressure test gauge connected but I did get a chance to hold up my crappy phone to the fuel pressure gauge and record a little of what it does. Note that the smoother action of the gauge is normal throttle variances but the quicker action is the "bobbing" down and back up of fuel pressure. I said "down" because it never bob's upward.....only downward and then back to running psi. Sorry ahead of time that the video is so poor quality. At least it shows something. https://www.youtube.com/watch?v=RccuEPhblAg&feature=youtu.be

I'm not so sure I agree here with the same level of concern..... I really dont think the friction or stress placed on the crank with the clutch pushed in during starting is something to really worry about. In saying that, I remember there being a lot of discussion years ago about how much "better" it is to start with the clutch in.....and remain holding it in until the oil pressure registers. That being so to alleviate any added load on the crank having to turn the weight of the transmission internals and those internals also pushing through cold gear lube. So which is it?..... Personally I'm not sure it matters much either way. If I remember correctly the load thrust bearing on these engines is located on the 6th main journal which gets supplied by the oil pump almost instantaneously. If the crank didn't receive lubrication as quickly as it does and instead took the 10 seconds it takes to register oil pressure on the gauge, the crank and rod journals wouldn't last a year. So why would the thrust bearing last any less?

I guess I've never heard of the issue with Carter pump cavitation. Thought I've heard them all too.....

I thought they were basically the same pump configuration but just on different bases which came with or without filters attached. The pump isnt "separating" the air from the fuel, the second filter is. Although I'm sure they've improved on the designs over the years.

The regulator is regulating "X" amount of pressure no matter if its on an Airdog or a Raptor but the amount of fuel being returned to the tank is not the same between those two pumps. The Airdog has the advantage of a dedicated return line from the pump and the excess return fuel from the VP. So maybe I'm not understanding what you mean here by what you said.