Has anyone ever thought about a bad or failing CPS would cause shudder/rough clutch engagements?

Might sound crazy, but this is my story and theory.

Ever since I installed my Valair clutch a few months back, the day I installed it I had a really bad shudder on engagement. It went from my old LUK clutch which was smooth as glass to this horrible truck shaking episode on 99% of engagements from a dead stop, I'd even park facing down hill no matter how big the hill it was so bad.

Thinking the flywheel was resurfaced improperly, I had it resurfaced again at a different place. The 2nd time wasn't as bad as the first but it still shuddered and shook the hell out of the truck. I've come to terms with it for all this time up until 3 weeks ago something odd happened.

2 Months before I replaced my clutch I got ahold of an original black CPS and installed it. I didn't see/feel/hear any problems with performance or running of the truck until about a month after installing it, after a month it would randomly die while idling, didn't think anything of it really. Then it got worse, running 65mph truck would hiccup and the truck would lurch, or it would start to sputter or fail to run after a few seconds after starting it and I kept thinking wth I need to replace that again but never did until 3 weeks ago.

So I drive to my buddies house, let the truck cool down, throw in the ford grey CPS, start it up. Starts quicker, runs quieter, smoother. Thinking dang I must have gotten a bad or used black CPS. Shut it down, go eat some BBQ and relax for a few hours then I left.

When I let the clutch out for the first time after changing the CPS, I shat a brick. To my amazement, the smoothness was back and I just sat there driving in and out of my buddies driveway for a few minutes. He came out to see what was up and when I showed him what I was doing he asked what I did to make it do that. All I did was change out the CPS.

So for 3 weeks I've been evaluating every time I let out the clutch, thinking oh great its going to shudder but 9 times out of 10 it doesn't. It's still there, I can tell but the way the stick shakes and the tone of the engine but it's 1/4 of what it was.

So I've been thinking about it....

The CPS is needed for the engine to run, proper running and idle whether it be under load or not.

A good CPS will keep the engine idling properly(quicker response to load) when a load is applied, in my case I'm talking about when the clutch is engaged.

A bad CPS might be able to run the engine and idle but could be slow to respond to a load on the engine, and I think in my case that translated into a shudder when I engaged the new clutch on a failing CPS.

I don't have any data or graphs supporting my theory but a different CPS sure as hell changed the manner in which my clutch engages.

What do ya'll think? Plausible?

 

I don't know about the cps theory, but I put in a Valair clutch and it shuddered for 30k until I put a stock clutch back in. Now its smooth as glass.

 

I'm guessing your issue has to do with the Valair clutch. Not the first time we've heard of it. The disc finally got smoothed out a bit I guess.

The CPS has to do with the computer reading timing. I recently had a black CPS act up on me every once in a blue moon. Never enough to throw a code, but the truck did sound / feel better when I replaced it and the problems went away. Never had any issues with clutch engagement.

 

Mine did smooth out before 30k, but I replaced it last week and the new one is smooth from the start.

 

Unfortunately, none of us were in the truck to feel the shudder under any of the combinations of CPSs and clutches. I will say this: Stinky has never stalled under any torture test I put him through, but I don't have a clutch. I drive clutches on other vehicles, so I know a stall is not just caused because of engine issues... only you can be the judge if you didn't do anything to stall the truck yourself. Was the black CPS a new OEM unit? If not, then your theory has credence.