Clutch pedal vibration

[Bengy88]

(01-15-2023 )tree98 Wrote:  I believe that 1-1/2 inch of free play comes from the 1/8" gap between the fork and bearing.

It could be. I’ve never checked it that way. Now you got me wanting to adjust a clutch lmao.

[snailexpress]

Rear axle pinion angle/drive line out of specs, bad U-joints, carrier bearing, engine mounts can cause this because weakest point is clutch torsion springs. Was the old clutch torsion spring and it's slots damaged?
Rear axle spring bushing are also can play.
Anything what can move, rotate when you apply more pull force to the truck.
Some people reported bad injectors did cause vibration as well.

[DVT873]

Bad or broken motor mounts will cause all kinds of vibration issues. Cummins recommends replacing the vibration dampner at I think 500K miles. I know Rawze has mentiond that several times.

Google NVH vibration app or vibratesoftware. It is a smartphone app that costs $99.00. I have had some success with it. It will usually identify the source driveshaft, engine or wheels. Actually rotating wheel end assys. Out of balence brake drums cause some weird issues. Once you know the source you can do more testing.

Look on you tube for WeberAuto vibration. The guy in the wheelchair made the app. Seems to know a little about vibration.

Once, just once I had a flywheel that was out of balance. It was a small tandem tanker truck. Had a bunch of issues including rear wheel seals leaking. When we pulled the axle shafts the splines had the same type of wear you see on trans input shafts. Called a very smart gear guy about it. He said flywheel balence problem.

Got the flywheel tested and it was way out. Had to get the specs from Navistar. Engine was a DT466. This was pre email. Took a day or two for info and I no longer remember the terminology. Only ever seen it that one time.

[DVT873]

(01-15-2023 )snailexpress Wrote:  Rear axle pinion angle/drive line out of specs, bad U-joints, carrier bearing, engine mounts can cause this because weakest point is clutch torsion springs. Was the old clutch torsion spring and it's slots damaged?
Rear axle spring bushing are also can play.
Anything what can move, rotate when you apply more pull force to the truck.
Some people reported bad injectors did cause vibration as well.

http://www.roadranger.com/ecm/groups/pub...230149.pdf

Once upon a time they gave this kit out for free. I've used it a few times. The data it wants includes the wall thickness of the driveshaft tubing. First time was on a new 5000 Paystar with an 8LL trans. On the road it sounded the trans was coming apart. It was loud. Eaton required that this program to be run before touching the trans. I'm thinking bull$hit, no way. First time using it took several hours to get all the measurements and info on the driveshafts. Had to have gear ratios, a bunch of stuff. Finally got all the boxes filled in, pushed the button and out popped a red result for the fwd axle angle. Put in a 2.5 degree shim on each side and went down the road. Noise was gone. I was amazed and humbled. I would have bet $100 (back when a $100 meant something) that one or more bearings were bad.

[hookliftpete]

This guy? https://truck-vibration-technology.mysho...ctions/all

[SudsyDiesel]

(01-14-2023 )Petegraintrain Wrote:  Just replaced my clutch because I thought that would fix this issue. But it's still there. Basically my clutch pedal vibrates/pulsates when it's pulling. It's the most noticeable when i put my foot on the clutch pedal and remove some freeplay. So it must be coming from the engine. What would cause this? The higher my rpms get the worse it seems to get.

Howdy
First post on the forum so bear with me if its abit rough around the edges.
If its most definitely RPM related and not speed related I'd say you can safely rule out driveline issues, in fact anything post input shaft should be unrelated.

is there really a vibration or is it just something you can feel in your foot on the pedal? mirrors shaking, coffee spilling type vibration would really concern me as a tech whos seen broken cranks and also seen the invoices that go along with them

Did you happen to notice any paint marks on the floater plate between the clutch disks, typically they assemble a clutch, balance it then spray bomb it in one spot in a fashion that gets paint on both the outer clutch housing/pressure plate and the center plate so upon install it goes in the same way, even after us uneducated have it kicked apart on the floor 15 times.

Also verifying your clutch adjustment would be a great idea, when the fork is riding on the throw-out bearing you tend to get some feedback in the pedal, ignoring your pedal free-play ensure you have your 1/2" between your bearing and your clutch brake, and then adjust your linkage till you have 1/8" between your fork and bearing wear pads.

If all those things are good I'd start looking into flywheel and engine related problems. Did you have flywheel turned when you replaced clutch? Do you have a million mile harmonic balancer on it? stuff like that.
Best of luck
Josh

[same101us]

Could be a worn input shaft and pilot bearing causing vibration

[Bengy88]

(01-15-2023 )SudsyDiesel Wrote:  

(01-14-2023 )Petegraintrain Wrote:  Just replaced my clutch because I thought that would fix this issue. But it's still there. Basically my clutch pedal vibrates/pulsates when it's pulling. It's the most noticeable when i put my foot on the clutch pedal and remove some freeplay. So it must be coming from the engine. What would cause this? The higher my rpms get the worse it seems to get.

Howdy
First post on the forum so bear with me if its abit rough around the edges.
If its most definitely RPM related and not speed related I'd say you can safely rule out driveline issues, in fact anything post input shaft should be unrelated.

is there really a vibration or is it just something you can feel in your foot on the pedal? mirrors shaking, coffee spilling type vibration would really concern me as a tech whos seen broken cranks and also seen the invoices that go along with them

Did you happen to notice any paint marks on the floater plate between the clutch disks, typically they assemble a clutch, balance it then spray bomb it in one spot in a fashion that gets paint on both the outer clutch housing/pressure plate and the center plate so upon install it goes in the same way, even after us uneducated have it kicked apart on the floor 15 times.

Also verifying your clutch adjustment would be a great idea, when the fork is riding on the throw-out bearing you tend to get some feedback in the pedal, ignoring your pedal free-play ensure you have your 1/2" between your bearing and your clutch brake, and then adjust your linkage till you have 1/8" between your fork and bearing wear pads.

If all those things are good I'd start looking into flywheel and engine related problems. Did you have flywheel turned when you replaced clutch? Do you have a million mile harmonic balancer on it? stuff like that.
Best of luck
Josh

I agree mostly with what your saying but you do realize that the entire main shaft spins in a transmission even in neutral. So with that being post input shaft that would be misleading. But with the transmission and clutch being replaced since the problem occurred then I would safely rule both out.

If it’s got a hydraulic clutch it also always has pressure between the fork and bearing. Also if you have a hydraulic clutch or any clutch for that matter you shouldn’t be riding with your foot resting on the pedal. But hydraulic clutches tend to apply pressure slowly while your foot rest on the pedal.

I guess what we need to know is do you feel it while sitting still and rev the engine? Is resting your foot on the pedal the only way you feel anything? You also need to keep in mind that the clutch spins 2000+ rpm’s just like the engine does and the clutch pedal is a direct line to the clutch with no bushings, isolators…etc. so you are going to feel something when in hard pulls if your foot is resting on it (which it shouldn’t be). So what you are feeling could be normal and it also could be something to worry about.

If it happens sitting still revving it could be anything from a balancer, cracked fan, bad fan hub, injectors, your gear train, flywheel, etc. if it happens only in a pull it could be all of these things including a carrier issue, driveline issue, air bag ride height, and the list goes on. Just remember anything on your truck that spins especially at high speeds has to be balanced. If not it will beat shi#t slap apart. Good luck finding your issue brother.

[DVT873]

(01-15-2023 )hookliftpete Wrote:  This guy? https://truck-vibration-technology.mysho...ctions/all

No, this guy https://www.youtube.com/watch?v=277UWQaG...F4Ge8plIdN plus more once your there. The old reed gizmos and the Syrometer are interesting.

If you want to "roll your own" there is this guy. https://www.youtube.com/watch?v=FElVgfi-zuY&t=768s

The NVH app was $400 when it came out. $99 now. The few times I've used it it has always indicated tires and it's been right.