Nv4500 chatter while coasting with clutch out, sounds like valve chatter. Goes away with slightest touch of clutch pedal

[daav544]

So I've been hearing some chatter while coasting on the highway, i initially thought I was just in need of a valve adjustment because it sounds so similar to chattery valves I've heard on other engines. Did a valve adjustment and the noise is still present. After some long drives on the highway I realized if I'm coasting and put the slightest bit of pressure on the clutch the noise goes away. And when I say slight I mean slight, you could lean and empty sneaker or work boot on the pedal and the noise dissapears. I also noticed if I'm coasting and press the clutch pedal in and let it out the noise is gone for 5 seconds or so then returns. There's no noise if I coast for a long time with the clutch in either. Any ideas what it could be? It's deffinetly coming from bell housing back of motor area that's why I initially thought the old girl needed a valve adjustment, couple were out of spec but nothing crazy and didn't effect the noise. I'd assume even with that tiny bit of pressure on the pedal it's doing something with the hydraulics to make the noise go away. And as I said it's eirily similar to clattery valves I've heard from different motors in the past. This weekend I'm going to grease that zero fitting that's under the cover by the bell housing, its probably been quite a while since anyone's touch it I've put 30-40k on the truck and havnt touched it myself. It has a valair single disk organic that my buddy installed before I bought the truck so the clutch only has between 30-50k on it since he didn't drive it much. Mostly grandpa style miles too lol

Oh and forgot to mention the noise only happened at higher roms between 2-2500rpm or so. Which made me wonder if its just the right vibration to be making something chatter

[IBMobile]

Sounds like a problem with the throw out bearing.

[Tractorman]

Agree on the throw out bearing.   Even with your foot off of the clutch pedal, an internal spring inside the slave cylinder places light pressure on the pushrod that engages the clutch fork.  This means that the throw out bearing is always in contact (even though lightly) with the diaphragm fingers of the pressure plate.  A lack of lubrication at the contact point can cause the chattering noise.  As soon as you touch the clutch pedal, you introduce a bit more force to that area and the chattering stops. 

 

Toyota trucks are notorious for the symptom you are experiencing.  A lot of people have carefully sprayed a lubricant in the area, or have just lived with the noise.

 

6 hours ago, daav544 said:

I'm going to grease that zero fitting that's under the cover by the bell housing

 

 What is a "zero" fitting?

 

- John

Edited November 9 by Tractorman

[daav544]

Sorry that meant to say zerk fitting, and yea i was figuring maybe throw out bearing. But the clutch and hydraulics are all new valair stuff. Doesn't mean it couldn't have gone bad already. Does anyone know what that zerk fitting greases its under and access plate on the front of the trans somewhere. Anywho I do need a better clutch I can slip it in 4th or 5th on a hard pull on the highway I would like to just change the friction disk to a dual friction or kevlar or even ceramic since everything else is fairly new with Grandpa style driving on it

[Tractorman]

6 hours ago, daav544 said:

Does anyone know what that zerk fitting greases its under and access plate on the front of the trans somewhere.

 

Large trucks (like Class 8 trucks and even medium duty trucks) use a special throw-out bearing that has a grease hose attached with a zerk fitting on the end, which makes the bearing accessible for maintenance.  However, the hose only puts grease in the actual bearing.  It does not put grease in the contact area of the bearing to the pressure plate fingers, which is where I think your noise is coming from.  The throw-out bearing in your truck is usually a non-serviceable sealed bearing and will normally last the life of the clutch.

 

You may have a custom throw-bearing that can be greased remotely.  I checked a Valair site, but I didn't see anything like that, but that doesn't mean that it can't be done. 

 

If that zerk fitting does grease the throw-out bearing, I would only give one or two pumps of the grease gun - you definitely do not want to over-grease that bearing and risk getting grease on the clutch facing.

 

- John

 

 

Edited November 10 by Tractorman

[daav544]

The grease fitting it supposedly on all nv4500s under a little surface panel on the passenger side it doesn't grease the throw out bearing It greases the fork and ball socket not many people know of this. And I hope it's not my throw out bearing everything is new with the clutch even flywheel

[Tractorman]

3 hours ago, daav544 said:

It greases the fork and ball socket not many people know of this.

 

I was one of those many people - thanks for the info. 

 

3 hours ago, daav544 said:

And I hope it's not my throw out bearing

 

I don't think it is your throw-out bearing - I think it is the contact area between the part of the bearing that contacts the tip of the diaphragm fingers.  There is nothing to hold a film of grease there.  I think the bearing itself is doing fine. 

 

In the "old days", before the common use of hydraulic clutch controls, clutch control was done mechanically.  The adjustment on mechanical linkage never allowed the throw-out bearing to contact the diaphragm fingers when the clutch pedal was released.  Not so with the hydraulic clutch control.

 

- John

[daav544]

So basically just a little "nothing to worry about" chatter like half the other things on these trucks lol? Drives great no funny feelings with clutch system at all

[Tractorman]

I would probably keep driving the truck and continue monitoring the noise.  If it truly is the actual bearing that is failing, it will get worse and you would be able to feel the bearing roughness with the clutch pedal engaged.  From what you said in your original post, "There's no noise if I coast for a long time with the clutch in either."  would indicate that the actual bearing is doing what is supposed to be doing.

 

- John

[daav544]

Yea pedal has always felt the same and maybe the noise has always somewhat been there i just really havnt noticed it with how loud the rest of the truck is. Is there any adjustment that could be done, like I said you could pretty much lean a sneaker on the pedal to make it go away so I feel like if the pedal was adjusted / pressed just that tiny bit all the time it wouldn't be engaging the clutch at all i feel like it's just taking up the littlest bit of slack in there. I also forgot to mention you can hear it as well while driving not just coasting just hard to hear over the engine. Alot of the time I'm driving I find myself resting my foot on the clutch pedal so most of the time I don't even hear it because my foot is just barely touching the pedal 

[Tractorman]

3 hours ago, daav544 said:

Alot of the time I'm driving I find myself resting my foot on the clutch pedal

 

I would re-train your left foot to not rest on the clutch pedal.  You may have contributed to this noise. 

 

There is already light spring pressure from inside the slave cylinder that removes the slack from the pushrod / throw-out fork and maintains zero clearance for the throw-out bearing while the clutch is engaged driving down the road.  Any additional force will make the bearing spin at engine rpm 100% of the time.

 

- John

[IBMobile]

4 hours ago, daav544 said:

I find myself resting my foot on the clutch pedal so most of the time

 

Also, this applies a slight pressure to the fingers of the pressure plate so that the clutch disk may not have the full force applied to it and possibly cause premature wear on components.  "Keep your foot of the clutch peddle" was empathized when I earned to drive. 

 

To hear the noise better have you tried turning the engine off while coasting? 

Edited November 11 by IBMobile

[daav544]

I'll try turning it off while driving. I don't think I'll hear anything though it seems the noise is only present at RPMs above 1500 or so, i just coasted in neutral a second ago and couldn't hear it while truck was running. It's louder on highway around 2-2500rpm. That's why it makes me think it's a vibration thing, something rattling at just the right vibrations

And as for my foot on the pedal I usually don't unless I'm doing city driving and I shouldn't say testing but like hovering / barely touching which I guess like my sneaker explanation how the very little pressure makes the noise go away, my very little foot resting is doing something possibly

[daav544]

So been doing alot of highway miles today and I thought it was higher RPMs that I would hear the chatter but I just was in 5th at about 2300rpm and started coasting, i didn't hear the noise till about 2000rpm, it slowly got louder towards 1700rpm then slightly quieter after 1700 down to 1500 to hardly any noise down by idle speed. Also no noise at all no matter the speed while coasting in neutral unless I rev the truck and hold it around 1500-2000rpm. I would assume it would make that noise as well while parked and revving it like that. I'm probably over thinking all of this but I can't be the only one on here who hears a odd noise and wants to know exactly what it is 😂. One of my older posts I was going nuts over what I thought was a bad front wheel bearing, i changed them all and noise was still there when I turned left, got new front tires and noise disappeared 🤷

[IBMobile]

Since the noise can occur in neutral by increasing the engine RPM 1500-2000 the problem lies between the flywheel and the counter shaft.  

This would include the clutch disk, pressure plate, throw-out bearing, and input shaft along with the counter shaft.  

I thinking it could be a loose/broken clutch disk spring, but I keep coming back to the T/O bearing.

Edited Friday at 05:56 PM by JAG1

[daav544]

I've heard of people having broken springs on these valair clutches before, and you can even hear the noise while driving not just coasting it's just alot more noticeable when you don't have a 5in straight pipe/side piped 24v screaming along lol, i do want to put a better friction disk in this truck anyways like a dual friction or kevlar instead of this organic. And I possibly have a little rest main leak that could be getting on the clutch causing it to slip or my truck is really just making more power than the 400 or 450hp it's rated for. My buddy who had the truck before me and did the clutch even did the rear main as well so that would be a bummer if it already started leaking. As far as clutches go I just learned of this company Kentucky clutch a guy on the Facebook forms said he's had real good luck with them and there a great company to deal with. Another guy had said Phoenix friction but I had read about some guys having some bad experiences with having a flywheel out of balance or not true or something. But anyways I'm thinking about dropping the trans before winter to put in a better friction disk since everything else doesn't have a ton of miles, mostly grandpa highway miles. Would be nice to get a good look at everything and reseal the case itself since it weeps a little.is there a gasket for the case or just rvt?

[daav544]

 

Here's a short clip so you can get an idea of the noise, in the cab to the naked ear sounds alot like valve chatter. Starting to drive me nuts and I'm dreading dropping the tranny, not that I haven't dropped plenty of tranny's over the years, I just really don't want to have to lol