Clutch Chatter

I hope you guys can save me again.  I recently changed the clutch in my 85 f150 with 4.9 and NP435 tranny.  Replaced the clutch, flywheel, pilot bearing, throw out bearing, fork, pressure plate, and even replaced the rear main seal.  The rear main seal was leaking before, and I figured my clutch chatter was either due to misuse by the PO or oil getting on the clutch.

Also had a broken motor and tranny mount, so I replaced both motor mounts and the tranny mount.  I took special care not to get oil on anything during re-assembly, and made sure everything was torqued to spec.

No more oil leak, but still have the chatter.  It only chatters in 2nd gear taking off from a dead stop.  Doesn't chatter in granny or reverse.  The only way to take off smoothly is to really rev the the engine and ease the clutch out way too slowly.  And yes, I've been driving a clutch vehicle for 40 years.

Any ideas or suggestions?

Did you have the flywheel resurfaced? If not that will cause a chatter and make the clutch grab and slip as well. Did you check the trans input shaft and bearing for wear as well? These will also cause a chatter.

Welcome back Rob!

Maybe it's just the torque springs in the pressure plate?
I know it's new, but if the clutch transmits enough torque to get the truck moving then the springs will rebound.
If you're just easing into it like that, it happens over and over.

I put a new flywheel in.  I had about 3-4 thousandths of play in the input shaft, but I've seen worse without any ill effect.  I really don't want to take out that transmission again unless I'm going to have it rebuilt.  That was a pain!

I replaced the clutch in by brother's E-150, same engine, same trans, about 35 years ago.  I did that without a transmission jack without any trouble.  Then again, I was 18.  

Jim, is there a way to solve this?  Will it work itself out over time?

Oh so many memories!
Thinking "if I don't get this off my chest I'm taking my last breath under here"

Clutches can be grabby until the friction beds in to the new flywheel and pressure plate.

How many miles do you have on it now?

About 600 miles on the new clutch, but 500 of that was interstate.

I'd say keep driving it.

I find it might take a few days for a clutch to settle in (in my truck, the way I drive)
But I think within 300 miles of stop and go it is going to be as good as it gets.

Oh, and try not to let it chatter too much.
You'll end up spotting the plate and flywheel.

Newbie here. I have 35 years as a Ford tech. I've seen engine performace issues mimic clutch chatter. Don't know what your running so here's a couple highlights. Worn cam, sounds strange but saw it with my own eyes. Bad air induction tube between mass air and tb,  wire shorts, bad tfi module. In my experience I've never seen a clutch chatter only in one gear. I've have seen other problems mimic it and be gear sensitive.

That's a real interesting idea.
I don't often consider that posters aren't able to articulate what they're actually experiencing.

I took it to mean he never used the granny gear in his NP-435 under normal conditions.
With many of these gearboxes you could literally sidestep the clutch at idle in first and the truck would lurch to a walking pace.
Not much chance for the clutch to shudder with deep ratios like that.

True, but my experience has been if it is the clutch chattering, under normal clutch application it chatters in all to various degrees. Also, to replace a clutch and still have the same problem is very unusual. The only remaining possibility I see is a excessively worn bearing retainer causing the throw out bearing to bind. That should be very noticeable.

You have more experience -with more clutches- than me.

Can you tell me what you mean by bearing retainer?
The release fork??
The input sleeve??

I usually apply the smallest bit of Moly-60 paste to these surfaces.
Graphite exhaust sealant works too.

It's what the throw out bearing rides on, your probably thinking input sleeve.  I've just used molly bearing grease to lube the throw out bearing. I've read that graphite can act as sand paper below zero farenheit. If the sleeve is excessively worn it could cause the bearing to bind  during release of the clutch.

Yes, I'm thinking input sleeve.

The Honda Moly-60 paste is meant for splines (extreme pressure and temps, little or no rotation)
It works great here without any chance of contaminating the clutch.

I am on my third Bullnose now and they ALL have/had the clutch chatter issue. My 74 F-350 doesn't do it, nor did my 73 F-250 or the 78 F-150.

I had an 81 F-150 with 300-6/T-18 and 2.75 gears that was just awful, my current 85 F-150 with 300-6/NP435 and 3.08 gears is somewhat better but if you get careless it will give you a good shaking as if to let you know who is really the boss.

I read on another forum that the firewall mounting position is weak and can be re-enforced with a thicker metal plate but I have never tried it.

This is definitely my biggest gripe with the Bullnose series even though I dearly love most things about them.

Your 81 doesn't have a hydraulic clutch, so there's no real difference between it and your '70's trucks in that regard.

If you're not getting smooth engagement I'd first look at friction contamination or a heat spotted flywheel.
There's no reason to have to put up with a shuddering clutch.

Gearhead wrote

 If the sleeve is excessively worn it could cause the bearing to bind  during release of the clutch.

I had this happen on my old mustang.  We replaced the T/O bearing and I don't remember how long it took to ruin the new bearing... but it was months, not years.