I purchased a 66 f-100 last year,and when I drove it, I had to basically ride the clutch in first or reverse to prevent the truck from violently shaking. My spring project was to replace the clutch , clutch plate etc., and to rebuild my 390. I adjusted my clutch but still have a significant chatter when starting out. Could there be another problem besides the running gear?

Thanks, Frank

 

Hello

At higher speeds does your truck violently shake or just take off. Sounds like the problem I had. Check your carrier bearing for your truck. I bet that's what the problem is. Report back on the findings.

 

Frank,
BIG END rear spring bushings & pins/ bolts are probably history. Replace your rear spring bushings & lots will improve including stopping the chatter you experience.
FBp

 

Swapping to a C6, can help there too.

John

 

It tends to shake alot more on take off then it does during shifting gears, but I have felt it while driving from time to time.

 

Frank,
It does so because worn BIG END end bushings allow pins to "seek" a center in all that slop & excess play of bad bushings. This allows springs & axle assy to float, that causes clutch to slip intermitently until it can load torque in driveline & mash springs into some position that will allow the inertia to be overcome so truck can move.

As it moves, "load changes values" as inertia falls. Intermittent slipping & grabbing starts again until everything works out & inertia's no longer a factor. If you are driving in neutral acceleration and let off and accelerate lightly at road speed same "seeking" occurs & same result happens, intermitent clutch slip & grab, just as if you pumped a clutch pedal across/ through its' friction point. . . . .

This effect is called clutch chatter, altho' it is not caused by the clutch it just occurs in the clutch.

The reason a C-6 or any A/T cures it is because the hydraulic forces applying energy of torque into your drive train are infinitely progressive [big words for smooth] and it holds even pressure/ force hydraulically in the driveline. So John is right and has given good advice too.

Unlike a clutch with 3 positions, disengaged, friction point and engaged, automatic transmissions have only 2 because their function is controlled hydraulic slippage. IOW they are made to slip smoothly. until reaching predetermined speed or RPM then they lock up and run without slpiiage. there is no mechanical "friction point" to deal with in an A/T. It's either Go or No Go and that's all.

Don't take my word, ask Arrow Rebuilders [rebuilder of automotive parts] including clutches, or ask a Suspension Engineer if you know or can find one. Believe me it's not a mystery, unless one is not aware of it yet. It's a real mechanical problem that can be repaired like I say it can. I have done many of them after prople have spent $$$ replacing clutches thet were good and still had the same problem. . . .

FBp

 

Resurecting an old one here but I'm having the exact same problem. Is the problem the bushings or is it in the tranny? This topic never had closure. If it is the bushings, how hard are they to find/replace?

 

How are your cab mounts? That sounds more likely to me than spring bushings.

 

I had a chatter problem and it was my rusted out cab mounts.

 

Clutch chatter can really be anything worn in the drivetrain from the throwout bearing to motor mounts and the transmission mount to the rear end bushings to any combination of the above. Start checking things and post back.

 

can also be the harmonic balancer.. like i was told. i have the same problem but i am a 460/c6 starts and idles fine but from 8-1500 rpm the truck shakes horrible. i have yet to really tear down to find as i hardly drive it. but ive been told balancer/weight behind it or flywheel/flexpate depending on auto/manual tranny

 

Where exactly are the cab mounts and how hard are they to replace? The floor of this thing is a giant rust hole so cab mounts are an extremely likely possibility.

If it was the harmonic balancer wouldn't it be shaking at idle as well?

 

4 cab mounts. Two in front and two behind the gas tank in the cab.

The two in the front are notorious for rusting out. The two in the rear tend to be okay. When I took my '66 apart I could lift the front of the cab off the frame b/c they were not even attached anymore (even though the bolts were still all intact). I cut off the old mounts and welded on new ones. I got mine from LMC and they needed a small amount of fabrication, but fit nicely and look great! I don't remember them being that much either. The donor truck I bought had rusted out front cab mounts too. These '66 models seem to all have rust there, below the headlights on the radiator mount, and on the cross member at the point of the threshold of the doors.