Clutch chatter or driveline shudder...

[7tee]

Just wondering if bad cab and bed mounts could cause this, hell I know I'm fishing but after all the new parts it still does it...Ed

[Kw69]

Got the same issue with my truck, I thought it could be the flywheel but not sure yet. It gets really bad in reverse. I heard the 2 piece drive shaft is to blame? Don't know yet but hopefully someone else chimes in.

[geezer#99]

Originally Posted by 7tee

Just wondering if bad cab and bed mounts could cause this, hell I know I'm fishing but after all the new parts it still does it...Ed

New parts!!
Like in everything!!
New pilot bushing, pressure plate and disc, tob, fork, pedal bushings or flywheel.
Depends on how deep you went into parts changing and the quality of your new parts. A 100 buck clutch is a crap shoot for quality.

Another clutch chatter symptom is motor and/or tranny mounts. Old ones flex more.
Another possibility is your gearing. Lower gear ratios(3.08) make it harder to get moving smoothly.

[7tee]

New motor, motor mounts, GM flywheel, pilot bushing, centerforce clutch and pressure plate and throw out bearing. Bellhousing mounts, driveshaft balanced, new u-joints and new front yoke. It still has the same 3.73 rear end with a T5 transmission that has the gearing, 1st 2.95 2nd 1.94 3rd 1.34
4th 1.00 rev.2.76. Any further suggestions are welcome...Ed

[geezer#99]

What does it do if you start out in 2nd gear?
What's your pinion angle?

Coil springs or leafs?

[7tee]

It does it mostly in reverse, pinion angle is -4* at the tail shaft of tranny and +4* at the pinion with coil springs and trailing arms, I was wondering if this angle is correct...

[geezer#99]

4 down at the tranny and 4 up on the rearend is good.
Are you stock or lowered suspension?

[7tee]

The PO lowered a little with springs. I'm still running 15"x10" wheels w/ 255/70 tires. Was wondering if trailing arm bushing could be bad and how to check...

[geezer#99]

Could be a bunch of things.
You could use a little hydraulic bottle jack to lift on each arm to see how much they move.

To eliminate motor/tranny movement you could try tieing the front drivers side of the motor solidly down to the frame. A small turn buckle would work for that.

You say po lowered it.
Did he or you change all the clutch components?

[7tee]

When I bought the truck 2 yr ago it chattered even worse. Since then I have resurfaced the flywheel twice, put in two new clutches and pressure plates,TO's and pilot bushings. Then installed a new 350 crate motor and all the new stuff again mentioned above in original post. Through all this time that I've had the truck there's only been about 5,000 miles put on it. I drove an 18 wheeler for 15 yrs and know to take care of a clutch so I know it's not me.

I checked the trailing arm bushings and they seem to be ok. Also checked the pinion bearing for play and it's good. I'm totally lost at what else to do or check...

[davepl]

I chased a bad shake/chatter on initial acceleration that had us all stymied. We took the driveshaft in to have it rebalanced just as a last resort, and the splines were apparently worn a little, so they replaced the splined section as well. In doing so they had to replace the actual bearing part of the carrier bearing, but it was already new.

This fixed it, though no one really knows how or why. Perhaps even tiny slop in the spline joint can get multiplied. I'm just really glad it went away because we were all out of ideas and everything else was brand new and in the right place!

Mine was fairly specific: when you tipped into the throttle maybe 20-30% from a standstill, as it rolled through 5-10mph, it shook the truck.

[geezer#99]

Originally Posted by 7tee

When I bought the truck 2 yr ago it chattered even worse. Since then I have resurfaced the flywheel twice, put in two new clutches and pressure plates,TO's and pilot bushings. Then installed a new 350 crate motor and all the new stuff again mentioned above in original post. Through all this time that I've had the truck there's only been about 5,000 miles put on it. I drove an 18 wheeler for 15 yrs and know to take care of a clutch so I know it's not me.

I checked the trailing arm bushings and they seem to be ok. Also checked the pinion bearing for play and it's good. I'm totally lost at what else to do or check...

Tie the motor down. See if it helps. Turnbuckle is likely 10 bucks.
A remote possibility is a cracked frame. Found that once by tieing a motor down.

[Ruscal]

I'm experiencing chatter also. If I gently take off at low rpm it's ok. A little more throttle during take off chatters badly. More aggressive launch and no chatter. It's that medium rpm take off that produces the problem. I have a t56 magnum with Mcleod RST twin disc clutch. I spoke with the tech at Mcleod and he suggested de-glazing the flywheel and pressure plate with 60 grit sand paper. Maybe I broke it in too gently in the beginning? All my mounts and bushings are new and tight.
In your case it seems you have done a lot of parts changing already, so probably not glaze related. A friend suggested that it could be pressure plate finger height related when the heights vary by just a few thousandths of an inch. Mine is a diaphragm type with no adjustment though. Let us know what you find. Good luck with it.
Russ

[7tee]

Thanks Ruscal, I feel there are others on here that have or had this same issue but after 2 cheaper clutch systems w/resurfaced flywheels and now with a more costly centerforce dual system and new GM flywheel etc., I just can't help but think the issue is somewhere else. As you mentioned about the low rpm and off the clutch quickly is the same here. I guess quality control is about the same no matter the cost, but I haven't given up yet...Ed

[Overdriven]

Some good info here. My 6cyl 3OTT chatters in reverse unless I get it just right. Whole damn engine and trans shakes the whole truck when I get it really wrong. All except the carrier bearing will be taken care of just by the drivetrain swap I have planned though. Good luck with yours, only thing I can think of you haven't mentioned is trans alignment in the bellhousing.

[Ruscal]

Originally Posted by Overdriven

Some good info here. My 6cyl 3OTT chatters in reverse unless I get it just right. Whole damn engine and trans shakes the whole truck when I get it really wrong. All except the carrier bearing will be taken care of just by the drivetrain swap I have planned though. Good luck with yours, only thing I can think of you haven't mentioned is trans alignment in the bellhousing.

My trans alignment is .oo4" off center which is not much. They don't offer offset dowels in such a fine increment. Tremec says .oo4 is about the limit though. Somebody needs to make .oo4 dowels!
Russ

[Ed F]

My '70 has a similar condition. If I don't think about and just start out easy without slipping the clutch it's very smooth. If I hit it hard and sort of pop the clutch it's fine too. It's that in between rpm/speed when I slip the clutch or slow maneuvering in first or reverse, slipping the clutch, that it chatters the worst. I had the driveshaft rebuilt, installing a slip yoke, new u joints and carrier bearing and then balancing. That made no difference. The PO said he replaced the clutch. A mechanic friend suggested that it may be a high performance clutch that isn't made for normal driving. Anybody have any thoughts on that theory?

[Overdriven]

Originally Posted by Ruscal

My trans alignment is .oo4" off center which is not much. They don't offer offset dowels in such a fine increment. Tremec says .oo4 is about the limit though. Somebody needs to make .oo4 dowels!
Russ

I was thinking the mating surfaces of the bellhousing not being parallel, but if you measured input shaft center down to .004 I'm sure you checked the mating surfaces too.

[Ruscal]

Actually I didn't think to check for parallel. It would have been easy to do at the same time with the magnetic mount dial indicator. I have a Quicktime scattershield bell housing which is made up of welded steel, so could be off a bit compared to a machined factory bell housing.
Racing clutches are known to be more finicky than softer street ones, but mine is a street setup.
Russ

[7tee]

Originally Posted by geezer#99

Tie the motor down. See if it helps. Turnbuckle is likely 10 bucks.
A remote possibility is a cracked frame. Found that once by tieing a motor down.

I wish it would have worked for me, but no...but thanks for trying...

I tried it on the right being the chatter is more in reverse...