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Clutch Shudder when cold, how to inspect, are any I phone snake camera's worth it? 260K mile decision time

S

schiker

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My truck's shudder on launch has gotten worse with age to point now its getting really aggravating sometimes Seems to have gotten worse this last winter. Might be getting better with warmer weather. But sometimes it's violent almost like its going to wheel hop spin. It only shudders when cold or its been sitting til fully cold.

It shudders on launch when cold with varying severity. It's worse in reverse. Its better in 1st gear. It's medium in 2nd gear. This is all letting the clutch out slowly then rolling into the fuel pedal. Once the engine is up to operating temps it launches smooth. But this is also a few launches so not just engine temp but clutch disc temp as well. Shifting has always been fine. Might be a tad sticky getting into 2nd gear if I launch in 1st while cold but 3-5 are always fine. By a 1000 ft rolling 1st-2nd shift is fine when cold. The transmission feels fine no clutch rattle but when it shudders badly it makes the clutch pedal spongy then a few pumps and it is normal. If I rev it up with a romp/release and the engine gets almost back to idle it has a little shudder like the engine mounts are shot. But I am not getting really bad stick wobble in the cab.

I have been trying to vary launches to see if it makes any differences. I tried engaging the emergency/parking brake and it was smooth maybe just a hint of shudder but not the violent almost wheel hopping shudder. I am going to try different levels of the emergency brake. Would this indicate worn out universal joints? There is slop in driveline but its doesn't "Tink" anytime.

I have tried a 4x4 low launch and its so low it covers up any shudder. I will try launching in 3rd or 4th gear while in lo next time.

At 260K miles on the truck (less than 60K on clutch, PP, Pilot, slave and transmission) its probably a combination of issues.
  1. Some oil/ fluid on disc. But there is no oil puddle under the truck just normal 260K seepage/drips.
  2. Tired/worn out engine mounts see above.

3. I think a worn IP not having precise idle control and weaker engine torque on launch.

What else could it be?

What is the best way to figure if its something else or what's the biggest contributor?

I will probably have to replace a bunch of parts while I'm there doing a water pump but I don't want to replace most everything and not fix it.

Any good diagnosing tips? I think I'll put the rear end on jack stands set parking brake a little and have someone simulate launch and see if I see anything noticeable while underneath.

Anyone ever tried a snake camera in the bell housing? There are some on ebay for <$50 that work with an iphone but I think the viewable area is going to be too tight to see much of anything.

Decisions decisions on what to do and how much money to put into this thing.
 
Classic burnt flywheel & clutch by the way you describe it...

I doubt inspecting from the bottom would show anything, if oil has made it's way to the disc it's time for a new disc and grind the flywheel.. motor mounts can contribute to the cause also..
 
I have heard of a burnt flywheel and a burnt clutch but never fully understood until I typed this all out if I have it right. It has bothered me why severity varies so much especially cold to warm, different gears, different loading on launch different weather and different fuel etc. So thinking about it I think that it makes sense but in my case, I think its a combo of things especially age.

I read Warwagon's description of braking hard then sitting is bad you should ease forward a few times after hard braking to keep the super hot pads from sitting on the rotor in one spot. The excessive heat locally under the pads can warp the rotor and I guess heat treat it under the pads to then wear differently.

A clutch is similar to brakes but with 360 degrees of contact. But there are always tolerances and nothing is perfect. Combine tolerance of spring clamp forces of PP leads to more variation of slippage around the clock. Throw in some oil, maybe even grease from a failed pilot bearing seal, old worn motor mounts, some surging of IP, weaker launch torque from age, looser idle control from aged IP and different fuel viscosity, age on the clutch disc hub springs (springy loading), some heavy launches, operator error and eventually you'll get a hot spot(s) that are high and or have some variation of coefficient of friction.

When I romp on it in neutral and it comes back to idle it has a little shudder of motor mounts at the end and I can get a slight variation of severity as it warms up from a cold start. There may be another very slight variation between transmission in gear transfer case in neutral heaviest neutral load vs clutch pedal to floor, transmission and T case in neutral lightest mount loading. So I do think the motor mounts contribute to a springy load up of the clutch lift off.

Combine all those things and I have some significant variation of clutch chatter/shudder. If I gear low the torque on the clutch isn't much so it masks the slippage variation because the loading is light and it just locks up. Load the launch and it increases the slippage to a bigger surface area. Warm the clutch disc is more consistently grippy and has less chatter. I suspect when it gets really violent shuddering its a snowball effect.

Regardless its going to take tear down and several parts to make it consistently smooth. I guess I'm going to live with it until I'm ready for some major maintenance.

Maybe moral of story buy good clutches that can take some abuse. Mine is an OEM Luk Gold clutch but dang anything GM clutch related is cheap and under strength.
 
Lube on clutch disk is the biggest contributor to cold clutch shudder.
Dont know if the inspection cover can be removed, if so, have someone disengage clutch and spray brake parts cleaner onto clutch surfaces, turn engine a ways and repeat, generously flooding the mating surfaces rinsing off the lube. This may help for a while.
 
The rear seal, the oil pan gasket, and or the remote oil filter adapter all seep a bit of oil. Not really a drip leak more a seepage. The oil pan gets wet between oil changes then I wipe it off. No significant wet spot under the truck and I park in the same spot.
 
A bad rear main or filter gasket seal can get there- but figured you would mention them if suspect.

The drain hole I mentioned is because you could spill fuel during a fuel filter change or have a leak at ip causing fuel to contamate it, and it takes a very very slow leak to do it.
 
Hubert I know you tow some, I think you said the clutch has some age & miles on it, hot spots & glazing on a tired clutch combined with week pressure plate, all will get worse as things heat up and be not so bad when cold..

You can have the flywheel ground cheaper than a new one, a new pressure plate U clutch would be required. If you have the fw ground just be sure and mic it first and after so you can shim it the amount that was ground off... Don't let anyone turn it on a lathe only have it surface ground.

And get ya some poly motor mounts & poly tranny mount and they will last longer than the truck will...
 
I've heard of a few flywheels that the surfaces aren't parallel. Old time machinst friend of mine likes to chuck them up in a lathe and indicate off the ground surface and then check the crank mounting surface. Said he's seen more than a few that were off quite a bit, gives the symptom of a bad pilot bearing
 
Chris, are you saying a burnt flywheel/clutch gets worse as temps increase?

Fully warmed and having driven around some the clutch chatter/shudder is minimal. I still feel it because I know its there but its smooth enough.

I did not mention this but the shudder comes on at the 1/2-3/4 end of clutch release after the truck is starting to roll.

I looked under the truck and the rear transmission mount looks pretty bad ( some cracking and stressed looking ).
 
It’s gotten a little better on its own. I had run some heavy doses of power service thru tank so suspect it’s IP and engine mount combo mostly.

I have a few projects I have to finish before I work on the truck.

I haven’t quite decided if I want to just pull the engine and shotgun it or do mounts in frame first.
 
I installed energy suspension engine and transmission mounts, Timing gears, Fluidamper, and solid crank pulley (also new water pump fan and fan clutch). On test drive 2 gear launch was much much improved. So was reverse. Silky smooth in 1st. I just feel the clutch engage in 2nd. Don't think I could ask for much smoother launch with tired suspension and shocks (rear bushings are worn out).

I think engine mounts and transmission mounts were toast. Maybe the transmission mount was the worst of it as it started to shudder when it started rolling.
 
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