I just installed a SB OK-HD Clutch. I do not think this is related but not positive.

I get a vibration when I am braking. It is not a warped rotor issue cuz the pedal is still very smooth. It feels like a drive line vibration. The harder I hit the brakes the more vibration. If I slow with easy pedal pressure there is no vibration. If I'm getting the vibration and then accelerate it stops immediately. I have no vibration or noise when driving. Only under braking. I checked the carrier bearing and tried to feel for play in the u-joints and it seems fine.

 

Could the front wheel bearings cause this issue?

 

Sure failing wheel bearings could cause vibrations while braking…but have you had the chance yet to pull the wheels and inspect the condition of the pads, calipers, as well as wheel bearings?? That's where I'd start.

That being said, interns of checking the ujoints, the driveline is so heavy that you pretty much need the truck up in the air and in neutral to feel for play in them…and its even better to use a pry bar and pry them around to LOOK for movement where it does;t belong.

An easier way to look for bad bearings or ujoints is to use an infrared thermometer (cheap and good at Harbor Freight) to check each and every u joint caps on the driveline for elevated temperatures after driving for awhile, You can also use it to check for bad wheel bearings and even sticking pads or caliper. Just drive around normally for awhile, use the brakes and then check the temps of all the different components you are suspecting….bad bearings or ujoints will always show up as higher temperatures then the good ones.

 

I have not had it in the air yet. Tonight when I got home I just crawled under real quick because my first thought was carrier bearing slop.
I have a Fluke infrared thermo. I didn't even think about checking the u-joint caps! Ill do that and the wheel bearing areas tomorrow.
I just drove it again and there is some type of low growl noise while driving that goes away when coming close to a stop. What makes this so much harder is the new clutch makes noise (normal) that it didn't make with the DM flywheel so that is adding to my confusion on where to look and what to check.

 

I would measure rotor runout, even if you don't feel pulsation in the pedal.

With u joints I've usually felt a pulsation at very low speeds. Looking very closely at them you may see a bit of rusty color around the seal
Of a bearing cap.

Checking wheel bearings would also be a good idea.

 

I can measure the run out too. Never hurts! Thanks for the idea.

And the reason I think U-joints, is during braking, the drive line angles change. This change could cause the failing joint to bind or just have additional pressure on it at an abnormal angle which I think would cause a vibration........ I THINK!

 

Could be. You can't always see a rusty discharge or feel slop when the drive shaft is installed. Sometimes it takes removing the shaft to detect a failing u joint.

 

It is a warped or rusty brake rotor

 

What about the drive shaft orientation? I can see where they marked the front shaft and replaced it the same but the rear shaft has no markings at all. I have heard not putting it back the same way can cause issues similar to mine?
I'm going to check this and rotors first.

 

Steve. I found this post from you in another thread. Any info on how much? Is there supposed to be a spacer at all from the factory?

 

DS orientation after DS removal can absolutely cause driveline vibrations, but the fact that the vibe only seems to happen under braking would indicate a problem with the rotors, pads or caliper or perhaps wheel bearings.

 

While using shims to lower the center being support can work magic on some trucks, particularly lifted trucks with a higher DS angle, the easiest permanent, though not necessarily cheapest, cure for inherent driveline vibration is to replace the 2 pice steel DS and center bearing with either an oem Mopar or custom driveline shop made aluminum, one piece driveline. Eliminating the center bearing, the center bearing bushing, and the center bearing support frame eliminates several vibration sources in one fell swoop. More then several people can testify to this, though it can cost $500 to $650, depending on how and where you source the driveline.

 

I will check the rotors and hub assemblies but I am really leaning to DS issues. It started as soon as the clutch was replaced. If it was a rotor issue I think I should have noticed it before the clutch work.

I will change the orientation first before I start throwing parts at it. The one piece DS is my goal to do and may happen sooner that I thought!

 

Rockcrawler,
Although the "U" joints are a common and persistent problem, it is unlikely to be the problem with your symptoms. When the "U" joint fails at the DS center, the vibration will appear at low speeds, 5-10 mph, When "U" joints fail a blossom of rust will usually appear on the joint. I suffered 3 DS joint failures before 20k miles. On the third failure I made a spacer 1.5" thick spacing the center shaft bearing down and have experienced no failures since. I don't know how common this fault is, but there is a test procedure in the manual for some models. I'm not sure if there are factory parts to address this though. Front axle "U" joint failure causes steering wheel oscillation just like you are in 4 wheel drive on pavement and executing a turn. In all those cases you must use the highest quality grease nipple equipped replacements and re-grease at least semi annually. The brakes can suffer two common problems. The first is rust and is a common fault on those trucks that are not used for a few days. This will cause corrosion in spots on the rotor. The other common fault is caliper seizure caused by the swelling of the plastic coating on the pistons. The only solution is caliper replacement. Rotor warping is unusual with these trucks because very heavy braking and the resultant heat doesn't often occur in a truck, but if you suffer a stuck piston, excessive heat can build up and rotor warping can occur.

 

Just food for thought- reading your symptoms, I agree with others that said rotors, calipers, and wheel bearings are the most likely culprits.

But I have been down this road myself (chasing odd vibrations)- so I'll quickly replay what happened here:

Had swapped to a single mass flywheel clutch setup (2nd one in the truck) just like you just did. My issue was different from yours- it was only while the vehicle was NOT moving. At about 1300 and 1700 rpms, there was a very noticeable shake.

At the behest of the installer- I replaced the damper on the front of the crank (which made sense) with the upgraded 6.7L version, and I even swapped the rear drive-shaft, dropping the 2-piece and installing the 1-piece aluminum mopar "upgrade" because I also was noticing a new shudder on take-off. These things made a noticeable difference in smoothing things out, but did not eliminate the odd vibrations at stand still.

Reverting back to an OEM style DMF clutch kit was what finally eliminated my vibration issue. The Dual Mass reduces vibrations in the drive-line by design, and the G56 is designed to have a dual mass in place to do just that. I wouldn't rule out an out-of-balance brand new single mass flywheel. It's rare- but it happens, I was lucky enough to find proof. Also- those added vibrations didn't just cause an annoying "chatter" in my transmission. When I removed my transmission I found my input shaft seriously loose and had to pay to have my G56 get all new bearings, etc. (basically rebuilt).

Running a single mass- I would highly recommend you upgrade your damper (if you haven't already), and consider the one-piece aluminum shaft update as well. The more vibrations you can eliminate from your drive-line, the longer everything attached to it will last.