mgarton

I've been reading all the shudder and vibration threads, and none seem to match my particular problem.

First, I have a 2010 SCREW Lariat with the 5.4. It has about 74k miles on it now. A few months ago it started with a light shudder whenever I would take off from a stop, but never when I would stop or at higher speeds like the other threads talk about.

The weird part is some days it will do it every time I take off, other days it won't do it at all. Lately it's been getting more of a violent shaking type feeling instead of the light shudder. But it still only does it about 50% of the time and only on take off from a stop. I also noticed lately that it's doing it in reverse now too.

My theory is that maybe the limited slip is wearing out. I'm not even sure if the truck has an LS rear? What other things should I be considering? Transmission? Axle wrap?

I hesitate to take it to the dealer because my luck would be that it wouldn't shudder at all for the technician. Thanks for any help you can provide!

slackwolf

take a look at this and see if it's what you are having happen.

I have a '10 SCREW 4x4 145" WB with the 1 piece drive shaft and occasionally get the shutter from the slip yoke on the driveshaft going into the transfer case as the truck nose dives while hitting brakes, or hitting bad bumps. Does not do it towing very often when the rear is sitting level, mostly just unloaded and braking. If I brake gently, I can prevent it from happening 99% of time. I used an SCT tuner with 5 star tuning maps to fix the transmission shift bumps. Leaf packs were squeaky prior to a cleaning and a good coat of corrosion-X. White lithium grease lasted maybe 500 miles and then attracted dirt from trails. Leaf springs being lubed helped with the shudder feeling somewhat, but the root cause was the slip yoke.


Tube of motorcraft XG-8 teflon grease will help it out for a while. Wondering if something like cat desert gold or the amsoil polymeric off-road grease would stay put longer and have more cushion on the splines. Haven't tested it yet but if I have to drop the drive shaft again soon, I have try it.

mgarton

Thanks for the suggestion! I'll be sure to check that out soon.

mgarton

It's been a while, but I wanted to report on what's going on with my truck and hopefully help someone else having the same problem.

I tried these things a couple of weekends ago.:

1) Changed diff fluid in front and rear
2) Lubed drive shaft

Neither of these had any effect on the shaking. I did find out my diffs are open and not limited slip, so that immediately threw out my theory of clutch packs causing it.

I have noticed that it only happens when the wheels are turned. It doesn't shudder at all when the wheels are straight ahead. My new theory is the transmission mount is deteriorating, but I'm not sure why having the wheels turned would have any effect on that. Could be a front CV joint? Maybe the rear Ujoint? Does the front shaft even turn when it's in 2WD?

I'm working on borrowing a GoPro from a buddy to mount underneath and see exactly what's happening. When I get that video, I will share it on here.

Yall have any other thoughts in the meantime?

SportsLab

Sounds very much like what my 2011 5.0 Screw was doing. Cured by a $6.00 bottle of friction modifier to the differential.

mgarton

Wouldn't that only apply to limited slip diffs though? I wouldn't think it would have any effect on open diffs.

SportsLab

Yes mine is an LS differential. And also seeing you have changed out fluid you would think that would help as well. In the process of elimination I tend to start with the cheapest and easiest fix so I was just throwing another option out there (sorry it didn't apply). Wear to ring/pinion gears causing excessive play? The good news is some on the forum will nail a diagnosis for you. The bad news is it may not be a $6 fix as mine was.

santa06

When you turn the wheels doing a corner the pumpkin or centre part of the diff that has the side gears in it, compensates to allow one wheel to go faster than the other , which is necessary to prevent skidding.

Front diff is free wheeling in 2 wheel drive so noise is more than likely from the rear diff.
I asume it is the 9.75" rear end. Any sign of leakage from the front pinion seal?
Any metal filings in rear diff when you dumped the oil.

mgarton

Yeah I know how differentials work, I've rebuilt several before. I was surprised to see they were both open instead of limited slip. Nothing unusual in the rear fluid, but the front fluid was milky gray like it had been underwater at some point before I bought the truck.

Since they're both open, I'm not convinced that the diffs are the problem. I'm leaning toward the transmission mount at this point, although I don't understand what having the wheels turned has to do with it.

Just waiting for my friend with the GoPro to get back in town and see what's going on under there.

Thanks for the suggestions, keep them coming!

SilentJoker

Crazy guess but does it do it if you lift it up and turn the wheels? Maybe grab a wheel lifted and shake the hell out of it see if it pops around when turned. Just what i would try