Vibration only in 4h at highway speeds.

In 4 high, only 2 wheels have power. One in front and one in rear. Both are open differentials, with auto LSD. It's fine to travel at higher speeds in 4 high.

 

haha cool, never realized that's how 4hi operated. This is all a learning experience for me haha which is why I love this forum, so thanks for the tid bit of info

 

Not totally true, in 4wd all 4 wheels are powered "given" equal traction, an open differential will send power to the wheel with the least amount of traction as in one tire on ice opposite tire on dry pavement, the one on ice will spin.
If your statement were true you could not get all 4 tires to spin in the snow.

 

That's where auto LSD comes in to play

 

Auto LSD was not part of my statement.
Auto LSD uses braking force to regulate spinning tires, it's not part of the differential.

 

I never really had the chance to drive the truck at the speeds I mentioned until after the ecgs bushing was installed. I just know that the vibration is still there. I have blocks in the rear. But don't feel any vibration at all in 2h. I've talked to several shops in the area. Most of them have said they don't even wanna touch the drive shaft because it's a modded truck.

 

I still think myself it might be the drive shaft angle. Or maybe out of balance. But even when I removed the diff drop and took it for a ride the vibration was the exact same in 4h. It's really pissing me off.

 

Do you commonly drive at 110-120km/h (68-75mph) in 4H?

My understanding was that was not recommended... seems like the manual said no faster than 62mph (100km/h). But I could be remembering something incorrectly.

 

There is no max speed recommendations in 4h. It just says you can only shift between 4h and 2h at speeds lower than 100km/hr

 

At 75 MPH on snow covered roads the OP will end up like the Beamer that passed me coming off a mountain pass in OR. Luckily for the Beamer they left the road on the ride side and not down the mountain to the left.

 

Hmm. Okay I wasn't really sure on that one. Haven't seen real clear answers on that one before.

Yeah I was cruising home last night at 75mph on the interstate (very straight road though, no cliffs, etc). We're seeing sub zero temps so roads are hard packed and slick. Some douche in an old Subaru was so close to my tailgate I couldn't see his headlights in my side mirrors (@ 75MPH, in the dark, on cold, icy roads). I let the jack wad pass me. Once he did I showed him my Baja Designs fog lights. He thought they were so awesome he rolled down his window, at probably 80mph in sub zero temps to wave at me. He must have liked them a ton to open his window at those speeds at such cold temps. Made me proud.

 

I know this is older but did you figure out the issue? I’m having the same exact symptoms, ecgs bushing installed, freshly rebuilt diffs, driveline angles are all correct. When driving in 4HI I get a nasty vibration starting around 30mph in snow today. I noticed my front diff was leaking the other day so maybe it’s leaked dry? Also those who are saying there’s a recommended speed limitation in 4HI is wrong.. I’ve done 90mph no problem.

 

Worn ujoints can cause this. Really hard to tell without removing the shaft.

 

Hey guys, did you ever solve your vibration issues?

I am having the EXACT same issues.
I am running a 3in Elka lift. I have the diff drop. I never had any vibrations until recently.


These are the symptoms:

• Vibrations when in 4HI on the highway accelerating passed 80km/h.
• Vibrations are steady when pressing the gas maintaining a speed of 120km/h.
• Vibrations reduce to almost zero when I let off the gas.
• The vibrations are felt in the gas pedal, gear shifter (manual), and in the seats.
• All tires have been rebalanced after feeling the vibrations, but obviously not the problem.

This is what has happened to the truck recently:

• I started having vibrations when in 4HI on the highway.
• I look under the truck and realize my newly installed (4,000km) driver axel outer boot is freshly torn. Axel is still strong.
• I seem to have a leak from the front diff as well.
• I bring it to shop I got the new axel from and they warrantee the axel but I got them to install it this time. (too cold for me to do it outside at -25°C)
• The shop replaced the axel, axel seal (the front diff was leaking like a sieve and seal was destroyed), installed the ECGS, and topped up the diff oil.
• The shop also replaced driver side UCA ball joint (SPC), passenger side LCA ball joint (Moog).
• Alignment was done.
• I drove the truck right after all new parts are installed but STILL have the vibrations.
• The shop took the truck back and looked over everything, but nothing seems off. They checked the u-joints as well.

ANY FIXES?!

 

My dumbass forgot to tighten up my front driveshaft bolts after installing URD headers. Almost had a catastrophic failure.

 

That could have been bad!

 

Maybe every one is looking at the wrong end of the truck.

 

Motor or trans mounts could be the issue. Carrier bearing, wheels out of balance or pipe clamps instead of oem boot clamps on the cv axle have given me a small but noticable vibration. Uneven tread wear could also be a culprit. Maybe stick a gopro in a few different spots while you drive. Rims bent?

 

All possibilities. Tires are balanced and apparently one rim is slightly bent.
Vibrations only happen in 4HI when accelerating passed 80km/h (50mph). That's the weird part.
Good idea on the GoPro!

 

You might want to be looking at the inside of the front diff. Dump some gear oil and see if there is metal in it.