Hey fellas:

I finally got my truck back from the shop that installed my cognito 4-6 (bilstein shocks); and h2 wheels with MThom AT - 35's.

The ride is as good as stock (with bilsteins) or better! If anyone is sitting on the fence this is definately the way to go!

Now for the questions....
Today I finally got a chance to put the truck in 4 wheel drive (ohio snow) and, on the highway above 40mph, I am getting a loud whirring noise or vibe that gets progressively worse as the speed increases. The noise can be modulated with the throttle load (above 40mph) as well.
This only happens in 4 wheel drive. The truck has 105,000miles with stock ujoints that are in good condition.

The vehicle is a 05 2500hd ext cab long bed.

Any ideas what could cause this?

thanks,
Lee

check the fluid in the front diff maybe?

did you opt to get the longer front drive shaft?

Front drive shaft. You need a longer one when in 4wd speeds over certain speed, or else it shakes like crazy.

Front drive shaft. You need a longer one when in 4wd speeds over certain speed, or else it shakes like crazy.

YEP!

Seems like I have heard that before... uh hmmm?? :rolleyes:

Makes total sense... is that an item that Norcal carries or do I get made somewhere??

thanks guys. I knew I could get the answer here.

As for the fluid level.... they're all topped off.



Lee

Im pretty sure you can get it from Nick. I know when you purchase the lift on the site, and pic the options, the new drive shaft is an option on there.

im gettin a wierd vibe in my truck as of today. its like hittin a rumble strip for a couple seconds and only happens at lower speed. like 20mph. switched to 2wd and never got the sound to come back. only does it in 4x4.

could be front diff maybe. My moms 02 denali did the exact same thing, had a rumble vibration at 20 mph like when coming to a stop. Turned out to be the front diff.

hmmmm i know the fluid is good cause i added a pint after the lift. ill have to take it to the stealer me thinks. im pretty sure it has nothing to do with the lift cause ive run it in the summer in 4wd just to check for vibes and it was good everytime i tried it out at different speeds.

fluid level!! add at least a pint, if not a quart more fluid to the front diff. otherwise you will smoke it. fill through the big round vent hole. my 02 with a fabtech 8" lift did the same thing. it was the diff.

good luck

if you would have looked at all the posts we have both added the required extra fluid after the lifts.

Im pretty sure you can get it from Nick. I know when you purchase the lift on the site, and pic the options, the new drive shaft is an option on there.

Thanks Kilo. I will check with Norcal. Any ideas what length I may need. The truck is set at 4 inches.

if you would have looked at all the posts we have both added the required extra fluid after the lifts.

i did look at all the posts, he said "fluid topped off." that doesn't mean he added extra.

what's with the attitude? just trying to help out. who pissed in your cereal? or are you just angry that your truck has problems and you have to take your frustration out on others? lame:rolleyes:

Thanks Kilo. I will check with Norcal. Any ideas what length I may need. The truck is set at 4 inches.

shouldn't need a longer front driveshaft for only 4"

my old '02 had a longer front shaft and that did not make a difference

good luck

I would just call Nick. He will know for sure if you need one or not. And if you do need one, just tell him what on the truck, and he'll know what length you need, if you need one.

I added one at 4.5 never ran without it so I dont know if it is required. Nick did suggest one for mine becasue I drive over 35 in 4x4. x2 on asking Nick. Hope you get it sorted out.

i did look at all the posts, he said "fluid topped off." that doesn't mean he added extra.

what's with the attitude? just trying to help out. who pissed in your cereal? or are you just angry that your truck has problems and you have to take your frustration out on others? lame:rolleyes:

Oh dont go and get your pretty pink panties in a bunch! trust me if i was being rude youd know!

thanks guys! I will give Nick a call on Monday and see what he recommends. I'll let you know what he says and hope it helps someone else!
Also, Additional fluid was added to the front diff. after the lift was installed.

I'll bet it is the front shaft; Here in Ohio...if there is snow on the ground... my truck is in 4hi. Therefore highway speeds are the norm. The supposed salt shortage has our local road crews rationing; and I don't like poking behind the mini van in the right lane when there is a perfectly good left lane with snow in it!! :cool:

hopfully that gets yah sorted out man!

Did you ever figure your vibration out? I am having the same issue.