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-   -   Kooks headers rubbing? (https://www.performancetrucks.net/forums/gmt-900-trucks-general-discussion-188/kooks-headers-rubbing-526516/)

AKlowriderZ71 02-12-2014 09:52 AM


Originally Posted by beastmode (Post 5191462)
I was telling Pat yesterday, its something you actually feel at your feet. It definitely feels like something under the hood or at the firewall.

I found it odd too that its very hard to recreate the problem in 4wd. I tried like 15 times and maybe did it once and it was ever so slightly.

Can you duplicate the noise without the truck moving, by power braking it? Or does the truck have to be rolling?

Vortec350ss 02-12-2014 09:54 AM


Originally Posted by AKlowriderZ71 (Post 5191468)
Can you duplicate the noise without the truck moving, by power braking it? Or does the truck have to be rolling?

good thinking...

beastmode 02-12-2014 10:11 AM


Originally Posted by Vortec350ss (Post 5191467)
what was adjusted in your front end to lower the truck? I'm sticking to my guns that its some sort of weight transfer and a rotating part is hitting/rubbing. Most likely a CV axle as I think the drive shaft would have a different tone spinning 3-4x faster than the tires.

Is it MOST noticable when getting hard on the throttle at high speeds or low speeds. You have more weight transfer at low speeds...

When I bought the truck I had the dealer install 2" belltech drop struts, set at 2"... and they removed the blocks and added lowering shackles set at 2". So essentially a 2/3 drop.
Back in December I dropped the truck off to just have a flip kit/hanger lift done and set the rear end at 6"... thus making it have a 2/6 drop (believe it or not it does sit level lol).
From the moment I picked it up from the dealer it has been making this noise. My first thought was pinion angle or driveshaft pushing in to the case. First I got the driveshaft cut by an 1", it needed this either way or else the yoke would be in to the case too far when I loaded the truck up with 2k lbs. After I realized that didn't fix it I removed the transmission spacer, didn't fix it. After that I ordered 4* shims in order to get the pinion closer. Still no go after all that.

I'm in agreement with you, it has to be something rotating... hence it sounding like more of a vibrating/grinding noise to me.

It physically feels more noticeable at low speeds, at high speeds you hear the noise but don't really feel it.

The truck never ONCE made this noise or anything remotely close to it prior to the flip kit... it was as quiet as can be.


Originally Posted by AKlowriderZ71 (Post 5191468)
Can you duplicate the noise without the truck moving, by power braking it? Or does the truck have to be rolling?

Pat suggested this last night, will give it a shot after work today and see if I can recreate the noise.

RacinRust 02-12-2014 10:12 AM

Have to be very careful when you do this. Lift the truck off the ground and support the truck by the frame. Let the wheels hang. Start the truck and put it in gear, Let the wheels rotate. See if you can duplicate the noise and vibration without a load by varying the wheel speed by just a couple of miles per hour forward and reverse. Don't spin the wheels very fast as this can be dangerous. This is a static driveline unloaded test that changes the dynamics of the frame while loaded in a different position. Once again BE VERY CAREful. Make sure you have help while doing this.

Robert91RS 02-12-2014 10:33 AM

I've seen other brands of headers rub after a motor mount got weak. I can't see your video at work so I can't tell anything about the noise besides what you have described. Could you give me any other descriptions of the sound, ie buzz/rattle/click and how it relates to vehicle speed and rpm? Had a friends OE muffler develop a rattle shortly after installing LTs.

lsxperformance 02-12-2014 12:12 PM


Originally Posted by 06tx4.8 (Post 5191365)
y pipe rubbing on tranny x member maybe where it merges?

Mines close here but dosent rattle check your motor mounts I have had them break.

beastmode 02-12-2014 02:26 PM

So I'm on my way home right now going to be quick. I power brake the truck for a few seconds and couldn't create the noise. So I get on the highway in floor it and It doesn't do anything until almost 4,500 RPM's now. WTF?!?!

beastmode 02-12-2014 02:33 PM

Just got to to make the noise while I was brake torquing it... ugh this is annoying

beastmode 02-12-2014 03:15 PM

Videos are a little short but unfortunately if I record for to long my phone won't send them lol.

Very faint but it starts to do it around 4200-4300 RPMs, this was after brake torquing the first time.

http://i1185.photobucket.com/albums/...ps52de74aa.jpg


Brake torque

http://i1185.photobucket.com/albums/...ps5610a414.jpg

cam 02-12-2014 03:57 PM

I dont hear anything odd in those clips ???

Maybe a bit of valvetrain noise, but certainly no pipes banging. Still on AFM lifters?


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