LMM: WTF is rattling under driver side foot area????

[cdbright]

when throttling up or just cruising i can hear a rattle(not a grind) under my feet, it goes away right away when i let off, but i can hear it when i break kinda hard, i am sick of laying under my truck looking for something loose. It seem to come after a good 120+ mph race i had with a goat in SLC over xmas but i still cant find anything. Is this my flex plate cracked????? it cant be anything w breaks but why the hell does it get a little louder when braking. It wont do it trying to power break so it seems to be something with drive train, cause there is torque being applied while power breaking. I dont know what to take apart first and nobody will drive my truck with my ass strapped under it to try to find the prob. So i rely on you guys to shed a little light if possible. thanks in advance.

 

[durallymax]

TC bolts?

 

[cdbright]

i hope not

 

[durallymax]

ehhh just tighten them back up to gudentight

 

[cdbright]

Mike L drove it and saidit was not tranny nor related, it is something on the back driver side of engine that rattles when it wants to, seems like an exhast clamp ring but no exhast leak

 

[SgtKilroy]

Downpipe rattling against your trans dipstick?

 

[LBZ]

Or the heatshield bolts on the up-pipe are loose?

 

[TeaBagger2006]

maybe a bad bushing,u joint,

 

[LBZ]

Or the heatshield bolts on the up-pipe are loose?

Actually scratch that (after I re-read the first post).
I'd look to a bad front/rear driveline including u-joint.
When you accelerate/deccelerate, your front and rear go up and down changing the angle of the u-joints and this in turn could cause your noise. Could also possibly be a bad CV as well I suppose. Was the 120mph run in 4wd?

 

[Steve W]

Check the transfer case oil. mine was low when I first bought it and it made a rattling noise like a chain slap. You would think a dealer would have checked stuff like that before they sold it.:roflmao:

 

[cdbright]

I was in2wd, but in did notice a little tcase
oil at the outpute shaft

 

[cdbright]

all fluids good, put on hoist, lubed every joint, checked everything possible, drove, put back on hoist, opened hood, drank beer, staired at it, put back on ground , drove around again, back to hoist, seeeeeeems to be slightly torque relatede as it has to be rolling (in 2w or 4w ) and have some tourque applied to get it to knock/tap/rattle. Starting to think it is something that rubs when there is just enouph tourque on engine to move it a little so something will touch when it otherwise does not, kinda whant to just tear all apart and add headers/2nd turbo, and just be deep in there to see what is going on anyway?

 

[Chevy1925]

motor mount shot? i use to get a screeching sound at certain outside temps and couldnt figure it out. wound up being the u-bolt type exhaust clamps on my exhaust, the u-bolt part would vibrate against the metal causing the screech. i cranked the hell out of them and it quit.

 

[cdbright]

ok so after the 5th time on the hoist and relubed the sh!t out of every joint and re- topped off all the fluids, the tap turned into a rattle, witch was the heat shield behind the driver side up pipe, it only has 2 mounting bolts and the top is loose, so i used my special pry bar/easy does it rod and made a pressure dent to add pressure to the top half and now all is quiet. I know i never found knock but i quess all is well (FOR NOW)