Lurking vibration

portlandareae28 · Feb 19, 2012

I am having a vibration (might call it turbulence) at 2100Rpm and up... I feel it in the floor and the shifter (ZF-5). Truck has 250k on it, I am thinking I am going to replace motor mounts and tranny mounts either way. Anything else anyone can think of? It does have a down pipe and still has hollow cat and muffler. Could it be exhaust turbulence? Seems like the truck should be smoother than it is..

mandkole · Feb 19, 2012

is the issue engine speed based in all gears or vehicle speed? loaded or unloaded? any downpipe/body interference?

portlandareae28 · Feb 19, 2012

all gears, seems RPM based, not speed based.. I think there is some down pipe contact, I will double check today.

7.3psd97444 · Feb 21, 2012

Most likely the downpipe rubbing the upipes and/or the pinch welds on the firewall. Mine does the same thing. Double check to see if its engine speed based by getting up to speed(55-65 mph) and putting the truck in nuetral. If niose persists you know its not engine/trans related.

brewer · Feb 22, 2012

Ask me how I know about dp interference :doh:. Could also be wheels out of balance, driveshaft carrier bearing, motor/trans mounts. Just some ideas.

portlandareae28 · Feb 23, 2012

its definitely not speed related (does it in the driveway sitting still in neutral), I will double check the down pipe, and maybe if they aren't too spend change the motor mounts too, as I have a clunk on shifting (not always of course it is a 7.3) that seems like it is more than it should be.. Carrier, ujoints, all new.. I understand its an old diesel truck, but it doesn't have to act like one all the time :shrug:

Fly By Night · Feb 23, 2012

Have the honey hold her in the rattle band and crawl around to find out where the noise is coming from.

portlandareae28 · Feb 23, 2012

the other thing that happens that leads me to really want to check into the engine mounts is.. If I am backing into my driveway, and the wheels get kinda caught in the rounded curb, so you give it some more power to get over that hump, and once it gets over the hump and you press the clutch to keep it from hitting the house, it Clangs and bangs and everything under there (I have had the neighbor back it in so I could watch) seems to slam back and forth... I won't be able to get under it til next weekend, but keep the ideas coming, so I can check it ALL at once..

Brian

Patrick Feeley · Feb 23, 2012

Do you still have the stock DualMass FlyWheel? Cheers!

portlandareae28 · Feb 23, 2012

nope, its got a single mass Southbend, it does have a US Gears overdrive between the tranny and t/c that I don't know a ton about, it is full of fresh fluid and functions as it should.

7.3psd97444 · Feb 23, 2012

I had the 13 inch single mass South Bend stock replacment clutch, then got a new 600hp ceranic one from Valair and my vibrations are pretty much gone. Whats left of the vibrations on mine is from the Downpipe.