Banks causing rattle at approx 1800rpm's

FlimFlamMan · 02-21-2006, 10:56 AM

I've had my Banks on for around 60 miles. Really dig the sound!

However, I just started getting a rattle (pretty sure it isnt a leak) today at about 1800rpm's (noticed while at lunch).

So I start at the back and notice the tip is kinda loose. I put it up as far as I could on the collar because I didnt want it sticking out so far. I live pretty close to work, so I cruised home and moved the tip out farther and cranked it down good. It won't be moving anytime soon.

I was hoping that would be the problem but it wasnt. With the back slider down I can hear it much better. Like something in the bed area has been rattled loose by this fierce catback exhaust system. lol. I don't have the utility bed package... only the factory sprayed liner.

I can't think of what else it could be so thats why I'm asking for help. All the other clamps are secure and torque'd to spec's.

Any idea's?

FlimFlamMan · 02-21-2006, 11:00 AM

Forgot to mention...

Another thing I noticed was that I couldnt reproduce the sound while parked.

markislive78 · 02-21-2006, 03:45 PM

i had a rattle only under acceleration at around 1800-2200 rpm after putting in my banks. Turned out being my overhead console around the courtesy lights/sunglass holder. I had to line the inside a lil peice of dynomat to resolve. This was really driving me krazy 4 a long time. I found it by accident under acceleration while clicking on one of the cortesy lights at night....every time the rattle would start i would touch the windsheild side of the overhead console and it would stop.

FlimFlamMan · 02-22-2006, 05:15 PM

Well... my rattle is definitely coming from the exterior. I haven't had the time to get under it to take a good look yet.

The first thing I'm going to check is the heat shield for the muffler. I had an old honda accord that basically made the same rattle, but it was a heat shield in the manifold area if I remember correctly.

I can hear it much better with the rear slider down. Yet... it doesnt always do it. But when it does its at around 1800 rpms. Grrrr!!!

sc186 · 02-22-2006, 05:50 PM

Check the exhaust hangers.

CoachBoone · 02-22-2006, 06:30 PM

Quote:

Originally Posted by sc186

Check the exhaust hangers.

But they're welded, and they have rubber grommets.

37L1 · 02-22-2006, 07:37 PM

Quote:

Originally Posted by CoachBoone

But they're welded, and they have rubber grommets.

But the bolts that hold them on might be loose or the mount bracket that is supplied by Banks might have been mounted incorrectly, a few of our members have had this problem. Also if all of the hangers somehow have not been slipped into all the mounts, this could also cause vibration at RPM's.

I would also check the metal heat shields that are mounted on the bottom of the truck that are over the exhaust.

**Kronos1965** · 02-22-2006, 07:43 PM

There's a good deal of expansion when the system heats up. Check the last bracket to make sure that the metal hanger is not in contact with anything.

I had to reverse mine to keep it from coming into contact...

Good luck.

FlimFlamMan · 02-22-2006, 08:09 PM

Quote:

Originally Posted by 37L1

But the bolts that hold them on might be loose or the mount bracket that is supplied by Banks might have been mounted incorrectly, a few of our members have had this problem. Also if all of the hangers somehow have not been slipped into all the mounts, this could also cause vibration at RPM's.

I would also check the metal heat shields that are mounted on the bottom of the truck that are over the exhaust.

Someone over at CT took an excellent picture/tutorial of that bracket installed. So I know I got it on right.

Definitely going to check the heat shields you are talking about. I've had a similar noise on a prior vehicle and it was a heat shield.

Dr_Combustion · 02-22-2006, 08:48 PM

Yet another example of the Bank's drone at the resonant frequency. Not only do we hear it, but so does your truck! This resonant fequency (at approx 1600-2000rpm) will cause a vibration throughout the truck. The only way to "cure" it is to move the frequency to an RPM range not often seen while you are driving.

sc186 · 02-22-2006, 10:08 PM

You probably wont be able to change the pipe length enough to create an antinode in a broad enough RPM range. So you move the tailpipe length a few inches and remove the drone for 25 RPM until the frequency changes. The end-all-be-all would have to be a variable length exhaust system with a way to re route exhaust through another length of pipe at the resonant frequency. Like a cutout attached to a wavemeter programmed to close off the main exhaust into say a dump pipe in the 1500-2000 RPM range.

Or you could turn up the radio.

Dr_Combustion · 02-23-2006, 10:40 AM

I have found that there are other ways to move the frequency (RPM) besides changing piping length. It all has to do with the system resistance. Adding or subtracting piping is one way of changing system resistance.

GotMyTruck! · 02-23-2006, 10:51 AM

I just had the same problem fixed today. You should be able to notice it when trying to power brake it.

I noticed right after I had my rear axle replaced, so I thought it was related. I took it back to the dealer today, and they tightened up the the nuts on the driver's side flange where the banks bolts on to the cat. It is completely fixed now.

sc186 · 02-23-2006, 09:00 PM

Quote:

Originally Posted by Dr_Combustion

I have found that there are other ways to move the frequency (RPM) besides changing piping length. It all has to do with the system resistance. Adding or subtracting piping is one way of changing system resistance.

Frequency is a function of oscillations and time, not resistance. The only way to "change" it is to alter the length.

FlimFlamMan · 02-24-2006, 08:29 PM

I found the rattle.

It's the heat shield that goes over the pipe between the cat and resonator on the passenger side.

I haven't fixed it yet... but at least I know what it is now.