New Y-Pipe.......Rumbling and Harsh Vibrations

[NewfoundlandDude]

I just installed a new Warpspeed Y-Pipe. Now on acceleration I feel a harsh vibration coming from the exhaust where the Y-Pipe is. There is no noise at all while parked in the driveway.....all the way to redline. On the highway, the vibrations can only be felt during acceleration, and not at a constant speed. Around town at lower speeds is where the vibrations are most intense, and it seems as if there is something rumbling and vibrating until you let off the gas.

I have attached a video here that is compiled from several sound clips taken with my cell phone today. Turn up your speakers a little, and you can definately hear the rumbling and vibrations that I am referring to. The clips don't nearly do the vibrations justice, as they feel and sound much more intense when you are actually in the car. My phone has a crappy mic I guess, but the video definately gets the point across.

I'm sure that someone has run into this problem before, What exactly is doing this, and what do I have to do to fix it? Any help is greatly appreciated....

Here is the video.....

[brianw]

You do not have the pipe properly installed.

You have a leak somewhere, probably due to all the broken exhaust studs-- did you reuse the stock Nissan metal gaskets? (I hope you threw away the crap paper ones that WSP/Cattman/Budget/everyone else includes)

Measure your clearance from the engine subframe to the pipe-- you should have at least 1/4" or so of clearance. If it's smaller than that it may hit the subframe-- loosen the y-pipe to manifold bolts, then use a prybar or something to shim the pipe further away from the subframe while you (or a friend) retightens the bolts. I've been installing y-pipes since the very first generation Cattman pipes in `98 or so (and I have personally see THE very first y-pipe that ST had done :p ), so I'm pretty sure this is your vibration problem.

The other noise may be the y-pipe to catalytic convertor, the additional play there may let things hit the heat shield-- you may need to check with a flashlight to see where any metal-to-metal contact is occurring and bang it out. It's possible your stock rubber exhaust hangers are stretched and should be replaced, too. Don't just randomly bang the heatshield out, you should be able to visually see any signs of metal-to-metal contact if you get a good look under there. Jack the car up as high as you can, you may need to pull the cat to shine a light everywhere.

It's a bit hard to tell what the noise is, the audio you provided is REALLY crappy. :p

[NewfoundlandDude]

I went to Napa and bought two gaskets for the cat (Front and back) because the Nissan metal ones were producing a tiny leak from when I got all 4 cat bolts removed and replaced. Warpspeed provided two new crush gaskets, and this is what was used on the headers. I replaced the broked studs in the header (4 of 5), and now have all 3 on the rear header and 4 of 5 in the front header (I'm going to have to get a garage to get at the 5th). All heat shields have been removed for the most part, so I'd say it is a clearance problem. There is an violent vibration on sharp acceleration, which tells me that due to flex on acceleration, something is not getting the clearance it needs.

Your pry and tighten idea is probably then best advice that I've gotten so far (I've gotten some on the other forum). I know that the audio I provided was REALLY CRAPPY, but it was all that I could do at the time. I think that the crappy Warpspeed hangar that they provide which is not threaded and just sits in the front rubber hangar (In front of the cat) is probably causing a problem as well. I'm going to try and thread it to try and stiffen up the damn thing too. The stock pipe was supported much more than the Warpspeed pipe, I can think of at least two places that the Warpspeed pipe can be supported better. #1 here is hidden on the picture, but was bolted to a bracket on the stock pipe, and #2 which was a welded flange is now just that non-threaded bolt on thing. I''m not sure what #3 is, but I'm sure that the cat could be supported a little better too. A rear rubber hangar (Near the resonator or B pipe or whatever) I think is stretched, or the weld to the pipe is breaking, because I can hear a faint vibration back there a bit too. I took a closer look after I posted this, so this is where all of my rambling is coming from.



If you can think of any other common install problems, please let me know .

Thanks.....

[brianw]

You shouldn't need to worry about hangers-- they're needed on the stock pipe because it weighs 25lb or 35lb or something ridiculous, and an aftermarket y-pipe only weighs 13lb or so, so the stress on the manifolds is greatly reduced.

An aftermarket pipe doesn't need nearly as much support. Check the hanger location 1, you'll see that the pipe dimensionally stays the same in relation to the rest of the engine whether or not that hanger is used, so it's impossible for it to be the problem.

As for #2, I'm not quite as sure since it appears to be after the flex section in your car, I haven't ever had a problem in a 5th gen but it's is possible you're going to want to tap the hanger on the WSP for hanger #2 and thread on a nut.... but again I have no idea if that's any relation to your problem as a fact. As I said earlier I would look for metal to metal contact to verify where the interference problem actually is.

If your rubber exhaust hangers in the rear by the cat are broken I would replace those.

[NewfoundlandDude]

Problem Solved.

It was the crappy Warpspeed hangar being a "generic size", and pusing my exhaust BACK and DOWN. This was causing everything to vibrate off of the cross members in front of and behind the cat when the car flexed on acceleration. The hangar had to be heated up and bent so that the pipe sat higher and more toward the front of the car. I then got a garage just up the road to do a horrible welding job on the weakened hangar near the resonator or b-pipe or whatever that thing is called, and for now I hear nothing except a deeper tone from the Y-pipe.

Thanks a lot for your help......

[brianw]

It's probably not WSP's fault... there's quite a bit of variance in the engines from the factory in the exhaust fitment, 1/4" for the manifolds alone is what I've seen.

Seeing hangar variance of more than doesn't surprise me.

I tend to forget the 5th gen has crossmembers in front of and behind the cat, the older generations don't have this.

[lowblocks]

so my 4th gen would not have this problem

[brianw]

Your 4th gen will not have the hanger-pushing-back problem that the 5th gen can have, but it can have the other issues I described.