Although, post install, the noise is pretty much exactly as expected when revving the engine across the power band, I am hearing a "bang" when I launch. There is a sound, clear, of something hitting something under there. I can rev from 500 to 6500 and nothing, but when I actually launch...that first second when the car lurches and you know the engine mounts are being stressed...that's when I hear a bump like something is hitting something. Any ideas?

I'm done working for tonight, but wanted to hear ideas of what I should look for tomorrow.

 

Your engine is probably hitting your Y-Pipe. Either it's the Y-Pipes fault, the installer of the Y-pipe or your engine mounts are on there way out. I am going to go with my 1st nad 2nd choice

 

Thoughts about why? The y-pipe itself seems to be a perfect fit. I installed it as close to perfect as I could get. One of the major problems was that the bracket which attaches to the rubber hanger from the stock pipe is not right. I had to push the pipe up VERY hard to get the pipe back on the rubber hanger. Almost pointless to hang it. I think one of my first changes will be "unhang" the pipe...any thoughts?

 

Don't worry. It's the Y-pipe rubbing on the cross-brace right by the cat. The one that's held on by like 10 bolts. Happens a lot, happened to me... I just took the cross-brace off, since it's only there in case your exhaust falls of at high speeds. Take the f**ker off and forget about it- or, if you're the paranoid type, go to a muffler shop and get a custom hangar for your y-pipe.

Oh... and... enjoy the gains! after 8K miles I still very much do!
T.

 

You have to lower the cross member or remove it completely - I recommend lowering it using washers (you'll need longer bolts as well). It does server a purpose insofar as structural rigidity is concerned. Also I wouldn't force the Y-pipe to align with the rubber hanger - the bolts attaching the manifolds to the block are only torqued to about 25 ft-lbs so you don't want to put any undue stress on these. Try haging the rubber hanger using only one of the fingers on the metal fork it's secured to - this will give you much more play to somehow attach it to the bracket. I had to "dremelize" this bracket and get creative to attach it to the rubber hanger. It does help dampen some of the noise and vibration as well so you want to attach it if at all possible. Which pipe do you have? If it's the Stillen - here's another dremel adjustment I had to make for a better fit. It's well worth the trouble though!

 

I had the same problem when I installed mines. It's definitely hitting the cross memberunder the cat. I didn't remove my cross member, I just took out out the 10 bolts and put washers underneath each one. That put about a 5/7" gap. That cleared up the problem. No more bangs when I floor it at the line

 

I bent my pipe just enough for it not to hit..

 

This site is great...where else can you get that kind of response, so quickly. So, I guess I'm going to do some mid-day automobile work. What with the new engine mounts getting installed tomorrow, I want the launch to be clean first.

 

Do you happen to recall what size the stock bolts are. I assume 14mm, but what length do you think I'll need (so I can run to the hardware store before getting underneath the car. Is it just the four bolts in your picture you are suggesting I lower?

 

You've gotta lower all eight. I just took one of the bolts to the hardware store (actaully it was a store specializing only on nuts and bolts) and told them I needed the exact same thing just about 1/2" longer.

 

How long did the install take? Did you have help or were you able to finish this yourself?

 

I spent about 3 hours on it...went slowly...had some particular problems with one bolt on the stock y-pipe attaching to the rear bank. I had to run to the hardware store in the middle to get a ratchet adaptor I was missing. Overall, not bad. Honestly, other than removing the bolts on the rear bank for the stock y-pipe, the process wasn't that challenging.

I had the jack stands set at about 20", giving me almost three feet of clearance at the front lip of the fender (and that's with my body kit). That was enough room for me to work.

 

Thanks. I'll go to Lowe's, they have a good selection of metric bolts usually (plus I own stock in them ).

 

Do you happen to know the torque specs on those bolts?

 

Thank You - donations can be sent to my e-mail address via paypal.

I'll check on the torque specs for the cross member bolts when I get home. I don't think these are that important to get torqued exactly to spec though as long as they are tight - probably 25 ft-lbs oughta do it as well.

 

Sorry, my year and 1300+ posts on the orgy make me hip to that $hit. I'll buy you a beer if you're ever in town (and you're 21) though.

 

I put seven flat washers under each bolt, between the beam and the underboady...plus a new flat washer and lock washer topside. It worked perfectly. No banging sound...and I look forward to the "bees in a can" sound disappearing shortly. My first drive after fixing the beam was in heavy rush hour, so still no serious test of the pipe. Tomorrow is the engine mounts, so the combination of intake on Saturday, y-pipe yesterday, and mounts tomorrow should make for a nice "new car" feel. I look forward to putting it to the test.

Thanks again.

 

The engine mounts are gonna make your idle harsh. The mounts will vibrate and make you car louder. Above idle you really cant tell they are there

 

Only a couple of people in the 5th gen forum have the Cattman mounts and I haven't heard anything that bad. Only a little shake in the steering wheel. No noise increase reported by them.

 

My friend had them in his 4th Gen and they increased the sound at idle and shook his whole car. But then again his car has 80k on it.

 

I'll let you know tomorrow.

 

What kind of Y-pipe are you using? You would think that the manufature could have perfected there pipe by now to fit the car properly. This is uneceptable IMO.

 

It is Cattman's. The part striking the cross beam is actually the b-pipe, but the y-pipe seems to bring the entire exhaust down an inch or so. Of course, since only a small fraction of people encounter this problem, its not likely a design flaw...more likely either a manufacturing flaw on either Nissan or Cattman's fault in this specific situation.

 

Small fraction? I’d say it’s approaching half of all Cattman Y owners. It seems like a smaller fraction because some people buy Stillen.

According to Brokenmotor, who helped me install my Y-Pipe, the issue is because Cattman made a hanger for their 4th gen Y-Pipes, but for some reason left it out on the 5th gen.

All that extra un-supported weight pulls down on the exhaust at the connections, i.e. at the cat and b-pipe. I would agree that letting it go for this long is unacceptable. By now, Cattman should have done something about this.

If I had it to do over again now, I’d go with Warpspeed’s when it comes out. But I’m still glad I didn’t give Stillen my money.

Anyway, moot point now. Enjoy your Y-pipe.

 

I'm not sure I buy that. Reason being, I had to push the pipe very hard to get it linked to the hanger for the stock y-pipe...the rubber hanger. The noise was present after hanging it up there. Maybe the Cattman design slopes, slightly, downward towards the main cat, bringing the cat and b-pipe down a bit. Either way, if it is a design flaw...it would have been nice for it to have taken care of by now. Either way, no harm...no foul.

 

i have that banging noise since when i first got the y-pipe on... i had the little cross bar removed (the one that is held on with 2 bolts, 1 on each side) but that didnt get rid of the problem... the rubber hangers are a little to long and soft i think... did anyone come up with a solution to it without lowering the cross member bar? i really dont mind the noise so much but my friends do they think my car is falling apart lol

 

The 5th Gen Fed spec dont have a hangar right aft of the flex section like the stock ones do. My flex section broked because it was left to support the extra weight. I sent it back to Cattman and he fixed the hole in the Y-pipe and welded a hangar on, which he said is gonna included in all the new ones sold.

 

Sorry for resurrecting this thread! But I have a couple of questions. I installed a cattman ypipe yesterday, after the install I noticed the same symptoms described in this thread. In fact after the install my pipe had my exhaust low to the point that it was rubbing with the cross member, so much so that I was getting hard vibrations (a creaking sound) along with the hard banging, when starting off. My pipe does not have hanger, so the first thing I did was to make one and see what happens. However, as many of you noticed with the flex after the hanger, it makes the hanger pretty much useless. I then lowered the cross member with washers and that got ride of the vibrations, however under hard jerking acceleration, I still get a banging noise. Unfortunately I found all this out after hours of troubleshooting the problem. Drove me nuts! My questions to you are.

-after 6 months how is everything holding up???

-did any of you hang your exhaust as well? Since I still get the knocking on the CM, I need to do this, but wanted to know how you went about it.

 

I've had mine for well over a year now (Stillen Y) and just checked it a few weeks ago. I wanted to make sure the flex section was OK. I dropped the cat, looked inside the pipe and the flex looked good as new!

You really need to get longer bolts and use more washers. The stock bolts aren't long enough and will not let you drop the cross member low enough (no need to drop anything else). It needs to be dropped at least 1/2" to 3/4". By the way, good job incorporating the rubber hanger in your set-up!

 

I have, since this thread, detached the y-pipe from the hanger and wrapped the pipe in exhaust wrap. With the crossmember lowered with a number of flat washers, the pipe does not bang into the crossmember despite not being attached to the hanger. I'm not positive the hanger is necessary, but I will be getting back underneath the car after another couple hundred miles to see how the pipe is holding up. I think the flex section is likely more useable now that the pipe has more freedom of movement.

As far as how I hung the pipe...my Cattman pipe had a small bracket welded on to the top of the pipe close to the stock hanger location.

 

I should have been more specific. I was actually wondering if any of you hung it back at the cat? I believe 4th gens have the exhaust hung around the cat as well. This would take car of the problem, and take stress off the flex.

 

ok, i'm a new owner of the used cattman y-pipe. It bangs agains the cross member exactly as described in this thread. Is it possible that i can unscrew and put washers in myself or would i need to go to the shop and have them use the power gun to get them off?
thnx

 

No need to take it anywhere. You can do this yourself VERY easily.