Was trying to figure out why there was a noise coming from the back of the car while driving..

Turns out that the cat-back magnaflow exhaust pipe was rubbing against the axle.

Strange that I bought this as a kit and there are issues with it...I thought Magnaflow was somebody you can trust... Had a professional mechanic install it too.


Here are some pics. Looking up into the area where the pipe snakes above the axle. There is about 1.5 inches of clearance between the pipe and the axle.

Is there something that can be done?

 

Could the rear springs or shocks need to be replaced? The mechanic that looked at it today thought the rear suspension was fine..So I dont know..

 

I have the 3" magnaflow cat back on my iroc. I didnt have any problems installing it or with the fit. All the pipes are a slip fit and use band clamps to clamp it all down. Maybe the pipes arent slipped in all the way or the system needs some adjustment to keep it from rubbing. My system has an adjustable over the axle hanger on the pipe that came with the system. Sounds like the system needs adjustment. This system is usually problem free.

 

i ran that setup before as well..no issues either...check into worn coil springs as well

 

I would hesitate throwing Magnaflow under the bus. Exhaust fitment is all about the install. I suspect you got a crap install. The entire system should be installed and checked for fitment before the first clamp is tightened. You may be able to loosen all the clamps and move the pipes around until everything fits well. Then tighten the clamps one by one checking the fit after each clamp is tightened.

John

 

Going to get the exhaust work checked out, when this snow storm passes....
I have a hunch that the problem might be the rear springs sagging.

 

Its a install problem most likely. I would also install a good set of rear shocks for more control of the rear axle.

 

I think this just gives me another valid reason for some new tear Koni's eh?

Moog 5665 springs are on the way.

 

I meant "rear" Koni's

 

I spent a good 25 minutes on the lift twisting and adjusting my magnaflow for the proper fit using the band clamps. I found lubing each joint with a little oil helps.

 

The rear suspension has nothing to do with it. The exhaust should clear with the car sitting on the bump stops. You are wasting your money.

 

Excuse me?

Wasting my money?

There are other reasons why I am getting new springs and shocks.

What do you know about my car anyway to pass such judgment? Wtf?

 

Hi Chuck.

No offense was intended.

But buying springs and shocks for the purpose of gaining exhausts clearance is a non-starter. Which is what you originally suggested.

Buying shocks and struts for the purpose of better handling and/or ride is just fine.

Look you came on here asking for help. I am trying to help. I am not BSing you. You should have exhaust clearance with the springs and shocks removed from the car.

Please remind me not to help you next time.

Merry Christmas,

John

 

Sorry, just a little testy with no sleep in tghe last 24+ hours .... Long work day ... You didn't deserve it.

My reasoning for the purchase of shocks is two fold...
. 1)My left rear brake caliper is leaking... From what I have heard, it is probably due to soft and/or bad springs

2) The ride is mushy and I want to upgrade the original suspension over time.

I may be wrong but From what I understand about shocks/springs, they keep the Body frame and axle (among other things) from impacting each other. So if the springs are worn, the "gap" between the axle and frame is lessened by the degree of spring softness.

NowBefore I had the new exhaust installed, the noise was there anyway


Anyway, sorry about my defensiveness....

 

Whoops

Let me finish that last line.

Now I just realized that the grinding noise was there before the m-flows were installed ... ... But the pipe is showing signs of damage above the axle even as it sits 1.5-2 inches and seemingly tight, btw.

 

Chuck, My Magnaflow system hits in the same exact spot as yours. As is stated in the replies from the rest, you are going to have to adjust and move things to make it perfect. This is not as easy as it sounds. If the system has been run for sometime it will be very difficult. You need to force the 3" pipe to the axle together just a bit more. It will fit it took a lot of sweat and time for me. It was hitting HARD. Major marks on the pipe after a few test laps it nearly bashed right through the over axle pipe. The advice the members are giving you is good (most of these guys are good) trust em. That Magna flow system is a very good product. It can handle a lot more power than you might think. I dyno'ed a motor that made 525 hp and 550 ft.lbs. of torque! When we put it in the chassis with the Magnaflow and gave it a few pulls I was confident I was going to loose a lot of ponies to shorty headers and a single 3" pipe split at the muff into duels. I was shocked that there was still 500 corrected hp and 510 lbs of torque! Here something that should be interesting to the group. On the motor dyno it was headers straight out. The Motor easily buzzed (7800+ rpm whoops) 6400 red line. Good thing I had 130 lbs on the valve seat. Rollers are heavy especially hydraulic ones. On the chassis dyno the motor was awesome until 7000 rpm. At that rpm it would not rev higher. The power moved quickly to 7000 and then quit rising. The exhaust was glowing red hot all the way back to the muffler. The 3" single pipe discolored to yellow and blue all the way to the muffler. Thats hot! I like the built in rev limiter! Built a lot of race cars in my time, never saw any thing like it. It is however all in the design. As the hot expanding gasses hit the muffler thee exhaust burst out into the large space with 2 - 2 1/2 outlets into long large 4" tips. This creates a strong pull on the gasses still in the system. Just like a vacuum sweeper hooked to the tailpipe.

Bob

 

Hey thanks for the input on your experience, did you hear a grinding sound coming from the rear axle area when driving? Wondering if that is connected to the same issue...

 

Yes indeed Chuck and it was loud!

 

I'm going to find an exhaust specialist, if there is one, to give this a look... It's been about 9 months since the install so hopefully it will not entail too much $$$$ I don't feel right about doing it myself

 

Always good to get as many opinions as you can. If the guy you take it to says beat the spot on the pipe with a hammer to make the clearance... leave.
One quick note. I know you and 87350IROC got a little confused with each other but... he is absolutely correct. With no suspension (read as vehicle setting on the bump stops) The exhaust should still not hit. That is basic design criteria. Bottoming out should not effect the system hitting the car. It might hit the ground but not the car.
Good luck let us know how it goes. It will work you can be confident of that.
Bob

 

From personal experience with this Magnaflow kit...

It is very easy to install the muffler upside down, which will reverse
the positions of the the inlet, and left side tail-pipe.
Check your documentation very carefully, there should be a small
diagram that illustrates the inlet/tail-pipe configuration.

(It's somewhat embarrasing to admit this, as it took me a MONTH to
accomplish this installation, which included modifying the over axle
pipe, and then the frame brace. The finished pics are on another pc,
which I will include later today.

Good luck.

 

here is the manual

http://www.magnaflow.com/07techtips/pdfs/16829.pdf

 

How NOT to mount this muffler..

Note that the inlet tube is at the front, and the tail-pipe is at the back.
Should be just the opposite, i.e. the muffler is upside down.

 

Here is my muffler, looks like its installed correctly

 

In there just like mine.
Bob

 

Same as the way mine is in. Bob

 

I'm a little pisses bought a new kit and cat and the guy who installed it must of messed up because its making noise like its up against the frame of the car. Cuz at certain rpms it rattles very loud

 

There is a good possibility that it is hitting right where the 3 inch goes over the axle. If he used a lift (and it sounds like he did) the rear axle will drop to maximum extension. When the axle comes back to its normal positioning it can strike the right center section on the casting ribs. Get it up in the air with the rear axle stretched out all the way. Look right at the 3" where it turns to go up and over the axle. There will be marks on the 3" pipe when looking from the rear of the vehicle. Position the car so you can still get under it with the axle in running position Jack stands under the axle tubes. It is tight right where we are talking about. Right where it is going up and over the axle. Push the suspension up and down and see if you can see or hear it hitting. You are not looking for a very big mark. It hits the webbing on the center section. After a lot of manipulation I was able to obtain clearance by turning the muffler more vertical. If you have it right the outlet tips will be almost flush or slightly under the back bumper. If the tips are sticking out at all it is probably hitting the axle.
And, yes it makes an incredible bunch of growling banging noise. It will be really bad if you have replaced the rubber bushings with polyurethane or solids.

 

Sounds like you need to get under the car and figure it out your self.