Vibrating Exhaust

[Heavenknows]

Hi! I have some questions which I hope the experts here can help.

 

I have changed my stock CAT to a sports CAT and also the rear muffler to a semi-flow SuperDynamics muffler. The car is more responsive and I like the set up except for the vibration which travels all around the car. My exhaust seems to be vibrating too much during idling at standstill with gear at "D" and stepping on the brakes. It is gone when I release the brakes and drive off. I've changed my engine mountings and also changed a longer flexible hose after the CAT. Still, the vibration is there. FK which did the job says that because the CAT is now flowing the exhaust much faster, the muffler is vibrating more.

 

Some questions:

Should I go back to the original stock muffler?

Will increasing the diameter of the piping from the CAT back help?

Will changing to a REMUS or SUPERSPRIT help? But this will be my last resort as it is rather expensive.

[Freemason]

hi there heavenknows

 

maybe u try using ur leg and gently kick ur end exhaust tip and see if it really moves when u kick it. if it does moves easily, then i tink the rubber support for the exhaust pipe is not there...go ask FK to fix 1 for u.

 

 

 

hope this helps

[Heavenknows]

Freemason, thanks for the tip.

I just went down to the carpark and tried kicking the exhaust tip. It can move about 1 inch to the left and right with some force. Trouble is, I don't know if this (the movement or "clearance") is suppose to be normal.

[Freemason]

hmm...

 

 

or else you can try bending down under and take a look and see if ur muffler's hook(i suppose all mufflers has a hook?) has been secured by a very very thick rubberband onto ur car?

[Pauly75ts]

"I don't know if this (the movement or "clearance") is suppose to be normal."

 

Hi! there, Heavenknows,

 

The exhaust system is mounted on rubber hangers & donuts. This will prevent the pipe from breaking when the engine is running. The only place not secured in this way is at the exhaust manifold.

 

Do you know the way that it's mounted? Check from the manifold to the cat, is there a bracket with a rubber bushing?

From you description, is the cat just after the manifold or further down the line & under the car?

At the same time, check whether any part of the exhaust system is touching the other parts of the car.

This must be done on a ramp, when you drive the car onto, or at the inspection pit. Don't do it at the hydraulic lifts, as it will lift the chassis and cause the suspension system to drop.

 

It seems the flex pipe is not doing it's job, that may cause the pipe to break soon.

 

Rgds

 

Paul Yong

[Heavenknows]

Freemason, I recall there being 2 hooks (yes, there are hooks ) wielded onto each side of the muffler by FK and these are in turn hooked on the underside of the car. Yes, there are 2 very think black rubbers supporting the hooks.

Could it be that the rubbers have hardened?

[Freemason]

errrr.......hardened, and in end up giving way and breaking away from the hook?

that could jolly be 1 of the reason but as far as i noe, that rubber can actually last for a very long time yeah... u go check if ur rubber is still intact anot 1st

 

or if the rubber is still there,

alternatively. refer to Pauly75ts's reply to you.

Edited September 10, 2002 by Freemason

[Heavenknows]

Pauly75ts, thanks for the tips....

the last time my car was jacked up, i did take a look at the exhaust system.

From the manifold to the CAT, I don't think there is any bracket or rubber bushing... is there usually one? From the manifold, there is a short downpipe that is bent almost 90 degrees and wielded to the CAT... that's all.

After the CAT, there is a bracket which I have asked my mechanic to modify so that it is not too tight. (That helped but only a little) After that, it is piping all the way to the muffler. Can't really see the exhaust touching the car body. Perhaps gotta check again using a ramp type.

[Andrewkb]

Talking abt that, my whole exhaust seems loose too ..

 

When the car idle, sometimes you can hear the exhaust "ringing" ...

Didn't know what's the cause of the ringing until one day I send my car for wheel balancing.

As the mechanic jack up the car, the familiar ringing sound appears. He was curious too ... got another guy to jack the car while he look below. Then he realised that the exhaust "tube" below is only being held by a "U" shaped bracket.

Everytime the car "move", the exahust tube will shake against the "U" bracket and causes the ringing sound.

 

Don't think it's dangerous in anyway, just irritating rite !

[Newkid]

me also got same problem of exhaust vibrating when car accelerates absolutely irritating. some ringing sound, like metal knocking against metal. me also got muffler changed and muffler is secured by two steel rods welded to muffler with some clearance left and right, when some force is applied. Am going back to shop to ask for review.

 

I think there are some shops in JB that can do a better job....me went there to change extractor and they even fixed back the heat cover and O2 sensor like the original condition.

[Lester]

Hi Heavenknows

 

 

 

Should I go back to the original stock muffler?

 

 

 

-No, stay the way you are enjoying the new found hps. But bear in mind, it's illegal. Be prepared to fork out S$750 for first time offenders if you are caught by Uncle Sam. You might void warrenty if you go back to agent to claim against something you refer to manufacturer's defect. They might say otherwise.

 

 

 

Will increasing the diameter of the piping from the CAT back help?

 

 

 

-No, it'll make you lose your lower torque more. You'll have difficulty moving off. Your fuel eocnomy will most likely suffer.

 

 

 

Will changing to a REMUS or SUPERSPRIT help? But this will be my last resort as it is rather expensive

 

 

 

Might help but pls be kind to your pocket. No gurantee.

 

 

 

Generally Paul has illustrated the purpose of hangers and rubber donuts. Exhaust pipes from manifold to muffler is supposed to hang freely from suspension with the above items. If it's secured tightly to the carbody or frame, you can get ready to enjoy maximum vibration at idle and maybe some kind of contact knocking and ultimately, you can kiss your exhaust goodbye as cracking will set in due time.

 

 

 

 

 

Regards

 

 

 

Lester

[Huggable]

Maybe there was too much free-play on the hooks? You can do with thicker rubbers.