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I have an extremely lowered car, the exhaust pipe moves, squeaks and clanks at times. The sounds are not so bad on smooth surface roads.

I had been getting a knocking sound from under car and just left of clutch(i'm right hand drive). This knocking sound was very bad earlier but seems to have calmed down but with that calming the exhaust sounds have gotten worse. this makes me think the knocking sound has something to do with the exhaust pipe. I think this sound is more pronounced on non smooth roads.

Besides the fact that you can move the exhaust with your hand and it often scrapes humps, there are no visible problems with it.

If the knocking sound is related to the exhaust pipe, can you think of what may be causing it?

I had the suspension checked and they didnt find anything that maybe causing the knocking sound. The driveshaft maybe causing the sound but for the reasons mentioned I feel it might have something to do with exhaust but not sure what might be wrong with the exhaust pipe such that it would cause a knocking sound.

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Because you can move it by hand means it can probably move enough to hit something.

So, replace the supports holding the exhaust for stronger ones or fit 2 loops instead of 1. Did that on a car once - worked a treat.

Another option to reduce movement will be to increase the number of support points so going from 3 to 4 or even 5 can help - you have to figure out fixings though....

  • Even changing old exhaust rubber hangers for box fresh ones may improve the situation. I've found "mini exhaust bobbins" to be massively useful for this type of application. Whatever you do, be careful not to use any materials that will melt or burn as a result of the heat generated by the exhaust. – Steve Matthews Aug 31 '18 at 8:26
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If you can move the exhaust by hand, there are a few options: (Remember that your exhaust line is steel, which typically doesn't flex well.)

  1. You've lost a stud or a nut where the line meets the catalytic converter ("cat.") (Which is not an acronym and should never be written as "CAT.")

  2. Many aftermarket exhausts join pieces of the pipe together with clamps. If these are improperly installed - they have a bolt or two which is used to tighten the clamps around the pipes that they are meant to join - the bolt can hit the ground and be damaged or destroyed.

  3. Exhaust hangers may be damaged or missing. These are a hook-and-big-rubber-thingy arrangement, typically close to the muffler. It should be easy to spot if one or more is missing or damaged.

  4. Broken pipe.

If you were hearing the noise near the transmission tunnel, I'd bet that it's become loose or disconnected where the exhaust line meets the cat.

In any case, get the car on some jack stands and start wiggling things around. It should be pretty easy to find the problem.

Good luck!

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It sounds like the exhaust are hitting against something medal. get under the car or put it on a lift if you have access to one. make sure the exhaust have cooled off, get hold of the exhaust and shake it back and forth and up and down and look for bumping sounds. The exhaust are quitter on smooth roads because there are less reasons for the exhaust to shake around. they are noisier on bumpy roads because that's when they bonce around and shake and bump what ever they are hitting. you need to find out where they are hitting and then you adjust them so they don't hit anymore.....

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By "knock" I assume you mean engine detonation (not the clank of metal exhaust pipes). If so, the answer to your question is "yes." An exhaust leak can allow oxygen into the exhaust, affecting the O2 sensors, triggering a change in the fuel metered into the engine which in turn causes misfire.

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