annoying harmonic in my exhaust system...

pretty much what it says on the tin, i have a vibrating harmonic at around 3k rpm, had it with my old back box and its still there having replaced it... can't hear it when accelerating through 3k rpm but when slowing down its there and if just happen to be cruising at just the right rpm its irritating as... well its irritating

so anyway it's not the backbox it seems (which is odd because it wasn't there with my original exhaust (im on no3.) any ideas what it is and how to fix it?

Could be a hole in the Downpipe mesh.

my oem back box was fine but the TT does this at about 3000 revs and under acceleration load, has calmed down a bit after getting some miles under the belt, I did notice that it was very close to the bumper trim and was probably vibrating against it at speed, so cut some away with a hacksaw which did improve it.

also started to get used to it now too.

hope you get it sorted as it can be very irritating, good luck

It could be the outer mesh loose on the flexi pipe.

My old R25 longlife exhaust did this, i think its the k series engine. It is anoying!

Reaper;5561 wrote: i think its the k series engine. It is anoying!

How very dare you.

Adam. Get it up on stands and stick your head under while somebody revs it. Be careful though and make sure it is securely chocked etc.

I have to admit I was surprised how good your home made system sounded. Even had a turbo sound to it.

CJJ;5564 wrote: Adam. Get it up on stands and stick your head under while somebody revs it. Be careful though and make sure it is securely chocked etc.

I have to admit I was surprised how good your home made system sounded. Even had a turbo sound to it.

thanks mate and i think its pretty dam good, if you think the other systems there cost in the region of what £300? mine cost me £30 if you include the welding gas, wire and buying the exhaust its self i know the daytona and miltek sounded better but for a cash strapped laddie it works im hoping adding mikeknights de-cat will give it a bit of a throughty daytona barrrrp to it

i think the "turbo" noise is more from the air filter than the exhaust

Gos;5484 wrote: my oem back box was fine but the TT does this at about 3000 revs and under acceleration load, has calmed down a bit after getting some miles under the belt, I did notice that it was very close to the bumper trim and was probably vibrating against it at speed, so cut some away with a hacksaw which did improve it.

also started to get used to it now too.

hope you get it sorted as it can be very irritating, good luck

thanks gos it might just need bedding it, its a 'used' backbox but now it's been rebuilt... kind of.

it could be vibrating against something like, when i put on my de-cat i think i'll try cjjs idea of running the car on stands

Adam-MGTF;5659 wrote: if you think the other systems there cost in the region of what £300? mine cost me £30 if you include the welding gas, wire and buying the exhaust its self i know the daytona and miltek sounded better but for a cash strapped laddie it works im hoping adding mikeknights de-cat will give it a bit of a throughty daytona barrrrp to it

Ah yes, but you must remember that the Daytona etc aren't designed just for noise but give better breathing and an increase in power too.

CJJ;5666 wrote: Ah yes, but you must remember that the Daytona etc aren't designed just for noise but give better breathing and an increase in power too.

ok make me feel bad









no wait...










come to think of it this is a call to arms i shall make a exhaust that humms "she'll be coming round the mountain" as the engine ticks cool

OK, go on then.