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hey guys, in order to not post multiple threads, i figured id post a thread with a few questions that i have wanted to ask but keep forgetting about.

1. i have this slight squeaking/chirping sound while driving coming from what seems like the back of the car and underneath. its only noticeable with the windows up and radio off. ive heard some thing about an r-break cable being loose.

2. i know how some car manufactures use fake engine sounds and plays them through the speakers of the car. could this be the case with my 03 se? my 2.0 sohc split port makes the glorious sound under moderate load and sounds the best from this inside of the car. it sounds like a duratec v6 or even the vulcan v6.


3. i have a whining/chirp coming from my tranny under load only in third gear. fluid is new and level is good. bad synchro?


i know its a long shot with these questions. but any info would appreciated. [:eek:]
 

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2 is a No, not until the ST was that used in a Focus, and it was the sound tube type.

1 is a maybe, cable through a loop in front of the wheel is a common spot. If worn to metal slice a piece of hose, slide over, and zip tie in place. I've heard of some noises where cables come to the interior, haven't seen that problem to give direction (supposedly a clip can be swapped around to help there).

3 - dunno, except that synchro's only work when engaging gears to smooth the engagement so that isn't it.
 

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2 is a No, not until the ST was that used in a Focus, and it was the sound tube type.

1 is a maybe, cable through a loop in front of the wheel is a common spot. If worn to metal slice a piece of hose, slide over, and zip tie in place. I've heard of some noises where cables come to the interior, haven't seen that problem to give direction (supposedly a clip can be swapped around to help there).

3 - dunno, except that synchro's only work when engaging gears to smooth the engagement so that isn't it.


Thanks for the info! What do you mean by sound tube? The car has always done the third gear noise since I bought it at 68k. Its loud when cold and goes away when warm. I think it was beat on and neglected
 

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2. asked about fake sounds through the speakers, not done yet in a Focus (but even BMW likes this).

Current ST has a diaphram & sound tube from intake to cabin that is turned on with a valve as the car's computers command for extra engine noise soundtrack. Mechanical & real except for the on/off controls for volume & tube to direct the sound. Sound is shaped & controlled, but real in it's own way. (common mod is to defeat this when other mods increase real noise levels)
 

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Synchros don't make gear whine noise, only gear to gear does, if bearing wearing to let gear tilt out of plane they do it. Or just uneven wear to where gear not loaded all the way across evenly any more.

Synchros really make no whine as there is no shape or action to be able to do it, all they do is grind when they don't synchronize with the opposing gear. Their teeth are clashing with the opposing gears' teeth.
 

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That's so cool!!! Do you know why all fired engines have that "growl"?
Well, you've got intermittent intake pulses from the cylinders filling. That means air movement is starting & stopping and you get reflections of pressure waves as a result. "Tuned" intakes (and exhausts) take advantage of this & reflect air back in the piping to either arrive at the intake valve as it opens or at the exh. just before it does so it reflects back & "sucks" some exh. out faster due to the lowered air pressure produced.

This creation of air vibrations in tubing resembles a musical instrument to a degree, creating quite a bit of sound. Tuned air intake systems & exh. pipes/mufflers/resonators take that & smooth it out for more even flow at the actual intake & exh. points.

There's still a fair bit of noise transmitted through the walls of the piping & you can hear that as the low RPM "growl" you mention. (plus some from the actual inlets/outlets that isn't muffled)

ST sound symposer takes it's impulses from part of the system where more noise is present, so a small tube can transmit appreciable sound.

[cheers]

P.S. - without any appreciable intake/exh. plumbing the sounds are very loud, even if the system isn't as efficient.
 

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Not all that distinctive, as it's a std firing order & crank 4 cyl. inline engine.

Something like a Harley with it's 45* V twin with a single pin crank has a sound unique enough to get a trademark.

90* V twins with the right crank can sound like a V8, old CX 500 Hondas did.

Inline 6 has it's own special sound, rather nice though you don't hear them often.

Boxer twins are unique, and boxer 4's can have a couple tones depending on exh. tube lengths.

Parallel twins have a few sounds, depending on the crank/cam setup used. Pistons can move together or in opposition, and fire alternatively or together. When fired together they're called a "Twingle" as they're working similar to a large single cylinder engine.

Lots of tones, and the exact intakes/exhausts can fine tune the sound.
 
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