leonbray

I had Pacemaker extractors and 2 1/2" system installed on the XG ute yesterday, re-using standard cat, and now I can feel a high frequency vibration through the car. The pipes don't appear to be rubbing on body work or chassis anywhere.

Anyone had a similar experience? Certainly be interested in a solution befor I take it back

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Leon
68 Cougar XR7 (302W), 69 Cougar Convertible(302W), 70 Cougar XR7 Convertible (428CJ), 70 Cougar Eliminator (351 4V), 77 Cougar Villager Waggon, XY Ute (302W), XG Ute (IL6 XR6 replica)

EFAug94

Ok, now before you get defensive, im a sound engineer!


You cant "feel" High Freq.......

You can only feel Freq's lower than 200Hz............ Is it high pitch, does it sound low pitch ? you need to give a better idea of what your hearing

leonbray

Ok - it must be low frequency - feels like i'm sitting on a vibrator (now that should open up the discussion)

My guesses - exhaust mounts too hard or pipe wall too thin

Vibration can be felt from idle, through steering column pedals, door panels

There is no sound

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Leon
68 Cougar XR7 (302W), 69 Cougar Convertible(302W), 70 Cougar XR7 Convertible (428CJ), 70 Cougar Eliminator (351 4V), 77 Cougar Villager Waggon, XY Ute (302W), XG Ute (IL6 XR6 replica)

EFAug94

Could be a exhaust leak at the muffler ?, they resonate around 100Hz...i.e low freq ?

deankdx

sorry this may be a little off topic i have same ute and planning similar.
did you get Cat cut to increase pipe size? how is the performance difference, how many mufflers and does it drone?
please post the solutin if/when you work out whats wrong thanx

jonbays

Well I find that at a little under 2000rpm on slight load there is a zone where I can induce this sympathetic vibration of the door trims and or dash but it never lasts long enough to find or really bother me enough to do something about.

At idle though its fine even with the cam making the idle less smooth than it was.

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AUII Auto wagon 4.0L InTech Pacemaker PH4480 extractors, 2.5" exhaust, JMM DEV3HL Cam Unichip 144rwkw. 1/4 mile 15.609sec@90.14mph

Soxx

Actually, whilst you are technically correct, 'leonbray' will certainly be able to 'feel' a high frequency 'vibration'.

You are using confusing audio terminology with auto terminology.

In audio, low frequencies are <100hz, mid frequencies are between 100hz an 5khz (very broadly speaking), and high frequencies are above 5khz.

However, in auto terminology, a 'low frequency' vibration could be caused by a wheel being out of balance, which will cause a thump-thump-thump kind of vibe, relatively slow in speed.

A high frequency vibration may be caused by an out of balance tailshaft or stuffed universal joints causing a very fine 'high frequency' vibration which feels much like vibrating mobile phone.

It's all in the context the word 'frequency' is being used in.

Rick.

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What's that?..... Did I hear you say TQE power?

EFAug94

You dick head Soxx,


Auto and audio both share the same freq's, that thump thump thump your talking about is still low freq (Hz). If your hear a high squeal, than it would be high freq.

Id love to learn more about your auto freq's and how they differ from audio freq's......fool

donno

Actually I'm with soxx. A mechanical vibration is naturally at a lower fequency then to a audio signal. A high frequency vibration in mechanical terms is completely different to an audio high pitched frequency. A vibration in a car is as a result to bumps in the road, the engine at revs etc. Any road car won't do over say 7000rpm, which has alot lower frequency then an audio signal, but is high in the terms of mechanical vibration. The signals are in different domains, therfore high and low for their respective domains are completely different frequencies, if you catch my drift. BTW, I'm doing 2nd year engineering, and this is from a subject dedicated to signals and systems

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useless

Hey ..everyone is entitled to their opinions but there is no need for bad language for you to convey your message.This is a discussion forum with a common goal to help each other .

Please leave that language outside the door ..