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how to attach exhaust and not crack / stress it
MikeR - 25/5/07 at 06:55 PM

Hopefully a simple question.

Got a crossflow car, so exhaust near side.

When engine revs, it tilts slightly to the nearside (i think, its been 12 months since the engine started)

So, when mounting the exhaust, do i have the exhaust pressing down onto the rubber bobbin or do i have it trying to lift off the bobbin.

eg, if looking from the rear wheels to the front of the car through the exhaust (ie not from above) so i have....

exhaust help pic
exhaust help pic







but leave the one nearer to the chassis (or exhaust depending how you mount) a little looser so it can flex more?



(this is so going to get edited about 10 times no to try and get the ASCII art to work!)

[Edited on 25/5/07 by MikeR]

[Edited on 25/5/07 by MikeR]


JohnN - 25/5/07 at 07:30 PM

Can't understand the ascii, but mine is just solid mounted downstream of the silencer and hasn't been a problem in a couple of thousand miles.

Ah a new diagram, now I see it.

If I were to use a single bobbin, I would arrange it so that the bobbin was in compression, ie the exhaust weight was resting on the bobbin

[Edited on 25/5/07 by JohnN]


MikeR - 25/5/07 at 07:40 PM

did say it would take a few edits


britishtrident - 25/5/07 at 07:40 PM

The engine tilts to the offside due torque reaction (i.e. the cylinder block tries to rotate anti-clockwise) but it will go the opposite way on over run (engine braking) + all the various vibrations in different axis so it won't make much difference which way round the mounts are.

Alternatively mounting the bobbins in shear would be the option that would allow most movement in both directions but it would be weaker unless you used more bobbins.

Solid mounting isn't a viable option (unless you fitted a flexible joint) eventually something would fail due to fatigue.


jacko - 25/5/07 at 08:12 PM

Hi mine is like the top diagram its been on for 3+ years thats about 7000 miles
Jacko


MikeRJ - 26/5/07 at 09:44 AM

Mount the bobbins in compression or shear, not in tension (i.e. middle pic) or they will fail quite quickly.