[Healeys] Fwd: Down pipes

[WILLIAM B LAWRENCE]

The flex sections are necessary because the engine moves on its mounts in relation to the chassis. and that would stress and destroy a solid exhaust connection. The rubber exhaust hangers don't have enough flex to compensate for the movement and would similarly be stressed. If the flex sections were to freeze in place all of the stress caused by the engine rocking and vibration would be transferred to the exhaust flange joints and/or the rubber mounts.

Most modern cars compensate by allowing some freedom of motion in the exhaust hangers, although some still have some form of flexible joint in the system.

Bill Lawrence
BN1 #554
________________________________
From: Perry <healeyguy at aol.com>
Sent: Friday, October 18, 2019 1:02 PM
To: healeys <healeys at autox.team.net>
Cc: WILLIAM B LAWRENCE <YNOTINK at msn.com>
Subject: RE: [Healeys] Fwd: Down pipes


Bill brings up something that I have thought about occasionally over the last 50 years, why is there a section of flex pipe used in the original production of Austin Healey’s?  I mention production because I’m not sure what was on the first prototype cars. Todays stainless or mesh type flex pipe does actually move even after the pipe has “aged” a bit. Not so much for the older mild steel versions. Once they take a set (rust) there is not much movement, but usually breakage.

My take on the flex pipe on Austin Healey is that it makes it a lot easier to fit the pieces together on the car. Exhaust manifold outlet(s) are fixed points. Same with the inlet(s} to the muffler. To get a perfectly parallel set of down pipes outlets into the muffler and still fit the exhaust manifold would be hard without the flex pipe sections. Note that the factory welded the two tail pipes together on the later 100-Six/early 3000.

OK I’m going back to sleep.  Perhaps I’ll dream about why the oil drips out of my gearbox/OD even with fresh “O” rings….

Perry



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From: WILLIAM B LAWRENCE<mailto:ynotink at msn.com>
Sent: Friday, October 18, 2019 12:50 AM
To: i erbs<mailto:eyera3000 at gmail.com>; Bob Spidell<mailto:bspidell at comcast.net>
Cc: Ahealey help<mailto:healeys at autox.team.net>
Subject: Re: [Healeys] Fwd: Down pipes



The rubber mounts shouldn't cause a problem, but the flexible sections of the down pipes may have become too stiff to flex, in which case the relative motion of the engine to the chassis may be transmitted to the down pipe flanges.








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