X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m28.mx.aol.com ([64.12.137.9] verified) by logan.com (CommuniGate Pro SMTP 4.3.5) with ESMTP id 1020547 for flyrotary@lancaironline.net; Fri, 24 Jun 2005 14:25:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.9; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m28.mx.aol.com (mail_out_v38_r1.7.) id q.ce.6b2e135e (4446) for ; Fri, 24 Jun 2005 14:24:43 -0400 (EDT) From: Lehanover@aol.com Message-ID: Date: Fri, 24 Jun 2005 14:24:43 EDT Subject: Re: [FlyRotary] Re: Engine Rebuild - Coolant Leak Cause To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1119637483" X-Mailer: 9.0 SE for Windows sub 5012 -------------------------------1119637483 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 6/24/2005 12:34:09 PM Eastern Daylight Time, eanderson@carolina.rr.com writes: Hi Georges, Yes, it was you that suggested the apex seal as the possible culprit. Actually, the flash point of the brake fluid used is only 240F! Not much above the boiling point of water! The brakes had been used - but, nothing abnormal, I did not make a panic stop or such, I have put on the binders much harder and never had a problem. But, it had to be the brake pads and I can easily see 240F of heat being generated by them. Also the brake pads always ride touching the rotor - nothing to hold them back. I guess this does not normally cause a problem. Ed The single piston slider type calipers rely to some extent on rotor runout to help knock back the pads, once pressure has been released. In aircraft applications this does not work worth a damn because the wheels are so light and are turned over so little. Also the slider mechanism has so much friction that the non piston pad almost always wears faster than the piston end pad. A plane used often has little difference in pad wear. Also when applying pressure the "O" ring seal will deform slightly as it is pushed along with the moving piston. When pressure is released, the deformed "O" ring returns to normal and retracts the piston. This may not move the slider end of the caliper at all. If there is some runout in the rotor, the rotor will knock back the slider end pad slightly. Even side loading the wheel will deform the assembly enough to knock the pads back. If there is no flex line to connect the caliper to the fixed brake line, then the aluminum brake line must flex with each brake application. Aluminum has a very short fatigue life. The tighter the bend radius, the lower the pressure rating, and the shorter the fatigue life. A racing tip. Fresh "O" rings keep the brake drag down. Lynn E. Hanover -------------------------------1119637483 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 6/24/2005 12:34:09 PM Eastern Daylight Time,=20 eanderson@carolina.rr.com writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D3>

Hi Georges,

Yes, it was you that suggested the apex seal as the possible=20 culprit. Actually, the flash point of the brake fluid used is only 2= 40F!=20 Not much above the boiling point of water! The brakes had been used=20= -=20 but, nothing abnormal, I did not make a panic stop or such, I have put on=20= the=20 binders much harder and never had a problem. But, it had to be the b= rake=20 pads and I can easily see 240F of heat being generated by them.

Also the brake pads always ride touching the rotor - nothing to hold=20= them=20 back. I guess this does not normally cause a problem.

Ed

The single piston slider type calipers rely to some extent on rotor run= out=20 to help knock back the pads, once pressure has been released.

In aircraft applications this does not work worth a damn because the wh= eels=20 are so light and are turned over so little. Also the slider mechanism has so= =20 much friction that the non piston pad almost always wears faster than t= he=20 piston end pad. A plane used often has little difference in pad wear. Also w= hen=20 applying pressure the "O" ring seal will deform slightly as it is pushed alo= ng=20 with the moving piston.

When pressure is released, the deformed "O" ring returns to normal and=20 retracts the piston.

This may not move the slider end of the caliper at all. If there is som= e=20 runout in the rotor, the rotor will knock back the slider end pad slightly.=20= Even=20 side loading the wheel will deform the assembly enough to knock the pads bac= k.=20

If there is no flex line to connect the caliper to the fixed brake line= ,=20 then the aluminum brake line must flex with each brake application. Aluminum= has=20 a very short fatigue life. The tighter the bend radius, the lower the pressu= re=20 rating, and the shorter the fatigue life.

A racing tip. Fresh "O" rings keep the brake drag down.

Lynn E. Hanover

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