REFLECTOR: Insulation?

[Chuck Jensen]

Kurt,

The phenolic board, as shown in your photo, seems to be the standard treatment.  It is both a heat shield against radiated heat as well as thermal break against conducted heat.  Yes, the bolts may carry some heat through to the leg, but the conductance is still reduced by the thermal break board versus intimate contact.

One would expect aluminum would also act as an adequate shield against radiated heat.  Yes, it will conduct heat, but when one considers the radiated heat required to heat the AL plate and then for the plate to radiate the heat on to the legs, all the while losing a great deal of heat because of its large surface area, it seem intuitive that little radiant heat will reach the leg.

The AL plate is certainly more conductive than the phenolic board, but again, the large surface of the plate will act as a radiator to dissipate heat to the atmosphere, effectively reducing the heat conducted to the leg.  The phenolic seems the better choice, but apparently the AL has proven adequate.

Chuck Jensen


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of NMFlyer1 at aol.com
Sent: Sunday, June 22, 2008 11:12 AM
To: reflector at tvbf.org
Subject: Re: REFLECTOR: Insulation?


Scott, 

I called the factory a while back  to ask what the "new preferred" method was 
to shield against heat from the brake  disc to the leg. I have been told by 
some to use an aluminum shield, but it  seemed that aluminum would conduct the 
heat TO the leg (while providing a bit of  a barrier against the air transfer 
heat that John mentioned). 

The  Factory is now using a high density bakelite type material. Now that 
makes sense  to me, so I bought some. They sell you 2 pieces about the right size 
and you  drill/trim to fit. They are 1/8" thick and fit flush against the 
back of the  gear leg. 

I placed my nifty 2-axis alignment shim between the axle and  the shield. You 
can see it in the picture:

Kurt  





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