Re: [ST] Tech Info

[Colt45 <colt4530@xxxxxxxxxxx>]

I saw DOT 5 swell the caliper piston seals in a Yamaha RD350 to the 
point the brakes locked on the first application after it had been in 
the system for minutes.  The caliper seals are the rubber that is likely 
attacked. 

Neil Lindsey wrote:

>OEM Sprint brakelines ARE stainless-steel braided lines.  They are just covered in rubber
>so you can't see the braiding.
>
>DOT5 brake fluid is silicone-based and DOT5 was originally designed for military vehicles
>which are often left unattended for long periods of time.  It doesn't attack rubber.  DOT5
>fluid is also not hydroscopic (it does not absorb water and will not mix with water).
>It's only major advantage is that it doesn't attack paint, unlike poly-glycol fluids.
>DOT5 brake fluid also has higher dry and wet boiling points, which means that it is better
>suited for extreme temperature situations.  However, since it does not absorb water, any
>water (which is heavier than brake fluid) that inevitably gets into the system will pool
>at the lowest points (usually the calipers) and when that water boils it will affect
>braking iin the same way that moisture in hydroscopic brake fluid does.  It will, over
>time, also cause corrosion of caliper pistons.  Also, as it approaches its boiling point,
>DOT5 fluid will become slightly compressible -- hence a spongy brake feel.  Lastly,
>silicone and poly-glycol fluids are incompatible and should therefore never be mixed.  So
>if you really want to switch to DOT5, you'll need to disassemble and thoroughly clean the
>ENTIRE system.
>
>So the recommendation against using DOT5 is correct, but not for the reason given.
>
>Neil
>
>  
>

- -- 
John Albright
'02 RS
'00 748 "Rosetta"
Chattanooga
C-RATs


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