[6pack] brake fuild

[Ashford Little]

One thing to consider in the eternal silicon vs. DOT4 argument is the  
condition of the brake system prior to switching.  I liken it to  
changing from dino oil to synthetic with a motor that has 80 thousand  
miles on it.  The motor will most likely start to leak oil in places  
it did not previously and I doubt that you'll receive any rewards in  
terms of longevity at this point.  I think the brakes are a similar  
situation.  If the rubber components in your braking system are not  
relatively new then switching to DOT5 may result in some negative  
reactions.  I don't think there is any chemical reaction; I just think  
that the chemical makeup of DOT5 might be similar to synthetic motor  
oil in that it will more easily leak.

Now, I must admit a few things for full and fare disclosure.  #1, I'm  
not an engineer and I don't play one of TV.  #2, Joe is hardly the  
person I or most of us should be disagreeing with on a regular basis.   
But, #3, I redid my entire braking system about 4 years ago and took  
the opportunity to switch to DOT5 and I've had no issues whatsoever.   
I also know people who switched in mid-stream with no issues, and I  
know of one TR enthusiast who switched 20 years and 100k miles ago who  
has also not seen issue one.

Now, this is subject to debate, but there is one question that is easy  
to answer - and that is what type of fluid you have in your car now.   
If the brake fluid is golden in color then you've got DOT4.  If the  
fluid is purple, blue or some other funny color then you've got DOT5.

My .02


Ashford Little
6-Pack Membership Secretary
'70 TR6




On Jan 24, 2008, at 8:53 AM, Joseph Grant wrote:

> Do what you like but I have a friend who owned a pristine TR250.  He
> switched to silicone fluid and after several months started having  
> issues
> with his brakes.  Eventually they ended up failing.  There are some  
> adverse
> reaction between the silicone and the rubber used in the master  
> cylinder and
> the rest of the braking system.  I realize there are many folks that  
> use it
> and swear by it, but I had a chance to see firsthand what happened  
> to my
> friend's car soon after conversion to silicone fluid.
>
> He ended up having to replace the entire system at quite a bit of a  
> cost.
> For me, that is just not worth the risk.  I don't use it.
>
> Joe
> '72 TR6 - CC77169
> http://www.bowtie6.com/