Date: Mon, 4 Jun 2012 14:24:23 -0400
Reply-To: Mike S <mikes@FLATSURFACE.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike S <mikes@FLATSURFACE.COM>
Subject: Re: front brakes
In-Reply-To: <OF21B0C9AC.17487126-ON88257A13.005FE6E4-88257A13.0060E55F@usgs.gov>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 6/4/2012 1:38 PM, Arlene K Sondergaard wrote:
> Its a twisty turny steep road that leads all the way to the top.
> I was pumping the brakes all the way down and going slow.
> Her front brakes were smoking when we got to the bottom and I had to use
> the e-brake when we parked.
> An hour later they were cool and we went back to Washougal.
> They smelled bad the whole way like they were welded together.
> But this morning going to work they were cool and non smelly.
They may be just fine. You overheated them. Best to use a low gear, and
let the engine do much of the braking when descending steep grades.
You're lucky you didn't overheat them to the point that the brake fluid
was boiling - because then you pretty much lose all braking. If you were
pumping the brakes because the pedal started getting spongy, you were on
the verge of boiling the fluid, and total (or rear brake only) brake
failure.
The stock brake friction compound on a Vanagon is made to work well when
cold, with minimal squeal. Compounds made for high temp ("race")
conditions don't stop as well when cold, and tend to squeal. Given the
nature of the beast, I doubt anyone makes a pad with a high temp
compound, and you wouldn't want it for everyday driving, anyway. What
you smelled was the overheated compound. In many cases, everything
returns to normal after cooling, but overheating can also cause the pads
to "glaze," and they won't work as well as before, and often start
squealing when stopping. You can sometimes fix that by taking some
sandpaper to them, roughing up the surface.
Common DOT 3 brake fluid boils above ~400F, when fresh. But, it picks up
water from the air. After a few years of that, it may boil at 300F. If
you haven't changed your brake fluid in the past 2 years, it's time to
do so now. Slightly more expensive DOT 4 or DOT 5.1 (do NOT use DOT 5)
fluids have higher boiling points, minimum 446F or 518F, respectively.
You can also get "performance" versions of any of these, with higher
temperature ratings - the temps given above are minimums.
If the automatic can't provide enough engine braking, then occasional
stops to let the brakes cool are called for if you get into a similar
situation.
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