Date: Sat, 14 Jul 2007 21:50:21 +1200
Reply-To: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject: Re: Need for upgraded brakes for engine conversion
In-Reply-To: <855EB89E57364B94A1EB1493F84F4E3A@Syncronicity>
Content-type: text/plain; charset=us-ascii; format=flowed
>One of the items I picked up in various engine conversion discussions is the
>need to upgrade brakes, or that the higher HP engine is harder on the
>brakes. I sure could use some insights on this need.
>
>In a way I don't get this, unless the assumption is that people drive faster
>with the higher HP engine, and therefore have to dissipate more energy from
>that faster speed. I suppose this applies only to freeway driving, since it
>seems like a higher HP engine won't cause faster speeds around town; seems
>the WBX goes plenty fast around town if we are willing to wait for the speed
>to build up. And if it only applies to freeway driving then generally
>speaking the only time the higher HP engine is hard on the brakes is on the
>off ramp or when the traffic slows which are relatively infrequent compared
>to around town braking. Or maybe the higher HP engine creates more
>opportunities to carry heavy loads, or use a trailer, which of course
>creates more energy that the brakes have to stop. Or maybe the new engine
>adds some weight, but fairly negligible. For example carrying people is
>much more weight than an upgraded engine. Exercising some intuition, does
>this logic make sense? I guess if someone drives the same speed as before
>the conversion and doesn't add extra weight then there will be no additional
>wear and tear on the brakes?
Unfortunately VW brakes in the days of the German T3s were not good.
They gave minimal retardation when new, and even for that they needed
a hard shove on the pedal. The garbage-quality stock discpads (and
most aftermarket pads as well) don't help. When potential extra
performance is thrown in, better brakes become mandatory.
There is POTENTIAL for additional use of the brakes; wear & tear
isn't the problem. It's outright performance. The stock brakes don't
have sufficient swept area & leverage, don't dissipate heat fast
enough and probably flex in the calipers & mounts. If you want to go
for a "fang" on twisty roads, or go down a LONG steep incline, you
want the brakes to retard and also not to fade (I remember losing the
brakes entirely in a 75 Scirocco TS on a long downhill... total
smokin' fade, and it wasn't fun! Had to turn the ignition off & run
it down through the gears to stop). Extra loads of course make the
need for better brakes more acute.
In some places there is a requirement for brake upgrades before a
vehicle is legal for use after a power upgrade; this is true here in
NZ. I have a set of 4 Porsche 993 brakes with Hansen adaptor kit.
That should appease the authorities. Hansen tells me the stock
mastercylinder is fine for the job.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<andrew.grebneff@stonebow.otago.ac.nz>
Seashell, Macintosh, VW/Toyota van nut
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