25mm master cylinder on eBay

[dan@angband.org (Runs With Scissors)]

On Wed, May 29, 2002 at 04:41:54PM -0700, Jonas K. wrote:
> On 5/29/02 3:42 PM, "Runs With Scissors" <dan@angband.org> wrote:
> >> 
> >> Thought someone might want this, I'm not the seller
> > 
> > What, for weaker brakes?
> 
> No, as an option aside from the 20mm or 22mm that are normal VW issue.
> 
> 4 thoughts:
> 
> 1) True, the larger MC diameter will lessen the clamping force of the pads
> on the rotor, for a given force applied on the pedal. But it will also
> increase the range of forces that you can apply to the brake pedal.

Why would it increase the range of force you can apply to the brake
pedal?  If anything, it will decrease it, because you will have a lower
maximum force available.

> 3) I don't see any 16v people out there rushing to get 20mm MC's to beef up
> their brake clamping forces.

Because: 

a) most people don't understand that a smaller diameter MC has higher
output pressure.

b) people who do understand that realize that you will need to find a 20mm
MC that has a long enough stroke so that you have enough displacement to
operate the 10.1: calipers.  There is no 20mm MC that has the same or
greater displacement as the stock MC, although there is one that comes
very close (something like 3 percent less displacement than stock)

c) The stock 16v MC is enough to lock good tires in dry
conditions. Upgrading to get a higher clamping force isn't needed, unless
you want to be able to lock your brakes without pressing as hard.

> 4) I wouldn?t put this on a car with 9.4's up front and drums in rear, but
> if you've got 11" dual pistons up front and discs in rear, you might find
> this necessary to set up a good balance, along with a proportioning valve to
> adjust for optimal brake balance.

If you're running 11" dual pistons in the front, , you'd probably need it
for the extra displacement.  Changing to rear discs does not require any
MC change, but does require different proportioning valves unless you like
the rear end to fishtail in the rain.

Dan


-- 
You have just destroyed one model XQJ-37 Nuclear-Powered Pan-Sexual
Roto-Plooker. And you're gonna have to pay for it! So give up, you 
haven't got a chance.  
		-- Zappa, "Joe's Garage"