FW: on prop valves

[andrew.stauffer@cannondale.com (Andrew Stauffer)]

Good call, Dan. I'm thinking that using both the stock alum block(aka "drum
brake prop valve") AND using the 16v rocco prop valves, in sequence, would
effectively choke the hydraulic pressure back to the point that things will
work properly.  

I know that my rocco/cabby Bently gives pressure values for before and after
the 16vprop valves.  If I can locate this same info for the drum brake prop
valve, we could probably figure out the proportion of pressure decrease and
whether that would be appropriate for a rear caliper providing 30% more
force, no?  Does anyone have a Rabbit Bently nearby?   

If we weigth the cumulative pressure reduction against the 30% increase in
force, it would give an idea of performance.  





-----Original Message-----
From: Dan Bubb [mailto:jdbubb@ix.netcom.com]
Sent: Monday, March 25, 2002 9:36 AM
To: Andrew Stauffer
Cc: 'scirocco list'
Subject: Re: FW: on prop valves


Well, I don't know shit about how these prop valves work, so no help
there.
But, I'd be willing to bet the bigger rear pistons are going to be an
issue.
~30% more area with the same pressure is going to be 30% more force,
should translate to 30% more braking torque! Doesn't sound good.
Dan

Andrew Stauffer wrote:
> 
> -----Original Message-----
> From: Andrew Stauffer
> Sent: Monday, March 25, 2002 9:05 AM
> To: 'Mk1gti@yahoogroups.com'
> Subject: on prop valves
> 
> Scott (and anyone else that has some info!),
> 
> I'm currently midway through the rocco 16v brake upgrade to my 83 GTI.
Rear
> discs, bigger fronts, and the mc/booster.
> 
> The question involves prop valves.  I've heard folks say that even with
the
> 16v rocco prop valves, the rears still want to lock up prematurely.
Perhaps
> because the rabbit rear end(with no spare or back seat) is so much
lighter.
> 
> At any rate, which prop valves did you use?
> 
> My situation is somewhat more complicated(heh, of course) as I'm not using
> rear calipers from a 16v rocco, I'm using the cast aluminum calipers from
a
> 2001 Jetta.  The piston diameter is larger(41 vs 36mm IIRC) than the rocco
> rear calipers, which, I think, is going to further favor rear wheel
lockup(
> I may be wrong on this last point, dunno).  So I was thinking about using
> *both* the Rabbit stock prop valve(the alum block) AND the 16v prop
valves.
> 
> Good idea?  Bad idea?  Why?   Any other thoughts?  I should probably, at
> this point, be seriously considering an adjustable prop valve, but I don't
> have one of those in the garage, where as I have every other piece of the
> puzzle.  Thanks.
> 
> -----Original Message-----
> From: Scott F. Williams [mailto:sfwilliams@comcast.net]
> Sent: Sunday, March 24, 2002 9:38 AM
> To: Mk1gti@yahoogroups.com
> Subject: RE: [Mk1gti] Digest Number 1423
> 
> Steve Heller wrote:
> > i'm not so sure i want to do it after
> > reading how you're still dissatisfied with all the 16V upgrades.
> 
> Steve, don't get me wrong. I absolutely *love* the performance of my
> Scirocco 16v brakes. I've got the entire set up: master cylinder, booster,
> 10.1" rotors and big calipers, rear disks, etc. It works really great and
> I'd recommend it to anyone. The pedal is hard and the modulation is easy.
> However, I'm always looking for more! I picked up a Corrado G60 master
> cylinder for super cheap and don't mind experimenting with it.
Furthermore,
> I am anticipating a move to some four pots sometime in the future.
> 
> Onward! In the name of SCIENCE! :^)
> --
> Scott F. Williams
> NJ Scirocco nut
> '99 Subaru Impreza 2.5 RS
> Mazda 323 GTX turbo "assaulted" vehicle
> Golf GTI 16v "rollycar"
> ClubVAC: "Roads found. Drivers wanted."
> 
> Check out our rally team's website!
> http://www.usrallyteam.com
> 
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