[DeTomaso] question about adjusting power brake booster

boyd casey boyd411 at gmail.com
Tue Apr 3 15:27:42 EDT 2012


I should have included more information. I have what looks like a fairly
common booster and master cylinder setup. I upgraded my brakes with the Ken
Green inspired , fabricated by German performance Saco Performance) Porsche
911 turbo 4 piston calipers and  oversize custom coleman rotors vented with
gas vents .  I also added the custom billet rear uprights These use modern
rear modular bearings that don't requiere removal of the uprights and a
press to change the bearings. It also did away with the half shafts and
replaced them with Porsche 930 CV joints. I also installed poly graphite
bushings and Koni coil over shocks from Dennis Quella. .   I purchased a
set up of CNC master cylinders with a balance bar that I want to use in
conjunction with the booster. My problem is that the original booster has a
black plastic push rod with a top hat type affair at the business end of
the push rod . The Black plastic push rod is hollow and slides over the
metal push rod. The metal push rod goes into the booster , slides into the
hollow black plastic push rod and the black plastic top hat ( it's really
more like an upside down top hat shape) goes into the master cylinder and
pushes into the master cylinder Piston. When I try to switch to the dual
CNC master cylinders with the balance bar the black plastic rod is not
used. The balance bar has a hollow opening that the booster push rod slides
into. It is not long enough to push the balance bar enough to engage the
dual master cylinders. So I either need a new push rod  or a way to adjust
the push rod so that it comes out far enough to engage the balance bar.

Boyd

P.S. Once I get the master cylinders working I plant to decommission the
 hydraulic brake pressure diffferential

On Tue, Apr 3, 2012 at 2:08 PM, Steve Hawkins <shawkins777 at comcast.net>wrote:

> My outer rod is adjustable, it has a screw on the end that can be adjusted
> longer or shorter.
>
> Steve
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com]
> On
> Behalf Of JDeRyke at aol.com
> Sent: Tuesday, April 03, 2012 12:58 PM
> To: boyd411 at gmail.com; detomaso at realbig.com
> Subject: Re: [DeTomaso] question about adjusting power brake booster
>
>
> In a message dated 4/2/12 7:18:52 PM, boyd411 at gmail.com writes:
>
> > Can someone tell me how do you adjust the pushrod in the power brake
> > booster?
> >
>
> Which one? The short outer rod that causes trouble in adapting other brands
> of master cylinders is non-adjustable except with grinders, hacksaws or
> welders. The inner one that goes between the diaphragm & foot pedal threads
> in &
>  out once you remove the connecting bolt at the pedal. There is no direct
> connection between the two.
> In case its the short outer rod giving trouble, the idea is to slack off
> the master cylinder nuts and closely observe the joint between MC and
> boster:
> if the MC pops out a little, you will need to shim the MC by that much plus
> a 'little' or shorten the rod by the same amount. A second problem
> associated with the outer rod is when the adapter plate has a tight fitting
> plastic
> guide-bushing in it. When the front trunk gets hot, everything expands but
> the bushing is constrained so it squeezes inward, grips the rod and the
> brakes
> stay on. The fix is to hand-ream the hole in the plastic a little larger.
> I've done this to cars during club outings using a jacknife. Good luck- J
> Deryke
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