Bypassing Brake Booster for Coupe

bobs600honda · Post by **bobs600honda** » Mon Sep 15, 2014 6:57 am

Good morning. I know somewhere in all the threads there was information on what the thread pitch / size, etc. for the brake lines going into the brake booster and exiting the booster. Any specifics greatly appreciated!
For the time being (perhaps for a long time!), I wish to take this booster completely out of the brake system and just use a "t" of sorts to connect the "in" to the "outs" for the booster.
Thanks for any reference to links here or elsewhere.
Bob
Tracy

bobs600honda · Post by **bobs600honda** » Tue Sep 16, 2014 6:28 am

Any help?

Mark P Hatten · Post by **Mark P Hatten** » Tue Sep 16, 2014 7:16 am

I would recommend repairing your booster and leaving the system as designed. Parts are available thru Honda 600 car parts .com
Only the z600 front discs are assisted, when you bypass the booster the pedal becomes hard as a rock and the normally unassisted rear drums lock up easy , it very dangerous to drive like this.
I put a adjustable bias control in to make the rears less sensitive but find the car is no fun to drive with rock hard brakes with no booster
www.mphspecialties.com
To: anzhonda600owners@yahoogroups.com From: anzhonda600owners@yahoogroups.com Date: Tue, 16 Sep 2014 06:27:03 -0700 Subject: [anzhonda600owners] Re: Bypassing Brake Booster for Coupe
Any help?

Bill · Post by **Bill** » Tue Sep 16, 2014 10:23 am

There is significant justification to maintain the power booster in the brake system. But without a vacuum diaphragm replacement all the other seals are useless.
Even sleeving the cylinders including the puppet valve at the front of the cylinder casting, will not cure the problem if the pistons for all these new surfaces are warn at their sealing areas.
However making this single component is not cost effective, tooling and injection mold processes are high and when you place the “Function of the part is an automotive brake system” DOT gets involved and that a loan is a game changer and will scrap all your efforts.
Costs will rise with liability for the product and the liability for brake component is considerable.
To verify the hard brake issue Mark is describing, turn the ignition off on any vehicle with power assisted brakes, push on the brake peddle three times.
There is some residual vacuum assist for the first two times the brake peddle is depressed but by the third time it’s hard as a rock.
This is where your brakes will be without the booster in place.
If you have removed it and are not feeling a harder peddle then there could be some air in the system which could give you a not so hard feel at the peddle.
Bill

Mark P Hatten · Post by **Mark P Hatten** » Wed Sep 17, 2014 7:25 am

no argument here , I completely agree !
www.mphspecialties.com

> From: theenginebuilder@...
> Subject: Re: Bypassing Brake Booster for Coupe
> Date: Wed, 17 Sep 2014 06:48:42 -0700
> To: mphatten@...
> Why would Honda install expensive parts if they weren't needed in the first place!?
> The booster was installed in front disc brake vehicles to increase the pressure to the discs only. You may not notice a difference during normal driving, but you will get wider eyes when roaring downhill and make a panic stop for something in your path! The rear end will try to come around first and since the fronts are not operating at full capacity it will take longer to stop than you might enjoy.
> I have modified many brake systems over the years for racing and spirited street driving and have found the Honda system to be just right as sent from the factory for what the cars are able to do power wise.
> If you want to start removing parts from your car to help it go faster then start with the glass. Lighter is faster! Then perhaps no booster would be a good idea as well.
> Bruce

bobs600honda · Post by **bobs600honda** » Sat Oct 11, 2014 7:00 am

Interesting comments posted on both sides of the booster (!)
Found the following thread (not brake connection thread!) in the posts....
Hmmm., Interesting.
Honda made three different power boosters for the 600's, the booster for the coupe is different in that it has one inlet and to outlets on the booster master slave cylinder. The sedan booster can be replaced with a Sedan rear brake line hose. And like has already been said there isn't much difference.
If having a working booster on your restoration is a must have; then there are key issues that you will need to deal with. The piston shaft will be warn and a warn shaft will have copper showing through the chrome plating meaning it will need to be rechormed. The puppet valve has a very small piston and seal, both of which are hard to come by. Besides all of the seals and rechroming the piston shaft, the cylinders themselves have corroded bores which will need to be resleeved in brass. If all of these issues are not a deterrent then look to see if the vacuum diaphragm (the parts manual referrers to it as the "Booster Plate") is in good condition, still attached to the plate and will seal to the base. All of which is necessary to complete the rebuild.
You can replumb the system and it will work, and there are brake line manufacturers that have the correct size and thread pitch for the flare nuts: See Miles input below from a while back...
Subject: [2cylinderhondas] Re: 600 brake lines threads

Brake Lines & Fittings Defined:
Wheel cylinders (rears) on the USA sold Honda 600 Sedan & Coupe:
The Hard lines and flex lines have 10 x 1.25 thread pitch.
The Bleeders are 8 x 1.25 thread pitch
The Calipers are 10 x 1.25 thread pitch on the Banjo fittings The Bleeders are 10 x 1.0 thread pitch
Brake Master cylinder hard lines are 10 x 1.25mm
Bleeders are 8 x 1.25
Brake Booster in & out 10 x 1.25 (early sedan bendix boosters differ) Brake booster low pressure switches 1/8 BSP not NPT thread pitch
Civic & most other later Honda's flare nuts are 10 x 1.0mm thread pitch and unless you use Civic wheel cylinder forcing the flare nuts in is not recommended.
You can cut the Honda 600 or S600/S800 flare nuts off the steel brake lines then install them onto your new 3/16" steel lines.
Finding the flare nuts in the Honda 600 pitch is difficult but I hear someone in Japan made new ones for the S600 people.
I bought a Double Flaring tool many years ago from Sears and recently used it to make hard lines for my Honda motorcycle using some re-zinc flare nuts and new 3/16" line.
Miles

Some places to go to for brake assistance:
http://www.brakecylinder.com/
http://www.classictube.com/
http://www.whitepost.com/brakeform.html
http://www.inlinetube.com/
To name a few.
Bill

Bill · Post by **Bill** » Sat Oct 11, 2014 10:17 am

Hi Bob;
Yes, it (a booster less brake system) will work, but the brake system will not be as good as it could be with the booster. Honda early on used an unassisted brake system when all drum brakes were used, but with the use of the disc brake system upfront Honda found that an assisted system (Booster) is needed for necessary stopping performance. See the article below;
Why Use a Brake Booster
In the old days, vehicles commonly used drum brakes, which naturally provide some of their own power assistance. Once disc brakes started to become more common however, the lack of braking assistance started to become quite noticeable. Brake systems work at rather high fluid pressures, and without the assistance of the brake booster, would result in a rather hard, and difficult to use brake pedal. While this in itself may not be bad for someone used to a manual braking system, or in very good physical shape, for many people it would simply be too hard to comfortably depress in the amounts required for every day driving. This would mean that proper stopping ability would be limited by personal strength, which erodes much of the accessibility that the modern automobile enjoys, and poses a safety concern to everyone on the road.
(From http://www.carsdirect.com/car-repair/wh ... booster-do Cars Direct)
So as stated before, if you pull the booster plan on making up the difference.
Bill

Robert James · Post by **Robert James** » Sat Oct 11, 2014 1:05 pm

Got it!
Sent from my iPhone

On Oct 11, 2014, at 10:19 AM, 'Bill'
billmyong@...
[anzhonda600owners] wrote:
Hi Bob;
Yes, it (a booster less
brake system) will work, but the brake system will not be as good as it could be with the booster. Honda early on used an unassisted brake system when all drum brakes were used, but with the use of the disc brake system upfront Honda found that an assisted system (Booster) is needed for necessary stopping performance. See the article below;
Why Use a Brake
Booster
In the old days,
vehicles commonly used drum brakes, which naturally provide some of their own power assistance. Once disc brakes started to become more common however, the lack of braking assistance started to become quite noticeable. Brake systems work at rather high fluid pressures, and without the assistance of the brake booster, would result in a rather hard, and difficult to use brake pedal. While this in itself may not be bad for someone used to a manual braking system, or in very good physical shape, for many people it would simply be too hard to comfortably depress in the amounts required for every day driving. This would mean that proper stopping ability would be limited by personal strength, which erodes much of the accessibility that the modern automobile enjoys, and poses a safety concern to everyone on the road.
(From
http://www.carsdirect.com/car-repair/wh ... booster-do Cars Direct)
So as stated before, if
you pull the booster plan on making up the difference.
Bill
From:
anzhonda600owners@yahoogroups.com
[
mailto:anzhonda600owners@yahoogroups.com
]
Sent:
Saturday, October
11, 2014 7:01 AM
To:
anzhonda600owners@yahoogroups.com
Subject:
RE: [anzhonda600owners]
Bypassing Brake Booster for Coupe
Interesting comments posted on both sides of the booster (!)
Found the following thread (not brake connection thread!) in the posts....
Hmmm., Interesting.
Honda made three different power boosters for the
600's, the booster for the coupe is different in that it has one inlet and to outlets on the booster master slave cylinder. The sedan booster can be replaced with a Sedan rear brake line hose. And like has already been said there isn't much difference.
If having a working booster on your restoration is
a must have; then there are key issues that you will need to deal with. The piston shaft will be warn and a warn shaft will have copper showing through the chrome plating meaning it will need to be rechormed. The puppet valve has a very small piston and seal, both of which are hard to come by. Besides all of the seals and rechroming the piston shaft, the cylinders themselves have corroded bores which will need to be resleeved in brass. If all of these issues are not a deterrent then look to see if the vacuum diaphragm (the parts manual referrers to it as the "Booster Plate") is in good condition, still attached to the plate and will seal to the base. All of which is necessary to complete the rebuild.
You can replumb the system and it will work, and
there are brake line manufacturers that have the correct size and thread pitch for the flare nuts: See Miles input below from a while back...
Subject:
[2cylinderhondas] Re: 600 brake lines threads
Brake Lines & Fittings Defined:
Wheel cylinders (rears) on the USA sold Honda 600 Sedan &
Coupe:
> The
Hard lines and flex lines have 10 x 1.25 thread pitch.
> The
Bleeders are 8 x 1.25 thread pitch
> The
Calipers are 10 x 1.25 thread pitch on the Banjo fittings
> The
Bleeders are 10 x 1.0 thread pitch
Brake Master cylinder hard lines are 10 x 1.25mm
Bleeders are 8 x 1.25
Brake Booster in & out 10 x 1.25 (early sedan bendix boosters differ)
Brake booster low pressure switches 1/8 BSP not NPT thread
pitch
Civic & most other later Honda's flare nuts are 10 x 1.0mm
thread
pitch and unless you use Civic wheel cylinder forcing the flare nuts
> in
is not recommended.
> You
can cut the Honda 600 or S600/S800 flare nuts off the steel
brake lines then install them onto your new 3/16" steel lines.
Finding the flare nuts in the Honda 600 pitch is difficult but I
hear someone in Japan made new ones for the S600 people.
> I
bought a Double Flaring tool many years ago from Sears and
recently used it to make hard lines for my Honda motorcycle
using
some re-zinc flare nuts and new 3/16" line.
Miles
Some places to
go to for brake assistance:
http://www.brakecylinder.com/
http://www.classictube.com/
http://www.whitepost.com/brakeform.html
http://www.inlinetube.com/
To name a few.
Bill