Manual brakes conversion

[ttypetex]

What is the benefit of doing this? Just weight reduction? Is this for racing only, or normal driving as well?

 

[ttypetex]

Is this a secret?

 

[Louie L.]

It is mostly a race car mod for weight savings and reliability.Some of the fast Buick do have problems with making enough vaccum for brakes.

I have seen some street Buicks with manual brakes, but If its a daily driver I would advise against it.

 

[Roger]

Manual brakes are lighter & the best if you subscribe to the KISS principle (Keep It Simple Stupid).

 

[novaderrik]

if you upgrade to bigger brakes than stock, you can ditch the extra mass, clutter, and complexity of the brake booster and go manual. the trick is matching the bore size and travel to the front and rear brakes.

 

[RmvBfrFlght]

What is the benefit of doing this? Just weight reduction? Is this for racing only, or normal driving as well?

My reason for having manual brakes (LS1 ft & rr) is that they will work no matter how many rods are hanging out of the block, how much of the crank shaft you have driven over, or whether it is just a loss of head gaskets.

On these cars it is an advantage when the braking system doesn't rely on a running engine.

Note that with PM, HB, & VAC, folks will claim that there are reservoirs that can be relied on. However, they go away quickly when the brakes are being modulated. Which is required when running over engine parts.

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[ttypetex]

My reason for having manual brakes (LS1 ft & rr) is that they will work no matter how many rods are hanging out of the block, how much of the crank shaft you have driven over, or whether it is just a loss of head gaskets.

I take it, then, that you use it for daily driving? Can you lock the brakes front and rear? I never have been able to lock mine even with the original Powermaster. Now using vacuum, but really not any better.

 

[RmvBfrFlght]

I take it, then, that you use it for daily driving? Can you lock the brakes front and rear? I never have been able to lock mine even with the original Powermaster. Now using vacuum, but really not any better.

It is a street driven car, although not daily. I've never tried to lock the brakes, so don't know. The stock brakes are marginal at best.

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[nonosv6]

RmvBfrFlght what master are you using with the ls1 frnt and rear brakes? im interested as this is the set up i have.....joel

 

[RmvBfrFlght]

RmvBfrFlght what master are you using with the ls1 frnt and rear brakes? im interested as this is the set up i have.....joel

It is a Dorman, number M39736. Under $30 at Rockauto, then shipping. It is used on Chrysler, Plymouth, & Dodge vehicles. Here are the specifics:

7/8" bore diameter
LH, 3/8"-24 ports
dimple: .725"

I think I have a picture here someplace...

Since I was putting new lines in between the M/C and distribution block the 3/8-24 fittings didn't matter. Also used a Wilwood proportioning valve to the rear line.

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[nonosv6]

and how would you say it compares to power brakes.how well does the car stop?

 

[ttypetex]

It sort of looks like the Dorman is counterbored for the plunger shaft. Can't really tell from the angle. Did you have to modify the plunger to use with it?

Also, if it is counterbored, is it deep enough to keep the plunger shaft from falling out accidentally, or do you rely on the rubber boot to keep the shaft centered?

 

[RmvBfrFlght]

It sort of looks like the Dorman is counterbored for the plunger shaft. Can't really tell from the angle. Did you have to modify the plunger to use with it?

Also, if it is counterbored, is it deep enough to keep the plunger shaft from falling out accidentally, or do you rely on the rubber boot to keep the shaft centered?

The counter bore is the dimple spec, 0.725" deep.

It is enough to prevent the rod from falling out. For this set up I made my own adapter plate along with the push rod. They are two aluminum plates that are mounted together to form one plate. The inner most plate received a smaller opening for the push rod as a just in case.

The reason for the two plates is that the flange bolt hole spacing isn't the same as a GM M/C. And I didn't want to modify the M/C. So the inner plate is drilled, tapped, and helicoiled at 3/8-16 to receive the pedal mounting bracket bolts through the fire wall.

The outer plate has the two M/C holes the same but in 5/16-18.

Then three holes in 3/8-16 (two bottom, one top) to fasten the two plates together.

I took a picture but with everything in black can't see much at all. The prop valve is mounted via a bracket off the side of the plate assembly.

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