Completely new brake system not working

Hi all. We are about to wrap up our restoration but are now trying to work out the bugs. We have a complete new brake system. It is a Wilwood Power disc brake system With drum brakes for the parking brake. The system was installed prior to us getting the car it did not have a power brake booster which we purchased new and is now installed. The brakes do not stop the car well they do kind of a slow down at best. The system has been bled out correctly and there is a proportioning valve in place. Any ideas would be appreciated.

On non original parts the best we can do is guess. In general you need to start at the master cylinder and then confirm the function across every part of the system. Might be well worth your time to read the theory of operation in the factory manual before starting

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Agree with above. Confirm the master cylinder is bled and that it’s interface to the booster is per specification. Power brake vs non power brake systems can have differ pedal geometry so you should think about that also. Then look at the lines and how the front rear pressure is proportioned. Then consider mismatched or defective parts.

I would ask at least two questions to start. Is the pedal hard or soft? How far does the pedal travel?

On a Bendix brake booster there is an adjustment on the rod. The service manual tells how to make a tool to measure the proper gap. Not sure if you have a Bendix booster, but I’d suspect with any booster the rod should have some adjustment.
Due to the leverage between the pedal and rod pivot, just a little gap on the rod can equate to a lot of useless pedal travel.

In #11 of my Eliminator 445 video, I show using the gauge at about the 4 minute mark.

If you can post some pictures of what you have and we might be able to help more. With a mix of factory and aftermarket you could have several things causing it. If going from non power to power it’s more then just adding a booster. You need the correct master cylinder, a power brake pedal etc. Depending on how your car was originally you may need to add a proportioning valve as well.

I have a similar setup with wilwoods. My car was a non power drum brake car originally. I needed to add a brake booster, power disc/drum master cylinder, power brake pedal, and an adjustable proportioning valve. I am using the stock rear drum brakes and installed a Wilwood front disc kit. It stops great when properly setup but you have to make sure you have everything working together.

Put a brake pressure gauge front and rear…you either have too low of brake pressure or too hard of disc pads