Odd power brake booster unit on an M38A1

[wesk]

We have a new member Eric who has one of these on his M38A1. Is anyone familiar with these?

[WillysMotors]

Odd. No. Uncommon, yes.

That is the same vacuum powered brake booster that was used on the Willys CJ5 tow trucks. Seemed a little unusual because they still used 9" drum brakes.

That is the same unit that George Barris and Jim Street (Skonzakes) used on the Golden Sahara II showcar, but not to boost brake power. By having an electric solenoid modulate the vacuum port, they demonstrated the car as having remote braking controlled with a television remote control...in 1955.

[Mike_B]

That's a Bendix Hydrovac Brake Booster. All of my big 1950's Chevrolet trucks have them, although they are physically bigger than this one.

To see if it's working, pump the brakes a few times with the engine OFF to bleed off and remaining engine vacuum, then push the brake pedal in and hold it while you start the engine. As the engine builds vacuum you should feel the pedal fade to the floor slightly, if it's working.

There are re-builders out there if it needs to be rebuilt.

Mike B

[tatacz7]

Thank you for the reply and info. I found the master cylinder under the vehicle. I removed the water pump and radiator, so once I get it running again, ill try the brakes to see if it works. I have lots of questions, just don't know how to post pictures. I was able to read "MD 62887" off the plate that was painted over and was mounted on the right rear fender well. I don't know what that means. Again Thanks for the info.

[wesk]

tatacz7,

Can you post a few more photos from a greater distance back of that power brake unit's installation to give us a better idea how it is plumbed into the brake and vacuum system.

The right wheelhouse patent plate serial MD62887 should match the serial on your dash serial plate. If it does not match then either the dash plate does not belong to your jeep or the tub is not the original tub for your jeep.

I strongly suggest you go to our downloads page and download PDF copies of the M38A1 manuals and parts catalog there to help you learn your way around your new jeep. Just click on "DOWNLOADS" on the welcome bar above under the web site title.

I also opened a photo album for you in our "Member's Albums" page:

Here's your album:
http://www.willysmjeeps.com/v2/modules. ... _album.php

Here's the rules:
http://www.willysmjeeps.com/v2/modules. ... opic&t=498

Here's the tutorial for loading your album:
http://www.willysmjeeps.com/v2/modules. ... _album.php

Here's the tutorial for posting your photos:
http://www.willysmjeeps.com/v2/modules. ... pic&t=8670