Brake Booster sources & replacement

[Colin]

Sent: 5/23/2003 11:29 PM

This new thread is related to my "brake problem" thread. I spent some time searching the web and made about 50 long distance calls to educate myself on the availability of thirty year-old Bendix brake boosters. A lot of our rigs have them. For those of you who might be interested, here's what I found out.

I couldn't find anyone who has rebuild kits, or who would tell me where to get them. The local distributor told me that the rebuilders fabricate or procure their own parts. If anyone has a source for rebuild kits, that would be great. Please let me know.

Bendix Corp. tech support was pretty helpful, call them at 1-800-247-2725. They don't sell boosters or parts that go back further than 1973, but they list several rebuilders. They directed me to Precision Rebuilders in St. Louis. They rebuild the old boosters and have a good selection in stock. Call 1-800-325-2690. Speak to Mike in tech. support. He helped confirm that my brake problem was a bad booster. I ordered a rebuilt hydrovac from them for $130.00 with a $60.00 core.

They are supposedly pretty easy to replace, I'll find out. I lined up a local shop to bleed the system for me, but is this something that I can do myself and be sure I did it right? If anyone has any step-by-step instructions I would appreciate it.

C.

[Dave1210]

Sent: 5/24/2003 11:35 AM

Thanks for the info, I sometimes wonder about the condition of my boosters as they look original but appear to be functioning ok. Its good to know there is someone out there who can rebuild these things.
As far as the bleeding goes, are you going to install the boosters then drive the rig to the brake shop or have them come to your house. I personally think they could bleed them better using their equipment rather than you crawling under the rig while someone else pumps the pedal. 

[denisondc]

Sent: 5/25/2003 9:45 AM

I think the boosters are straightforward to replace, though easy or not - depends. I soaked all the fittings on mine in penetrating oil for days before I used a refrigeration wrench to loosen/free-up the brake line nuts. You don't want to twist the brakes line tubing. The attachment bolts for the booster assembly would be about as rusty - that may not be as much of a problem in Colorado as here in humid weedy Virginia. Getting them bled once the new one is back in is a trial of patience - how much brake fluid do you like to have spattering in your face, running down your arm, etc. You have to work from under it of course, and you have to keep the master cylinder well topped up. You bleed the brake system from the master cylinder, then the booster inlets, then the booster outlets, then the wheel cylinders. When you are done you will probably scare your own dog. It takes me almost a quart of brake fluid to completely bleed my brakes. Since my brakes work easier if I pump the pedal quickly once, I am now saving up to buy a pair of rebuilt boosters, and THANK YOU for the info and phone numbers!!! denison

[Rick Shaw]

Sent: 5/26/2003 9:34 PM

Md,
What were your symptoms of a bad booster?    I would like to know because I think mine might be bad.
Rick

[Colin]

Sent: 5/26/2003 11:19 PM

Re: symptoms

Originally I had to stand on the brakes to get them to stop and the brake light went on every time I braked. I took the rig to a brake shop and they overhauled the brakes all around and even put oversized brakes on the front. They said that the boosters were fine. The brakes have much better pedal, but the brake light still comes on and the rig is hard to bring to a stop. I noticed that the sound of air at the breather never stops even when the brake pedal is pushed to the floor. I got under the rig and put my ear to the brake boosters while my son stood on the brake. One has a sound of airflow at the control valve that the other doesn't. I called the Bendix tech and he confirmed that it was the booster. What are your symptoms?

[Rick Shaw]

Sent: 5/27/2003 10:41 AM

colin,
I have somewhat the same symptoms.   My brake light is forever coming on when I press the pedal.   I do not hear any air.   I did bleed the brakes with the help of another person.   I have leakage of brake fluid at the master cylinder.   I thought that the part that the master cylinder hooked up to was the power booster.   I had fluid leak before I installed a new master cylinder and still have the leak with the new one.
Rick

[Dunnohow2]

September 27, 2011, 07:27 PM

I send you all greetings and hope that you are enjoying good health.
Last year, I bought a new master cylinder and brake booster for my '73 Brave and the project got deferred for too many unforeseen reasons.  I made the necessary brake cylinder bleeders and tried to fit the two units.  Revisiting the scene, somehow, I've managed to unscrew the booster adjustable rod which attaches to the brake linkage and pushes the cup into the brake cylinder.  Can someone please tell me what the standard rod setting should be (dimensions from anywhere I can locate!) and how much engine vacuum do I need to get the booster to fully "load"?  Apparently, the Mopar booster came already pre-set! Any references to other related posts would be greatly appreciated.  I've been away too long and forget how to find my way around!
Many thanks,
jenni.
"I ain't been to anywhere but it's on my bucket list"

[DaveVA78Chieftain]

September 27, 2011, 10:38 PM

The information is not in the Service manual.  You will most likely have to contact a booster rebuilder and con the information from them.  Google "bendix master-vac booster" and see if they can help you.

Dave

[Dunnohow2]

September 28, 2011, 03:23 PM

Thanks Dave, I'll take the whole unit to the local clutch and brake specialist and seek their advice.
Cheers,
jenni.
"Never drive faster than your guardian angel can fly."

[Chief Crazy Canoe]

Colin-

I know this is bringing up a really old thread - but I'm curious as to how this was resolved.  I've got the exact same scenario - except I don't have anyone else to push the pedal for me everytime I get a moment to wrench on the Winnie.

I've got rushing air in the breather and the pedal goes almost to the floor - even with new pads up front.  I've got to take a few days and tackle the rear shoes and have the drums turned just for good measure.  The front ones were toast with little to nothing left of the pads (30,000miles) - so I'm pretty sure they're all original equipment in the rear as well.  With new shoes and turned drums up front it has great pedal feel - but takes all I've got to come to a stop.

I'll try to contact the Precision Rebuilders mentioned earlier in the thread - hopefully they'll have the two boosters.  The way I see it - when it comes to stopping - there is no expense spared for my family.  Best to have all new equiment under the chassis for that reason.

Thanks,

CCC