Brake Booster idle issue

[67gt500]

Hi, Looking for some advice on my brake booster issues.. the car has been off the road for a few years while i did a number of tidy up things..
I decided to change the service replacement, bendix booster with a Midland Ross one.. I had the Midland booster rebuilt a couple of years ago. So a few weeks ago i installed it and the problem i am having is when you touch the brake pedal the RPM increases by 150 - 200, Which didn't seem right.. So i took it out and sent it to the Brake shop where they went back though it and said all looks fine. Holds pressure etc.. I put it back it today, and same problem.. Something is not right.. frustrating..

[1967 eight barrel]

The Brake shop did my rebuild. Let's just say I had no power brakes. I sent it to Booster Dewey at the suggestion of Bob Gaines. Not only does it now work, but something was done that helps being the cam in the vehicle makes less vacuum at idle that stock.  Here is the website.

                                                               -Keith
http://boosterdeweyexchange.com/

[Shelby_r_b]

The Brake shop did my rebuild. Let's just say I had no power brakes. I sent it to Booster Dewey at the suggestion of Bob Gaines. Not only does it now work, but something was done that helps being the cam in the vehicle makes less vacuum at idle that stock.  Here is the website.

                                                               -Keith
http://boosterdeweyexchange.com/

These guys are awesome! I was looking for the correct tag for my brake booster and called them.  Not only did they have one, but they sent it to me and said, "We'll pay to ship it to you. When you get it, send us whatever money you feel is fair for the tag and shipping."  Who does that?!?!?

[67gt500]

That's what i was thinking.. Send it there.. But i just thought i might have missed something, before i have to spend more.. Especially when they say "it all tests fine".. and "we have gone back though it" and its all good. So you start to look else where. but everything else seems fine too, new check valve, no engine vacuum leaks etc..

[greekz]

Before you send it off, if you have not isolated the booster try that.  That is what I did when my trans would not shift, the idle was rough or engine would die.  Isolating the booster pinpointed the problem.  If your idle problem goes away, send to Booster Dewey.  They are the best.  You will also get a bag of "Booster Nuts" which are peanut M&M's

[67gt500]

yes, i removed the vacuum line and it runs great.. reconnect and just when you depress the brake pedal, the RPM goes up.. which tells me there is an issue with the booster.. The engine must be drawing air from inside booster..

[shelbydoug]

It happens to all of the boosters eventually. Consider though that it lasted 50 years?

[greekz]

Or you may be momentarily sealing the vacuum leak when depressing the pedal.  Either way you have it diagnosed.  Good luck!

Greek

[67gt500]

It happens to all of the boosters eventually. Consider though that it lasted 50 years?

Well kind of, the inside's, they are new..

[67gt500]

Or you may be momentarily sealing the vacuum leak when depressing the pedal.  Either way you have it diagnosed.  Good luck!

Greek

Thanks, i just pulled it out.. 3rd time, i'm getting quite good at that part..

[1967 eight barrel]

Let us know what the outcome is when Booster Dewey looks at it. He will usually do a preliminary inspection/test reasonably. Did you happen to test the booster check valve?

[67gt500]

After seeing another Booster issue on the forum, i thought it about time i posted the out come of my idle issue when pressing on the brake pedal..

I spoke to Steve at Booster Exchange about the problem and he made a comment "yep, these Midland boosters are a little bit tricky to do,". Once i got the booster to him and he went though it, the problem was the "control valve poppet" which is often over looked and not replaced, but is an important part to the rebuild..
I got the booster back and installed it and its perfect.. No idle issue..

Some other things that Steve said to be aware of with the Midland Booster.. The band has to be a perfect seal.. Also they don't like sitting around on a shelf or in the car un-used.. 2 years max on a shelf or you might as well get it rebuilt again..

As other forum members have mentioned, Steve and his team are great from the beginning to delivery,  top notch..