[Logan]

A fellow DFW Cougar owner sent me this...

Anyone have a response to his query?



I recently replaced the power brake unit and master cylinder on my 68 XR7 because the power brake unit offered very little help in stopping. The replacement unit provides too much help (in my opinion). There is no proportioning valve with my setup. Perhaps one of you guys have dealt with this problem? Your expert advice would be appreciated.

Thanks, Phil Broughton

 

[bruter]

The PO of my 67 replaced the brake booster/master cylinder and the brakes also have too much assist for my liking. I find it difficult to get the proper pedal feel. I would also be interested to find a solution for this...and still be able to stop! lol

 

[ronzoni]

I'll start by saying I don't know. It would seem that the only way to do this and maintain pedal feel would be to reduce the amount of vacuum acting in the assist chamber. Is there such a thing as a regulator similar to compressed air applications for use in vacuum application? Seems like reducing the vacuum "pressure" in the chamber would reduce the assist force.

 

[TheRktmn]

We had this problem on my father's 66 'stang. The P/Bs would put you through the windsheild with next to no pedal pressure. We limited the vacuum to the booster by inserting a valve stem cap (it was the correct diameter) with a hole drilled in it into the vacuum feed. We "fine tuned" the feel by enlarging the hole in the cap.
Has been working great for almost 20 years now....

 

[TheRktmn]

We had this problem on my father's 66 'stang. The P/Bs would put you through the windshield with next to no pedal pressure. We limited the vacuum to the booster by inserting a valve stem cap (it was the correct diameter) with a hole drilled in it into the vacuum feed. We "fine tuned" the feel by enlarging the hole in the cap.
Has been working great for almost 20 years now....

 

[TheRktmn]

Dang - I seem to have developed a stutter! :
Sorry 'bout the double post.

 

[bruter]

That sounds like a plan, TheRktmn, especially since its been working for 20 years! Where did you locate that cap in the vacuum hose? How did you prevent it from being drawn into the engine or booster? And that would have been a metal cap?

 

[TheRktmn]

We used a plastic/rubber cap.
Made sure that
1) It was snug in the hose and
2) It was too large to draw into the intake.

That's all it took. Still working today!
Hope this helps.

Bob

 

[bruter]

Cool Thanks

 

[modifiedmark]

I'm going to take a stab in another direction and suggest that the master Cyls are of a different bore size. That will make a difference. mm

 

[bruter]

If that is the case, then will the vacuum modification still work??