Vacuum pump and brakes still arent great
 

I just installed a leed black bandit vacuum pump for the power brakes on my 69 gto. It holds vacuum well but I really dont have good brakes even with the pump. The complete system is new and completely stock including all lines rubber hoses ,calipers and rear wheel cylinders. I did install an 8" booster in place of the stock one for more clearance for the highports, could the booster be the issue? It almost feels like non power breaks at this point. I also used a new stock replacement perportioning valve from inline tube.

Stock GM disc front brakes?

Stock gm discs up front. Im wondering if the stock booster would fit with highports. Or does the duel 9 bolt right in?

Is this a single or duel?

Another

Probably a single diaphragm?? I've found those tiny diameter single diaphragms aren't all that great.

They do make a dual diaphrahm version that works well enough but honestly I'd just go hydroboost and forget it.

This Hydroboost. Never look back.

Unless you have a physical problem there is no reason you can't just use manual brakes. My 1965 GTO and 1962 Catalina had them and I never found them hard to stop. Just make sure you use the correct master cylinder bore size. Too LARGE a bore diameter and you won't stop with 2 feet.

Agreed. When I changed my ‘66 Catalina to a dual master, I also went with manual brakes as my vacuum was iffy at idle. Stops great, 4 wheel drum too. The other thing you need to do is change the brake pedal. Different pivot point for more leverage. Much simpler than a hydro boost system.

Go with manual front disc and get rid of all the clutter.

go manual brake
 

manual solves all issues.

We did a bunch of testing on a friends 66 GTO and found out the only booster that equaled the original 11" stock unit was a dual diaphragm 9" booster. Neither the 7" or 8" dual diaphragm units offered much assist. I wouldn't go as far as saying the 9" was better than the 11" stock single, but I doubt anyone driving the car could tell them apart.

That said, the friends that have went to manual brakes with the smaller diameter master cylinder and the top hole in the brake arm have adapted quickly and have no remorse on the decision.

I think I will try manuel, stinks that vacuume pump wasnt cheap!

Looks like you have room , try the 9" it should be fine.

On the GTO we used a vacuum pump ($20) from a newer mustang grabbed from a junk yard that worked quite well but we used that on the factory 11" booster. Dad ran that setup for several years before finally just going hydroboost.

I for one also like manual brakes as there really is no issue that can crop up with them. As long as the master bore is sized properly and the rod ratio is correct. I've daily driven cars for years with manual brakes and perfectly fine with that.

Where the hydroboost comes in for me, or proper working power brakes in general, is that other people in the family drive these cars and manual brakes end up becoming a one person driver (namely me) as no one else wants it.

Same problem here. I ended up going to hydroboost and am extremely happy. Very responsive. If I didn't do that I would have went manual. Personal choice (although the hydroboost wasn't cheap).

LOL yeah that's the catch with hydroboost, it's a bit spendy, and it takes a bit of effort to hide things, but boy does it work good.

For the lines I ran three along the lower edge of the inner fender, and the fourth just beneath the upper a arm. Reasonably clean and easy. For me the pain were the attachments to the power steering reservoir and , but not that bad.Attachment 603334