How to change brakes to none vacuum assist system?

[crashmy911]

Car is 1980 sc. Would like to put a none vacuum assist system in. What do I have to do?

[javadog]

Remove the booster and linkage, plud the vacuum line, change the pedal cluster to accomodate an earlier master cylinder, add the master cylinder and make new hard lines from the master cylinder to the wheels, add a brake light switch and do a little rewiring of the brake light and warning light circuits.

JR

[crashmy911]

I'm not getting enough vacuum off my throttle bodies. Maybe there is a way to get more vacuum?

[JohnJL]

Are you pulling off a manifold from all 6 throttlebodies?

You can plumb in a vacuum reserve tank which has a 1-way valve. You can also buy supplemental vacuum pumps at summit.

Are you sure your booster is in perfect condition, no leaks? No leaks along any of the lines or connections?

[boyt911sc]

Originally Posted by crashmy911

I'm not getting enough vacuum off my throttle bodies. Maybe there is a way to get more vacuum?

Jim,

Test the vacuum reading going to the brake booster. I have a vacuum set-up/tester you could use to determine if the vacuum to the brake booster is good or deficient. Or the brake booster might be getting tired and old. Test and confirm.

Now that you have a 255 HP 3.0 liter SC motor, you would need a good and efficient braking system to keep you on the track.

Tony

[Bill Verburg]

Originally Posted by crashmy911

Car is 1980 sc. Would like to put a none vacuum assist system in. What do I have to do?

Just plug the vacuum likes the system still function in non boosted mode

leg effort goes way up

the mechanical pedal ratio for the non boosted setup is 5.8 for the boosted it is 5.4, so you will be giving up a little mechanical leverage but not a huge amount.

[fanaudical]

My opinion - I would keep the brake booster and do as others suggest (test the booster and add vac pump or additional plumbing to ensure a good vacuum supply).

[crashmy911]

I don't like the assist. Car brakes too much and hard to modulate. Will try w out the vacuum. So I just plug it?

[crashmy911]

Tony brakes r overrated!

[Quicksilver]

You can mount a master cylinder where the brake booster is and actuate it directly from the pedal. You will need a smaller diameter MC to offset the lost boost from the brake booster. That will increase the pedal travel but it is workable. The best solution would be to end up with a pedal that is higher effort then what you started with.

If you don't want to experiment with different sizes till you get what you want, Bill V would be the best person to give you a range that would be close.

[Ayles]

Originally Posted by crashmy911

I'm not getting enough vacuum off my throttle bodies. Maybe there is a way to get more vacuum?

I have not driven my car yet but I have a vacuum pump from Metric Mind that I will be using. It's swiss made and very nice. A much more elegant pump solution than what you will find in the Summit/Jegs catalog.

[Walt Fricke]

You can purchase a used 1976 or earlier pedal cluster and parts easily enough. You can cut a hole through the firewall so you can mount a 19mm MC (assuming stock calipers) down there, as Porsche did. And reroute the lines, block the hole where the vacuum assist stuff sat up in the trunk. That will give you what the earlier cars had.

I have had a hard time adjusting to going the other way - adding the power system so my car meets class rules as an SC. I can't just breath on the brake - I almost always get just a little more brake than I want in that situation. Heavy braking at the end of the straight, no problem. But trail braking is a bit trickier to start.