Brakes and low vacuum: hydroboost or vacuum pump?

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Sep 25, 2017 | 01:52 PM

Cool bean

Thread Starter

Racer

Joined: Jan 2015

Posts: 314

Likes: 50

From: Woodbury NJ

Brakes and low vacuum: hydroboost or vacuum pump?

I'm resto-mod'ing a 74 coupe (355, aggressive cam with 7" of vacuum at idle.)
I see two paths to solving for brakes and vacuum. In both cases I'd use engine vac for lights and hvac controls. Going to manual steering and brakes is not an option.

add a vacuum pump for brake booster
convert brakes to hydroboost

I have a borgeson steering box.

Are there pro's and cons to either option?

Sep 25, 2017 | 05:31 PM

mrvette

Team Owner

Joined: Jul 1999

Posts: 65,492

Likes: 230

From: Orange Park Florida

HB is the way to go, no question, the stock factory boosters are notoriously soft pedal, no matter what.....

Sep 25, 2017 | 09:57 PM

'75

Le Mans Master

Joined: Dec 2007

Posts: 6,422

Likes: 591

From: McHenry Illinois

Quote:

Originally Posted by mrvette

HB is the way to go, no question, the stock factory boosters are notoriously soft pedal, no matter what.....

Sep 26, 2017 | 08:44 AM

BlowAMouse

Racer

Joined: Nov 2011

Posts: 285

Likes: 36

From: Cedar Park TX

Love my HB on my 73. Will be installing one on my camaro next year.

Sep 26, 2017 | 09:29 AM

Engage

Racer

Joined: Oct 2001

Posts: 474

Likes: 64

From: Portage La Prairie Manitoba

Quote:

Originally Posted by Cool bean

add a vacuum pump for brake booster
convert brakes to hydroboost

I have a borgeson steering box.

Are there pro's and cons to either option?

Do your headlights work with this vacuum?

Sep 26, 2017 | 11:29 AM

Cool bean

Thread Starter

Racer

Joined: Jan 2015

Posts: 314

Likes: 50

From: Woodbury NJ

Quote:

Originally Posted by Engage

Do your headlights work with this vacuum?

That's a really good question, and I don't know yet. My system is rebuilt (new hoses, switches, solenoids, seals, etc) I tested the system using vacuum machine (harbor frieght/AC vacuum machine.) the headlights snapped up and down perfectly. However i think that thing draws more than 20 inches.

I already have an electric vacuum pump I had planned to use for the brake booster. However, if I switch to hydroboost, I plan to see if the engine vacuum is sufficient for the headlights and hvac controls. If yes, i won't install electric vacuum pump. If no, i'll install it. (or may try out electric headlights upgrade...we'll see.)

this thread, (https://www.corvetteforum.com/forums...ht-vacuum.html) gordonm's reply in particular, gives me evidence that i might be able to have engine vac work. We'll see.

In the meantime, the replies are unanimous. I'm going with Hydroboost upgrade.

Last edited by Cool bean; Sep 26, 2017 at 12:39 PM.

Sep 26, 2017 | 11:52 AM

BlowAMouse

Racer

Joined: Nov 2011

Posts: 285

Likes: 36

From: Cedar Park TX

Headlights work, great question..

They do work on mine (with HB installed), but take a second or two to pop up. I just have to watch the vac/boost gauge to ensure there is enough vac to open them.

They have not yet closed under boost, but again it's only seen 10lbs so who knows when I really try...

Sep 26, 2017 | 01:23 PM

v2racing

Melting Slicks

Joined: Mar 2008

Posts: 2,666

Likes: 289

From: Spring Park MN

I have a HB for mine that's going on. The headlights have a large enough vacuum tank to store the higher vacuum the low vacuum engines achieve at cruise. As long as the one way check valve is OK and there are no leaks, the headlights should not be a problem.

When my 406 was in my 80 Vette, it had 9" of vacuum at idle in neutral and 7" in gear, but at cruise it would pull 20 plus inches. Headlights would always pop right up.

Mike