Welcome to the Connecticut Z Car Club Forums




Username:  
Password:  
Log me on automatically each visit
Register 
It is currently Thu Mar 28, 2024 4:11 am
Welcome to the Connecticut Z Car Club Discussion Forums   
If you have trouble logging in or encounter any issues, please send an email to webmaster@ctzcc.com.

All times are UTC - 5 hours





Post new topic Reply to topic  [ 4 posts ] 
  Print view Previous topic | Next topic 
Author Message
 Post subject: '72 Z Brake Booster
PostPosted: Mon Nov 11, 2013 7:41 pm 
Offline

Joined: Mon Jan 28, 2013 8:48 am
Posts: 47
Location: OH
Need to replace or have my existing brake booster re-built. Any recommendations as to sourcing & BTDTs would be greatly appreciated. I've read a couple of posts about subtle year-to-year differences in boosters. Prelim web searches also indicate wide price range. I'm in SW Ohio.

Thanks,
Chris
'72 240Z


Top
 Profile  
 
 Post subject:
PostPosted: Mon Nov 11, 2013 10:06 pm 
Offline

Joined: Wed Apr 09, 2008 5:53 pm
Posts: 14778
Location: CT
Not me, but a number of us have done this. As soon as the Holiday Dust settles and people find their way back to their computers, I'm sure you'll get lots of input about which MasterVacs fit which years. Some of us know about using ZX dual-diaphragm brake boosters on early 240s, too. Never did that myself.

Make sure that 'One-Way-Valve' on the firewall is facing the correct direction before you replace anything. My 1970 Z came back to me (2nd purchase) after other people had their hands under the hood, and stomping on the pedal with both feet wouldn't stop the car. One day I pulled that valve out to Zee if it looked clean inside. Blowing on one end showed me it was installed backward, so the booster was getting no vacuum from the intake manifold. Next time I touched the brake pedal it nearly sent me thru the windscreen.

Tell me if you need a photo of what I'm talking about.

Frank T

_________________
1970 240Z


Top
 Profile  
 
 Post subject:
PostPosted: Wed Nov 13, 2013 9:28 pm 
Offline

Joined: Mon Jan 28, 2013 8:48 am
Posts: 47
Location: OH
Frank,
When you have a chance a photo of one way valve (to confirm I have it positioned correctly) would be appreciated.

Thanks,
Chris


Top
 Profile  
 
 Post subject:
PostPosted: Wed Nov 13, 2013 11:11 pm 
Offline

Joined: Wed Apr 09, 2008 5:53 pm
Posts: 14778
Location: CT
Proudly, Sir. I borrow this picture from another online Z forum because I'm having trouble making my camera and my computer play nicely together just now.

The One-Way Valve is mounted on the driver's side of the firewall. It is actually pretty well concealed and I didn't even suspect there was a valve in there until I took the hoses off. I thought the hose was all one piece and just mounted to the firewall with a wide clamp.

Your MasterVac brake booster gets vacuum from the intake manifold. You can follow the black, pre-formed vacuum hose from the brake booster up to the firewall, then down to the intake manifold. Where the hose mounts to the firewall there's a valve hiding in there.

The hose is actually two parts, joined by the One Way Valve. The valve itself is held to the firewall by a wide clamp which completely covers the valve (which is why I didn't see it in the first place). Unscrew the single screw and the hoses and valve will pull away from the firewall.

Pull the two hoses off the valve. You'll notice the valve looks identical on both sides, but it isn't. Close inspection will show you the tube on one side is slightly larger diameter than the other side. The difference is so slight, it's easy to install the valve backward (which had happened on my car). Either end will even fit into either hose convincingly snug. It's a classic "Murphy", and anything which CAN be installed backwards, usually gets that way.

It's important to mount this valve properly, because it only allows air to flow in one direction (hence the name). The air must flow from the MasterVac into the intake manifold when you step on the brake, or you'll get no power brake assist.

The only way I knew which way to install the valve was to try using one end as a balloon and the other end as a straw. Once I knew which way the air flowed thru the valve, I could mount it back on the firewall so the air would flow into the intake manifold. As soon as I did that, the power brakes became fully functional and I about killed myself at the end of the driveway when I stomped on the brake pedal with both feet and nearly put my head thru the windscreen.

I honestly can't tell you which size tube faces left or right on the firewall, and I doubt you'd be able to see the difference just by looking at them (it's that slight). The only way I know of to make sure it's mounted correctly is to take it off and do the balloon/straw test.


Attachments:
File comment: The elusive One-Way Valve, after you've found it and pried both hoses off. Note that the tubes appear to be the same size; they aren't.
One-Way Valve.jpg
One-Way Valve.jpg [ 4.26 KiB | Viewed 3932 times ]
File comment: The One-Way Valve is mounted onto the driver's side of the firewall, hiding beneath a wide clamp
One-Way Valve, 240Z.jpg
One-Way Valve, 240Z.jpg [ 254.96 KiB | Viewed 3941 times ]

_________________
1970 240Z
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 12 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron









Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
mile200 v1.0.1 designed by Team -Programming forum- .