I hate power brakes!

[datsunfreak]

Question, If I simply remove (and plug off) the vacuum line to the booster, what will happen? I would rather my car did not have power brakes. Personally I hate the way they feel compared to regular manual brakes. Anyone ever tried to bypass it before?

[2ManyZs]

If you block off the vacuum to the master vac, you'll need both feet on the brake pedal to stop.

I mistakenly installed the check valve in backwards once... scared the you know what out of me when I came to the first stop sign.:cross-eye

You can't just block off the vacuum and expect the brakes to work correctly, you'd need to use a totally different master cylinder designed for manual brakes, such as the Tilton master cylinders you see on race cars. Cost a bit to convert it, but, it's the only way to do it correctly. You need a master that will supply the proper line pressure to the brakes, the stock master only works due to the input of the master vac.

[frank13]

put it best "WHAT GA SMOKING MAANNNNN!!!!" Ever drive a car as fast as a Zed with NO Power assit????????????????????????????????????????????????????????????????????????????

Besides feeling like you have no brakes till the end of the brake pedal travel, unless your a granny and have the time to be pumping and hold them all the time. Your Zed is fatter than the 240Z. More weight=longer stopping distance= more time needed to avoid all the stupid people out on the road! The extra constant high pressure needed to do the job will wear out your master and seals at the calipers and RWC's. Trust ME! Think about it, if you have to pump your pedal 2 to three time to build pressure instead of just appling the brakes once you 2X-3X the work load of your system. All parts have a basic "in use "life span. Lines swell and burst, then there will be even less stopping power! Lots of fun! Also instead of having a nice even feel you'll be that much closer to locking them up and skidding instead of maintaining an even and controlable stop (= accident). My two cents. :devious:

[datsunfreak]

Originally posted by frank13

Ever drive a car as fast as a Zed with NO Power assit?

Every day. It's my 510. :classic:

But you make very valid points. I mainly just wish the pedal felt a little firmer, less soft. Any thoughts? I'm also not 100% sure yet they are bled as well as they can be. That would explain some of the sponginess.

[frank13]

Spongy you say? Air. And More Air! Bled the holy crap out of them. Can I get a witness! 510's don't have pwer assit? Or your Vacumbooster just out? 510 does not create the power/torque that the Z does. 510's have disc/drum set ups just s the Z With Vacum power assit. What color is your brake fluid bro? If any thing other than slightly tinted clear like brown, black, or freash motor oil, it's contaminated with water. Unless it's the purple DOT5 or some racing brand synthetic stuff. Datsunfreak check your front and rear brake lines. When these go south the outer rubber shell cracks and splits. Allowing the inner one to expand as it pushes the outer layer about which gives a spongy feel. The air is much more noticable as the pedal will travel with a springy feel. The water one is less springy but will allow to drive the car and still sorta stop as opposed to not having any brake with the air. Check brake fluid resevior for fluid condition/color. Check brake lines for condition. If lines are still good bleed the crap outa the system. Try braided lines. Late! :devious:

[frank13]

O yeah. Check to make sure that your M/C is not Bypassing internaly.. Which if slight leakage might also feel sorta spongy. :devious:

[RB30-ZED]

Originally posted by frank13

The extra constant high pressure needed to do the job will wear out your master and seals at the calipers and RWC's. Trust ME! Think about it, if you have to pump your pedal 2 to three time to build pressure instead of just appling the brakes once you 2X-3X the work load of your system. All parts have a basic "in use "life span. Lines swell and burst, then there will be even less stopping power! Lots of fun! Also instead of having a nice even feel you'll be that much closer to locking them up and skidding instead of maintaining an even and controlable stop (= accident). My two cents. :devious:

Wow, now ive heard every thing!

Frank you said "think about it" in your reply,,,, did you?

Yes removing the Vacuum booster from a zed will increase the effort required by the driver, by about 2 times for a 240z and about 2 and a half to three times for a 280XZ, but the ONLY components to be effected by the greater force would be the brake pedal assembly and the fire wall, oh and your leg. NO change to the master cylinder hoses or any other hydraulic component.

If it took "X' amount of brake fluid pressure applied to the brakes to stop a car in "X" distance from "X" speed with a booster , then it will take EXACTLY the same amount of brake fluid pressure to stop it with out a booster. Only the driver will notice the difference in the application pressure needed to generate that pressure.

The first thing I did when I rebuilt my 240 was to remove the booster and replace it with two master cylinders and a Tilton brake balance bar, with a small change in the pedal ratio by moving the push rod about 3/8th's of an inch closer the pedal pivot.

With out the booster it is a little bit harder on the pedal, but you only notice it at slower speeds. But the brake pedal feel is vasty improved, with excellent brake feel and modulation. This makes the much easier to control braking in to corners, as there is much better feel and as you can make very small changes to your pedal pressure with out the booster doubling it or tripling it.

I wouldn't make this modification to a family car, but for a performance car its a good way to go.

Steven

[datsunfreak]

>510's don't have pwer assit? Or your Vacumbooster just out?

None of the sedans pre-75 had power assist. Only the Z.

>510 does not create the power/torque that the Z does.

Mine does. :devious:

FYI, it ain't exactly stock.

>510's have disc/drum set ups just s the Z With Vacum power assit.

Again, none of the early sedans have power assist. I really love the non-assist brakes on the 510, and the only real issue I could see with taking it off the Z is the extra weight of the car making it reallly tough on the firewall... and the leg.

>Try braided lines.

That's coming soon enough. :devious:

[datsunfreak]

My 510...

[gramercyjam]

I find it easier to modulate my brakes with booster disconnected. But my car is very light and they lock up very easily.

[datsunfreak]

Originally posted by gramercyjam

I find it easier to modulate my brakes with booster disconnected. But my car is very light and they lock up very easily.

I'm going to try disconnecting it in a controlled environment just to see what happens. Worst case scenario, I don't like it and I hook it back up. Thanks for the reply.

[frank13]

Hey RB30-ZED, what's up? I don't think What I wanted to say and what I wrote come across very well. Let me try to clarify it. I was talking about the service life of the seals in a 30+ car. The constant pressure instead of applied for short periods of time IMO will wear them out. Besides the fact that if this is to be driven on the street it would have come with a different set up if NON Power brakes were used. It is NOT. NOR was it ment to be used in this fashion. I speak from experience. More than one time have I been to cheap to replace the Master Vac With original brake system components. And more than once have I shot the entire system! Hoses & M/C. You are speaking of a race proven system designed and used on the track. Race components are not designed for long CONSTANT service life. They are built to be constantly rebuilt after short hard service life. You system that you are talking about has been adapted to what you want in a brake sytem not using the stock M/C or pedal/rod ratio. Datsunfreaks Zed is stock. Different animal all together! :devious: