1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

brake booster begone

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Old 05-12-08 | 06:16 AM
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brake booster begone

Good morning,

Is there a master cylinder that allows me to get rid of the brake booster?

Thanks!
Vin
Old 05-12-08 | 06:31 AM
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Originally Posted by Vin
Good morning,

Is there a master cylinder that allows me to get rid of the brake booster?

Thanks!
Vin
A master cylinder is a master cylinder. If you want to retain power brakes you need a booster. Options are to get a smaller booster from another car and retrofit it to work.
Old 05-12-08 | 06:46 AM
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That's just it...
I don't want power brakes
Old 05-12-08 | 07:48 AM
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Originally Posted by Vin
That's just it...
I don't want power brakes
Well then whats the question? Bolt the master cylinder to the firewall and be done.
Old 05-12-08 | 08:00 AM
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Not exactly sure why you wouldn't want power brakes, but either way there isn't going to be a master cylinder that will just bolt right up and work without it. You would need to make some kind of bracket and custome linkage to make the stock one work on there...
Old 05-12-08 | 09:09 AM
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I don't really need power brakes, but if it's going to be hard I'll just leave it
Thanks!
Vin
Old 05-12-08 | 10:17 AM
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Yea its probably going to be more trouble than its worth for you....
Old 05-12-08 | 10:59 AM
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agreed, more trouble that its worth... and WHY wouldnt anyone in their right mind want non-power brakes on a sports car???
Old 05-12-08 | 11:10 AM
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Originally Posted by mazdaverx713b
agreed, more trouble that its worth... and WHY wouldnt anyone in their right mind want non-power brakes on a sports car???
Well...
I can do a few 505lb competition squats in a row...
Old 05-12-08 | 11:14 AM
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Does not matter if you could squat a building.

Without power assist the car is unsafe and would not stop in a timely manner. Modern brake systems were not designed to be used without power assist for safe stopping distances.



quote=Vin;8182926]Well...
I can do a few 505lb competition squats in a row...[/quote]
Old 05-12-08 | 11:18 AM
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where do they come from...... i can bench 260 too does not mean i crawl under a car with only a jack under it
Old 05-12-08 | 11:43 AM
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It's not hard at all people. You just drill holes in the firewall to mount the cylinder, re-hook it to your brake pedal and your done.
Old 05-12-08 | 11:52 AM
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You would need to make a linkage of some kind at the very least.... The part that actually attaches to the pedal is build into the booster...
Don't forget none of the lines will work correct since its now several inches farther back....
Old 05-12-08 | 12:16 PM
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It's common to retrofit a master cylinder designed for unassisted braking when racing because it allows the driver greater sensitivity. I've never had a problem doing it on a VW...
Old 05-12-08 | 12:40 PM
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Is this vehicle going to be used only for off road racing?
Old 05-12-08 | 01:14 PM
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No, I will be driving it to work sometimes. Why?
I appreciate the help, but this doesn't seem like help anymore.
Old 05-12-08 | 01:43 PM
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Back when I had my CRX, eliminating the booster was a fairly common mod, because the car weighed less than 1800 pounds dry. I also see it done on VWs quite a bit. You need to make sure you source a properly sized MC, and ditch the stock one.

Now I've never done it myself, or probably ever will, but with a properly sized MC, you should not have to put a huge amount of effort into stopping the car, and you should have greater pedal feel.


See the box behind the MC? (this is the only picture I have, I used to have one of the MC setup on a '76 Rabbit that was booster-less stock)
Old 05-12-08 | 01:52 PM
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I agree, I was just wondering if there's an off the self solution for the RX7...
Thanks!
Vin
Old 05-12-08 | 01:59 PM
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Originally Posted by 82transam
You would need to make a linkage of some kind at the very least.... The part that actually attaches to the pedal is build into the booster...
Don't forget none of the lines will work correct since its now several inches farther back....
Several inches? Are you crazy? More like 2 inches. Brake lines bend and form very easily, thats not a problem.

No, the master cylinder is bolted on to the brake booster. It's as simple as unbolting it and bolting it to the firewall, at most it will make your brkae pedal sit closer to you, what you can do to remedy that is just shorten the linkage a little bit and your done.
Old 05-12-08 | 02:10 PM
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There is no linkage if you remove the booster, the rod that attaches to the pedal is part of the booster, if you remove the booster its gone and you will have to make a new one.... And its more like 3-4 inches and yes I know that brake lines bend easily I've made dozens, but its still something to consider. The short line going to the left front wheel will definatly have to be redone, there is no way you could stretch it enough...
Old 05-12-08 | 02:11 PM
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speed turn has manual brakes on his race car. of course, he also has wilwood brakes and a lot more goodies.
Old 05-12-08 | 02:16 PM
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Wilwood is a little out of my budget, but I would love to see that!
Old 05-12-08 | 03:02 PM
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Why????? No powersteering is bad enough when you're not moving.
Old 05-12-08 | 03:09 PM
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Not quite sure you posted this? The subject is "Brakes. " :-)



Originally Posted by Dr Rx
Why????? No powersteering is bad enough when you're not moving.
Old 05-12-08 | 08:35 PM
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I've done manual brakes on an all disc car before. What you'll need is some calculations comparing the piston area of your master cylinder to the piston area of your calipers. This will give you an idea of the force required at the MC. You will need to factor in the pedal ratio (distance from the pivot point to the MC divided by the distance from the pivot point to the center of the pedal). What you'll probably find is that with the original MC, you'll need a very big pedal ratio to keep the efforts in a reasonable range (and yes, I can squat a lot too).

To get a feel for what your stock setup feels like without the vacuum assist and your stock pedal ratio, find a vacant lot, disconnect the vacuum line to the booster, plug it so your car will run, get it up to say 10 mph, and try the brakes. You probably won't like it (and remember you can use the hand brake or turn off the engine to stop you too).

The bigger issue you may encounter is keeping everything rigid enough to take full advantage of the manual setup. The dash panel (fire wall) is likely to flex unmercifully unless you reinforce it significantly. On my setup, I braced the MC directly to the strut tower bar.

In all reality, you probably gain more from eliminating the prop valve and going to a dual MC setup with a balance bar -- although you typically can't get this without ditching the booster first.

I liked the higher effort setup. We used a twin MC Tilton setup with a different pedal ratio and smaller MC bore to keep efforts reasonable. Once I got used to it, I was more able to keep it at the verge of lockup.


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