720 Brake Booster Eliminator

Dnatoli · May 9, 2019

I am slowly but surely building a 720, and as I have been encountering issues, I have been trying new things to overcome them. I would like to share one of them that has been thusfar successful for those who may (or may not) be curious. I used a Chasebays BBE (brake booster eliminator) for a 240sx, amongst other chassis's that have the same bolt pattern, and upon ordering it figured I would make an adapter plate of some sort to make it work, but found I did not have to. Below is an image of the rusty nasty, poorly painted set up I had.

<a data-flickr-embed="true" href="https://www.flickr.com/photos/91162902@N03/32862951777/in/album-72157680305874288/

So, I received the Chasebays BBE and bias valve and mocked it up to the firewall:

But realized that wasn't going to work very well so I mocked it up to that long tube thing that the Booster bolts to in the factory set-up and found it bolts right up!

The next thing I had to figure out was the length of the push rod. The threaded portion of the BBE is 5/16-24 threaded rod (if memory serves, can verify 100% if someone needs) and the tube thing measures 5". I went to Fastenal and got myself a couple of unions, extra hex nuts and a 3ft stick of threaded rod in that size then cut the rod to the same length as the tube thing and put it together. Used the extra nuts I bought to lock it in place.

I test fit the set up, and found it worked! so I test fit it all, then painted the tube thing and bolted it all up. After assembling it all, I mounted the bias valve to adjust the proportion of the front/rear braking and found it hits the sheet metal of the fender well. In my case, my truck is a rusty hunk of cr*p so I cut it out to fit the bias valve. If you're not willing to do that, the bias valve can be mounted very easily. in-line inside the cab, under the truck or where ever you desire. Chasebays uses -3AN fittings for their stuff which is widely universal. They also make custom lines and have all sorts of fitting and adapters to make their stuff work in any application. The customer service has always been phenomenal so if you need help I can try to if I am on this forum or I am sure they will do their very best. I also used their products to make a custom clutch line for the swap I am doing.

All said and done, I have not ran lines yet and I don't have a running truck to tell you pedal feel, but I have driven cars with their products before and it has been just fine, although needless to say this is not for everybody.

<a data-flickr-embed="true" href="https://www.flickr.com/photos/91162902@N03/47753059262/in/album-72157680305874288/

<a data-flickr-embed="true" href="https://www.flickr.com/photos/91162902@N03/47015951244/in/album-72157680305874288/

thisismatt · May 9, 2019

Wait, your replaced a dual master power assist brake master for...a manual single master? Wha...why?

bottomwatcher · May 9, 2019

I could see the elimination of the booster with turbo applications. If no turbo well like you said it's not for everybody. I went the opposite since I am 4x4. Larger dual diaphragm booster from frontier, slotted rotors and manual proportion valve. When driving barefoot I can lock it up with my big toe! Anyways your truck go nuts and with the proportion valve you can dial those drums in, no need for discs.

datzenmike · May 9, 2019

There is a reason all cars today have dual masters. If you ever tear out a line or have a leak you loose ALL brakes. The dual system divides the front from the rear brakes so any failure leaves you with half your hydraulic brakes working. When I was a kid it was very common to hear the cause of a crash was 'brake failure'. You never hear this today. I would even hazard a guess that it is illegal to do his to your vehicle. This is probably recommended for single master cylinder cars of the '60s and earlier and not for replacing a dual or tandem system. Please re-think this. It's wrong headed no matter what they say.

1 minute ago, bottomwatcher said:

I could see the elimination of the booster with turbo applications. If no turbo well like you said it's not for everybody. I went the opposite since I am 4x4. Larger dual diaphragm booster from frontier, slotted rotors and manual proportion valve. When driving barefoot I can lock it up with my big toe! Anyways your truck go nuts and with the proportion valve you can dial those drums in, no need for discs.

Why would you eliminate the booster if turbo?????

Dnatoli · May 9, 2019

26 minutes ago, thisismatt said:

Wait, your replaced a dual master power assist brake master for...a manual single master? Wha...why?

Well, there are several reasons. The first and most simple is.. why not?

But the reality for me is that with the weight of the truck, it will work just fine. For my particular application, I am 2wd and would like the truck as simple as possible. if I decide to turbo charge it, the engine I have in it will need the space on that side of the bay for the manifold and turbo.

This by no means will fit everybody’s application and I’m sure I will get a lot of confusion by doing this on here, but at least we know it for sure bolts up. The driveability of it is still TBD, but when the day comes that my truck is road worthy I will update this. I will also update it in between then when I have the hydro mounted and all the lines ran.

Dnatoli · May 9, 2019

Just now, datzenmike said:

There is a reason all cars today have dual masters. If you ever tear out a line or have a leak you loose ALL brakes. The dual system divides the front from the rear brakes so any failure leaves you with half your hydraulic brakes working. When I was a kid it was very common to hear the cause of a crash was 'brake failure'. You never hear this today. I would even hazard a guess that it is illegal to do his to your vehicle. This is probably recommended for single master cylinder cars of the '60s and earlier and not for replacing a dual or tandem system. Please re-think this. It's wrong headed no matter what they say.

Why would you eliminate the booster if turbo?????

I get where you’re coming from. The bbe keeps the front and rear brakes separate to avoid this. I also believe they are road legal. You should do some research on this, you will probably find it is more common than you think and on many road vehicles. Although outside most people’s common thought process the initial reaction I have always found is exactly what you said. A lot of Honda and Nissan guys use this for drift cars, track cars and to have show worthy shaved bays.

datzenmike · May 9, 2019

Ask the DMV if you can convert to single master legally from dual.

If you can disable the rear and the front's keep working then I have no concerns. Maybe a way was found around the reservoir draining if there is a leak... I doubt it. It does say single outlet.

Drift, track and show cars are not always street legal cars. You can get away with a lot of dodgy stuff if not on the street. Manually adjustable proportioning valves are one.

...and my initial reaction (and perhaps Matt's also) is from just plain common sense. Replacing a perfectly designed boosted hydraulic brake system with something from the '50s does not seen wise.

bottomwatcher · May 9, 2019

Mike my guess would be if you are on the boost a lot and no vacuum to power the booster would be an issue. This wouldn't happen in daily driving.

thisismatt · May 9, 2019

13 minutes ago, Dnatoli said:

I get where you’re coming from. The bbe keeps the front and rear brakes separate to avoid this. I also believe they are road legal. You should do some research on this, you will probably find it is more common than you think and on many road vehicles. Although outside most people’s common thought process the initial reaction I have always found is exactly what you said. A lot of Honda and Nissan guys use this for drift cars, track cars and to have show worthy shaved bays.

Keeps them separate how? I see one outlet from the master, and fluid has to return, so no way to have check valves to keep it from bleeding out if there was a failure anywhere. The only way I could see it keeping them separate is if the master drove an intermediary dual master/slave...

bottomwatcher · May 9, 2019

Only one outlet? What about the residual valves for drum and disc? They have different residual pressure needs. Mike I had to install a manual proportion valve on mine because I know some folks say snake oil but the drilled and slotted rotors I installed on my 82 4x4 would lock up long before the rear drums no matter how much adjusting I did. This is the old non vented system. The drilled and slotted grabbed so hard I would nosedive with the big tires. The proportion valve was installed in the front brake line and I was able to adjust it so the rears kick in and the truck stops level and quick. Happy with my set up.

datzenmike · May 9, 2019

48 minutes ago, bottomwatcher said:

Mike my guess would be if you are on the boost a lot and no vacuum to power the booster would be an issue. This wouldn't happen in daily driving.

There is always manifold vacuum at start up and driving around with the exception of when under boost, however the booster stores it's vacuum by having a one way valve in line to the intake. It would allow the engine to stall on the highway (zero vacuum in the intake) while driving and you would still have at least one or two good applies of the brakes before the assist is exhausted. Boost pressure can never get into the booster because... one way valve.

I should imagine that if boosting down the road and you have to slam on the brakes, intake vacuum would be returned fairly quickly.

datzenmike · May 9, 2019

From the Chase Bays site.

Brake Lines and Single Output
This does not work with factory brake lines. This is due to the master cylinder being a single outlet design instead of dual/triple/quad like most OEM master cylinders. A common misconception is to believe this causes a higher risk of failure due to a lack of a back up line should one line fail. Most OEM master cylinders are still single feed internally and have the same assumed “risk” to our Master Cylinder. Always use good quality brake lines that are clear of moving parts.

Dastuns are not single feed internally, they have discrete front and rear systems from separate reservoirs. Some ZX and later have a single fill reservoir with a wall separating front and rear so draining either front or rear leaves the other unaffected. So I totally disagree with this statement else why have a dual system if not to make braking more secure from failure from a single leak????

Pull one line off to simulate a leak or other failure and see if you can stop but do this in a safe place! I've had a brake system failure from a rock hit to one of the rear lines and the brakes became noticeably mushy as the rear hydraulic system emptied and it took longer to stop but with caution, I could easily drive home only on the fronts.

I've used a Willwood adjustable proportioning valve and they say right in the instructions they are illegal for use on the highway. The thing is the truck was safer with it than without. Just saying some things are wrong and illegal even though you may take a chance on them. Again removing a dual hydraulic for a single system is wrong headed no matter what Chase Bays says. Have a good look at the packaging and see if there is some fine print disclaimer about it's use on public roads.

Dnatoli · May 9, 2019

While I do enjoy this debate, I am going to continue to build this to see if it can be done and if all said and done all my attempts at different things don’t work, I will admit my wrong and we will close this. But for now, the bbe is verified to work on that truck.

Let me clear some things up about this:

Although new to this site, I am no stranger to building cars.

My particular set up for this truck will have dual rear calipers as the drums will be deleted. This will eliminate what was said above about the residual pressure issue as well as the fact that there will be a separate hydraulic system operated by a hand brake in the cab to its own rear calipers so if there is a line failure, there will be means of stopping.

The reason I had mentioned wanting it for a turbo was NOT because of anything to do with vacuum but simply to increase space in the engine compartment.

Hindsight, I probably should have put more information in this, but I had worked a very long day and shared anyway. This post so far has been to share that this product does in fact work to bolt up to our cars and as I continue to work on this, I will supply more information. The purpose is not to create a discussion board of how/why things should not be done but to create a space in which my trial/error can be shared to those who may consider for whatever reason they choose. Datzenmike, I see where you come from by calling me “wrong-headed” but I am fully aware of what I am doing, changing and the potential consequence of doing so.

thisismatt · May 9, 2019

9 minutes ago, Dnatoli said:

While I do enjoy this debate, I am going to continue to build this to see if it can be done and if all said and done all my attempts at different things don’t work, I will admit my wrong and we will close this. But for now, the bbe is verified to work on that truck.

Let me clear some things up about this:

Although new to this site, I am no stranger to building cars.

My particular set up for this truck will have dual rear calipers as the drums will be deleted. This will eliminate what was said above about the residual pressure issue as well as the fact that there will be a separate hydraulic system operated by a hand brake in the cab to its own rear calipers so if there is a line failure, there will be means of stopping.

The reason I had mentioned wanting it for a turbo was NOT because of anything to do with vacuum but simply to increase space in the engine compartment.

Hindsight, I probably should have put more information in this, but I had worked a very long day and shared anyway. This post so far has been to share that this product does in fact work to bolt up to our cars and as I continue to work on this, I will supply more information. The purpose is not to create a discussion board of how/why things should not be done but to create a space in which my trial/error can be shared to those who may consider for whatever reason they choose. Datzenmike, I see where you come from by calling me “wrong-headed” but I am fully aware of what I am doing, changing and the potential consequence of doing so.

Your system might work fine, that's not the issue. The issue is that you went back to an over 50 year old brake system. Great, a separate system hand brake so you can fishtail around in emergency braking situations if your single master system failed. You're on a discussion board...

Dnatoli · May 9, 2019

And we’re discussing it, eh? I’m enjoying all the feedback. I want this system to be as simple in design as possible, so sure it is 50 years old in design and I fishtail around. Let’s start by seeing if I can even make this whole abomination I’m midway through creating even work 🙂

thisismatt · May 9, 2019

I drive a vehicle with a single circuit master and no booster. Yeah, it works fine. I wouldn't purposely neuter a better system for it, though

datzenmike · May 9, 2019

We like to keep our members.

I grew up in a world of no seat belts, single master cylinders, nylon tires, steel dashes and protruding knobs, no head rests, no crumple zones, no ABS, no disc brakes, no air bags, no collapsible steering columns. Doors that flew open in roll overs, poorly designed gas tanks that caused fires in an accident.... It's obvious we've come a long way since then to protect ourselves and others.

thisismatt · May 9, 2019

2 minutes ago, datzenmike said:

We like to keep our members.

I grew up in a world of no seat belts, single master cylinders, nylon tires, steel dashes and protruding knobs, no head rests, no crumple zones, no ABS, no disc brakes, no air bags, no collapsible steering columns. Doors that flew open in roll overs, poorly designed gas tanks that caused fires in an accident.... It's obvious we've come a long way since then to protect ourselves and others.

So how many accidents were you in to end up the way you are? 😅

Fat510 · May 9, 2019

Charlie69 · May 10, 2019

On 5/8/2019 at 7:58 PM, datzenmike said:

We like to keep our members.

I grew up in a world of no seat belts, single master cylinders, nylon tires, steel dashes and protruding knobs, no head rests, no crumple zones, no ABS, no disc brakes, no air bags, no collapsible steering columns. Doors that flew open in roll overs, poorly designed gas tanks that caused fires in an accident.... It's obvious we've come a long way since then to protect ourselves and others.

That explains al ot Mike!!! LOL

Stoffregen Motorsports · May 10, 2019

One option to keep the booster and make room in the engine bay is to move the clutch pedal and master over a bit towards the door. This will allow you to mount the booster directly to the firewall without that stupid standoff spacer. You may have to bend the clutch pedal to get it to fit around the inner fender in the foot-well area, but not much.

I am with the rest of the guys on the dual master cylinder. It would be wise to keep it.

Dnatoli · May 13, 2019

Love the meme!

Charlie69 · May 29, 2019

On 5/8/2019 at 5:41 PM, Dnatoli said:

Well, there are several reasons. The first and most simple is.. why not?

But the reality for me is that with the weight of the truck, it will work just fine. For my particular application, I am 2wd and would like the truck as simple as possible. if I decide to turbo charge it, the engine I have in it will need the space on that side of the bay for the manifold and turbo.

This by no means will fit everybody’s application and I’m sure I will get a lot of confusion by doing this on here, but at least we know it for sure bolts up. The driveability of it is still TBD, but when the day comes that my truck is road worthy I will update this. I will also update it in between then when I have the hydro mounted and all the lines ran.

If you wanted simple you should have bought a 320!

720 Brake Booster Eliminator

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