B210 brake booster install

[jeffball610]

I gathered some other parts to make this work, but now I'm looking at the master cylinder. Even if I cut off the bleed ports, it will likely hit my intake manifold. Looking at potential MC replacements, I see the 280Z unit places the bleeders on the other side. However, the 280Z unit is only a 7/8" instead of 15/16".

I'm running Z31 300ZX brakes all around and the Z31 uses a 15/16" MC. Obviously I'm much lighter than a Z31, so will it be okay to step down that 1/16"?I don't have any issues with using the Z31 units un-boosted right now other than lack of modulation. The pedal is stiff and it takes a lot of effort to lock the brakes. I've only done it once at the last autocross and it took quite a bit of effort while turning to make it happen.
The 280ZX does have a 15/16" MC with the ports on the other side, but the mounting holes are on the wrong axis.

I'm considering the 280Z unit, but I would like to hear other's thoughts. Does the 280Z have a rear drum valve in it? What other things should I be looking for? How hard would it be to cap off my existing MC flush with the body? Any other crazy thoughts anyone have?

[Fred_L-P]

I recently bought 2 Cardone 280z bmc (pn: A1 13-1658). I returned the first one because it had 3/8-24 ports instead of M10x1. Both valves were identical on both units, with very short springs. Idk if it was also a mistake, but that's what I got. Were they 2x drum or 2x disc? I can't tell, I don't have an old bmc to compare the valves.

[jeffball610]

I’m currently running Z31 front and rear calipers and rotors with a 15/16” MC. Although this is adequate for street driving, the pedal is stiff and does not allow much modulation. This will make racing the car much more difficult. Recently I picked up a B210 brake booster, and although it physically fits in the car, the master cylinder bleeder screws touch my intake manifold. In fact, the casting of the MC touches the manifold. However, the booster should allow for more modulation of the pedal and make it safer to drive at a high level.


So here’s my plan. It seems that I only need 8mm of bleeder screw engagement to seal the hole.


The holes are approximately 12mm deep.

I can “mill” off 4mm of the casting for clearance and still have a sealed MC. That being said, the bleeder screws are much longer than that. Since their only purpose is to bench bleed the MC, I can do that with full screws, and replace them with cut and welded screws.


When welding the screw closed, I will need to make provisions for something to torque the screw into the hole. This should be simple enough by making a slit for a flathead screwdriver.
I didn't take a picture of this. I was too busy getting things working right.



Right now, I seem to have clearance and the MC seems to hold fluid. I haven't pressurized it yet to see if the bleeder screws will leak.

What’s wrong with my plan? My other option is to use a ⅞” MC with the bleed screws on the other side. I will still have some clearance issues on that side, but not nearly as much. The downside is the reduced braking force from the smaller MC.

[bertvorgon]

The one thing I did that made a tremendous difference in BOTH pedal FEEL and MODULATION, was to put a weld in a 2" extension into the brake pedal...it's all about leverage. It also let me heel and toe, which is a bit of a misnomer as I only use both sides of my foot.

I think the English came up with that name as their cars have insane pedal locations relative to each other. I can leave my foot virtually on the floor.

A thought at any rate if the booster does not or modulation is still not great.

[JordanTr]

Could shim the mounting plate to cock the whole thing a little closer the strut tower. I did that on my car and it gained some room at the manifold. It’s probably not best practice but there’s enough play in the clevis etc to allow for it.

[yenpit]

Sounded like you were asking about the brake master cylinder (BMC) bleed screws. The Z car BMC's have the bleeders facing OUT towards the fender, will bolt up, but will have a different bore diameter.........maybe that bore is better for whatever brakes you are using........?? FYI the 280ZX BMC went back to the bleeders facing IN, so you would have same issue.

TJ

[yenpit]

..........All 240Z-280Z were DRUM rear brakes.

[JordanTr]

How about a RHD S13 or S14 brake master or a USDM WD21 pathfinder master? All those are available in 15/16" (not sure on the pathy) or 1". In fact I'm running a Pathy 1" master on my S14 Silvia. I still have the 15/16" master I believe. Bleed screws would face the fender.

RPS13 shown.



Any of the above would require an adapter plate on the booster itself though so that's more work.

I think you'll be surprised by how much boost the booster provides. I ran mine with a 7/8 master which was totally overboosted so I got rid of the whole shebang and went with 7/8" non boosted and haven't looked back.

[jeffball610]

How about a RHD S13 or S14 brake master or a USDM WD21 pathfinder master? All those are available in 15/16" (not sure on the pathy) or 1". In fact I'm running a Pathy 1" master on my S14 Silvia. I still have the 15/16" master I believe. Bleed screws would face the fender.

I'm not sure of the size of that booster. The reason everyone runs the B210 unit, is that it's so small. I think it's only 7" in diameter.

I'm going to work with what I've got right now. If the bleeder screws leak, or it seems to overpower my brakes, I'll likely switch to the 7/8" unit. I have a small line leak right now that is preventing me from testing them on the road. I'll sort that out and update.

[zKars]

Many new vehicles are packed so tight under the hood that they put things like washer bottles in the wheel wells and provide access panels in the wheel wells to get to common service items in the engine bay that cannot be accessed without an engine pull. A couple of small carefully placed round holes (1/2 or 3/4") in the shock tower where the bleeder screws are located, with little rubber plugs to fill, would allow access and have little impact on strut tower strength. Just an idea.

And trust Jordan to find alternative 7/8 and 1" masters that could work with a little adaptation. Nice!

[jeffball610]

I have had everything installed for about a week now. The pedal is almost nonexistent until the last few inches, and then it still doesn't stop very well. I presume there is air in the lines despite a complete fluid flush and bleed. I even went as far as to bleed the system using a tube from the caliper to the MC. The rear had a lot of air in it, but the fronts had none. When I press the pedal, I can feel it "wanting" to brake, but there just isn't much resistance or stopping power. It's not very safe to drive on the road, but I'm still doing it hoping I can bleed out whatever is trapped in there. If anyone has a better method, please let me know. I have a road course event on Saturday that is already paid for and I'm super excited for. However, if the car can't haul me down from 100mph, then it won't be safe on the track.



Any input is appreciated.

[JordanTr]

I’ve spent hours fighting air until I reverse bled them. Get an old school oil pump can and hose and push fluid from the bleed nipple back to the master. A turkey baster is good for pulling the reject fluid out of the master as you go. It hasn’t failed me yet.

[jeffball610]

I’ve spent hours fighting air until I reverse bled them. Get an old school oil pump can and hose and push fluid from the bleed nipple back to the master. A turkey baster is good for pulling the reject fluid out of the master as you go. It hasn’t failed me yet.

Thanks. I was considering that, as it seems like that would push the air in the right direction. I'll give it shot.

[jeffball610]

I tried everything I could, and it still wasn't working. I took the car to a friend with a shop and we started from square one. We plugged a few minor leaks including redoing my MC bleed screw block offs. The bled the system again. Still felt like crap. So, we took the pushrod out from the booster and extended it some. It seems that the 15/16 MC has a deeper hole than the 7/8 MC. We extended the rod about 1/4 inch and it improved considerably. I'm still not happy with the engagement of the pedal, but it was good enough to get me on track and not fear for my life. I'll keep adjusting, but I'm still open to suggestions.

[jeffball610]

2 months later, and it's still not any better. My current explanation of the brake feel is "it slows the car, but it doesn't stop". I can feel the brakes engage at a decent spot in the pedal, but there is no more engagement with additional travel. At the bottom of the travel, the pedal stiffens up, but pushing harder doesn't do anything more.

I'm out of ideas and I'm open to any and all suggestions. My current mood it to go back to manual brakes. I'm fine with that, but I was hoping the booster would add some needed brake pedal feel and modulation. What are others running for brake set ups? Is everyone just running 15/16" or 7/8" manual brakes? Why do I see so many cars with B210 boosters if it doesn't work? I assume my booster works and holds vacuum because pressing the pedal with the motor off goes from "boosted feel" to manual feel after a press or two. I don't think my brake caliper set up is so far off from what others are running that it would have this profound of an effect. I'm at a loss here.