You now NEED to make a brace to stop the firewall from flexing when you have an OH SHIT moment because you can't slow the car down.

 

Why wouldn't I be able to slow the car down? And the firewalli is pretty firm there, I have never had a problem with it flexing noticibly in any honda I have driven since 2003, that includes this 90 crx, an 88 crx, an 87 CRX, an 85 accord and a 98 civic.

 

You've never driven a car with manual brakes I see.

The firewall will flex, 88 Civic/CRX all and 89 HF are known for this.

Also when going from power to manual brakes a different MC is used to INCREASE the leverage since there is no assist.

Yes, old school muscle car info is still valuable

 

None of those cars I listed had power brakes, I always unhook the brake booster right away in any hondas I have owned since 2003.. When I bought that 90 CRX the first thing I was adjust the clutch, then I disconnected the brake booster and drove it the 4 hour trip home.

With stock sized brakes and a large bore master cylinder a CRX without power brakes has a pretty hard pedal, my first 88 CRX had a 15/16 master cylinder with stock sized roters and drums. I had no issues with it, but the rare times other drove my car (besides Luke) they mostly didn't like it.

Once I upgraded to integra sized front discs it wasn't an issue even for my sister. This car just went through inspection with a 13/16 leaky master cylinder and integra sized front discs with no power brakes, the tech drove it around the block to test the brakes and noise level and didnt even mention the brakes, when I asked him about it he said they felt good.

Personally I think overly strong power brakes are far more dangerous than no power brakes as long as tbe driver still has the ability to lock up the brakes in the best case traction scenario.

 

The smaller bore master cylinder HELPED with the leverage issue.

89 HF, stock booster, 15/16" MC and prop valve (AFAIK) with stock front brake and rear discs.

Aka Poor mans ABS because even on Hoosier A6's I could NOT lock them up on all corners. There was no modulating, it was jump on the pedal, flex the firewall and PRAY you got stopped.

That said, less force needed, 15/16" MC, Accord Wagon brakes up front with NAPA?Raybestos OTS pads, 60 mph and if you jumped on the brakes the speedo went to zero, you didn't slow much.....yet those two black strips in the rear view mirror, locked the fronts up too easy.

BTW, the above Civic which I locked the brakes up on was on "Are You Faster than a *******" Taylor Swift and the Easter EGg.

 

I know smaller bore size makes braking effort easier, I we just saying with the 13/16 and 10.3" brake size even a random inspections tech thought the brakes felt good driving around the block.

All other things being equal, brake pad material, car weight etc, brake effort is a factor of surface area of master cylinder bore and diameter of brakes (mostly front)

So as a fast and rough comparison of those 2 basic factors:

HF 9" rotors = 100% effort
SI/DX 9.5" rotors = 95% effort
EX/Integra 10.3" rotors = 87% effort

13/16" bore size = 0.518 = 100% effort
7/8" bore size = 0.601 = 116% effort
15/16" bore size = 0.690 = 133% effort

So we can multiply these together to get a rough idea of pedal effort when switching things around, the combo you were running on the 89 HF was 9" rotors and 15/16 MC, so lets call that 133% effort, when you switch to 10.3" brakes and 13/16 MC you get 87% effort.

So in a nutshell my current CRX takes about 65% of the pedal effort as the 89 HF you were driving did, and since I am on street tires and you were on race tires, you had WAY more traction than I do, so my maximum applicable braking force is also lower.

Basically that 89 HF had the worst possible scenario for braking effort, with the exception of weight.

Anyway, for street driving I feel that as long as you can provide the effort to lock the brakes up, under maximum traction conditions, having manual brakes does 3 good things:

1) If you hit the brakes in a panic situation, you are FAR less likely to lock them.

2) You can modulate the brakes better when you get used to them.

3) Normally I don't tailgate, or brake at the last second, but I am lazy, as I feel most people are, and when daily driving with manual brakes I automatically get into the habit of braking way earlier and following a bit further, so that normally I don't have to press the brakes very hard to stop.

The upside to all of this for me is that when something unexpected does happen, I am further away from it and have more reaction time, I can stop faster because I can modulate the brakes better and I am FAR less likely to lock up the brakes in a panic situation.

Anyway, if anyone considering this actually gets this far in this post, you don't have to take my word for it, just take off your brake booster line and plug it and drive around a bit and see how comfortable you are with it, it will feel odd at first, but try it out and see if you like it.

 

Whats the point?

 

You mean of removing the brake booster rather than just unhooking it?

 

nice write up if i didn't daily my civic id do this.

 

I would still say give blocking off the brake booster a shot. People seem so scared to try this, I know I would have never thought to do it on my own if a good friend of mine had not suggested it. It really felt weird the first day I tried it, but now I do it to every honda I own.

As long as you can press the pedal hard enough to go past the traction limit (skidding) without resorting to wild measures, power brakes are simply a false sense of security. They do not make you stop faster, they just make you unaware of the effort it is really taking to stop the car.

 

So after a couple days of driving the car after switching from a leaky 13/16 master cylinder with an unhooked brake booster to a rebuilt autozone 7/8 master cylinder with the brake booster delete, it SEEMS that the pedal effort is quite a bit lower even with the slightly larger master cylinder. Of course its hard to compare apples to apples on this, since the new one functions better and I did a full brake bleed after I changed, however I tried to pay close attention to the pedal effort the last couple days, since I usually don't even notice it, and while it feels firm, it does not strike me as hard.

I wish I had a way to actually measure pedal pressure, but I would say that my unknown clutch typical of a heavy duty/stage 1 pressure plate upgrade and my brakes take about 1.5x-2x the pedal effort of the clutch pedal to lock the street tires (ziex) up doing 60MPH on 80F blacktop. I weight a TON and my car is full of shit, so if your car weighs less than say... ~2600lbs with you in it, your effort should be less.

The removal of the booster also gave a more direct feel and removed a noticeable amount of pedal play.

Also, I should be up in Houston next weekend, and will try to take a video of the 88 CRX firewall then.

 

I fully agree with the direct feel, but with a small brace it will be even better!

 

I don't doubt that, but the firewall is flexing maybe an 1/8 of an inch in that video, and that is at LEAST 400lbs, probably closer to 500, that I am putting against that pedal. In daily braking and even emergency stops its not even noticeable with this setup.

If I was a real person with a welder and not currently going to college and living in an apartment, I would probably make a 3 point brace up front between the shock towers and attaching to the bolts on the master cylinder. However I am a broke college student, and I don't see any useful firewall braces anyway. The 3 point braces I see are all attached to the firewall on the passenger side, which is completely useless.

I did see a few master cylinder braces, that attach to the shock tower and then push against the end of the master cylinder, but from what I read most of the people who have them say they make the brakes feel vague and squishy. I assume they must be distorting the master cylinder somehow and allowing bleed by. Also they would not work for me because my master cylinder is now to far away from the shock tower.

It is quite likely that I am going to be stripping both CRXs I own this winter and putting together the 88 as my daily driver and this 90 will either be a spare car or I might just sell it. When I take the dash out of the 88 I will check the feasibility of reinforcing the firewall on the inside to the steering column support somehow.

By the way, do you know any super good deals on hydro GSR syncros? I am on a SEVERE budget, however my car suffered from an extreme case of short shifter before I bought it, and so I am lucky to slip it into 3rd gear under 3-3.5k without grinding, and anything over 4k is hopeless, I usually skip it entirely and go for 4th.

If I do strip both CRXs I will probably put the hydro GSR tranny guts in a LS cable case, and it would be a shame not to be able to swap the syncros when I have it apart.

 

LS and GSR synchs are different IIRC.

But if the brass is bad so will be the 3-4 slider.

 

Less dangerous in panic situations? GTFO.

You've just list the ability to modulate the brakes easily.

That "little" but of flex translates to several extra feet before stopping from highway speeds.

I drove my CRX around the block with the check valve accidentally installed backwards. Holy crap was that very uncool, and I drive unassisted vehicles at work.

The HF master isn't even that big. Geez.

 

HF booster provide very little assistance....and with 15/16" MC, HPS front pads, on race rubber, full lockup is NOT possible. It sounds like I had ABS as the tires were catching and releasing.

Poor mans ABS

 

HF booster provide very little assistance....and with 15/16" MC, HPS front pads, on race rubber, full lockup is NOT possible.

I drove my CRX around the block with the check valve accidentally installed backwards. Holy crap was that very uncool, and I drive unassisted vehicles at work.

I do find your experiences odd, I am a big guy, and have strong legs, but I don't work out, and I certainly don't have the strongest legs in the world or anything close to them, and working my brakes, even hitting them hard enough to lock is not a difficult action, I don't have to think about it, or leverage them oddly, or brace myself, I just press the pedal and they work great.

To be fair here, I have never driven with stock HF brakes in the front, I have always had at least DX/SI sized and usually 10.3" EX/Integra sized fronts along with a 13/16 master cylinder. Perhaps the HF brake calipers themselves are just WAY harder to push? Perhaps the 15/16 master cylinder makes more braking much harder than I would expect? Since I dont have any direct experience with them, I cant say.

That "little" but of flex translates to several extra feet before stopping from highway speeds.

I am not sure why you believe that. Does your car accelerate slower if your throttle cable has a little slack? As long as the throttle plate can open all the way, any extra cable slack may be annoying, but it wont make the car slower. The situation is no different here. The same throttle example could be applied to force requirement and modulation: Would your car be faster if you had less throttle control because it opened all way if you breathed on it hard? The answer is of course not, in fact you would probably be slower, because instead of being able to accelerate smoothly, you would loose traction constantly. The brake situation is exactly the same, but we are raised with the idea that brakes should be stupidly easy to push, so we panic if they do not work the way we are used to.

Less dangerous in panic situations? GTFO.

You've just list the ability to modulate the brakes easily.

A firmer more direct pedal allows better pedal modulation which allows you to brake in a more consistent manner under normal or performance stops. This allows you to be closer to your traction limit without going over it, lowering your overall braking distance. A firmer pedal is ALSO more resistant to panic stops. Here I am referring to the surprise situation where most people slam on their brakes to hard and lock them up or over brake while also trying to perform evasive maneuvering. This is the main reason for ABS. When you hear about spinning or flipping on a freeway it is most usually due to this.

Here is an example: In 2003 I was driving north on I-5 into Seattle, Washington in an 88 CRX SI with stock brakes, taking the West Seattle Bridge exit and was in the exit lane when a car changed lanes without looking as I was right next to it, and slammed me over onto the right shoulder. I panicked and hit the brakes, however my right tires were on the loose gravel and my left tires were on the hot asphalt, since I had overly strong power brakes, when I hit the brakes to hard in this surprise panic situation, my left tires gripped, and my right tires skidded, this caused me to sharply spin left back onto I-5 where I slammed into the back passenger side of a mercury sedan the next lane over, which then spun and hit the back of my car on my passenger side. The car that pushed me off the road fled the scene.

It was not pretty, and if I had not had overpowered power brakes, the accident with the mercury sedan would have never happened, and I would have either driven away with a big scrape up the side of my car and a missing mirror, or would have followed the guy and called the police. Either way it would have saved me a LOT of pain and money.

Since then I have not owned a Honda with power brakes, and while it felt wierd and dangerous at first, I quickly realized I COULD easily stop the car, it simply took more force than I was used to applying. Not more than I COULD apply, just more than I was used to.

 

I don't know what you mean, Bone. My brakes work just fine, aside from a leaky wheel cylinder.

 

While I am out of shape, 30 years ago in HS I did max out the leg press sled while on detention.

But I have also drove a Honda with real brakes that were touchy when cold, but once hot were perfect.

"Taylor Swift and the exploding easter EGg"

 

While I am out of shape, 30 years ago in HS I did max out the leg press sled while on detention.

The thing is, even in the worst case scenario I doubt I am breaking 100lbs of force.... Any normally sized adult should be able to apply that kind of pressure, thats the part I don't get, I know if you drove my car you would not have a problem braking in it.

"Taylor Swift and the exploding easter EGg"

I watched that video, it was pretty funny. Sad that the civic blew, because it would have mopped the floor with any of those cars in the corners and held with them on straights that short, although the Camaro at the end looked like it could handle pretty decently for what it was.

That kid in the Subaru did ok, but even without him missing that shift he was not going to be able to hold with a car that was only 350lbs heavier and packing and additional 250hp and handled as well as that Camaro, although if it had been any of the previous cars with 600hp and their existing handling he would have taken them.

 

Newbie from Netherlands just posted a picture of his CRX del Sol.....

Do you see it????

 

Newbie from Netherlands just posted a picture of his CRX del Sol.....

I didn't see the original post, but I do like that angry beer/master cylinder cozy.... =)

 

and the MC brace

 

I did see a few master cylinder braces, that attach to the shock tower and then push against the end of the master cylinder, but from what I read most of the people who have them say they make the brakes feel vague and squishy. I assume they must be distorting the master cylinder somehow and allowing bleed by. Also they would not work for me because my master cylinder is now to far away from the shock tower.

Out of the few reviews I read on those type of master cylinder braces, all the people who had them removed them.

When I take the dash out of the 88 CRX I will check the feasibility of reinforcing the firewall on the inside to the steering column support somehow.

I'm still got from to shake my head in incredulity.

Over what?

 

I'm still got from to shake my head in incredulity.

 

From the fact that I think you're completely bonkers.

You obviously can drive. I just think it's crazy. Nothing too serious, though.

 

Here is a video of me locking up the brakes on my way home today. This is on 15" ziex 912s tires and im doing 40 on a dry asphalt that was repaved less than a year ago, sorry the video is upside down, usually my phone corrects them:

 

Here is a video of me with the 88 CRX HF, shoving against the brake pedal WAY harder than needed, this is probably in excess of 500lbs of pressure against the pedal:


I don't know what others have dealt with, but it just doesn't flex that much, even under extreme force. If I do decide to reinforce the master cylinder I think I will probably just do something simple, like tying into the steering wheel reinforcement under the dash.

For instance I could get 4 threaded long rods (~18") from Home Depot and bend them slightly, then put them through the firewall on one side, and use them as the master cylinder attachment studs, and clamp them to the steering wheel support up top and just tighten them down so they are putting some tension pulling in on the firewall.

Here is the inside drivers side of the firewall, without the dash in place, the 2 arrows are the master cylinder bolts coming through the firewall:


Here is the passenger side:


The end result would be a reinforced firewall right at the brake master cylinder, without anything visibly obvious.

 

It occurred to me recently that you have to push against a fairly thick rubber diaphragm in the brake booster to activate the brakes when you dont have the vacuum hooked up.

Assuming the rubber is about the same thickness in all the various models of brake boosters from Honda, that means that the smaller the diameter brake boosters would actually be harder to push than the larger ones without the assist. Since the CRX HF is about the smallest one available, maybe that is why its so hard to push without power brakes? Just a thought.

 

I used to compete in Rallying in a 1970 Mazda (and Datsun h510). In both cars the boosters were removed. Nothing else done to the braking system, which was stock except for better pads (and shoes for the rear drums). These cars were driven daily as "normal" transport (too poor to have a second car) but were modified to the max while still being street legal. I must point out this was in Australia where I lived for too many years.
Just about every other competitive car had NO booster. Why? There are just too mushy. To drive flat out with no idea where the road goes, relying on the navigator for instructions, you have to have full confidence in the car. This includes braking. With boosted brakes there is no "feel", they are way too easy to lock up - especially when on dirt/gravel. With non boosted brakes you push on the pedal ... if you are not slowing down fast enough .. PUSH HARDER. If wheels lock up (with you not intending them to) simply release pressure a touch. I drove cars this way for years both on and off track.

Also note that most circuit cars ( as an example Australian V8 supercars, sports sedans, club cars, etc...) do NOT use brake boosters.

Just my $0.02

 

As an update I just put a HF brake booster back on this car in preparation to sell it. This time there was NO other changes. I did not even crack the lines, I just removed the bolts, pulled the MC back, slipped in the brake booster and hooked everything back up.

Now I can tell you without a doubt, that at least in my case (EX sized fronts, Si discs rear, 7/8 MC) that a HF sized brake booster is ONLY a downgrade over a booster delete. The effort barely changed at all (maybe 10-15% at MOST), and the brake pedal slop was HUGE compared to the booster delete.

I actually had to double check that I had the one way valve in the right way, it felt almost exactly the same, but with more freeplay and total compression distance during brake activation.

So anyone considering doing a booster delete, I would say go for it if you have a CRX or comparable weight Civic, just make sure to get a 13/16 MC (or maybe 3/4 MC if doing an aftermarket one) and a moderate big brake upgrade isnt a bad idea either.

I will go out on a limb and say that a 13/16 MC with manual brakes will very likely be easier to push AND have less pedal travel than a 15/16 MC with an HF brake booster.

 

The subject of manual brakes came up in another thread, and I made a couple videos comparing pedal travel of boosted and boosterless brakes pedal travel distance, and I figured I should update this thread with the videos as well.

This is the pedal travel of my boosterless CRX with 13/16 MC, 10.3" EX/Integra fronts and stock Si rear disks, keep in mind my brake hoses are ancient and are high up on my replacement list, and that my brake pedal height is set exceptionally low to match my stock gas pedal height and hydro clutch conversion, so judge the distance the pedal travels, not how close it is to the floor.

The video of the pedal travel in a 13/16 MC CRX without a booster:

http://vid18.photobucket.com/albums/b124/JoelEspinoza/20151206_104718.mp4

Below is my other CRX, it has an HF booster, a 7/8 MC same 10.3" front brakes and stock rear drums. I had JUST finished bleeding all 4 corners and adjusted my rear drums tighter than normal so they wouldnt add pedal travel. I plan to sell this car, which is why it has a booster, I dont want prospective buyers scared by the lack of power brakes.

I had something of a brain fart during the video and couldnt remember my words, but I was trying to say that about the same pedal pressure caused a LOT more pedal movement in the booster car, and because it has a larger MC and a booster that both increase pedal effort when the car is off, the same pedal pressure in the booster car results in a lot less line pressure. So in order to produce the same line pressure in the boosted car I was getting in the non boosted car, I would have had to move the pedal even further than I did.

The video of the pedal travel in a 7/8 MC CRX with a booster:

http://vid18.photobucket.com/albums/b124/JoelEspinoza/20151206_124342.mp4




Since originally doing this I have moved my brake pedal downward to move it to the same height as my gas pedal as I showed in the boosterless video above. To do so I removed the adjustment rod below:



And I used a M8 1.25 die to thread the shaft down as far as I could, just through the short section of grooves running parallel to the length of the rod. Then I threaded the lock nut and clevis pin holder all the way down as far as I could, marked the excess threads and removed the clevis pin holder and cut off the excess threads with a grinder, then cleaned it up and put the clevis pin holder back on and installed it. Sadly I didnt think to take any pictures of that modification.

This mod is not required, but it is nice if you want to move your brake pedal downward to move all your pedals closer to the same plane.

 

Dude put a brace on the mc and call it a day, its an easy thing to do that will both stop the firewall from flexing and possibly cracking and improve braking.

Why are you so against something like that?

 

I am not against it at all, but it is by no means required, and to have it be useful I would have to make it myself. I dont own a welder, a garage or much of a budget.

I don't doubt that [adding a firewall brace will make it better], but the firewall is flexing maybe an 1/8 of an inch in that video, and that is at LEAST 400lbs, probably closer to 500, that I am putting against that pedal. In daily braking and even emergency stops [the firewall flexing] is not even noticeable with this setup.

If I was a real person with a welder and not currently going to college and living in an apartment, I would probably make a 3 point brace up front between the shock towers and attaching to the bolts on the master cylinder. However I am a broke college student, and I don't see any useful firewall braces anyway. The 3 point braces I see are all attached to the firewall on the passenger side, which is completely useless.

I did see a few master cylinder braces, that attach to the shock tower and then push against the end of the master cylinder, but from what I read most of the people who have them say they make the brakes feel vague and squishy. I assume they must be distorting the master cylinder somehow and allowing bleed by. Also they would not work for me because my master cylinder is now to far away from the shock tower.

I dont know exactly what transzex was running into, but my firewall doesnt flex anything like he describes, I would bend the crap out of the brake pedal assembly before I could make the firewall flex noticably. I have discussed this in other threads with him but my theory is that he has something missing that connects the top of the pedal assembly to the tubular brace that goes under the cluster and around the drivers legs. There is a single bolt up there that, if removed or loosened, causes the whole pedal assembly to rock freely back and forth against the firewall and it feels terrible.

He could be missing that bolt, or have one of the brace bolts loose or any number of things. But something is wrong with what he has. He even states the different models have different firewall stiffness and that the 88s and 89HFs are significantly weaker than the later models with door mounted seatbelts, but I have driven both a 90Hf and an 88Hf back to back with manual brakes and cant tell a difference at all, or even notice any flexing in my 88Hf daily with manual brakes.

Hell, my first CRX was a B18A1 88Si with factory brakes and a 15/16 MC with the brake booster disconnected but still present, which is almost the hardest possible pedal combo you can get in a CRX, with the nicest street tires available, and firewall flexing was never any issue for me

 

I will probably do this mod if my car ever becomes a serious track car. With a shock tower brace as well.