Finally went to pull my once DX hatch out of the paint shop today and the brake pedal went all the way to the floor. Checked fluid and it was 3/4 a pint low. Filled her up without bleeding and brakes still do nothing.

I guess I could bleed it but the pedal has always been squishy/ goes down further then any other EF I've drivin. Despite that fact, the car used put your eyeballs on the back of the windshield once the pedal got close to the floor.

I'm pretty sure I need a MC. What I'm wondering is should I get a larger one(EX MC)? My brake upgrades are SS lines, Crossdrilled stock size rotors, Hawk pads, Just rebuilt calabers. Back brakes are stock.

 

get you a (da mc) that should be good. thats what im using on my ef.

 

Well I want a bolt on replacement. I believe you have to get the brake booster if you go with the DA MC.

Was also wondering if say a 91' CRX Si would have a larger MC due to 4 disk brakes. I've already read that the EX model is a bit larger and bolts right up.

 

i got a eg mc from a 4 door civic i think its 13/15 its way biger than the 7/8 one on my crx si make sure it from a lx or ex no abs modle

 

bleed the system first. your problem is not necessarily a mc issue.

if you want to replace the MC, just get stock. no reason to get any other bore size if the system remains the same.

 

and yes i had to change the brake booster for the da mc

 

No, the CRX Si does not have a bigger MC. If you really want to get a bigger MC then yes a 90-91 EX Civic MC will bolt right on. The size on that one is 15/16, the stock one is 13/15 (IIRC).

 

Partially because it was available for tomorrow, and I am also planning in the future to do a rear disk swap I picked up a 91 prelude w/o ABS MC. Dealer told me that a 91 4dr EX non-ABS was the same part number as my 89 DX.

I know it may just need to be bled, but as I did say the pedal feel is crap in this car. I'm hoping that this will solve that problem. Still going to bleed the brakes tonight in hopes of getting it on the road; my temporary drive permit runs out tomorrow.

and just cause I like seeing picks here's one for you guys as a small thanks for the help and advice (first time I've done a pic since the new site...not sure if it will work)

 

the 90-91 CRX Si with rear discs and a larger front caliper has a larger MC as well.

7/8" vs 13/16" of normal DX. and yes, the EX is 15/16".

http://www.norcalcrx.org/tyson/pics/brakepartslist.jpg

but theres no point in going bigger if nothing else is different.

and dude, your symptoms are not of a bad MC as youve described. just of air being in the system. you MUST bleed every time you open the system. this is not a mystery why you have horrible brake feel at the moment.

once youre confident you bled the system properly and still have mushy pedals, then you need to start looking at other parts like leaky rear wheel cylinders or blisters in the brake lines.

 

Tyson, maybe it is my medicine but since when did the CRX Si have larger front discs/calipers and MC?

 

since 1990?

larger caliper, not discs. same discs, different pads tho. check the link.

 

Oh ok, I got the two mixed up! But it did come with a bigger 7/8 MC?

 

wtfomgbbq read the faq noob!

 

No!!!! I guess I have seen too many 88-89 Si's and just had it in my head they all had the same size MC.

 

Well there actually was a small point in going bigger-price and availability. I see what your saying about the MC- if it works don't fix it. Perhaps I should return the MC and just go for the 91' CRX Si model, as the one I got will definately fit but is much larger then the stock DX one. Obviously, I'm not trying to lose my pedal modulation.

The mystery behind the no pedal feel was that the car really wasn't used at all and the brakes quit working, which I discovered last night is as you said Tyson, a leaky rear drum cylinder. This must have just started happening because I've never seen fluid on my wheels before, which in turn does not explain the weak pedal feel that has been going on since I bought the car.

 

Well if you leak fluid their is a big chance that you might have gotten air in the line.

 

your saying the ex 15/16 brake master cylinder will fit the dx model sedan without changing out the booster? I was researching that i will not get the full potential of the mc because the bb wont provide enough boost.

i need to change out mine today and i already have a 15/16 mc laying around, i got a leak at my mc......

 

Mitsu - It will bolt up just fine without a booster swap. Since you have it sitting around then why not, but going up to a larger bore MC does have an effect on your braking system. Depending on how you drive and what you use the car for then you may want to reconsider.

Upgrading the MC without doing anything else to the system reduces brake feel. A larger bore MC pushes more fluid per stroke. Figure you press the brake pedal down 4 inches and the MC dispenses 'X' amount of fluid to the calipers. Replacing the MC with a larger bore will dispense more fluid in the same amount of brake pedal travel. This reduces the distance you need to push the pedal down before lock up your brakes - therefore it reduces the zone in which you can modulate the brakes.

I have no idea how much the zone will be affected when going form a DX to EX.

 

alright atleast it answers my question. Thanks so much


im running a 1991 honda civic dx sedan daily driving, no track. As long as i can stop i wont mind, your saying my pedal will be stiffer because of more fluid being pushed into the lines?

 

Not stiffer, but you won't need to push it down as far to stop the car.
Lots of people have swapped to the EX without any problems for street driving. I find myself driving my cars a bit harder than I should so having great contol over my brakes is a personal concern for me.

 

well for now my brakes are failing so its a must! i will get the matching bb as well as other brake components to help me improve the over all feel. thank you so much, i will change out my mc today!

so if i were to stop i wouldn't have much control over my stopping power? like a small push on the pedal and my car will skid?

 

youy body will adapt. its just relative.

point is, changing a MC alone doesnt "add more braking" power or any sense of that. it just moves more fluid per pedal travel. nothing more.

 

Depends on how big of a MC you get. Maybe a 2" can get you a small push to skid effect. I ran an ITR 1" on stock LX sedan brakes for a while. It was very obvious that the pedal didn't need to go down as far to stop the car. Jumping on the brakes for a quick stop was hard to NOT lock the brakes up (maybe if I got used to it, but I didn't roll like this for long).

Not sure if a brake booster is going to do much for feel. It's like power steering ... just makes it easier for you to press the pedal down. Stainless brake lines are a good upgrade as they take out the expansion of the rubber lines. Multi-pistion calipers are good stuffs too.

 

I'm looking at the same problem. I got a '91 DX with upgraded cross drill rotors in front, perf brakes and the rear has a '90 Integra disc brake with the 4040 valve.

Should I use the '90 EX master cylinder? My MC is going out so I know I gotta replace, might as well upgrade.

 

The 90/91 CRX Si MC would be more logical since your setup is closer to that one.
If not, then the EX will do just fine - it's not all that much bigger.
If you ever plan on doing EX or Teg fronts then the EX MC would be great.