BMC on its way out?

[dhill_cb7]

Hey guys I have done a lot of research on this topic. I am pretty sure my BMC is shot. Ok so about a week ago i noticed that at a stop light i felt the car rolling a bit forward so i pumped the brakes. Flash forward a week and now i feel like i have to do it a few more times at a stop light or a stop sign. BTW the pedal slowly loses its tension. After a while it will almost touch the floor.
There are no puddles or any sign of a leak. I ran my hand behind the tires to feel for any type of liquid. There was none.
The reservoir was about half full. I topped if off at "max". Didn't stop the persisting problem.

The weirdest part is that my car only has 100k on it. I am honestly out of ideas. If there is a few different possibilities then i will have a trusted shop look at it. But i like to do it myself. If it is the BMC i think i can do it myself with out a car lift. All i have if jack stands and a floor jack.

Any kind of insight would be greatly appreciated!!!!

Thanks guys.

[Accrdwgnguy]

That was my symptoms. Car would starting rolling with brakes applied. There is a rubber seal that goes bad inside the BMC, age and wear and tear are both factors. My car had 175k at the time of BMC replacement.

[deevergote]

It's not so much a matter of how many miles are on the car, but how worn/corroded the inside of the BMC is. What's happening is that the seal inside is shot, and the fluid allowing to pass when it shouldn't be. It's an internal leak, which is why there are no puddles, and no fluid loss. Brake fluid is very corrosive, and old components exposed to it for 20 years will fail! The symptoms are always more noticeable as it gets warmer... and these past couple weeks have been killer.

Replace the BMC, bleed the brakes properly, and you'll be good to go.

[dhill_cb7]

It's not so much a matter of how many miles are on the car, but how worn/corroded the inside of the BMC is. What's happening is that the seal inside is shot, and the fluid allowing to pass when it shouldn't be. It's an internal leak, which is why there are no puddles, and no fluid loss. Brake fluid is very corrosive, and old components exposed to it for 20 years will fail! The symptoms are always more noticeable as it gets warmer... and these past couple weeks have been killer.

Replace the BMC, bleed the brakes properly, and you'll be good to go.

Hey thanks very much deev. Would you recommend this to be a DIY? Or one for a pro? I'm just short on cash with school payments and such.

[deevergote]

It's not too hard to do DIY. Just be careful not to get brake fluid on your paint, and follow the directions for bleeding.

I had mine done by Jak Frostwhite at the dealership he works at. Took him like 15 minutes... Had I done it myself, I'd have taken a couple hours... and I'd probably still have the car sitting with the brakes half-bled (that's what happened with my clutch hydraulics, and why I haven't driven the damn thing in 3 years!)

[dhill_cb7]

Ouch 3 years is a long time hope you get it running soon.

I called the local honda dealership earlier to get a price on one just in case. They quoted one brand new for 150.

[Losiracer2]

yeah definitely a BMC problem. Mine would sink all the way to the floor at lights so I replaced it before I had to start pumping the brakes to get pressure.

I got a Fenco one at Autozone with a lifetime warranty for 50 bucks including tax. You can buy a Honda OEM, but honestly, this one worked just as well on my 91 LX coupe. Pedal felt nice and firm afterward.

All I had to do was bench bleed it and it even came with its own little bench bleeder kit with 2 clear hoses and a bracket that routed them back to the reservoir so it eliminated the bubbles.

I had one friend hold the MC and I poured in brake fluid and compressed the piston until all the bubbles were gone. You can do it in a vise too, but I didn't have one available.

I didn't have to bleed any of the brakes suprisingly...I simply bench bled it and installed the hardlines back on and there was firm pedal pressure. Drove it for 3k miles like that and the pedal pressure felt just as firm as when I installed it.

[dhill_cb7]

thanks man i wanted to go oem but if i can get an aftermarket one with a lifetime warranty that would be awesome as well. When you mentioned that you didnt have to bleed any of the brakes how did you know?

[deevergote]

I'm using one from Pep Boys, I believe... Works fine for me! Honda is always best, but some things are fine to go with aftermarket. A BMC is unlikely to fail suddenly... so even if the cheapie doesn't last as long, I'll know when it's going out (it'll start doing what yours is doing now), and I'll replace it. Lifetime warranty, and a price that's 1/3 of the cost of a Honda part... it'll be a LONG time before the cost of aftermarket replacements equal that Honda price!

Now, on things like ball joints... I would only trust Honda. If they fail, I crash.

[dhill_cb7]

I'm using one from Pep Boys, I believe... Works fine for me! Honda is always best, but some things are fine to go with aftermarket. A BMC is unlikely to fail suddenly... so even if the cheapie doesn't last as long, I'll know when it's going out (it'll start doing what yours is doing now), and I'll replace it. Lifetime warranty, and a price that's 1/3 of the cost of a Honda part... it'll be a LONG time before the cost of aftermarket replacements equal that Honda price!

Now, on things like ball joints... I would only trust Honda. If they fail, I crash.

Haha yes very true. Well I am going to try my local pep boys and autozone after work today. I am hoping they have it in stock. If not my cb will be taking up driveway space (maybe ill get my fogs and sub in while it sits lol). Anyway thanks guys for all of the insight. Really appreciate diagnosing the problem before taking it to a mechanic and getting ripped off.
I'll either be doing the swap sat or sun if anyone wants to help out just shoot me a pm (first time doing this so im a little nervous haha)

[Noridetoolow]

Hit the websites for all your local parts stores, you can see 1. the cost of the part, 2. the warranty and 3. if a specific location has it in stock. And check em all, you will be surprised at variances in price! It will literally take you 30 minutes to install, its super super easy! You MIGHT need brake line wrenches which you can also buy at auto parts store for around $10 for a pack of three with 6 sizes between them,...of course get the metric set You may not need these but the nuts on the brake lines LOVE to strip very easily sometimes with a regular wrench, just depends on how tight yours are on there....play it by ear. The bleeding of the brake will take the longest and you will need a buddy to help, gf, wife, heck anyone....just someone that understands simple phrases like "press the pedal and hold it!"...."ok...pump the pedal 3 times and hold it in"..."Ok, let off the pedal", lol

GL!

[dhill_cb7]

Hit the websites for all your local parts stores, you can see 1. the cost of the part, 2. the warranty and 3. if a specific location has it in stock. And check em all, you will be surprised at variances in price! It will literally take you 30 minutes to install, its super super easy! You MIGHT need brake line wrenches which you can also buy at auto parts store for around $10 for a pack of three with 6 sizes between them,...of course get the metric set You may not need these but the nuts on the brake lines LOVE to strip very easily sometimes with a regular wrench, just depends on how tight yours are on there....play it by ear. The bleeding of the brake will take the longest and you will need a buddy to help, gf, wife, heck anyone....just someone that understands simple phrases like "press the pedal and hold it!"...."ok...pump the pedal 3 times and hold it in"..."Ok, let off the pedal", lol

GL!

Hey man thanks very much i will be searching for the best possible price within driving distance. I really appreciate all the help and advice thanks! (wish there were cb7 members closer to my house haha, i guess i "could" ask the gf but other than that idk who is around to help)

[deevergote]

Where are you located? I'm just over the bridge... not that I've done it myself, or that I have a whole lot of time...

[dhill_cb7]

Well right out side of philadelphia. Familiar with the platt bridge or the stadiums? Well i am roughly 10-15mins away in Upper Darby. What bridge are you right over?

[dhill_cb7]

Just got the part for around 25 dollars and i attempting to get it finished today

Thanks guys for all the help you have all provided.