Brake Wars..Episode 3.. The mechanic strikes out..again

midnight sun · June 10, 2006, 05:20:47 PM

The other thread was getting long so I decided to carry on with the same problem only with a different thread.

Today I swapped out the 2 lb residual valve (SSBC) to the front calipers and EUREKA...Same old problem..soft pedal. Then I took off the calipers, made a spacer for between the pads and bled them with the bleeder straight up. Got a lot less bubbles/air but unfortunately got the same result. I think I have tried everything that has been recommended except changing over to a firewall M/C. I finally gave up and started working on my fence. This is just way too frustrating. It shouldnt be this hard should it?? Any other suggestions??

TIA

Dave · June 10, 2006, 05:37:47 PM

Quote from: "midnight sun"The other thread was getting long so I decided to carry on with the same problem only with a different thread.

Today I swapped out the 2 lb residual valve (SSBC) to the front calipers and EUREKA...Same old problem..soft pedal. Then I took off the calipers, made a spacer for between the pads and bled them with the bleeder straight up. Got a lot less bubbles/air but unfortunately got the same result. I think I have tried everything that has been recommended except changing over to a firewall M/C. I finally gave up and started working on my fence. This is just way too frustrating. It shouldnt be this hard should it?? Any other suggestions??

TIA

Without going back to the first thread did you try a new M/C ? Ive got a couple numbers for outlets on right or left side whatever you need. Also the new ones with ports on both sides work nice. We bought the one for the 30 a from old dog street rods. They make em so they say for both power assist and manual. I bought the manual one and as ive said before no other added stuff like residual valves or prop valves and the system is fine. Sure there is a little extra pedal than my 32 but i liked it . The braking and the feel of it better than my 32. Other than that sorry i got no answers.
Ive been thru the bad brakes deal and i know its frustrating. Hang in there. You have a little problem but you will find it in time. Kinda like the 2 year shake in my 34 with the MII. Found out the rotor bolt patern was drilled at least 100 thousands off center.
Dave

enjenjo · June 10, 2006, 10:27:22 PM

Well the symtoms are common for a residual valve, but if it's still doing it with a new valve, the only thing left are the front hoses and calipers. See how far the caliper pistons are retracting, it should be just enough to release the rotor.

I hate to ask this, but are you sure you installed the valve the correct way? Arrow points to the brake calipers.

SKR8PN · June 10, 2006, 11:00:22 PM

Just for the heck of it................how many MILES and how many actual STOPS have you put on the new rotors and pads?

?
It may just be possible that you need to "seat" the new pads to the rotors to get that firm peddle feel you are searching for. One mans idea of a "soft" pedal,may not be the same "soft" as the next guys.
Just my 2 centavoe's.

slocrow · June 11, 2006, 10:02:30 AM

MS, I'm bringing this over so new reads know what you've done bulk, so far!

Quote from: "midnight sun"I have read and reread and reread all of the previous posts on braking. I plugged off both outlets on the M/C and got a good hard pedal. I then reattached the front line to the M/C and left the rear portion plugged off. Soft pedal. I then reattached the rear line land plugged off the front outlet and got a good hard pedal. Okay so I surmise that the problem is somewhere in the front system (disc). I unhooked the line just before it goes into the thru frame fitting where it proceeds to both calipers. Hard pedal. Plugged off the right side. Soft pedal. Plugged off the left side. Soft pedal. So its in the calipers, right? I removed the calipers, and caliper mounts and tried different combinations to see if I could get the bleeder valve any more upright. No good. I cant figure out anything else to do. Im sure its in the calipers somewhere but they are not leaking anywhere so Im out of ideas.

Unless those braided lines are expanding somehow, which I doubt, it's a problem in the calipers.
When you isolated the right & left front individuality, how did you cap off the dead line? I might suggest that you do that double, to the L and at the same time too the R. Cap it off at the end of the braided line. If you get a hard peddle then, which I bet you will, then it's the calipers for sure.
Maybe the piston seals are the problem and letting air back in. The rebuilder may have made a mistake in assembly. That's where your problem is located and unfortunately you've got to find out where and how the air is getting in.
It's frustrating I know but stay with it or put the wrench down and sit a while, have a beer, it will be there when you are ready again. Best of luck and keep us informed as we all learn through each other......Frank

Sean · June 11, 2006, 01:38:19 PM

Quote from: "SKR8PN"One mans idea of a "soft" pedal,may not be the same "soft" as the next guys.

Thats what I was wondering too.Especially since you have gone through just about everything in the brake system and still have the problem. Regardless of how the pedal "feels", do the brakes work correctly? The pictures I have seen of the under-floor type master cylinders look like the leverage point of the swingarm is pretty close to the pivot point, which would give you better leverage, and less "feel" to the pedal.

My two "modern" vehicles are a '93 Lebaron, and a '04 Mitsubishi Montero. There is a distinct difference in how the brake pedal feels in the two vehicles. The Chrysler feels pretty firm, while the Montero feels mushy.

In my work truck, a 2003 F150, the pedal is firm, but if you keep pushing you can get it nearly to the floor. Seems like it has way to much travel for some reason, but it works just fine. On the other hand, the pedal in my '65 F100 is hard as a rock and has very little pedal travel.

enjenjo · June 11, 2006, 02:03:40 PM

On the 34 Desoto, the brakes just never felt good enough. Even pulling a trailer, it never failed to stop, but it just felt iffy. It had a 7" street rod booster on it, I checked it, and it was bad after 2 years. I replaced it, and it was better, but still not good enough. After another season, I replaced it with a dual diaphram street rod booster, again better but still not where it should be.

Calculating master cylinder bore from caliper sizes, brake pedal ratio, wheel cylinder size, and vehicle weight, it needed a 1 1/8" master cylinder bore, which is what it had. So on a hunch, I replaced it with a 1" bore master cylinder, and all was as it should be. Great brakes.

exsedan · June 11, 2006, 08:34:55 PM

I was thinking along the same line.......maybe the next size smaller (bore size) master cylinder is the next step. I am sure that all of the "engineering steps" were calculated (as you mentioned above) and everything is operational, to include the PARKING BRAKE assembly.

Just went thru a system that had a "lock-up" problem due to the emergency brake being out of adjustment. So, i'll throw my 2 cents in here as a "possible" for you to look at/think about.

As long as the travel (not much) of the front caliper pistons is correct and the rear emergency brake is adjusted properly, so that the spring retracts the shoes only enough to release the brakes (with proper shoe to drum clearance), the master cylinder piston travel/volume should be sufficient to make up for the next smaller master cylinder bore diameter to be used. I know there are formulas for all of this, but I have not used any of it for many years. I just depend on the suppliers of the brake kits to do their homework prior to selling their products.

Might give this a try.......jb EXSEDAN

sirstude · June 12, 2006, 10:18:41 AM

One last thing, do you have access to a power brake bleeder? Not the vacuum type, but the type that has a plate over the master cylinder. I have seen some brakes that the only way you can get them to bleed correctly is with a power unit. Also great for purging old brake fluid. Jegs and summit both sell an inexpensive unit. One of the boards (don't remember which one) had a tech article on how to build one from a bug sprayer.

Doug

slocrow · June 12, 2006, 10:42:31 AM

Quote from: "sirstude"One last thing, do you have access to a power brake bleeder? Not the vacuum type, but the type that has a plate over the master cylinder. I have seen some brakes that the only way you can get them to bleed correctly is with a power unit. Also great for purging old brake fluid. Jegs and summit both sell an inexpensive unit. One of the boards (don't remember which one) had a tech article on how to build one from a bug sprayer.

Doug

I think this is it....................
http://www.bmw-m.net/TechProc/bleeder.htm

sirstude · June 12, 2006, 11:27:40 AM

That's the one.

48builder · June 12, 2006, 12:23:39 PM

Quote from: "slocrow"
Quote from: "sirstude"One last thing, do you have access to a power brake bleeder? Not the vacuum type, but the type that has a plate over the master cylinder. I have seen some brakes that the only way you can get them to bleed correctly is with a power unit. Also great for purging old brake fluid. Jegs and summit both sell an inexpensive unit. One of the boards (don't remember which one) had a tech article on how to build one from a bug sprayer.

Doug

I think this is it....................
http://www.bmw-m.net/TechProc/bleeder.htm

Hey, thanks! I'm going to make me one of these. As soon as I finish enjenjo's english wheel that I started three years ago.

Bob Paulin · June 12, 2006, 01:18:18 PM

Quote from: "slocrow"
Quote from: "sirstude"One last thing, do you have access to a power brake bleeder? Not the vacuum type, but the type that has a plate over the master cylinder. I have seen some brakes that the only way you can get them to bleed correctly is with a power unit. Also great for purging old brake fluid. Jegs and summit both sell an inexpensive unit. One of the boards (don't remember which one) had a tech article on how to build one from a bug sprayer.

Doug

I think this is it....................
http://www.bmw-m.net/TechProc/bleeder.htm

The only problem with that setup is that you are pressurizing the fluid with ambient air that is loaded with moisture.....concentrating the moisture into the fluid.

Commercial bleeders have a diaphragm separating the fluid from the air pressure.

Once they have been charged correctly, there is no more air on the fluid side of the bleeder and the diaphragm separates pressurizing air from the fluid.

If you leave fluid in this shade-tree setup between uses, it would be akin to leaving the can open....

And, if you pour the fluid back into its original container, you are pouring back fluid that has been contaminated with ambient humidity pressured into it.

Some of these "shade tree" solutions aren't all that great if you sit and think about them a bit.

C9 · June 12, 2006, 02:30:48 PM

Here's one way to do it at home . . . no worse than a regular driveway bleeding job.

Make a plate - 1/2" aluminum works well.

Drill and tap it for a couple of Schrader Tank Valves.
One over each reservoir.
(Schrader Tank Valves are a fitting with a tire stem on one end and 1/8-NPT on the other. Available most real parts houses.)

Use copper coat to glue a thick piece of Vellumoid gasket paper to the plate bottom.

Bolt or clamp - as the case may be - the plate to the M/C.

Set your regulated dry air supply to 35# or so.

Bleed one wheel.

Refill the reservoir.

Repeat as necessary.

If you don't get carried away there's plenty of fluid in the M/C reservoirs to bleed a wheel.

The obvious problem is pumping air from the air supply into the lines so be careful.

tomslik · June 12, 2006, 04:50:27 PM

Quote from: "Bob Paulin"
Quote from: "slocrow"
Quote from: "sirstude"One last thing, do you have access to a power brake bleeder? Not the vacuum type, but the type that has a plate over the master cylinder. I have seen some brakes that the only way you can get them to bleed correctly is with a power unit. Also great for purging old brake fluid. Jegs and summit both sell an inexpensive unit. One of the boards (don't remember which one) had a tech article on how to build one from a bug sprayer.

Doug

I think this is it....................
http://www.bmw-m.net/TechProc/bleeder.htm

The only problem with that setup is that you are pressurizing the fluid with ambient air that is loaded with moisture.....concentrating the moisture into the fluid.

Commercial bleeders have a diaphragm separating the fluid from the air pressure.

Once they have been charged correctly, there is no more air on the fluid side of the bleeder and the diaphragm separates pressurizing air from the fluid.

If you leave fluid in this shade-tree setup between uses, it would be akin to leaving the can open....

And, if you pour the fluid back into its original container, you are pouring back fluid that has been contaminated with ambient humidity pressured into it.

Some of these "shade tree" solutions aren't all that great if you sit and think about them a bit.

although here in colorado, that ain't a huge problem.
we don't have much humididity.....
wish it'd rain......