When I replaced the small manual brake MC on the firewall of our ram-engined 300K , I bought a new/rebuilt MC and had to slightly disassemble it so as to have access behind the little check valve in its nose and drive the valve out with a slender rod. Easy disassembly, valve removal and reassembly. The check valve looked like a little button that held a small amount of pressure on a manual brake system (to minimize air/moisture from leaking in at the wheel cylinders). There were no mechanical elements to it—more like a variable synthetic orifice that must let fluid back into the MC chamber when the pedal is released. The brake springs drive the brake fluid back into the MC chamber on a standard boosted or non-boosted system. The remote booster in a ram car has no such spring system to drive the fluid back so the brake fluid oozes back slowly or not at all. The remote boosters in SWB ram cars were installed because there was not enough clearance between the ram air cleaners and the plumbing/body of a boosted MC. I have seen a ram car with a standard booster—slightly replumbed and having about 3/8” clearance with engine still. Not sure if that engine had been shifted forward or not. Rich Barber in cool CA. CU in October From: 'Mike Cortel' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> Thanks, Mike for the suggestion on checking the slave. I will take a look at the manual Mike Cortel On Tuesday, May 10, 2022, 12:50:57 PM EDT, 'mwl1967' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote: Agree with Chris. I've heard stories of brakes completely locked when the residual check valve is in master and slave. Having said that, if you're missing the check valve in the slave that could also cause your problem. Easiest way to check if disconnect the line exiting the slave. Unscrew the end cap to expose the spring and see if it's there. Picture in the service manual if you need. Mike Sent from my Verizon, Samsung Galaxy smartphone -------- Original message -------- From: kmaniak via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> Date: 5/10/22 9:24 AM (GMT-07:00) Subject: Re: {Chrysler 300} 300K Ram Brake Problems - URGENT, DON'T IGNORE THIS REPLY! Good day, all: I have been reading through the responses and there is one important design feature of the ram brake system that has not been discussed, and if overlooked, can cause severe brake fade and possibly a FIRE! The master cylinder used in the ram car is the same as the one used in manual brake cars, WITH ONE EXCEPTION! The master cylinder used with the remote booster DOES NOT AND SHOULD NOT HAVE A CHECK VALVE INSTALLED INSIDE. The slave cylinder should contain the only check valve. Since the master cylinder did not have a check valve installed is the reason the factory directs power bleeding of the system, and does not recommend bleeding with the brake pedal. The biggest problem mechanics make when servicing the remote brake booster system is simply installing a manual brake master cylinder, which usually has a check valve installed inside. They do not check for or remove the check valve. BIG MISTAKE! The check valve is omitted from the master cylinder in this application to allow the residual pressure induced in the brake line between the master cylinder and the slave cylinder when the brake pedal is depressed to bleed back to zero when the brake pedal is released. Here is what happens when a check valve is present in the master cylinder in this application. When you push the brake pedal for the first time, an even pressure is induced in the system from master, through the slave, to apply the brakes on all four wheels. When the brake pedal is released, the check valve keeps the master cylinder circuit pressurized, which in turn, keeps the slave cylinder engaged and the brakes partially applied. This condition mimics a driver who constantly rides the brake pedal. As you drive the car and keep using the brake pedal, the brake system continues to heat up since the brake pressure in the secondary circuit never goes back to zero or fully releases the brakes. Once the brakes get hot, the brakes will fade and require more pedal effort. Once the brakes get hot enough, the brake fluid will boil and brake pedal will go to the floor. I think you have a check valve in your master cylinder causing this condition. There is a quick way to check. Drive your car around the neighborhood until you start to feel brake fade or no more than one-two miles. Pull back into your driveway. Then take a garden hose and squirt all four brake drums and backing plates from underneath. If the water boils violently from all four drums, you have a check valve in the master cylinder. Side note: If the car is driven on a long trip at freeway speeds, the drums can heat up enough to ignite the rear tires. I have knowledge of more than one ram equipped car catching fire and burning everything from the trunk to the interior side of the firewall from rear tires catching fire after a recent brake job where the master cylinder was replaced. Read what I have wrote more than once and let it sink in. Chris the K MANIAC -----Original Message----- The bleeding was being done manually with my wife at the pedal and followed the order based on the service manual posted below. I did consider getting a Power Bleeder but again got frustrated and just parked the car. Any recommendations for a power bleeder? Thanks for the reply
Mike Cortel On Monday, May 9, 2022, 01:20:57 PM EDT, dplotkin@xxxxxxxxxxxxxxxxxxx <dplotkin@xxxxxxxxxxxxxxxxxxx> wrote: Mike- How are you bleeding? Manual with a friend on the pedal? Gravity? Power bleeder? You have two circuits and need to rule out which one is the problem. I believe air is the problem and you want to know if its in the master or slave circuit. Danny Plotkin -----Original Message----- Hi to all A little background. Approx 2 years ago I was having leakage at the master cylinder and the brakes felt weak. I figured it was time for a rebuild. I removed both the master cylinder, the remote brake booster, and the slave cylinder and took them to Power Brake Exchange in Pittsburgh for rebuilding. They did find a broken spring in the remote booster and were able to replace it as well as the additional seals and such. They provided a test report and it showed the booster providing 300 psi? (I can not find the paperwork at this time but I believe that was the number.) I got everything back home and got back together. I also replaced the front wheel cylinders, shoes, and front hoses. Also, replace the vacuum line from the intake to the booster with the correct type of hose. I followed the service manual for the bleeding order of the system more than once. Here is the problem. I have brakes when the car first starts up. But after a couple of stops, the brake pedal starts bottoming out and the brakes do not hold. I was so frustrated and fed up that I just put the car away. In the meantime, I have become a cancer patient and I would really like to get this fixed and possibly enjoy the car this spring/ summer while I can. I have considered taking the car to the local Chrysler dealer whose ownership is into Mopar Muscle as I am not sure how much I can still do. Any thoughts or suggestions are appreciated as well as any shops in Ohio that may be able to work on this. Thanks in advance Mike Cortel -- -- -- -- -- . -- For archives go to http://www.forwardlook.net/300-archive/search.htm#querylang --- You received this message because you are subscribed to the Google Groups "Chrysler 300 Club International" group. To unsubscribe from this group and stop receiving emails from it, send an email to chrysler-300-club-international+unsubscribe@xxxxxxxxxxxxxxxx. To view this discussion on the web visit https://groups.google.com/d/msgid/chrysler-300-club-international/007501d864b9%24a5b24240%24f116c6c0%24%40ez2.net. |
Back to the Home of the Forward Look Network
Archive Sitemap
