robbie95 Posted February 5, 2017 Share Posted February 5, 2017 So I recently replaced my MC and Brake Booster because I saw my MC was leaking pretty badly into the brake booster. I bench bled my MC, tried bleeding the brakes but it seems like they are still too soft whenever I am driving it.. No problems when the car is off, brake pedal is firm. Someone informed me that there is a specific bleeding procedure for comanches, if that's the case, what is it? I did the classic, have your buddy press the brakes then open the bleeder valve, then close it and tell him to let off, but there still seems to be air in the system. I bled the Passenger's Back Wheel first, then Driver's Side Back Wheel, Passenger's Front Wheel, then Driver's Side Front Wheel. Link to comment Share on other sites More sharing options...
Pete M Posted February 5, 2017 Share Posted February 5, 2017 skim though the link in my sig. I thought we had a writeup on that. Link to comment Share on other sites More sharing options...
Gene Posted February 5, 2017 Share Posted February 5, 2017 Hi Robbie, First thing, before even bleeding the brakes, is to be sure the back brakes are adjusted properly. Self adjusters don't always work. With the parking brake off, there should be very slight drag when you spin the wheel. Improperly adjusted brakes, which may be from a stuck or otherwise not working self adjuster, will certainly cause a low pedal. Here's how you think of bleeding the rear brakes. There are two sets of lines that go to the rear. One, for normal use, goes from the master cylinder, to the proportioning valve under the master cylinder, to the height sensing valve on the rear axle, to the wheel cylinders. When you do a standard brake bleeding, you are bleeding this line. But there's another line that goes to the back. This is the line that bypasses the rear height sensing valve, so that rear brakes will get full braking. This one is used only when there is a failure of the front brake hydraulic system. To bleed that, it has to be activated. And to activate it, there has to be a "failure" in the front brakes hydraulics. So, after finishing the regular bleeding, open one of the front brake bleeder screws, put a rubber or plastic hose on it and put it in the container of brake fluid to try to keep air from getting sucked back in. Now, with the front bleeder valve open, go back and re-bleed the rear brakes. You are now bleeding the second, emergency circuit, that bypasses the height sensing valve. When you're through with this, you then have to bleed the fronts again. And then, probably, bleed the backs again the traditional way. I'm not sure whether the above is the official factory procedure, or if it's what Pete references. This is what works for me. Finally, after this, the brake warning light may be on, because it has sensed the front hydraulic system failure. Usually, stomping hard on the brake pedal several times is enough to equalize this. If not, you may have to rebleed one of the hydraulic systems, to get the plunger to return to center position. Good luck! Gene Link to comment Share on other sites More sharing options...
Eagle Posted February 5, 2017 Share Posted February 5, 2017 skim though the link in my sig. I thought we had a writeup on that. We do. I transcribed it directly from the MJ FSM. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 5, 2017 Share Posted February 5, 2017 Then why not link to it in the DIY search index? I have no idea where it is. Link to comment Share on other sites More sharing options...
Gene Posted February 5, 2017 Share Posted February 5, 2017 http://comancheclub.com/topic/40428-brake-bleeding/?p=407703 might be the link you referenced. I did not find it necessary to disconnect the link to the height valve. But perhaps things would have been quicker if I did! Gene Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 5, 2017 Share Posted February 5, 2017 That's a piece of it Gene. There was another link posted by Eagle somewhere that detailed the the whole MJ brake bleeding procedure per the FSM. I know not where... Link to comment Share on other sites More sharing options...
Eagle Posted February 5, 2017 Share Posted February 5, 2017 I don't remember where. Here it is again: After bleeding the brake calipers and cylinders the rear brake by-pass line must also be bled.Open a front caliper bleed fitting and depress the brake pedal to the floor. This will shuttle the by-pass differential valve and allow fluid to flow through the by-pass line. The brake warning light on the instrument panel will illuminate when the ignition key is in the ON position. This signals the shuttling of the valve.Re-Bleed the rear brake cylinders with the front caliper bleed fitting open.After re-bleeding the rear brake cylinders the entire system must be bled again.Bleed the brake calipers and cylinders in the following sequence:1st -- Right rear2nd -- Left rear3rd -- Right front4th -- Left front Link to comment Share on other sites More sharing options...
Pete M Posted February 5, 2017 Share Posted February 5, 2017 I don't remember where. Here it is again: After bleeding the brake calipers and cylinders the rear brake by-pass line must also be bled. Open a front caliper bleed fitting and depress the brake pedal to the floor. This will shuttle the by-pass differential valve and allow fluid to flow through the by-pass line. The brake warning light on the instrument panel will illuminate when the ignition key is in the ON position. This signals the shuttling of the valve. Re-Bleed the rear brake cylinders with the front caliper bleed fitting open. After re-bleeding the rear brake cylinders the entire system must be bled again. Bleed the brake calipers and cylinders in the following sequence: 1st -- Right rear 2nd -- Left rear 3rd -- Right front 4th -- Left front that's in the link that Gene found in the DIY index :thumbsup: http://comancheclub.com/topic/40428-brake-bleeding/?p=407703 Link to comment Share on other sites More sharing options...
Eagle Posted February 5, 2017 Share Posted February 5, 2017 that's in the link that Gene found in the DIY index :thumbsup: http://comancheclub.com/topic/40428-brake-bleeding/?p=407703 Similar procedure, but not a direct quote from the FSM. The FSM doesn't say anything about disconnecting the link rod at the rear axle. Link to comment Share on other sites More sharing options...
Pete M Posted February 5, 2017 Share Posted February 5, 2017 scroll down a bit. it's at the bottom of the first post. Link to comment Share on other sites More sharing options...
robbie95 Posted February 5, 2017 Author Share Posted February 5, 2017 Thanks guys, gonna start the bleeding process soon. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now