ronin2120

I just installed my lift and the big brake kit by Teraflex with their large bore master cylinder and crown extended brake lines. When I removed the stock master cylinder there was a audible vacuum sound with a strong suction. I installed the new master cylinder and bled the brakes from rear passenger all the way around to the front. The brake pedal would only harden after the 3rd or 4th pump. I have taken the Jeep to 2 different shops and both bled the brake systems but couldn't figure out why the brakes won't harden. The first shop said that I might have gotten air in the ABS line and the only way to get the air pushed out was to find some gravel and get the ABS to kick in that would push the air into the brake lines where it could then be bled out. I decided to remove the master cylinder and and recheck the seal when I removed it the vacuum seal wasn't nearly as strong as when I removed the stock one. My last course of action is to head to the Jeep dealership and have them look at the system but I really don't want to hear them ramble on about warranties and such. I haven't called Teraflex only because it's the weekend and I'm heading out of town for the next 2 days. My Jeep is a 2012 JK so any suggestions or ideas would be appreciated.

aermotor

It sounds like you didn't pull back on the check valve and relieve that pressure before removing thus sucking a ton of air into the system and possibly into the ABS as you said. I would drive it a bit then re-bleed it again. I keep finding air in my lines somehow.

I just installed the Big Brake kit as well and pedal is definitely not as hard as I would like it to be. I really have no idea how to get it better sadly. Seems like there should be a lot more tension without having to really press on it.

ronin2120

Yeah I forgot to relieve the valve and as soon as I pulled the master cylinder off and heard the air getting sucked in I messed up. I'll drive it some more and every couple of days I'll bleed the brakes. When did you install your brakes? Is there a way to bleed the ABS line?

olram30

yeah, but you need a scan tool. here are the instructions



ANTILOCK BRAKE SYSTEM BLEEDING
The base brake's hydraulic system must be bled anytime air enters the hydraulic system. The ABS must always be bled anytime it is suspected that the HCU has ingested air.

Brake systems with ABS must be bled as two independent braking systems. The non-ABS portion of the brake system with ABS is to be bled the same as any non-ABS system.

The ABS portion of the brake system must be bled separately. Use the following procedure to properly bleed the brake hydraulic system including the ABS.

NOTE: During the brake bleeding procedure, be sure the brake fluid level remains close to the FULL level in the master cylinder fluid reservoir. Check the fluid level periodically during the bleeding procedure and add Mopar® DOT 3 brake fluid as required.

BLEEDING
When bleeding the ABS system, the following bleeding sequence must be followed to insure complete and adequate bleeding.

1. Make sure all hydraulic fluid lines are installed and properly torqued.
2. Connect the scan tool to the diagnostics connector. The diagnostic connector is located under the lower steering column cover to the left of the steering column.
3. Using the scan tool, check to make sure the ABM does not have any fault codes stored. If it does, clear them.

WARNING: When bleeding the brake system wear safety glasses. A clear bleed tube (1) must be attached to the bleeder screws and submerged in a clear container filled part way with clean brake fluid (2). Direct the flow of brake fluid away from yourself and the painted surfaces of the vehicle. Brake fluid at high pressure may come out of the bleeder screws when opened.

NOTE: Pressure bleeding is recommended to bleed the base brake system to ensure all air is removed from system. Manual bleeding may also be used, but additional time is needed to remove all air from system.
4. Bleed the base brake system. (Refer to 05 - Brakes - Standard Procedure)
5. Using the scan tool, select ECU VIEW, followed by ABS MISCELLANEOUS FUNCTIONS to access bleeding. Follow the instructions displayed. When finished, disconnect the scan tool and proceed.
6. Bleed the base brake system a second time. Check brake fluid level in the reservoir periodically to prevent emptying, causing air to enter the hydraulic system.
7. Fill the master cylinder fluid reservoir to the FULL level.
8. Test drive the vehicle to be sure the brakes are operating correctly and that the brake pedal does not feel spongy.

olram30

also, scan tool with abs run around 250 from auto parts stores. good tool to have.

ronin2120

Alright so just to make sure I understand this correctly. I use the ecu reader to check for the abs error then bleed the base break system. Clear the codes and rebleed the base brakes again continue this process until the brake pedal hardens. Sounds like I'm going to be going through a lot of brake fluid. Thanks for the info

aermotor

Awesome post olram30, thanks!

JaySC

I have the same problem after installing a big brake kit (not Teraflex). The shop tried bleeding my brakes and the ABS. They also did a reverse bleed but nothing seems to work. So, I'm curious to see what others have done and if they have successfully fixed the soft pedal.

ronin2120

ok just fixed my brakes started looking at pictures of other brakes and noticed that my bleeder valves were on the bottom instead of the top. I swapped the bleeder valve around and bled the brakes again BAM pedal is firm and the Jeep stops like a champ! I guess having the bleeder valve on the bottom allowed the air to remain in the top of the caliper thus not purging the system completely.

aermotor

My bleeder is on the top and I still have sponge fest. I prolly need to bleed again and bleed my ABS.