But I bought the new master cylinder from Teraflex. Are you saying that one is too small?

Also, I get what you are saying about pumping the brakes and what it does, hence my analogy to mis adjusted drum brakes. However, I wouldn't think there is that much travel of the piston within the caliper as compared to drum brakes because disc brakes rest much closer to the rotors than drums do.

Bottom line, why are some guys able to have high, firm pedals and others have long traveling ones with same parts?

 

I get it wont purge so to speak but are you saying if there is air in the abs and you activate it that air will not move out of there at all. But i agree its not easy to get air in there and the master cylinder may also be a problem if its not up to par.

 

Trust me when I tell you, bleed the system until you see no more bubbles. It took me hours to do this and make sure your MC is purged of and air by using the Starscan tool or several dirt/gravel stops.

This is what I did after having the spongy pedal you described in your first post.

 

Yup, that's what I intend to do. I paid big bucks to upgrade the entire system, in part because my son just got his permit and is now driving range JK so I need the added margin for safety!

 

Last summer, I did the Mopar BBK replacement. I liked it at 1st, but now things aren't quite right. I'm getting the occasional 3 Dash lights coming on (Brake Light, ABS Light, Traction Control) and the peddle is just not feeling right. It's not squishy but just not right.
I bled the brakes using a vacuum pump but I didn't do the Starscan bleeding, so I'm thinking this may be related to the problems I'm seeing now.

To do the starscan bleeding do you have to take it into a dealer to do it or do other shops have this ability? How much does it typically cost to have the dealer do it?

 

Indy shops can do it if they bought the tool. My guy said it was $3k to buy to tool.

 

Had the dash lights come on, too. As it turned out, the battery was dying, which can trigger the light gremlins. The stock battery died after only two years, but now I run a Walmart AGM battery which constantly holds 14 plus volts. The AGM batteries are the best.

 

Yes. It is the 2011 & later master and has a slightly larger bore. It's better than the early stock master cylinder, but still not large enough to accommodate the much larger piston are of the dual piston calipers.

A tiny amount of travel at the caliper will translate into noticeable travel at the pedal. When you quick pump the brakes and the pedal level comes up slightly & firms up, you're taking up all the slack in the caliper pistons and the pins. If
You hold the pedal down and it doesn't move there's no air in the system. If it firms up but then slowly drops you still have have residual air in there.

It's a good question re: high, firm pedal on some but not all JKs. I did a BR6 conversion a couple years ago for one of my fellow club members. We swapped over the calipers (single piston), bled just the fronts and the pedal is high & firm. Do the TF BBK conversion and in most cases the pedal travel will increase and the feel will be a bit squishy. I've pressure bled mine while tapping the lines, etc. and had the dealer do the Starscan. They're just the way they are. I may try the Mopar BBK master & booster to see if they tighten up, but since they work great I don't see the need.

 

According to a couple sources the only time the Starscan is really required is when the ABS unit is replaced. Changing the master generally won't let air into it because the spoils are closed and sealed off. If you do the old gravel road brake slammed, letting the ABS cycle, the only way you'd get any air out would be to pressure bleed right there on the spot. If you don't it will just end up back in the motor pump unit, rather than in one of the circuits.

Fwiw, after I installed TF's master I had the local dealer do the Starscan bleed, made no difference whatsoever.

 

I did the Teraflex Performance rotor upgrade, front and rear with Hawk LTS pads this week. It's 2015 JK with 35's.
I'm very happy with the results as the Jeep will really stop now. I mean throw you into the seat belt stop.

I'm at about 150 miles on them and it will stop fast and controlled. The roads have been wet ever since I did the day after the upgrade and the braking is twice as good as with the stock parts even in the rain. It feels more powerful and controlled at the same time. Now I don't wonder if I can stop in time, I wonder if the guy behind me will stop in time.

Cost with tax about $780, I got it all from Amazon. Took 4.5 hours to install by myself including lunch and couple brakes, phone calls, etc. I think it really is about 2-3 hours of actual work in a home garage.