Hopefully this subject hasn’t been beaten to death but my stock brakes aren’t cut out for pulling the reins on my Jeep anymore. Driving down a mountain today was a bit sketchy... so, I’m thinking crown big brakes up front and power stop z36 in the rear. For now I’ll leave the master cylinder and booster alone unless anyone thinks I need to change them. What does the crowd say about this setup?

 

Sv. i'm running the Crown Bigs on the Front of my 16 JKU w/35s.. Stock on the rear.. NO Change on Booster, M/Cyl .. Much improved. Will be putting same on the 13 JKU w/35s & stock on the rear. Will upgrade the pads on the rears when they need replaced. Most interesting with the Crown BB Fronts is that all the parts are MOPAR from a 1500 Ram so getting new pads etc will be NP.

 

I am running Crown Big Brake mainly because Mopar is almost always on back order. So far happy. Kind of wish I had changed my master cylinder. And I did change my brake lines to Metal Cloak, which are beasts.

 

Z36's are good, I'm on my second or third set now (total, not per axle). I was looking into the G2 for the rear to give me more bite back when I saw a kit on eBay for $250.

 

I picked up the Crown kit off eBay for $350 good while back. Seemed like a bargain at the time. I currently run those crown calipers with TF 13.3" front rotors (long story). At the time the Mopar J8 brake booster/MC kit was coming available again, and I picked one up (from a friend with a shop, cash deal, no warranty). That was a mistake. I had so many issues with that booster....blew the Mopar MC first drive. Replaced that with a Crown J8 MC cuz you couldn't buy the Mopar separately. Blew the seal on that one too. Got a replacement Crown J8 MC and pulled that booster off and moved it on. I'm back to the factory booster and MC, and on the '12+ it's ok. I don't drive like a racecar driver.....but I'm sure many would think the pedal needs improvement. If it was the MC on 3.8L I think you really need to upgrade. If I did anything further, I'd probably add the TF MC, but that doesn't seem like a gigantic improvement over the MC we already have ('12+).

Well, I just went to dig up that TF MC, and it's been discontinued?

 

Resharp I am wondering about your comment re "the 3.8 MC"? Is it the lack of vacuum from the engine that makes it not as good or is it a totally different MC on the 12+? The reason I raise this is my 2008 (obviously a 3.8 once) has much improved brakes with the Chev engine driven, oil lubricated vacuum pump and has vastly improved the stopping power for this Jeep. I was planning the BB kit for the front. And awesome news that the RAM 1500 forms the parts lineup for this. Does that mean the longer caliper mounting brackets from the RAM fit the Jeep?

 

It's been a long time since I've researched/read up on this, but I generally recall the MC bore size increasing with the model/engine change. This is also the reason TF used to say if you were doing their BBK for an '07 - '11 you should do their MC, but it wasn't really required for the '12+. I could not tell you the actual specs off the top of my head, but I'm sure they are floating around out there. There is also a thread out there where someone, maybe Rednroll, had all the part numbers to piece this kit together. It seems that the caliper brackets were not directly off the Ram 1500, but I could be wrong about that one. It's been a long time since I've gone down the "brake" rabbit hole. Karl might recall some of this, maybe. I'll see if I can locate that thread.

 

The Crown BBK components and MOPAR PNs.. Kit purchased from Quadratec..

 

I ordered the crown front and the dynatrac rear big brake kit. I figured that for playing in the rocks and driving on a lot of dirt roads, having the z36 rear brakes may not be a good idea since they’re drilled and slotted. I don’t want to leave room for small pebbles to get stuck in the rotors. Next week I’ll install them and post pics of the shiny parts.

 

Here we go... problem and I’m stumped. A few days ago I installed the dynatrac rear brakes, everything went fine and brakes worked normal. This morning I install the crown front bbk, bleed the brakes and after getting all the air out of the system, the brake pedal goes to the floor once I start the Jeep. So, I bleed the system again and do a full flush starting from the right rear, left rear, right front, left front. I bleed till fresh fluid comes through. There’s no air in the system that I can tell, I bled it very thoroughly. The brake pedal is super soft and I have to pump it several times with the engine off to get solid pressure. Once I start the engine, the pedal goes to the floor again.

I didn’t replace the front brake lines when I did the install and prior to the front install the brakes worked fine. Typically if I had this problem I would thing maybe the master cylinder would be bad but it’s such a coincidence that this problem comes up after just replacing the front calipers. How likely is it that after pushing the brake pedal all the way to the floor that the piston of the MC got jammed and now the MC is bad? Any suggestions?

Edit: there’s no fluid loss, no leaks, and as far as I can tell, there’s no way for air to get into the system.