My own JK 'Big Brake' research:

Majik

Majik

Member
Everyone here has been so nice and welcoming that I wanted to try to give a little back. I figured we all could use some extra braking power for big tires, etc. There seems to be so much secrecy about the Teraflex kit and also the Jeep J8 brakes, so I've been doing some investigation, and I think I'm making progress. Please let me know if you guys are interested or if I'm just talking to myself so I don't waste time with posts if I'm beating a dead horse.

1. I have contacted the company that produces the J8 Jeeps and they have been wonderfully helpful, up to the point where they are legally allowed to share info. So, they are clearing it with their legal guys and I should hear more info this week.

2. I think I make have found the master cylinder that is used on the J8, and likely, the Teraflex upgrade. Check this link:

Click here

Take a look at the 2nd part listing (Part Number: MC391385 - Raybestos). It is for a Jeep JK with 13.07" rotors!!
Now check the 7th part listing (Mopar Part Number: 68091278AB). It is for the BR6 brake package: a heavy duty package I've seen listed as used on the J8!!

I am going to call Raybestos tomorrow to get the bore diameter and verify that the mounting base dimensions are the same. The cool thing is that if its the master cylinder Teraflex is using, it is in stock for $80, instead of the $190 Teraflex is selling it for. It would either be a 1 1/16th or a 1 1/8th inch bore diameter. A 1.25" diameter bore would be ideal, I think, and really give us some fluid movement for big calipers, but I'm going to have to hunt for a 1.25" bore MC with a bolt pattern to mate to our boosters.
For $80 I might just buy one and check it out for the benefit of everyone on this forum.

3. I verified with the installers for the J8 (they did volunteer this info freely) that the brake pads on the J8 truly are just late model Ram 1500 pads.

4. So, if the master cylinder above is truly a bolt on fit with a larger bore, then I just have to hunt rotor and caliper specifics.

I'll keep posting here if there is interest....
 
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Update regarding my search for a master cylinder:

Even though I haven't even finished checking the heavy duty/offshore JK master listed above, I may have found another option:

99-2004 Dodge Ram 2500/3500 MC's appear to have the same bolt pattern, same thread size for the brake line attachment ports, and have a 1.25" bore! Have to check on the height of the reservoir to see if it hits the hood, and the push rod length.

I love having options. This one, if feasible, should give considerably more flow than even the upgraded Teraflex (aka OEM BR6 heavy duty brake option master cylinder) unit.
 
Awesome job! Would love to see a write up if you pull the trigger on everything!


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I would be very interested in this as well,as a brake upgrade is on my list.

2011 JKU 3.5 R.E. Longarm lift.
 
Oh, and I forgot to mention... I'm trying to dig up an upgrade option for the rear as well. :) Given the rear is a nice, healthy 12.4" diameter, I am going to explore keeping the size roughly the same, but going from a wimpy 0.5" thick, solid rotor, to something like a 1" thick, vented rotor and a small twin piston or large single piston caliper, if possible.
 
OP dont forget that discs from Teraflax are huge and may need to be ground down a bit to fit in stock wheels. I read it in a JP magazine I have. I will dig it out and post exactly what they said. You have a very accurate thread going and dont want to throw a bunch of falacies in here messing you up.


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Man this is cool info! Big brake kit is on my list. I haven't had any real brake issues yet after upgrading to 37's but I'm wondering if my pads are wearing down at a faster rate then before with the 33's?

Is Wayalife's Moby running a big brake kit? I know in an write up thread he said how many miles he got out of a pair of pads but I don't think what rig he was running them on was mentioned.
 
Philip *AZ* said:
OP dont forget that discs from Teraflax are huge and may need to be ground down a bit to fit in stock wheels. I read it in a JP magazine I have. I will dig it out and post exactly what they said. You have a very accurate thread going and dont want to throw a bunch of falacies in here messing you up.
Click to expand...

Thanks! Yeah. The TF rotors are about 1.25" bigger. Give or take. The J8 rotors are 13.07", While Teraflex claims 13.3" (which I believe is 13.25" more exactly after researching the sizes that the casting houses that actually make the rotors have available). From what I've been able to extrapolate, the 13.07" J8 rotors fit inside 17" rims. Checking my factory Rubi brakes and rims, I have more than 1" available between the back side of the calipers and the inside of the rim. Sooooo.... 13.07" rotor should fit. I'm gonna bust out the calipers and micrometer tomorrow. I need to get some I.D. measurements, though, on several common 17" rims just to get some data.

For reference, my 2007 Dodge Ram 2500 diesel had HUGE 13.9" rotors, thick as hell, but still fit inside a 17" rim because the back side of the caliper was very shallow (there wasn't much metal caliper housing above the top edge of the pads). A efficiently-design caliper might let us run some REAL meaty rotor! :D


Easy brake torque increases do mainly come from the diameter of rotor, but you also need to be able to easily apply sufficient pressure and flow. Thus why I kinda elected to start at the master cylinder and move down.
 
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wow very informative!! looking forward to later posts on this! you deff caught my attention
 
Philip *AZ* said:
I dont want to step on Teraflex, but www.rebeloffroad.com offers another big brake kit. The rotors dont need modification. Looks like a nice kit.
<img src="http://wayalife.com/attachment.php?attachmentid=25175"/>

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Click to expand...

The only issue there is that that kit just upgrades pads and makes your rotors slotted and drilled. That really does little for increasing brake torque. There is no upgrade in rotor size, thickness, or material in that kit. Master cylinder is still unchanged, and rotor size (the most important aspect) is still stock.
 
Brakelabs.com you can get front and rear rotors drilled and slotted for around 240.00, running there rotors on my Charger and they made one hell of a difference, plan on running them on my commander as well, and depending on what this thread turns up, I will run them on my wrangler as well. .

2011 JKU 3.5 R.E. Longarm lift.
 
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