My own JK 'Big Brake' research:

Majik said:
Well I just didn't want it to end up being a "you can bolt it on, but only if you have < 4 in of wheel backspacing, with only certain brands of wheels, only installed on the second Tuesday of the month, and an angle grinder might be needed..." kind of 'Bolt-On'. ;)

It was just a matter of doing a little more thinking to make up for a slightly smaller rotor (but still much bigger than stock) with other ways of improving the brake torque. Like I discussed way, way back... we can gain from either rotor size increase, clamping force increase, or pad to rotor friction increase. So I'm just focusing a little more towards #2 and #3 on that list. Where I should have been focused all along :D...
Click to expand...

Really cool to see this approached by looking at so many aspects of the "big picture" :rock:

Kudo's to you Majik :thankyou: If you happen to make to San Diego sometime Cold beer is waiting in the shop fridge :beer:
 
i just picked up a jk front d44 for my wj and i'm excited to see the end result of this! thanks again for your hard work!!!
 
Thanks for all the hard work Majik. The project looks amazing and can't wait to see the final project. I can't believe I read through all 51 pages in one sitting. My head is killing me. :banghead:

I look forward to seeing a simple JK8 inspired bit on kit as well as the dual caliper design, should you keep pursuing that route.
 
I too am waiting for this mod........ I tow a pop up camper with my 12' JKU and would like some more stopping power.
 
Majik said:
14" will work with the 17" wheels. I agree...18s just limit tires too much.

Thank you all for staying tuned. Almost there! I just keep thinking of it this way: If it was an easy kit to produce, then there would be bunches out there to choose from. If only a rare few companies that do such mods as their business have been able to put a kit together, then I feel better about the time, difficulties, and effort I've put into it. Thanks again for your support. It will be worth it...
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Signed up for wayalife just to subscribe to this thread. Thank you Majik for all your work! Any new developments? I'm hoping to upgrade my fronts and rears soon. Rear pads are almost gone.
 
did I miss where...

this became a done deal, or are you still working on it? I saw the pics of test fitting the beatlocks over the calipers etc, but I didn't see any finished product did I just miss that page?
 
jknit said:
this became a done deal, or are you still working on it? I saw the pics of test fitting the beatlocks over the calipers etc, but I didn't see any finished product did I just miss that page?
Click to expand...

nah, I think it's still in progress...like many of us I'm sure the end of year holidays, family, real job, just put it on the burner...but we hope to hear something soon!

I have wheels and 37's ready to mount, I think my brakes will work just fine but always nice to have that extra confidence.
 
jeeeep said:
nah, I think it's still in progress...like many of us I'm sure the end of year holidays, family, real job, just put it on the burner...but we hope to hear something soon!

I have wheels and 37's ready to mount, I think my brakes will work just fine but always nice to have that extra confidence.
Click to expand...

for sure, I didnt mean it as a criticism, all the work he's done is amazing I just wanted to make sure I didn't miss anything
 
Hello again to everyone and thanks for the kind words and following along! First, no, I haven't given up :). Just as was mentioned by a few above, the holidays , family stuff, etc have limited my updates.
I'm falling asleep while typing this so I will give a concise update:
-- calipers are chosen. Four piston fixed. Common donor vehicle.
-- had to redesign adapter bracket - this has been largest delay
-- have put dual caliper option on hold mainly due to finding a larger, much more rigid single caliper. Dual caliper option required smaller caliper with less rigidity.
-- have learned that rigidity is key to brake feel and efficiency. Spoke with numerous performance braking specialists regarding this.
-- have chosen new rotor to allow more clearance with wider range of wheels. slightly smaller, but calculations and experts have shown this will be negligible given massively stronger caliper.

-- really cool point --> have been in contact with a popular brake manufacturer regarding pad selection, trying to maximize cold coefficient of friction (mu). Have found pad with mu of 0.53 cold, which rises when hot (like a race pad does) to over 0.62 when hot. For comparison, our average OEM pad is in the ballpark of 0.36 when cold and drops when hot. This is a huge point that can't be overstated. That means a 50% increase in brake torque cold with nothing but pads. Wow. Nearly all pads that reach a mu of 0.60+ are crazy rare sintered pads for supercars or motorcycles. And, when cold, they usually suck with a mu of around 0.3. This is amazing.

(OK... Here is the geek section so tune out now if you dont like this part...)

Keep in mind that the braking force is the caliper clamping force times this "mu" coefficient. So if you increase mu from 0.40 to 0.50, you get a 25% increase in brake force (which is then multiplied by rotor radius to get brake torque). For comparison, a "big brake conversion" simply increasing rotor diameter from 12" to 14" only increases brake torque by 16%. So pads are THAT important. We are talking potentially a 40-50% increase from pads alone! (Again, OEM mu = 0.36 to new mu = 0.53). We can't forget however that brake torque is dissipated as heat, and has to go somewhere, so a larger and thicker rotor with a good vent design is still a wise part of this equation.

OK...that wasn't so concise. Anyway, I thank you all for your kind words and patience. Once the brackets are finalized, I am ready to release the parts list. The special pads aren't due for availability until next month.

Sent from my Nexus 7 using WAYALIFE mobile app
 
Awesome! I have one question about the calliper bracket. Is your machine shop going to build 200 of these things and sell them to guys wanting the upgrade or do you plan on just releasing the specs so that guys can have their own bracket built locally?
 
I was just planning on posting the CAD drawing with a liability disclaimer but I'm sure I could convince the machine shop to do it :) I just don't want people to think I'm trying to turn a profit on it. And, honestly, I don't want to get into a liability issue. Everything I build is overbuilt, so I'm confident in it in the utmost... I wouldn't put my kids in the Jeep if I wasn't. But... I've already had to deal with rumblings of legal stuff regarding this personal little project. In fact, I think that is the reason I haven't heard a peep from some of the main guys on this forum... and I understand how that goes. It's unfortunate but understandable. Who knows, though... maybe it could eventually be a 'Wayalife' logo'd upgrade :)
 
Hey Majik, can you give us an idea what the rear upgrade will look like? You mentioned before that you were working on an upgrade for the rears at the same time. Is this still the case. Thanks again
 
I am so glad I found this thread. I was linked to it starting at page 22, tho'.
Doin' the roundy-round with distributors, looking for the BR6 components, always leads to a dead-end.

One thing I took notice of in your calculations, Majik, was the one piston vs two piston line of thinking. I am not an engineer nor have any formal training in the field but I did have a two cent thought. Tell me I'm going down the wrong path, if I am.

While I agree with the piston areas being used to determine an appropriate MC, I'm not so sure about that calculation being relevant at the pad, if in fact you used it as such. My thoughts, calculated off the top of my head for "close enough for examples sake", do not attempt to take into account any reasoning you may have previously relayed.

Let's say your single piston is 4" diameter and your dual pistons are 3" diameters, about an 1.5" difference in area. (Like I said, close enough).
Now look at the circumference of each...I went there cuz it's only the lip of the pistons exerting pressure on the pads.
4" dia. piston x1 = about 12.5" circ.
3" dia. piston x2 = almost 19" circ.

It seems to me, and I've since noticed your decision to use multiple piston calipers, that the multi-piston set-up is preferred simply due to the applied pressure being spread out roughly 50% more.
So, does using a larger pad with the same pressure affect a similar net increase of friction or is more pressure necessary to account for the increased pad to rotor contact area?

Anyway, I'm glad you're smarter about it than I am and look forward to the final results.
Thanks for undertaking this brobdingnagian endeavor.

FYI, my limited brake knowledge is centered around competitive roadracing motorcycles. If it weren't for the thin solid rotors we use, there'd be a ton of fairly standard mounted calipers from which to choose. And, yeah, pads definitely make a difference.
 
funfred said:
I am so glad I found this thread. I was linked to it starting at page 22, tho'.
Doin' the roundy-round with distributors, looking for the BR6 components, always leads to a dead-end.

One thing I took notice of in your calculations, Majik, was the one piston vs two piston line of thinking. I am not an engineer nor have any formal training in the field but I did have a two cent thought. Tell me I'm going down the wrong path, if I am.

While I agree with the piston areas being used to determine an appropriate MC, I'm not so sure about that calculation being relevant at the pad, if in fact you used it as such. My thoughts, calculated off the top of my head for "close enough for examples sake", do not attempt to take into account any reasoning you may have previously relayed.

Let's say your single piston is 4" diameter and your dual pistons are 3" diameters, about an 1.5" difference in area. (Like I said, close enough).
Now look at the circumference of each...I went there cuz it's only the lip of the pistons exerting pressure on the pads.
4" dia. piston x1 = about 12.5" circ.
3" dia. piston x2 = almost 19" circ.

It seems to me, and I've since noticed your decision to use multiple piston calipers, that the multi-piston set-up is preferred simply due to the applied pressure being spread out roughly 50% more.
So, does using a larger pad with the same pressure affect a similar net increase of friction or is more pressure necessary to account for the increased pad to rotor contact area?

Anyway, I'm glad you're smarter about it than I am and look forward to the final results.
Thanks for undertaking this brobdingnagian endeavor.

FYI, my limited brake knowledge is centered around competitive roadracing motorcycles. If it weren't for the thin solid rotors we use, there'd be a ton of fairly standard mounted calipers from which to choose. And, yeah, pads definitely make a difference.
Click to expand...

I wouldn't think that circumference matters as much as area does. The area difference is significantly different.

Sent from my SGH-M919 using WAYALIFE mobile app
 
Funfred... I will try to answer your question as best as I understand it.

The calculation of piston area is simple. The pressure in a hydraulic system is equal on all internal surfaces of the system. So... If you have a 1000psi line pressure, then you have 1000psi on the caliper piston(s). If your piston area is 4 Sq inches, then u have 4000lbs of force on the rotor. If you increase piston surface area to 6 sq. inches, then you have 6000lbs of brake force. So that is the simple part.

The piston lip pushes on the backing of the pad. Part of the reason this is done is to minimize contact area with the pad to avoid heat conduction into the piston and thus the brake fluid. The pad is rigid enough that it is assumed that the pressure from the piston, applied to the rigid pad backing plate, is roughly equal to that applied if the piston was solid. The pad doesn't really deflect enough directly under the edge of the piston to matter, so the circumference issue you mentioned is not really an issue.

My push toward a multi piston setup is not really for multiple pistons, but more for a FIXED CALIPER, which incidentally only comes in a multi piston setup. The fixed caliper helps us because of the rigidity inherent in them, not so much by the number of pistons. I recently made a video of the caliper flexing when you mash down on the brake pedal. The amount that the crossover bridge flexes and spreads open when u really hit the brakes is insane!! This is a key point: When it flexes, it indirectly slides the cylinder bore away from the piston (towards the frame of the vehicle) and so more brake fluid has to pour in to fill this expanding chamber, even though no extra brake force is being added to the pads. When fluid rushes in, your pedal gets mushy. This phenomenon is often thought to be because of the "fluid boiling", but most often, it is because of flexing of the caliper. Fluid rarely boils in daily driver applications. I proved this in my little homemade video clips by reproducing the same mushy pedal under hard brake force with the VEHICLE STANDING STILL!! So no heat added. Just flex.

So caliper flex is the enemy. To combat this further, a non-aluminum caliper is ideal. Aluminum flexes more as it gets hot, while a cast iron or stainless caliper does not have this issue. The caliper I have selected for the front is a massive, overbuilt four-piston two piece caliper. The first test caliper in my photos from months ago (the red one) is a three piece, and two of the three are aluminum. Three piece means more seals to leak and less rigidity, so I moved on to a better caliper. But it's sheer mass required a slight downsizing of the rotor to fit the caliper without its top side hitting the rim.

So... Don't worry about the piston edge concern. The force is distributed evenly across the pad even though the piston is hollow. And four pistons are plenty. Any bigger requires funky pads due to shape, and the caliper gets less rigid due to having to be so long and curved. Four pistons are plenty, but it is the fixed caliper, matched well size-wise to the master cylinder, that is the important part.

Hope that helps!!
 
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