Hey majik I need brakes, my feet are getting sore.. Just sayin'. 
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My own JK 'Big Brake' research:
- Thread starter Majik
- Start date
I thought you were wheeling? We playing musical forums now? Lol
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Majik
Member
Hey guys. Thanks for all of the patience and support. As you all know, this project is a research project, and sometimes during research, you find that the direction you were originally heading runs into an issue. One issue I've encountered involves the available thickness of the test adapter bracket I've machined for the caliper. The rotor I've been working around meets alot of criteria that needed to be met, however, because we are using a fixed caliper, the offset (aka rotor hat height) of the rotor dictates the caliper position. And with the caliper in the correct position, the available space between the mounting tabs of the caliper and the mounting holes on the knuckle is only around 0.200".
After much analysis (and thus alot of my delay in releasing updates), I've determined that I do NOT think that this is enough material to support a caliper trying to suddenly stop a 120+ lb 37" wheel/tire combo, spinning at 70+mph. The massive forces involved have the potential to deflect the adapter bracket at this thickness, and that's not a good thing. Now, there are some adapters out there in this thickness range, but they are mainly being used on lightweight muscle car wheel/tire setups that may only be 50 lbs total. I simply don't like this for use on our rigs. I think that this is one of the issues that has prevented the mass release of Big Brake Kits for JKs from tons of manufacturers.
The JK uses a PITA combination of a very shallow rotor with oddly spaced mounting points on the knuckles. This severely limits my options. HOWEVER...there is good news
I believe I have located a different rotor that will allow me to increase the caliper adapter/bracket thickness to around 3/8" (0.375"), which would be perfect for our use. I hope everyone understands that this is why I haven't just thrown the part numbers I've experimented with out there... I know that there are some that would rush out to buy parts, and then be irritated when I was forced to change direction. I will already eat the cost of the rotor, possibly the caliper, and maybe even the Reid knuckle I machined.
In an effort to make this phase of the project work, I even went so far as to mill down the thickness of the caliper mounting tabs on the knuckle. If I mill 0.150" thickness off the outer side of the mounting tabs on the knuckle, then I can add that thickness to the adapter bracket. But I realized that this is moving the project far away from even more listeners, if I continue to machine the knuckles, etc trying to FORCE the rotor/caliper combo I chose to work. And I really want to make this as close to a bolt-on fitment as possible...to make it available to more people! So, I'm rethinking the direction of the parts selection and going to see if we can make this work with NO knuckle modification. And I think we can... :clap2:
So...the point of my ramble is: Let me spend my money to make this work. I know I'm going to eat some of the mistakes I make along the way, but I'm really, really close to finding the magic combination. And I would much rather only one of us loses a few bucks instead of several of us. So, please be patient. I will continue to post updates. I hope that I haven't irritated too many of you with the slow progress. I really, really want to contribute this back to everyone that has been so supportive...I just want to contribute a QUALITY solution, however...not just a half-assed fix. I look at it this way: if this parts selection process was simple, there would be 20 different JK brake upgrades out there, right?
The final pieces of my complete JK makeover project just arrived today from Brown Santa, and are sitting in the garage, so I have PLENTY of inspiration to bust my ass and get this brake upgrade finalized!! I hope a few of you continue to follow...
After much analysis (and thus alot of my delay in releasing updates), I've determined that I do NOT think that this is enough material to support a caliper trying to suddenly stop a 120+ lb 37" wheel/tire combo, spinning at 70+mph. The massive forces involved have the potential to deflect the adapter bracket at this thickness, and that's not a good thing. Now, there are some adapters out there in this thickness range, but they are mainly being used on lightweight muscle car wheel/tire setups that may only be 50 lbs total. I simply don't like this for use on our rigs. I think that this is one of the issues that has prevented the mass release of Big Brake Kits for JKs from tons of manufacturers.
The JK uses a PITA combination of a very shallow rotor with oddly spaced mounting points on the knuckles. This severely limits my options. HOWEVER...there is good news
I believe I have located a different rotor that will allow me to increase the caliper adapter/bracket thickness to around 3/8" (0.375"), which would be perfect for our use. I hope everyone understands that this is why I haven't just thrown the part numbers I've experimented with out there... I know that there are some that would rush out to buy parts, and then be irritated when I was forced to change direction. I will already eat the cost of the rotor, possibly the caliper, and maybe even the Reid knuckle I machined.
In an effort to make this phase of the project work, I even went so far as to mill down the thickness of the caliper mounting tabs on the knuckle. If I mill 0.150" thickness off the outer side of the mounting tabs on the knuckle, then I can add that thickness to the adapter bracket. But I realized that this is moving the project far away from even more listeners, if I continue to machine the knuckles, etc trying to FORCE the rotor/caliper combo I chose to work. And I really want to make this as close to a bolt-on fitment as possible...to make it available to more people!
So, I'm rethinking the direction of the parts selection and going to see if we can make this work with NO knuckle modification. And I think we can... :clap2:So...the point of my ramble is: Let me spend my money to make this work. I know I'm going to eat some of the mistakes I make along the way, but I'm really, really close to finding the magic combination. And I would much rather only one of us loses a few bucks instead of several of us. So, please be patient. I will continue to post updates. I hope that I haven't irritated too many of you with the slow progress. I really, really want to contribute this back to everyone that has been so supportive...I just want to contribute a QUALITY solution, however...not just a half-assed fix. I look at it this way: if this parts selection process was simple, there would be 20 different JK brake upgrades out there, right?
The final pieces of my complete JK makeover project just arrived today from Brown Santa, and are sitting in the garage, so I have PLENTY of inspiration to bust my ass and get this brake upgrade finalized!! I hope a few of you continue to follow...
No worries,Doc. Brown Santa brought me some shoes to tie me over. Let me know if you need help sourcing anything, I'm through your area a couple times a week.
We are Jeep..Resistance is futile..
We are Jeep..Resistance is futile..
OhhSeven
New member
Hey man take your time and do it right (which you already are). You are messing with the most important system on the entire vehicle. I'm more comfortable with with quality vs. speed on this one. Personally, I appreciate all of the effort you have into this even if it validates that some of the products currently on the market are as good as it's gonna get.
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Majik
Member
Update!
So I decided today to swallow my pride and set out to see if there was a better solution out there that was still along the same lines as the path I've been travelling so far with this project...
Let's just say that:
1. I found a nice, fat, 14" rotor with even less offset than the last one I was using. Oh, and it's still off the shelf at your local parts store.
2. I found a late model vehicle with 4 piston calipers, from the factory, with MUCH larger caliper piston bores (thus more potential clamping force at the pads), and is MUCH more common a vehicle than my last donor.
I was so pumped and optimistic, that I drove one with 35" tires on it (this is not a vehicle that hardly a soul that I am aware of has EVER put 35" tires on), pulled the ABS fuses, and wailed on the brakes so hard and so often that I needed to clean the wheels when I was done. I was able to lock all 4 wheels at will, up to 55mph (as fast as I was willing to lock 4 tires), and do it repeatedly.
And you know what was also reassuring??? The master cylinder bore size (which has been a problem thus far with so many potential choices for calipers) is actually SMALLER than what is stock on our JKs!
I was really scared to put aside what was what I thought a great combo, however, instead, I used my first attempt as insight into details I needed to fine-tune with the second trial. I learned that a fixed caliper, if possible to find a good one for our use, is really a good choice for better pad pressure distribution, easy pad changes, and better heat dissipation. I learned that 14" is the magic rotor size that we have to stick to to still have a chance at keeping 17" wheels. I learned the necessary clearances and rotor offsets to allow a caliper adapter to be sufficient thickness...
So I am going to buy a test caliper tomorrow. Really excited. And am trying to learn from prior mistakes and be willing to change directions. The benefit is that I am going to avoid knuckle machining to try and make this an easier install for everyone still listening. After driving a vehicle with 35s and these factory calipers, I'm pumped!! :rock: It's nice to have the reassurance of feeling all four 35" wheels lock easily, over and over again, knowing that that is the kind of brakes I'm shooting for...
Thanks for following
So I decided today to swallow my pride and set out to see if there was a better solution out there that was still along the same lines as the path I've been travelling so far with this project...
Let's just say that:
1. I found a nice, fat, 14" rotor with even less offset than the last one I was using. Oh, and it's still off the shelf at your local parts store.
2. I found a late model vehicle with 4 piston calipers, from the factory, with MUCH larger caliper piston bores (thus more potential clamping force at the pads), and is MUCH more common a vehicle than my last donor.
I was so pumped and optimistic, that I drove one with 35" tires on it (this is not a vehicle that hardly a soul that I am aware of has EVER put 35" tires on), pulled the ABS fuses, and wailed on the brakes so hard and so often that I needed to clean the wheels when I was done. I was able to lock all 4 wheels at will, up to 55mph (as fast as I was willing to lock 4 tires), and do it repeatedly.
And you know what was also reassuring??? The master cylinder bore size (which has been a problem thus far with so many potential choices for calipers) is actually SMALLER than what is stock on our JKs!
I was really scared to put aside what was what I thought a great combo, however, instead, I used my first attempt as insight into details I needed to fine-tune with the second trial. I learned that a fixed caliper, if possible to find a good one for our use, is really a good choice for better pad pressure distribution, easy pad changes, and better heat dissipation. I learned that 14" is the magic rotor size that we have to stick to to still have a chance at keeping 17" wheels. I learned the necessary clearances and rotor offsets to allow a caliper adapter to be sufficient thickness...
So I am going to buy a test caliper tomorrow. Really excited. And am trying to learn from prior mistakes and be willing to change directions. The benefit is that I am going to avoid knuckle machining to try and make this an easier install for everyone still listening. After driving a vehicle with 35s and these factory calipers, I'm pumped!! :rock: It's nice to have the reassurance of feeling all four 35" wheels lock easily, over and over again, knowing that that is the kind of brakes I'm shooting for...
Thanks for following
OverlanderJK
Resident Smartass
At this point isn't it just easier to buy the teraflex big brake kit? :thinking:
Majik
Member
Not putting on lift and tires. Need Jeep to get to work
I have the Hutchinsons mounted with Toyo 37s. Leaning against the wall next to thw Jeep in the garage... (sniff...) I work in the ER and I often get to see the result of what happens when people forget the safety features to simply have fun... :/ Brakes...then tires.
Majik
Member
Easier, yep. What I want out of brakes, Nope. Because IMO, its not that big of an upgrade. Thats only my opinion...and that isn't worth much. But if for the same price and a little research I can do 14" rotors and 4 piston big calipers on FOUR wheels, thats what I am gonna do
TF has a great product. Its just doesnt achieve what I am looking for.
Majik
Member
It is not a single system. Rotors from one and calipers from something different. It gets really complex trying to use OEM stuff and achieve far beyond OEM performance. But it is doable
I have withheld the details to keep people from buying parts that I then find a conflict with...like I did last week. I get PMs constantly asking for part numbers. Dont worry. Im not looking to make money on this. I will divulge it all in detail the day I bolt it on and lock all four 37s up from 50mph
My goal is to help make us all safer...not to make a profit on this. Sometimes we all have to just give a little back for the good of it....
10frank9
Web Wheeler
It is not a single system. Rotors from one and calipers from something different. It gets really complex trying to use OEM stuff and achieve far beyond OEM performance. But it is doable
I have withheld the details to keep people from buying parts that I then find a conflict with...like I did last week. I get PMs constantly asking for part numbers. Dont worry. Im not looking to make money on this. I will divulge it all in detail the day I bolt it on and lock all four 37s up from 50mph
Sometimes we all have to just give a little back for the good of it....
Sounds like a plan. I'm waiting patiently for this info.
DunnyBunny
Member
Great job man I haven't seen this much dedication from anyone else on here so keep it up. Ill be looking into whatever your final product will be. All 4 wheels for the price of teraflex front only is pretty sweet.
Majik
Member
Thanks for the kind words, guys. I've wanted to beat my head on the wall a few times, but when you are trying to do in your garage what Mopar has a team of engineers to figure out, I kinda expected bumps in the road. It is close, though.
Another fun detail tonight: I'm gonna go do some informal testing with the ABS disabled in the Jeep tonight and see how the weight distribution affects wheel lockup. This helps me to determine caliper piston sizing front versus rear to keep brake bias ideal. What I want to see by repeated hard braking is if the Jeep already has decent bias, or if I may be able to adjust caliper sizes in my project to improve this. I've found that alot of factory systems could actually use a touch more rear-wheel braking power and thus not rely quite as much on the fronts. But it's usually not alot of difference. Every bit helps, though.
That means alot of fun, hard stops. I'll post the results.
Another fun detail tonight: I'm gonna go do some informal testing with the ABS disabled in the Jeep tonight and see how the weight distribution affects wheel lockup. This helps me to determine caliper piston sizing front versus rear to keep brake bias ideal. What I want to see by repeated hard braking is if the Jeep already has decent bias, or if I may be able to adjust caliper sizes in my project to improve this. I've found that alot of factory systems could actually use a touch more rear-wheel braking power and thus not rely quite as much on the fronts. But it's usually not alot of difference. Every bit helps, though.
That means alot of fun, hard stops. I'll post the results.
