V-MAXX 290mm Big Brake Kit for 15" Wheels

[AZSP33D]

^^^Those are the Carbotech 'autocross' pads?

So, I need to mention that others may have a completely different opinion about this, and that the 2018 all OEM brake setup was great, the 2014 all OEM brake setup was not... and I’ve tried a few different things. I don’t open track the car, or at least haven’t, I have a full blown Superbike for that.

for your question... Yes... have the rears also CT886 AX6, SVTF larger rotor. Unbalanced with too much front braking in my opinion for those pads, happy with those pads on the rear. Now we’ll add the new variable V-MAXX setup with the Ferodo DS pads, no idea what to expect but I’m OK with the specs... in theory We’ll see, none of us are quite satisfied for too long, are we?

 

[ron@whoosh]

I dug into these a little more with measurements from @Questionable . The calipers have a 21% decrease in clamping force when compared to the OEM front calipers (54mm piston), not ideal. Braking torque is about 15% less (due to the larger rotors of the Vmaxx vs OEM). You still get the beneficial heat dissipation from having multiple, smaller pistons though. And because of the decrease in piston surface area, the pedal has to travel less than with OEM brakes.

Typically, you will see a BBK be designed with 0-15% MORE clamping force (calculated using piston surface area on one side of the caliper). You typically do not want to have more than this without upgrading to a larger master cylinder, as pedal travel will considerably increase to move the larger volume of fluid.

In conclusion, I don't think these are a great design. I understand the trade off to fit 15" wheels but I think they would have been better off using 36mm and 40mm pistons rather than 32.5mm and 35.5mm pistons.

I've sent this infoto VMAXX
I'll post their reply when and if they provide one

 

[JDG]

I've sent this infoto VMAXX
I'll post their reply when and if they provide one

Very cool, thanks! Will be interesting to see why they designed them this way.

 

[MagnetiseST]

Very cool, thanks! Will be interesting to see why they designed them this way.

I'm going to guess that it was an existing caliper design that they just made discs to fit. Its an AP racing style pad that the caliper use, I wouldn't be surprised if it wasn't totally bespoke.

 

[VirtualRonin]

I dug into these a little more with measurements from @Questionable . The calipers have a 21% decrease in clamping force when compared to the OEM front calipers (54mm piston), not ideal. Braking torque is about 15% less (due to the larger rotors of the Vmaxx vs OEM). You still get the beneficial heat dissipation from having multiple, smaller pistons though. And because of the decrease in piston surface area, the pedal has to travel less than with OEM brakes.

Typically, you will see a BBK be designed with 0-15% MORE clamping force (calculated using piston surface area on one side of the caliper). You typically do not want to have more than this without upgrading to a larger master cylinder, as pedal travel will considerably increase to move the larger volume of fluid.

In conclusion, I don't think these are a great design. I understand the trade off to fit 15" wheels but I think they would have been better off using 36mm and 40mm pistons rather than 32.5mm and 35.5mm pistons.

I have a hard time agreeing with some of your findings, mainly the claim of decreased clamping force. To help clear things up and further my understanding, can you provide more background information on how you came to the conclusion that these calipers have a "21% decrease in clamping force when compared to the OEM front calipers"? Some math calculations or references would be very helpful.

The idea that these calipers provide less clamping force just didn't make sense to me so I had to do more research. I have provided some proof in the form of mathematical calculations below.

With regard to hydraulics, the equation for force is;

Force (lbs) = Area (sq.in.) x Pressure (psi)

*In the following calculations, I will use 500 psi for the applied braking pressure to simplify things.

To find area of a piston, I will use the equation;

Pi (3.14) x r2 (radius squared)

OEM Caliper
Single piston caliper
Piston diameter: 54mm or 2.13"
Piston area: 3.14 (Pi) x 1.13" (radius squared) = 3.56 sq. inches

Force per caliper: 3.56 (sq. inches) x 500 (psi) = 1,780 lbs

Total force applied (both front calipers) = 3,561 lbs

V-MAXX Caliper
4 piston, differential bore caliper
Large piston: 35.5mm or 1.38"
Small piston: 32mm or 1.26"
Piston area (large piston): 3.14 (Pi) x .48" (radius squared) = 1.50 sq. inches
Piston area (small piston): 3.14 (Pi) x .40" (radius squared) = 1.26 sq. inches
Total piston area: 1.50 x 2 (large pistons) + 1.26 x 2 (small pistons) = 5.52 sq. inches

Force per caliper: 5.52 (sq. inches) x 500 (psi) = 2,760 lbs

Total force applied (both front calipers) = 5,520 lbs

Percentage change:
5,520 - 3,561 = 1,959
1,959 / 5,520 = .35 x 100 = 35% increase

Conclusion

The V-MAXX calipers provide a 35% increase in clamping force due to the increased surface area provided by the 4 pistons versus the OEM single piston.

Feel free to check my math. I want to present the most correct information regardless of how it reflects upon myself or the V-MAXX 290 BBK. The big difference here is the piston surface area that the hydraulic pressure is being applied to. The OEM caliper has one large piston, whereas the V-MAXX caliper utilizes four pistons that have a greater surface area altogether.

References

Piston Area Calculator (used to double check my math, plus a useful tool)
https://brakepower.com/help_abc_27_PAC_t.htm

Basic Hydraulic Formulas
https://flodraulic.com/formulae/basic-hydraulic-formulas

 

[JDG]

I have a hard time agreeing with some of your findings, mainly the claim of decreased clamping force. To help clear things up and further my understanding, can you provide more background information on how you came to the conclusion that these calipers have a "21% decrease in clamping force when compared to the OEM front calipers"? Some math calculations or references would be very helpful.

The idea that these calipers provide less clamping force just didn't make sense to me so I had to do more research. I have provided some proof in the form of mathematical calculations below.

With regard to hydraulics, the equation for force is;

Force (lbs) = Area (sq.in.) x Pressure (psi)

*In the following calculations, I will use 500 psi for the applied braking pressure to simplify things.

To find area of a piston, I will use the equation;

Pi (3.14) x r2 (radius squared)

OEM Caliper
Single piston caliper
Piston diameter: 54mm or 2.13"
Piston area: 3.14 (Pi) x 1.13" (radius squared) = 3.56 sq. inches

Force per caliper: 3.56 (sq. inches) x 500 (psi) = 1,780 psi

Total force applied (both front calipers) = 3,561 psi

V-MAXX Caliper
4 piston, differential bore caliper
Large piston: 35.5mm or 1.38"
Small piston: 32mm or 1.26"
Piston area (large piston): 3.14 (Pi) x .48" (radius squared) = 1.50 sq. inches
Piston area (small piston): 3.14 (Pi) x .40" (radius squared) = 1.26 sq. inches
Total piston area: 1.50 x 2 (large pistons) + 1.26 x 2 (small pistons) = 5.52 sq. inches

Force per caliper: 5.52 (sq. inches) x 500 (psi) = 2,760 psi

Total force applied (both front calipers) = 5,520 psi

Percentage change:
5,520 - 3,561 = 1,959
1,959 / 5,520 = .35 x 100 = 35% increase

Conclusion

The V-MAXX calipers provide a 35% increase in clamping force due to the increased surface area provided by the 4 pistons versus the OEM single piston.

Feel free to check my math. I want to present the most correct information regardless of how it reflects upon myself or the V-MAXX 290 BBK. The big difference here is the piston surface area that the hydraulic pressure is being applied to. The OEM caliper has one large piston, whereas the V-MAXX caliper utilizes four pistons that have a greater surface area altogether.

References

Piston Area Calculator (used to double check my math, plus a useful tool)
https://brakepower.com/help_abc_27_PAC_t.htm

Basic Hydraulic Formulas
https://flodraulic.com/formulae/basic-hydraulic-formulas

I’ll write up a detailed response later tonight but after skimming your calcs, the one major mistake I see is that you are only supposed to be using one side of a multi-piston caliper for the force calculation. I’ll go into more detail as to why that is, but basically, divide your vmaxx value by 2, and you will have the correct answer (although units should be lbs not psi for the final answer).

Jump to the part about “clamp load” and “system pressure” to understand why you only use one side of the disc for the calcs.

http://www.engineeringinspiration.co.uk/brakecalcs.html


Sent from my iPhone using Tapatalk

 

[VirtualRonin]

Interesting....looking forward to your response. Thank you for catching my units mistake, I'll correct that.

 

[JDG]

Made some edits so my calcs read like yours (trying to keep it simple but I think I may have made it more confusing). Let me know if what I wrote isn't clear and I will try again.

Interesting....looking forward to your response. Thank you for catching my units mistake, I'll correct that.

I copy/pasted your response to my calcs so that I could go step by step:

I have a hard time agreeing with some of your findings, mainly the claim of decreased clamping force. To help clear things up and further my understanding, can you provide more background information on how you came to the conclusion that these calipers have a "21% decrease in clamping force when compared to the OEM front calipers"? Some math calculations or references would be very helpful.

The idea that these calipers provide less clamping force just didn't make sense to me so I had to do more research. I have provided some proof in the form of mathematical calculations below.

With regard to hydraulics, the equation for force is;

Force (lbs) = Area (sq.in.) x Pressure (psi)

*In the following calculations, I will use 500 psi for the applied braking pressure to simplify things. We should assume identical line pressure in both cases (OEM being case #1, Vmaxx being case #2) which therefore makes the proportion between the forces in each case and the proportion between the piston areas in each case the same. So no need to actually calculate the forces, you can just compare the areas to get the percentage difference in force. I will compare this at the end of my response.

Basically P1=P2=F1/A1=F2/A2

So the larger the surface area of a caliper, the larger the clamping force of that caliper.

To find area of a piston, I will use the equation;

Pi (3.14) x r2 (radius squared)

OEM Caliper
Single piston caliper
Piston diameter: 54mm or 2.13" Agree
Piston area: 3.14 (Pi) x 1.13" (radius squared) = 3.56 sq. inches Disagree, I will use 3.55 in2 PER SIDE of caliper. Must be multiplied by 2 to get the total clamping area of a single OEM caliper, or 7.1 in2

Force per caliper: 3.56 (sq. inches) x 500 (psi) = 1,780 psi (Disagree, units should be lbf (but as stated above, force doesn't really matter here to get the percentage difference).

Therefore value is 1,775 lbf * 2 = since the caliper is floating and reactionary force has to be identical to that of the piston (Newton's third law)

I think you must have missed the note I underlined below. It is straight from your first cited source on brakepower.com:

Total area of caliper pistons per axle in case of FIXED MOUNT calipers.

This is the area of one piston, multiplied by the number of pistons in one caliper, multiplied by the number of calipers on that axle.

In case of different piston diameters per caliper, calculate the area of every different piston, multiplied by the number in which every one of those different pistons occur in one caliper, add those numbers and multiply the result by the number of calipers on that axle.

Total area of caliper pistons per axle in case of FLOATING calipers: Do the calculation as described above, and multiply the result by two.

Total force applied (both front calipers) = 3,561 psi Disagree, see above

My value is 3,550 lbf Per Caliper or 7,100 lbf total for both calipers

V-MAXX Caliper
4 piston, differential bore caliper Agree
Large piston: 35.5mm or 1.38" Disagree, I have 1.40" Piston Diameter
Small piston: 32mm or 1.26" Disagree, I have 1.28" Piston Diameter (Should be 32.5mm diameter)
Piston area (large piston): 3.14 (Pi) x .48" (radius squared) = 1.50 sq. inches Disagree, 1.53 in2
Piston area (small piston): 3.14 (Pi) x .40" (radius squared) = 1.26 sq. inches Disagree, 1.29 in2
Total piston area: 1.50 x 2 (large pistons) + 1.26 x 2 (small pistons) = 5.52 sq. inches

(1.52 in2 * 2) + (1.29 in2 *2) = 5.64 in2 (Per Caliper)




Force per caliper: 5.52 (sq. inches) x 500 (psi) = 2,760 psi 5.64 in2 * 500psig = 2,820 lbf (Force per Caliper)

Total force applied (both front calipers) = 5,520 psi 2,820 lbf * 2 = 5,640 lbf (Total force of both front calipers)

Percentage change (FORCE)
5,520 - 3,561 = 1,959 7,100 - 5,640 = 1,460 lbf
1,959 / 5,520 = .35 x 100 = 35% increase 1,460 / 7,100 * 100 = 20.5% DECREASE in Total Clamping Force

Percentage change (AREA) (We should get the same result as the force calc above)

7.10 - 5.64 = 1.46 in2
1.46 in2 / 7.10 in2 = 20.5% DECREASE in Area (Same as decrease in Force above)

Conclusion

The V-MAXX calipers provide a 35% increase in clamping force due to the increased surface area provided by the 4 pistons versus the OEM single piston.

Feel free to check my math. I want to present the most correct information regardless of how it reflects upon myself or the V-MAXX 290 BBK. The big difference here is the piston surface area that the hydraulic pressure is being applied to. The OEM caliper has one large piston, whereas the V-MAXX caliper utilizes four pistons that have a greater surface area altogether.

References

Piston Area Calculator (used to double check my math, plus a useful tool)
https://brakepower.com/help_abc_27_PAC_t.htm

Basic Hydraulic Formulas
https://flodraulic.com/formulae/basic-hydraulic-formulas

 

[JDG]

Interesting....looking forward to your response. Thank you for catching my units mistake, I'll correct that.

Sorry I had to edit my response a few times to make it read a bit easier. Let me know if it is confusing to read.

 

[VirtualRonin]

Sorry I had to edit my response a few times to make it read a bit easier. Let me know if it is confusing to read.

It's making more sense now. During my calculations I didn't quite get that I have to multiply the "floating" caliper piston area by 2. There were other errors as well on my part so I appreciate the corrections.

Thanks for clarifying your statement, sharing your reference material, and going through the calculations. I can appreciate your attention to detail.

21% decrease is not good news, but then again I'm not cooking my brakes on the track anymore which is one of the main reasons I upgraded. To be honest, I just assumed 4 piston calipers would increase my braking force because "4 must be better than 1". It's good to understand this system more completely so this was helpful.

You have a StopTech BBK, correct? Maybe you already answered this question in your build thread but I'll ask it here since it's relevant to the discussion. How does that system compare to the OEM caliper? Is there an increase in braking force over OEM?

 

[JDG]

It's making more sense now. During my calculations I didn't quite get that I have to multiply the "floating" caliper piston area by 2. That would have given me similar results to what you found, showing a 21% decrease in force.

Thanks for clarifying and sharing your reference material.

21% decrease is not good news, but then again I'm not cooking my brakes on the track anymore which is one of the main reasons I upgraded. To be honest, I just assumed 4 piston calipers would increase my braking force because "4 must be better than 1". It's good to understand this system more completely so this was helpful.

You have a StopTech BBK, correct? Maybe you already answered this question in your build thread but I'll ask it here since it's relevant to the discussion. How does that system compare to the OEM caliper? Is there an increase in braking force over OEM?

I am still using OEM brake calipers. I think you may be getting me confused with Woods247 who has Stoptech front brakes. In my build thread, I do have some photos of my latest project which does involve upgraded brakes to fit 15" wheels using monoblock calipers. But I am not quite ready to go into details about that yet but it was the reason I dove super deep into the Vmaxx design because it was my initial benchmark since it was the only other kit that fit 15" wheels reasonably well.

The decrease in clamping force is definitely an odd design choice by Vmaxx and why I was voicing my concerns earlier in this thread. I think they likely took a caliper design from a lighter car and built an adapter bracket to work with the fiesta, even if the caliper wasn't properly sized for the fiesta master cylinder and curb weight.

A monoblock aluminum design with multiple calipers is MUCH better for brake cooling when compared to the OEM caliper. Likely why you are still seeing an improvement despite the smaller piston surface area.

Edit: I don't have piston data for the Stoptech brakes, but my guess would be that it has somewhere between 0-25% more clamping force since that is the rule of thumb used by reputable companies for BBK using the OEM master cylinder to ensure pedal feel doesn't get too soft (more piston area requires more fluid to move the piston the same distance as the OEM caliper). The wilwood kit, for example, has an increase in clamping force of 14%.

 

[VirtualRonin]

I am still using OEM brake calipers. I think you may be getting me confused with Woods247 who has Stoptech front brakes. In my build thread, I do have some photos of my latest project which does involve upgraded brakes to fit 15" wheels using monoblock calipers. But I am not quite ready to go into details about that yet but it was the reason I dove super deep into the Vmaxx design because it was my initial benchmark since it was the only other kit that fit 15" wheels reasonably well.

The decrease in clamping force is definitely an odd design choice by Vmaxx and why I was voicing my concerns earlier in this thread. I think they likely took a caliper design from a lighter car and built an adapter bracket to work with the fiesta, even if the caliper wasn't properly sized for the fiesta master cylinder and curb weight.

A monoblock aluminum design with multiple calipers is MUCH better for brake cooling when compared to the OEM caliper. Likely why you are still seeing an improvement despite the smaller piston surface area.

Edit: I don't have piston data for the Stoptech brakes, but my guess would be that it has somewhere between 0-25% more clamping force since that is the rule of thumb used by reputable companies for BBK using the OEM master cylinder to ensure pedal feel doesn't get too soft (more piston area requires more fluid to move the piston the same distance as the OEM caliper). The wilwood kit, for example, has an increase in clamping force of 14%.

I did have your build confused with Woods247, my apologies. I was probably thinking "white Fiesta race car" and got them mixed up for a second.

I appreciate the informative responses. I really think it helped expand my knowledge of not only the V-MAXX BBK, but of braking systems in general. Best of luck with your BBK project, it looks promising.

 

[MagnetiseST]

The decrease in clamping force is definitely an odd design choice by Vmaxx and why I was voicing my concerns earlier in this thread. I think they likely took a caliper design from a lighter car and built an adapter bracket to work with the fiesta, even if the caliper wasn't properly sized for the fiesta master cylinder and curb weight.

I still stand by that it wasn't a bespoke move on their part. It looks like the same caliper that they use for their Abarth kit, and others on their website.

A monoblock aluminum design with multiple calipers is MUCH better for brake cooling when compared to the OEM caliper. Likely why you are still seeing an improvement despite the smaller piston surface area.

So the sole improvement over stock is the cooling effect? Thats sort of disappointing.

 

[AZSP33D]

Flawed argument. Decreased clamping force per hydraulic PSI can be a benefit just as much as increasing, as it's not a fixed PSI system with a hydraulic pump, and these factors are considered for balancing brakes and dialing in brake feel rather than anything to do with braking performance of the caliper.... so if the brakes are over boosted with excessive front bias, it's a positive step in overall performance. Such a reduction in clamping force would not be a reduction in braking capacity if the PSI is variable, it may involve a very slight increase in pedal pressure if all other factors are equal.

 

[M-Sport fan]

So the sole improvement over stock is the cooling effect? That's sort of disappointing.

Also less chance of pad 'knockback' with fixed calipers.

 

[VirtualRonin]

Flawed argument. Decreased clamping force per hydraulic PSI can be a benefit just as much as increasing, as it's not a fixed PSI system with a hydraulic pump, and these factors are considered for balancing brakes and dialing in brake feel rather than anything to do with braking performance of the caliper.... so if the brakes are over boosted with excessive front bias, it's a positive step in overall performance. Such a reduction in clamping force would not be a reduction in braking capacity if the PSI is variable, it may involve a very slight increase in pedal pressure if all other factors are equal.

Interesting point of view, sounds agreeable. Any reference material to help support this? Not to question the idea, but to increase available useful information.

From my understanding, even if the pressure changes you still are always working with a specific surface area of the piston. We were mainly comparing the available piston surface area of the V-MAXX caliper to the OEM caliper. Doesn't matter what pressure you apply, the OEM caliper yields greater clamping force compared to the V-MAXX due to surface area and Newton's third law. Not saying it makes the V-MAXX good or bad, it just interesting to compare and have actual data.

I am personally still very happy with my V-MAXX BBK. At the end of the day, that's all that matters.


Sent from my iPhone using Tapatalk

 

[AZSP33D]

Interesting point of view, sounds agreeable. Any reference material to help support this? Not to question the idea, but to increase available useful information.

From my understanding, even if the pressure changes you still are always working with a specific surface area of the piston. We were mainly comparing the available piston surface area of the V-MAXX caliper to the OEM caliper. Doesn't matter what pressure you apply, the OEM caliper yields greater clamping force compared to the V-MAXX due to surface area and Newton's third law. Not saying it makes the V-MAXX good or bad, it just interesting to compare and have actual data.

I am personally still very happy with my V-MAXX BBK. At the end of the day, that's all that matters.

If the clamping force increase per PSI is the goal, then the resized master cylinders would be the cheap big brake upgrade Brake torque per PSI is more significant than clamping force, but braking improvements are more like problem solving excercises, meaning let's determine what problem needs to be fixed or improved, what are the constraints, and let's develop a solution. From that perspective, one factor may be, do we need to increase or decrease clamping force per unit of PSI? That's a ratio of master to slave area that we're arguing here, and that is a consideration for feel and balance, pedal distance, etc. More rigidity or less flex in the system is usually the right direction in most cases (caliper material design, brake lines, pedals and mounting, etc)... more heat absorption and dissipation capacity is another (mass, diameter, pad and rotor surface area, cooling, etc)... brake torque generated and the balance within the design parameters of the pressures generated (compounds and Cf, diameters, areas, pressures, etc)... so lets put that clamping force into perspective.

 

[Sever]

Anyone know if this will clear oz racing formula hlt 4f 17x7 ET42 wheels?

 

[MagnetiseST]

Anyone know if this will clear oz racing formula hlt 4f 17x7 ET42 wheels?

I'd imagine so, it fits under 15" brakes if you choose the 290mm option.

 

[MagnetiseST]

Update on our set of Vmaxx brakes:

-Flipped the calipers side to side so that they were actually facing the right direction from Vmaxx, thought this might eliminate the pad wear as well.
-Pad wear on track was terribly uneven. Completely ruined a set of EBC orange pads. They probably have another day or two in them but they are so unevenly worn that they are trash.
-Powdercoating on the caliper does NOT stand up to high track temps (its bubbling inside the calipers)

And my biggest complaint: There are NO spare parts available in the US. Ron does not yet stock spare parts for these calipers. We lost a brake pad retaining clip / spring. No big deal right? Wrong, they are $90 shipped from Vmaxx. That is INSANE. The parts are $15 for a pair, then throw in the mandatory FedEx shipping at $56 and the 5% paypal fee and here we are.

Nick Carl has had success with these brakes, but I do not think I can recommend them for a car which is daily driven as well as tracked. The lack of spares and the cost of those same spares makes this as costly as an EBC kit in the long run.