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

[VirtualRonin]

They suggested I try stepping up the rear compounds to something more aggressive than the fronts

Hmmmm...I might have to try that this summer. I'll be interested to see how that turns out for you.




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[VirtualRonin]

Okay, my tapered pad wear isn't just me. Are your pads tapered top to bottom or left to right? I.E. is your thin end of the wedge at the top of the caliper or the leading edge?

I did have my pads in the garage. After looking at them I'm still leaning towards trapped gases in the caliper due to overheating/boiling fluid which caused the uneven pressures and wear on the inside pad. Here are some pics of the pads. The wear isn't all that bad but definitely indicates an issue was present at the time.

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[Questionable]

My old pads look more like your passenger side, but I've forgotten which side was the leading edge. They taper in both left-right and top-bottom, which I didn't notice when I replaced them.

Luckily, fresh pads for the front and rear were delivered today, so I'll be swapping those over this weekend if the weather goes back to pleasant-ish. Sunday it hit the upper 70s, but tomorrow the high is supposed to be mid-30s and there's a winter weather warning for tonight (basically apocalyptic for Texas).

I'll try to take pictures when the pads come off the car and post them here.

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[JDG]

Do you guys consider these "issues" just part of the deal when tracking your car? Your conversation is sort of turning me off of these brakes...

 

[Questionable]

Do you guys consider these "issues" just part of the deal when tracking your car? Your conversation is sort of turning me off of these brakes...

I'm chalking this up to just part of track abuse, not a failure on the brake hardware. They are performing better than the stock front brakes in every respect except pad wear. And it's so much easier to replace the pads now.


EDIT: I should mention that the pads for this kit are about half as thick as the pads for the stock calipers. So this might just be exacerbating existing poor pad wear. I had tapered pads on the stock calipers, too. It was just less of an issue than boiling brake fluid.

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[VirtualRonin]

Do you guys consider these "issues" just part of the deal when tracking your car? Your conversation is sort of turning me off of these brakes...

I think the issues are acceptable. These are still pretty small brakes but a definite improvement over stock. They aren't going to be as effective as say a 330mm brake setup but that's part of the deal when running 15" wheels. My pads were almost worn out so that may have been a factor in the uneven wear. I could have bled my brakes between sessions and that might have helped prevent the uneven wear too. Not many people are running these brakes under track day conditions so we're putting them through their paces. No actual brake failures or brake fade so I'm still very happy with them.


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[Questionable]

As promised, I took a picture of the pads after replacing them. My inside passenger pad had the worst taper, and the driver's side had very little. I guess despite my LSD, the torque vectoring is still more active than I'd like. I also stepped up the rear pad compound this afternoon, so hopefully that will help. The calipers are still leaking, though. They'll get rebuilt next week.

I'm switching to slicks (Spec Miata takeoffs I scored for cheap) for the next event, so I'll check the pads at the end of day when I swap to street wheels to drive to the hotel/home. I'll flip the pads while the wheel's off, since it won't take much more effort.



Just the inside passenger pad, highlighting the taper:

 

[dudhunter]

Thank you for the deep dive on these I’m looking at a set as my next upgrade. Any recommendations on a rear brake upgrade that might balance well with the VMAXX?

 

[Questionable]

Thank you for the deep dive on these I’m looking at a set as my next upgrade. Any recommendations on a rear brake upgrade that might balance well with the VMAXX?

Just more aggressive pads than the front in the stock rear calipers.

Unless you've ditched the factory ABS system, then the ABS does automatic brake biasing.

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[VirtualRonin]

Thank you for the deep dive on these I’m looking at a set as my next upgrade. Any recommendations on a rear brake upgrade that might balance well with the VMAXX?

I did the SVT rear disc upgrade. It was a noticeable difference on track.


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[CFRmotorsports]

Hey guys! Hopefully I can chime in as well. I have ran this kit for about a year and 6 track days so far and ran into the same issue with very very badly tapered pads. I’ve read that can be a case of 4 piston calipers as equal pressure will always eat the leading edge. I also ran into a extremely bad vibration that we chalked up to overheating the pad material and buildup on the rotors. I’ll be running hawk dtc-60‘s this season and also run motul rbf600 and the SVT focus rear upgrade

 

[dudhunter]

Thanks for posting this love the idea of these but I’m a little nervous after hearing about some of the issues. How is the performance? Taking 10 pounds of unsprung weight off each corner is very appealing.

 

[CFRmotorsports]

Thanks for posting this love the idea of these but I’m a little nervous after hearing about some of the issues. How is the performance? Taking 10 pounds of unsprung weight off each corner is very appealing.

Honestly I’m not as impressed as I though I would be, but with that said I’m not done trying to improve to system. I’m reaching out the AP to see if I can get some J hook replacement rotors and with the hawk pads I may be on to something. What I do like about the kit is it IS a improvement and running 15’s anything is better then nothing. It is also extremely easy to switch pads ( even better since they should be rotated after every day to help prevent the tapering).. overall I think it’s a good kit for the money. Being a dedicated track day car it falls a little short of what I’m going after but it is a step in the right direction. I’m also eyeing importing a set of AP bbk that I think could potentially fit under the 15’s but would likely be 2500+ after shipping

 

[AZSP33D]

How's the brake pedal feel compared to stock? To me the stock brakes feel very overboosted touchy especially with proper pads and earlier model pads, but feel good with the 2018 OEM pads. Thanks.

 

[M-Sport fan]

Are there ANY 15" wheels (or even 16") out there which these brakes will NOT fit inside of?
(i.e.; Method MR501VTs)

I am in need of new brakes soon and trying to decide whether I should stick with factory replacement stuff, or go aftermarket fixed caliper fronts, and these are MUCH less coin (a little more than half that kit's co$t) than the (specifically for 15" 'gravel' wheels) gravel spec R2 M-Sport/AP Racing setups.

 

[VirtualRonin]

Are there ANY 15" wheels (or even 16") out there which these brakes will NOT fit inside of?
(i.e.; Method MR501VTs)

I am in need of new brakes soon and trying to decide whether I should stick with factory replacement stuff, or go aftermarket fixed caliper fronts, and these are MUCH less coin (a little more than half that kit's co$t) than the 15" gravel spec R2 M-Sport/AP Racing setups.

V-MAXX has a template available on their website if you want to check the fit with your wheels. Not much info out there as far as confirmed wheel fitment goes. I used the template to confirm the fit with my TD 1.2s before ordering.


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[AZSP33D]

I have a set of these... not sure if this was mentioned but perhaps worth mentioning again if it was.

The calipers are designed with what's called a differential bore.

When installing... don't look at the bleeder position when assigning LH RH, but make sure that the "small" pistons are at the leading edge of the pad (top end) and the large pistons are at the trailing edge, as mine were delivered backwards (bleeders on wrong side but arrow decal correct). The offset bore is designed to reduce wear on the leading edge. Also refer to the part numbers as 03 is LH and 04 is RH.

I see that the OP had the same issue... and in all fairness the instructions do indicate to make sure bleeders are at the top, so that can be confusing, is the sticker correct or the installation of the bleeders and crossover. In my case the sticker was correct as this is where the smaller caliper piston is.

 

[JDG]

I have a set of these... not sure if this was mentioned but perhaps worth mentioning again if it was.

The calipers are designed with what's called a differential bore.

When installing... don't look at the bleeder position when assigning LH RH, but make sure that the "small" pistons are at the leading edge of the pad (top end) and the large pistons are at the trailing edge, as mine were delivered backwards (bleeders on wrong side but arrow decal correct). The offset bore is designed to reduce wear on the leading edge. Also refer to the part numbers as 03 is LH and 04 is RH.

I see that the OP had the same issue... and in all fairness the instructions do indicate to make sure bleeders are at the top, so that can be confusing, is the sticker correct or the installation of the bleeders and crossover. In my case the sticker was correct as this is where the smaller caliper piston is.

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.

 

[AZSP33D]

The pad area is less also... on the positive side, this translates into reduced interference from the nannies and the stock brakes are over boosted and over sensitive without the heat capacity to back it up. If braking balance is better or worse, depends on a few other factors, but we’ll see.
I have the tranny out sitting on the bench, so I haven’t done any testing, but I was not at all happy with the feel of somewhat aggressive (CT1730AX6) pads on the front of the OEM setup, that was a move in the wrong direction for sure.

 

[M-Sport fan]

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