Who has the VAS/wilwood big brake system?

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caferacer

Re: Who has the VAS/wilwood big brake system?

Post by caferacer »

FulviaHF wrote:I can’t directly answer surfingfreeman’s question. But I’ll say that Mark’s right that vented rotors make no sense on the street. Drilling and slotting doesn’t do much of anything there either, but I won’t argue with anyone who wants the boy racer look. Frankly, on the street keeping some heat in the brakes is usually a bigger issue than dissipating the level of heat that will fade the pads. And if retaining heat is the bigger problem, the very last thing you need are vented rotors that dissipate faster. So I’d say stick with solid.

@ Fiatmonkey: sorry, but (as maytag put less delicately) accusing a vendor of dishonesty isn’t any better if you do it indirectly.
+1 to surfingfreeman. This idea of vented rotors only being necessary for the track is the exact opposite of the truth. On the track you will not see any puddles (hopefully), which can quench (in effect, unevenly tempering) your hot brake rotors, potentially causing dangerous warpage. This IS an issue on the street, making vented rotors maybe MORE important on the street than the track, particularly if you enjoy spirited driving on twisties. Thus NO company makes street cars (or vans, or busses, or 18 wheelers) with solid rotors anymore, to speak of.

Really, tell me Peterbuilt was thinking of using the boy racer look for marketing big rigs. :) Or those 18 foot tall Dodge Sprinter cargo vans. They have vented rotors, too. Not drilled/slotted, but vented.
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Kevin1
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Re: Who has the VAS/wilwood big brake system?

Post by Kevin1 »

I have the Whoa 2 setup with the larger rotors. All I can say is they work well and are a worthwhile upgrade, no question about it. Much better than the original brakes were, but still not quite like the brakes we are used to on new cars. I have no idea how they compare to the vented rotors, but if the rotor size and swept areas are similar it seems that the improvement to the braking would be similar. In that regard I think you would be very pleased with either setup.

As cars become heavier and more powerful, vented rotors help manage braking heat better than solid rotors. I don't know how much that comes into play with the average spider as they are still light weight cars and only have around 100 hp. But I can't see how it could hurt if the money's in the budget along with the desire to have them.

If I planned to autocross or do track days I might lean harder toward vented disks. For street use and some rather "spirited" driving I am completely happy with the Whoa kit.
CajunMike
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Re: Who has the VAS/wilwood big brake system?

Post by CajunMike »

Complete novice with brakes here but I can't see how there would be no benefit from a drilled/slotted or vented rotor for street use. I have an auto trans and routinely experienced brake fade just in traffic situations from brake overheating. I know that with the auto much more pressure is put on the braking system because there is no clutch control. Just an observation but better heat dissipation should theoretically help my situation. So what if the pads wear out more quickly. I only care about stopping the car.
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kmac33
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Re: Who has the VAS/wilwood big brake system?

Post by kmac33 »

I have the Whoa kit with solid rotors and LOVE it. Big improvement over the stock brakes. I have never experienced a bit of fade with this set-up even after extended bouts of very "spirited" driving in the mountains.
Kevin McMullen

1974 Fiat Spider - Restoration Complete! But the mods/refinements continue
1980 Fiat Spider
2013 Subaru WRX
TX82FIAT
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Re: Who has the VAS/wilwood big brake system?

Post by TX82FIAT »

So general opinion seems to be that the drilled and slotted rotors do help in some situations. I agree. We all take heat for various opinions expressed at some point. Boy Racer look! Ha! LOL! :lol: :lol:
Buon giro a tutti! - enjoy the ride!

82 Fiat Spider 2000
03 BMW M3
07 Chevy Suburban
FulviaHF

Re: Who has the VAS/wilwood big brake system?

Post by FulviaHF »

caferacer wrote: Really, tell me Peterbuilt was thinking of using the boy racer look for marketing big rigs. :) Or those 18 foot tall Dodge Sprinter cargo vans. They have vented rotors, too. Not drilled/slotted, but vented.
The physics here isn't complicated. Kinetic energy is mass times the square of velocity, and disc brakes work by converting kinetic energy into heat, dissipating that heat over the total surface area of the brake rotors. Vented rotors have approximately twice the surface area of solid rotors, and therefore dissipate heat at approximately twice the rate of solid rotors, diameter for diameter. Traveling at the same speed, a Peterbilt pulling a loaded semi-trailer is carrying about 25 times the kinetic energy of a Spider, yet the semi doesn't have anywhere near 25 times the total swept rotor area of a Spider. Therefore the semi has much longer stopping distance from the same speed, and transfers far greater heat into its rotors. Again, vented rotors transfer heat about twice as efficiently as solid ones, but it always comes down to the proportion of intertial mass to total rotor surface, and that's still far greater on a loaded semi than a Spider. So that's why Peterbilt uses vented rotors.

But tell me the last time you saw cherry-red glowing brake rotors on a street-driven Spider. Or the last time you heard reports of Spider brakes bursting into flames at the bottom of a long downhill grade.
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maytag
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Re: Who has the VAS/wilwood big brake system?

Post by maytag »

FulviaHF wrote: But tell me the last time you saw cherry-red glowing brake rotors on a street-driven Spider. Or the last time you heard reports of Spider brakes bursting into flames at the bottom of a long downhill grade.
or even on the racetrack, for that matter.
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
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Curly
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Re: Who has the VAS/wilwood big brake system?

Post by Curly »

If you're interested in a ventilated kit that fits inside 13" wheels, this is one way to go.

Image

The kit is available through Bits of Italy in Melbourne, Victoria, Australia. http://www.boiperformance.com.au/performance-parts
It utilises Alfa 33 Ti ventilated rotors and Renault Fuego calipers. I use them on my AC coupe which is primarily a classic tarmac rally competition car as well as my more mildly tuned Spider.

Here's how they look with a 15" wheel:

Image

I've tried various pad compounds, and never had them fade on the Spider, but under very severe provocation I've still had a degree of fade from a set of EBC yellowstuff racing the coupe on a tight tcircuit. Next stage is to duct air onto the brakes.
surfingfreeman
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Re: Who has the VAS/wilwood big brake system?

Post by surfingfreeman »

Hi curly
Thanks for the heads up on that kit, but @ $1400 it's a bit pricey for a similar sliding caliper system with single piston as opposed to the Wilwood caliper with 4 pistons.
vandor
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Re: Who has the VAS/wilwood big brake system?

Post by vandor »

TX82FIAT wrote:So general opinion seems to be that the drilled and slotted rotors do help in some situations.
Well, I disagree a bit.
Rotors are drilled for lightness. However, since the total unsprung weight of the Spider suspension is around 60-80 lbs per corner, a drilled rotors that is 100 grams lighter will not make much difference.
Rotors are slotted to allow the pads to de-gas (let out gas), however modern brake pads do not need that, as they do not create gases.
A drilled/slotted rotor is lighter than a solid one, so it has less mass to absorb the same amount of heat, therefore it may be marginally worse for high-performance driving.
Csaba
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opus10583
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Re: Who has the VAS/wilwood big brake system?

Post by opus10583 »

Hi,

You've just save me ~$150, thanks.

What was the change in pad composition that leads to no gas generation?

Mark

vandor wrote:
TX82FIAT wrote:So general opinion seems to be that the drilled and slotted rotors do help in some situations.
Well, I disagree a bit.
Rotors are drilled for lightness. However, since the total unsprung weight of the Spider suspension is around 60-80 lbs per corner, a drilled rotors that is 100 grams lighter will not make much difference.
Rotors are slotted to allow the pads to de-gas (let out gas), however modern brake pads do not need that, as they do not create gases.
A drilled/slotted rotor is lighter than a solid one, so it has less mass to absorb the same amount of heat, therefore it may be marginally worse for high-performance driving.
...Yes; I know what it means: Fabbrica Italiana Automobili Torino.

DOLCETTO: 1978 CS1; 10:1, DMS, 4-2-1...
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maytag
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Re: Who has the VAS/wilwood big brake system?

Post by maytag »

surfingfreeman wrote:Hi curly
Thanks for the heads up on that kit, but @ $1400 it's a bit pricey for a similar sliding caliper system with single piston as opposed to the Wilwood caliper with 4 pistons.
I agree, that's a chunk of change.
However your statement made me remember something I heard argued once, that is a valid point to consider, and if you're planning to purchase, maybe research.
I've heard that the Wilwood calipers offer no dust-seals. Apparently designed for racetrack use where they would be cleaned / inspected / rebuilt more frequently. But that for road use, this can cause issues?

Again, this isn't first-hand. And my use of my Spider isn't far off from some racers' routines as far as maintenance & care goes. You may be the same. ?? (I think I put 800 miles on my spider last year, and hear it is apart again in my shop :roll: )
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
surfingfreeman
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Re: Who has the VAS/wilwood big brake system?

Post by surfingfreeman »

excellent point maytag and worth some investigation as this is my everday driver so it would see alot more of those unsavory elements which might well cause trouble to a dust-coverless piston.
So Cal Mark

Re: Who has the VAS/wilwood big brake system?

Post by So Cal Mark »

Wilwood makes lots of street upgrade kits, so I'd find it hard to believe none of them have dust seals. I can imagine a race-only caliper without dust seals, but not a street caliper
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