We expect that to be IRO $700-800 per axle.

 

[QUOTE=Gasman2;2650072]If you are a track junkie then race pads and race fluid is required
brake fade is the fluid becoming too hot to function [QUOTE=Gasman2;2650072]

With all due respect, brake 'fade' is classically when the pads are overwhelmed (i.e. too much input when new, and off-gassing of the glues OR more common, the pads cannot handle the heat input and no longer provide the rated friction coefficient).

Fluid 'becoming too hot to function' is called boiling of fluid. This is when the cooling of the brakes is insufficient to draw the heat off the rotors enough to where the fluid boils. The heat source is the (likely unfaded) pads transferring heat through the backing plates, through the pucks, and into the calipers where they continue to heat up until the fluid is beyond it's rated temperature.

 

Unfortunately braking optimization reduces lap times far less than exit times from corners. This hypothesis assumes you have reasonably good brakes to begin with. If your brakes to start with are crap, this response does not apply.

For anything other than flat out racing, people get all too excited about trail-braking, 99/100s (vs. 9/10ths) braking and think it's nirvana. The reality is you can screw up a line so fast by being just a bit too hot INTO a turn that you blow the lap time due to the exit (primarily exits on long straits). Here you may have optimized 0.05 seconds in braking to blow 0.2 seconds due to your exit speed being compromised (integrate the area under the curve - exit speeds are the key to lap time reduction).

For even aggressive track event driving - focus on THE LINE. You'll do far better than trying to eek out another 5% of your brakes. More importantly, if you overdue the brakes and go off track, you can rack up lots of dollars in damage repairs. Is this really what makes sense with a street car having the occasional fun on the track? I'm not talking my inexpensive Fox body Mustang that's not a lot of money - we're talking F types here. They are fabulous cars.

EDITED to state - BTW - I love VAP and their products. My remarks are not directed to them nor an attempt to denigrate their products. In my experience they truly vet and test all of their products so that you clearly know what you're getting.

 

Difficult to say in the 1/4 Mile, lots of variables there. If you look at static weight, dropping 50lbs out of a 3800lb 550bhp car the car is equivalent of adding 7-8 BHP in terms of power to weight ratio. So, not a whole lot. However, we know rotating mass has a much higher influence than static mass. Most people will usually use a rough ration of 4:1. If that's accurate, you're looking at something comparable to 200lbs static mass reduction, which would be similar to adding 30BHP.

Another rough calculation on ET, using a 550BHP 3800lb car, versus 550BHP 3600lb car does estimate a 0.2 second improvement. So, it's entirely possible but yet to be proven!!!

In terms of overall performance, I think it is significant. When I was attending and helping out with data on a bunch of Pirelli World Challenge events 8 years back, they would look at a bunch of things to equalize BOP. They were working off the rough estimate that 100lbs of static weight was equal to roughly 1 second in lap time, at an average track. So 50lbs of static mass is probably IRO 1/2 second in lap time. 50lbs of rotating mass should show more than that.

 

I doubt spring vs. unsprung weight matters much in the 1/4 mile. HUGE difference on a road track, but in a straight line, I don't think so.

 

Why do you doubt this?

 

When we road raced in the day, mind you a different car with 1/2 the power of this one but a lot lighter ('87 5.0 Mustang Showroom Stock) - my partner weighed about 60lbs. less than me. We both had countless laps on the same track in that car and both knew the line - so best lap for either was likely about as good as we could get. In other words, it's likely safe to say that if we added 60lbs. to the car with him driving we'd be the same lap time on any given day. His best time was 0.1 seconds faster than mine on a 2 1/4 mile track.

 

Unsprung weight helps in accel/decel, and changing direction. only 1 of those 4 modes are used in the 1/4 mile, and it is likely the lowest impact direction. Not saying it won't help but I think it would not be as much as in a road course. Don't get me wrong, ANY weight reduction will help, but the fact that it is unsprung weight is less impactful on a 1/4 mile vs. road course use.

 

I agree, that it's more impactful over a road course, it's a longer period of time and more dynamics. I do think the math supports a 0.1-0.2 second 1/4 mile improvement however.

 

Stuart or Chris,

I’ll be installing the rotors and pads next week. Do you have a prescribed method for breaking them in?

 

Hi Stuart,

The lighter brake discs are much smaller to the ratio of a rim and probably have a smaller effect. The moving mass is too close to the center of the axle. Lightweight rims (10 lbs less per rim) in combination with these new brake discs would probably work wonders, and also cause 2 tenths or more on the 1/4 mile!

Andi

 

@Stuart@VelocityAP We can't customize the rotors right? I'm fine with slotted and black center hubs, but wanted to know if there are options.

 

When I bought them (two cars in the past), there was only one (very nice, cool) color. I'm happy VAP is doing this for us - it is expensive for a vendor to initiate a model of rotors...had looked into it in the past. Thank you VAP team - am saving up for hopefully 380's in front and 326's in the back....so at least the fronts is the plan. Wonder what 326's for the rear would weigh...central hub/hat savings is probably similar to the front, so hopefully a big weight savings.

 

Generally the pads will wear in (i.e. mate) as needed to the rotors. The only other consideration is off-gassing of the pads (glues/binding agents and the like). It's been a while since I've needed to do this, but take your car up to some nominal speed (in the day 30 mph), then apply a medium to firm brake application slowing down. Repeat this 4 or 5 times, OR until you smell any off-gas, OR feel any reduction in brake torque - cease braking at that time and drive a bit until they cool back down. Rinse and repeat. It used to be 10 or so off-gas cycles was all I needed with semi-metallic in the day to get ready for a track event. Normal street driving will ultimately get you to the same place (provided you occasionally put some heat in the pads). Note, however that with these large brakes, you may or may not get them loaded enough to generate the temps needed to get there with 30 mph. Avoid any full panic stops until similar driving has invoked stops like that.

 

30 mph is no where near fast enough. The break in procedure is done to apply a light layer of pad material to the rotor, so you actually get pad on pad contact. This requires heat. You want to brake to the limit of ABS (just before ABS engages) - can't really do that at 30 mph. 50-60 is a better range:

https://www.brakes-shop.com/brakeped...k-in-procedure

 

Something Henry Ford said about having whatever colour you want, as long as it's Black?

 

The procedure below is taken from the Girodisc instructions which come with the rotors, and can be found on their website:

GENERAL BEDDING PROCEDURE
 While the vehicle is stationary, pump the brake pedal to ensure pad contact. The brake pedal should feel firm, and
have standard travel.

• Drive the vehicle cautiously a short distance to test fit and function. The brakes should be smooth, with no
• vibrations, judder, etc. Drive the vehicle to a remote area and perform at least 20 brake applications of 3-second duration. Use light deceleration with varying starting speeds. Stoplight traffic can work well for this. The purpose of this procedure is to gradually increase the temperature in the components without inducing thermal shock, and to mate the brake pad and disc friction surfaces.
• After the repeated stops, drive the vehicle for several miles (on highway generally) with little or no braking in order to adequately cool the components.
• While on highway, perform 10 braking applications using light to medium pressure for periods of about 5 seconds.
• After the above process is completed, the system is ready for normal use.
• Note that pads and discs are a set once mated together. Changing to a different pad material after the previous material is bedded into the disc may cause pedal judder, vibration and squeal issues.
• Because of the heat build up in the brake system during extreme use, you need to let the brakes cool down by driving normally for a short distance before stopping. This cool down period not only helps the longevity of the brake system, but also the entire vehicle.

 

Sounds like people have received the rotors. I ordered mine May 10 and received the pads about a month ago but have never received the rotors. Any information on rotor shipment would be helpful.

 

The only customer who received rotors ordered first, and received the set which we used for verification fitment. We're following up with Girodisc to see what current status is, should not be long.

 

In the process of analysing the cost/weight savings of upgrading my OE 325mm rear discs to the VAP 2 piece rotors (376mm), as part of a full front and rear swap out, I'm struggling to understand the quoted weight savings for the VAP 2 piece rear rotors. VAP claim the stock rear 376mm rotors weigh 33lbs (15kg), but I can't find any comparable figures to support this. The stock 376mm disc (T2R5942) is listed as 11.6 kg on the Britcar website and I'm pretty sure this is the packaged weight. The equivalent Febi and Brembo replacement discs are listed as 11.2kg and 11.3kg respectively. Has anyone actually carried out the VAP brake upgrade and confirmed the weight of the OE 376mm disc?

The claimed weight for the OE 380mm front disc (39lbs, 17.7kg) is consistent with other available figures (Brembo equivalent also 17.7kg). Given that the vast majority of weight saving moving from 1 piece cast to 2 piece rotors is the replacement of the cast iron disc bell by aluminimum, I would have expected the weight savings for front disc (10lbs, 4.5kg), to be similar for the rear. Same hub size, although the rear disc bell height is slightly higher at 16mm compared to 12mm for the fronts. So yes, slightly more cast iron that can be replaced with aluminium, but I can't fathom how a similar weight saving design can generate a 16.6lb, 7.5kg weight saving on the rear. That's a 66% improvement over the fronts on an already lighter disk to start with.

Am I missing something, or is the VAP/Girodisc design really that ground breaking that you can virtually halve the weight of the rear discs by moving to their 2 piece design?

Any real world figures or first hand exerience of this upgrade would be appreciated to help me figure out my next steps.

Thanks in advance.