RCR Brake upgrade?

Hi All-

If one were to buy the MKI delux-plus kit with the upgraded 17" BRM's could you also upgrade to a larger rotor/calipers at that time or would this have to be done after delivery and aftermarket?

I'm wondering if one upgrade can be followed through with the next, and if credit is given toward those upgrades from what comes in the kit?;)

Just wondering if there is much flexability in building into the kit/roller chasis from RCR.

Thanks again-:D
 

Fran Hall RCR

GT40s Sponsor
You had better call us to discuss your thoughts....we manufacture everything in house, so anything is possible.
Our standard brake package uses Nascar style 1.25 thick rotors and six piston Caliper up front with four piston in the rear.....

Regards
 

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Dutton

Lifetime Supporter
Robes,

A few have unintentionally found that opening up the rear half of the bodywork at speed works especially well. It's a little hard on the hinges and the bodywork, but is quite effective. For a single use only, however, you might look into the parachute used by the NHRA boys. Jegs or a similar company could help. ;)

Best,

T.
 
My knowledge is limited, but aren't manufacturers seeming to fight a "biggest rotor is best" battle, especially on street cars, but more as a marketing ploy?
Without ABS, my understanding is that rigid calipers and lines should be important on a setup for good pedal feel. And cooling is better via open rotors with directional vanes and good access (ie ducts) to cool air. So a bit less than 12 inches isn't a big rotor by today's production car standards. But on a 2000-2200 pound car, shouldn't the basic RCR setup be more than adequate for hot laps at the track, probably full-on racing, and over the top for street use? These are much better brakes than on the originals, and the car is lighter.

Of course, I have not yet got the talent to threshold brake, so I am certainly no expert.
 

Sandy

Gulf GT40
Lifetime Supporter
I run the Same 6 Piston SL's on the front of the 65' mustang with 13" coleman 1.25" curved vane rotors of similar thickness and a much smaller 4 piston caliper and rotor on the back axle. The weight is likely in the 2800 lbs range and has plenty of brake capacity. No drilled rotors, no air feeds to anything. The only issue was the choice of pad compounds, and the stock pads that sometime come with the calipers are not something you would use on the track. Work great for the street, but on the track too spongy. Replaces with a more appropriate compound and all good and their were several more aggressive compounds beyond what I selected (Wilwood 'J'). The RCR is several hundred lbs lighter and likely a more balanced use of the brakes then the mustang so for anything you would likely do with the RCR40, correct pads, and some ducting would be my guess as all you would ever need unless your really doing competition racing. From the look perspective, can't say but you can't see the brakes on the rears on my car since the tires are really wide, the fronts are not really all that visible as your eyes don't focus on the wheels, the cars lines are what your focused on!

Sandy
 

Randy V

Moderator-Admin
Staff member
Admin
Lifetime Supporter
Just for a point of reference;

I raced a Factory 5 Challenge Series car which weighed in around 2550 with me in it. I raced at trackes where I would have to repeatedly bring the car from close to 150mph to 35-50mph.
I could and frequently did outbrake Vipers and Z06 Vettes with stock to HUGE brakes but had a little problem with some of the newer Porsche GT cars from time to time.
I did this with standard Mustang brake rotors and single piston calipers while using Carbon-Metallic competition brake pads and no cooling ducts.

Not that I would advocate putting less on the RCR's but it is my opinion that these cars have more brake than you will ever truly need.

Something else to think about - the heavier the brake rotor, the more inertia it gathers and it actually can become somewhat of an impediment to braking in certain conditions. Not to mention more unsprung weight.
 

Ron Earp

Admin
J
Not that I would advocate putting less on the RCR's but it is my opinion that these cars have more brake than you will ever truly need.

I was writing something like this at lunch but forgot. I'll throw in with these two fellows.

I race a 2650 lbs car with 10.5" SOLID rotors, 2 pot iron calipers, and drum brakes. With good ducting, they last for 30 mins and brake as well as anything I'm racing against or you find on track days (Vipers, Corvettes, Lotus, etc.).

That standard package has way more brake than needed. I will be using it on the RCR Lola race car we'll race in SCCA SPO that will be several hundred pounds lighter than 2610 lb. And that will be for a 13 hour race, if it doesn't last and make it I'll be VERY suprised.

If you are going for looks or bench racing you might want larger ones, but I don't think for a second you need them.

R
 

marc

Lifetime Supporter
See you guys don't get it. As a ZR1 owner (ME! #1468) and #418 have a common ailment. A ZR1 Corvette is 3300lbs and the rotors and brakes are desparately in need of upgrade to track properly. I will have to get with one of you left coasters for a test ride some time ( I'll bring the vette) and you will under stand what these cars are. I took mine to Nellis Air Force Base back in October with the ZR1 Gathering. Stock, from a standing start, at the end of a measured mile, I was radar checked at 151mph. The cars have bolls. Stopping them was more the issues. You can stand the thing on its nose but thats a instant out of controll. but more to the point the next day we were out at Las Vegas Motor Speedway on the roadcourse and my brakes faded out after 4 laps and that was with stock calipers and some aftermarket (Porterfield Rotors and Pads) stuff and some clean fresh fluid.

So yeah, we worry brakes!

BTW Ron I got to get with you about the SCCA but I keep forgetting to PM you.
 

Randy V

Moderator-Admin
Staff member
Admin
Lifetime Supporter
Marc / All - Whenever you take your car out on the track and REALLY USE your brakes (regardless of your choice of brake calipers/rotors/fluid) - you should always bleed your brakes before the next time you hit the track.
When you put a lot of heat into your brake fluid, you lower it's boiling point each successive time out. You need to get the fluid that is currently in your caliper's bled out and replaced. That's not to say that you need a total changing of the fluid from the master cylinders all the way to the bleeder valves on the calipers - just that fluid that is in the calipers itself.
The rule of thumb I've used for years quite successfully is at least 4 full strokes of the brake pedal per axle if I did not experience much if any fading. 6 full strokes if I did have fading.

Running fresh air ducts to the insides of your rotors will generally reduce the need to do 6 pump bleed sessions a lot but does not negate the requirement to bleed the brakes.

Note - When you have experienced brake fade due to boiling fluid, you will usually notice that your brake pedal is much more firm once it has cooled down. This is what gives so many people a false sense of security about their brakes. You have reduced your 600f brake fluid to something close to half it's original temperature tolerance.

Marc - also to your particular brakes - Having also used the Vette PBR Calipers not only in Corvettes but in SCCA American Sedan cars, I found these calipers to "Splay" causing a very un-even contact with the rotor and very poor wear charateristics on the pads. We tried everything to make these calipers stronger so they would not splay out but where unsuccessful. Since it was the outboard pad that would not contact well, we were putting much more heat into the inner pad. One thing that I tried (and it worked quite well) was to put a thin bead of Hi-Temp RTV around the part of the pad that contacts the caliper's piston. Let it skin-up for about 30 minutes and then install the pad, bleed caliper and seat the pad pretty quickly. The (now very thin) layer of RTV between the piston and the pad's backing plate was a very good insulator that would transmit MUCH less heat into the piston and fluid.
 

Ron Earp

Admin
stock calipers and some aftermarket (Porterfield Rotors and Pads) stuff and some clean fresh fluid.

So yeah, we worry brakes!

BTW Ron I got to get with you about the SCCA but I keep forgetting to PM you.

Hey Marc,

What kind of fluid? That is the key.

If you aren't using something like Motul 600, or Castrol SF (the later is about $80 a bottle, the former about $16 a pint, or maybe 1/2 pint) then you should. None of this stuff is available at any parts store, except a race shop or track shop. If you put that fluid in the morning of your track day, bleed out all the old stuff, then I don't think you'll have any boiling issues. There are a number of guys running C4 vettes at VIR with standard brakes and no issues, but they're all over the bleeding and fluid stuff as Big Foot says each morning. I'd imagine that will solve your issues.

Now, if you are already using that fluid, and really changing it the morning of the track events, then you'll need to do more with duct, heat sinks on the pads, and possible thermal isolators that go beyond what BigFoot has posted. I'm getting ready to put these on my Z car to help out, and they might make them for Corvettes:

Fade Stop Brake Heat Sinks

I have a set in the garage and they are well developed and fit in perfectly into the caliper.

For us racing these cars with solid discs, small calipers, and abusing the heck out of them, a race morning AM purge with fresh Motul is standard operating procedure. After the races we measure the caliper temps and routinely get in the 400F-550F range and even higher sometimes (my pyrometer quits at 550F, once measured that high when the TR8 had some issues but it still stopped fine that session, this was pre ducts). Seals are important and need to be fresh, and up to the task.

But, we don't have fluid boils and maintain brakes throughout a 30 min sprint race with heavy abuse. The times when we've not done the bleeds with new fluid we get boiled fluid, or blown out brake seals, or both and it happens in a few laps.
R
 

marc

Lifetime Supporter
dont you hate when you type a great reply only to do something stupid to lose it!:eek:

Thanks Ron about the fluids. In prepping for the event I secured some SS brake lines to add to the vette. Unfortunately I had a little rat or mouse rain on my parade that chewed up my ignition wires (I did not know silicone is a staple of rodents!) I spent so much time getting those done, I did not have time to put the lines and the new fluid in for the event. (I live in San Diego and had to drive to Vegas) Plus my wife would have had a cow, asking why there was a problem with the brakes! (she was not born with the car gene). So I figured I had just done the fluids 2 weeks ago no problem right?

The other item I wanted to share with you is I met with the Wilwood rep at the GoodGuys show and he had some great info regarding pads and all. He mentioned that the type of pad used also contributes to the temperatures also to swap in a more aggressive pad at the track for the event, but to remove afterwards as they will chew up a rotor in no time. There is supposed to be a balance of metal from the rotor and material from the pads that are lost due to the braking process (I don;t remember the numbers he talked about) Another thing that we talked about is a 6 piston brake package for the zr1 with a soon to be release rear caliper. Talked about it ready for SEMA.

One other thing comes to mind. my car and driver are almost 1000 lbs than your setup (3300 or so with out driver) a

I will bet that the RCR on 15" Wheels with the 1.25 rotors with 6 pistons will stop on a dime and make change. especially if we are around a ton on the scales.
 
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Motul 600 is avaiable at most performance motorcycle shops.

Oh and something else, 6 piston calibers are not all that just because they have six pistons... Suzuki offered up some on thier street bikes some time ago because well, all the racers were using them. Only problems were the pads were so long they easily warped and the caliper was so long they easily flexed. All in the name of marketing, they requiered a lot of service to make them work on a racetrack (production classes).

The current hot ticket in bike racing is one pad per piston setups, no warpage and excellent leading edge bite (many leading edges) along with heavily groved 'snowflake' rotors.
 
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