[nate340]

Originally Posted by jafo1701

Nate. I tried the brakes for you and it goes firm and stays firm and doesn't sink. If I release it the pedal is nice and firm and feels normal. Hope that helps

Thanks I'm now aware my braking issues are most likely related to this.

Originally Posted by fe1rx

HP+ are barely adequate for lapping with a street tire and completely inadequate for lapping with an R-compound tire.

If you are running HP+ you are not putting more heat into your brakes than everyone else regardless of your tire. These pads fade well before say a DTC 70. By pad fade you mean the pedal is hard but the braking effect is reduced, right?

The reason I’m using HP+’s is that I received 3 sets of them for free but I do plan to move to something more track orientated.

Originally Posted by fe1rx

Your brake fluid can't boil before your pads fade, because when your fluid "boils" (fluid fade) the pedal goes to the floor with no pressure going to the pads and so no friction (or further heat) being generated. What exactly do you mean when you say your fluid is boiling?

When brake fluid starts to boil the pedal starts to sink, the more air in the line the further the pedal sinks. Lap after lap my brake pedal sinks further and further down. It will eventually go to the floor. What I’m doing is using my left foot to pump the brake pedal down the straight to build pressure in the brake lines so that when I do arrive at the braking zone I have enough pressure to brake adequately and after doing this for a bit my pads begin to fade (brake pedal firm yet applying a lot of brake pressure while not slowing down at the typical corresponding amount.)

Originally Posted by fe1rx

If you have air in your hydraulics, the pedal will be soft all the time, so that isn't likely your problem.

Opinions differ widely on the fluid front, but my experience has led me to using Castrol SRF and nothing else, flushing it once a year. It seems expensive but isn't if you can avoid multiple flushes.

In my experience, once a fluid is overheated, it is never right again and should be flushed. It will recover once it cools, but not completely.

Once I have a track event and boil my brake fluid the pedal does remain fairly soft until I bleed the brakes and I always see significant air coming out of the calipers.

I’m flushing my brake fluid at every track event using Motul RBF 660 which allows me to run significantly longer before running into my brake issues when compared to ATE Super Blue, since moving to a fluid with a much higher boiling point significantly helped my brake issue I assumed it's vapour lock caused by overheating and boiling my brake fluid.

Originally Posted by fe1rx

How much effort do you expend in cooling your brakes after a lapping session. If you come in and park with your pads stinking hot (literally) and just park, you are abusing your fluid.

Before I bring my car into the pits I take two cool down laps if I’m unable to properly cool my car before bringing it into the pits the pedal does sink straight to the floor when I return to the car to go back out on track.

Originally Posted by fe1rx

If your pedal is getting a bit soft or the travel is getting a bit long but not going to the floor, there are other (than fluid fade) possible explanations, including pad knockback and thermal deformation of your shims (if you are using them). Shims may help with thermal isolation but they don't help when it comes to a firm pedal.

I may be having pad knockback as I do recall once or twice that my pedal is suddenly firm while at the last braking zone it was very soft. I’ll have to look more into it and keep a close eye on it next time out on track. I am running titanium shims which seemed to help a reasonable bit but am willing to remove them and see if it helps.

Should i be running the stock steel backing plates along with the titanium shims? As right not i’m only using the titanium shims.

Originally Posted by fe1rx

What track are you at? Is it particularly hard on brakes? When you don't have brakes that can take anything you can throw at them (and you don't) you have to manage them as a limited resource. Examples:
- limit the number of hot laps
- alternate hard laps with cool-off (minimal braking) laps
- brake earlier
- brake less
- don't make every lapping day an experiment to find out how quickly you can fade your pads/fluid

The track where it is most noticeable is TMP Toronto Motorsports Park in Cayuga. I have 3 Major brake zones with the most significant being 190KPH down to 110

I’m currently trying to resolve the issue so that I’m able to push harder and enjoy more track time without having to run cool off laps every few laps.