How much do rear brakes matter on track?

[Fyren]

At my first HPDE at Laguna, I ran Hawk DTC-60 pads and blank rotors up front and kept the rear brakes completely stock, as well as flushing the system with fresh RBF-600 fluid. This setup worked perfectly with no fade. However, as I get better, would the rear brakes start to fade before the fronts? I've seen a few guys on other ST forums run upgraded pads in front and stock rears and they've turned out fine. I would guess that our front brakes do the most work given that most of the weight is towards the front anyways?

 

[Intuit]

Rear brakes represent much less than half of the forward braking however they do play THE key role with stability/yaw/torque-vectoring control.

 

[faust]

Rear brakes represent much less than half of the forward braking however they do play THE key role with stability/yaw/torque-vectoring control.

isn't torque vectoring all in the front? That's where the torque is...

 

[M-Sport fan]

Do you turn off the stability control system as much as you can/we are allowed to (by holding down the 'ESC' button until the traction control symbol shows up on the dash lights) before going on-track, or do you leave it engaged even when open tracking?

 

[green_henry]

The rear setup is very inexpensive and while it may not make a big difference under normal conditions, it will be greatly appreciated if something goes wrong up front. Cheap insurance.

 

[Woods247]

You need to keep the bias in check. As you get faster and brake later, the rear brakes are critical in keeping the car pointed straight. If the car exhibits excessive “tank slapping” under heavy braking, try running a more aggressive rear pad. You should also consider the rear pads if you upgrade your front calipers. Goldcoast Automotive has a fantastic inexpensive option for us as does Whooshmotorsports

Also keep an eye on rear tire pressure and temps across the tread. Rear grip is also critical for stability under heavy braking from high speeds. I added a little rear camber as well (-2.1 degrees) using washers on my lower hub bolts. Ghetto I know, but it’s cheap and I’ve been running it like that for a few years without a problem.

I boiled the Motul fluid more than once when my car had stock brakes, so I switched to Type 200. The next step is Castrol SRF, but I never needed it in this car.

I trail brake a lot as well. I replace rear pads just as frequently as I replace the front. If you leave the car in Sport mode, the rear brakes are activated often so keep that in mind. There is nothing wrong with using Sport mode while you’re learning the cars limits. It’s safer for everyone on the track.

 

[Fyren]

Thanks for the input everyone! I turned ESC off as far as it would go for every session last time to save the brakes and plan to stick to that.

I think I will stick to the stock rear pads for now, but if I notice excessive rotation under heavy braking, then I’ll consider upgrading the rears as well as adding camber.

 

[maestromaestro]

Thanks for the input everyone! I turned ESC off as far as it would go for every session last time to save the brakes and plan to stick to that.

I think I will stick to the stock rear pads for now, but if I notice excessive rotation under heavy braking, then I’ll consider upgrading the rears as well as adding camber.

Rear brakes are ancillary. Do about 30% or less - trim. I do have Wilwoods with their pads in the rear. The pads last for close to 40k miles, and that includes quite a few HPDE sessions. Unless you’re mashing the brakes like an ape, you’re going to be OK on the OEM. And, the rear rotors still have slots on them - and they have close to 70k.

 

[maestromaestro]

Also I added a little rear camber as well (-2.1 degrees) using washers on my lower hub bolts. Ghetto I know, but it’s cheap and I’ve been running it like that for a few years without a problem.

I boiled the Motul fluid more than once when my car had stock brakes, so I switched to Type 200. The next step is Castrol SRF, but I never needed it in this car.

Over 2 degrees is a LOTTA camber in the rear. That’d be too much for a street car.

I also had to switch to SRF - everything else boils in TX heat.

 

[ronmcdon]

Its a lot easier to rotate the car with esc turned completely off vs just sport mode. never found the rear of this car difficult to control but I don't trail brake either. currently using dtc-30 front and ebc yellow rears. will switch to hawk hp plus rears when the yellows are done. wanting to move spring rates from 8k/6k to 8/8 to get the car rotate even more.

with pad wear, think im wearing out the front pads approx twice as quickly as the rear pads. have not observed my car noticeably unstable with hard braking during hpde or maybe I just don't push the car hard enough.

 

[Woods247]

Over 2 degrees is a LOTTA camber in the rear. That’d be too much for a street car.

I also had to switch to SRF - everything else boils in TX heat.

Fortunately neither are a concern here.

 

[Woods247]

Its a lot easier to rotate the car with esc turned completely off vs just sport mode. never found the rear of this car difficult to control but I don't trail brake either. currently using dtc-30 front and ebc yellow rears. will switch to hawk hp plus rears when the yellows are done. wanting to move spring rates from 8k/6k to 8/8 to get the car rotate even more.

with pad wear, think im wearing out the front pads approx twice as quickly as the rear pads. have not observed my car noticeably unstable with hard braking during hpde or maybe I just don't push the car hard enough.

Yeah Sport mode has limitations for sure. It will definitely eat brakes on fast tracks.

 

[Woods247]

Rear brakes are ancillary. Do about 30% or less - trim. I do have Wilwoods with their pads in the rear. The pads last for close to 40k miles, and that includes quite a few HPDE sessions. Unless you’re mashing the brakes like an ape, you’re going to be OK on the OEM. And, the rear rotors still have slots on them - and they have close to 70k.

I suppose I’m an Ape 😂 I definitely won’t disagree with that. Apes also spend $1000 on rear brakes then say they aren’t worth it. We must be cousins. 😘

 

[Jabbit]

I'm running PowerStop "Track Day" rotors and pads in the back to compliment the Whoosh front BBK. Have yet to run the setup at an HPDE but I'm confident they will do well.

 

[M-Sport fan]

I boiled the Motul fluid more than once when my car had stock brakes, so I switched to Type 200.

That Ate fluid has a lower dry AND wet boiling point than the RBF 600, despite it probably taking on, and retaining moisture at a slower/lower rate than the Motul stuff (which makes it better for long term street use than the Motul, or any of the other racing fluids save for the SRF).

Your experience is that it still boiled out on track less than the RBF 600??

 

[Tonda-B]

If the original pads had the same coefficient of friction and now the front pads have a higher coefficient of friction, you have an overbraked front axle.
This means an unnecessarily high temperature in the front and additional braking distance as the rear brakes do not try hard enough...

 

[Jabbit]

If the original pads had the same coefficient of friction and now the front pads have a higher coefficient of friction, you have an overbraked front axle.
This means an unnecessarily high temperature in the front and additional braking distance as the rear brakes do not try hard enough...

By that logic, then upgraded front pads = longer stopping distance, always. That is not true.

 

[Tonda-B]

No.
Upgraded front pads and unupgraded rear pads means longer stopping distance comparing with all the way round upgraded pads.
Not comparing with stock pads.

 

[Woods247]

That Ate fluid has a lower dry AND wet boiling point than the RBF 600, despite it probably taking on, and retaining moisture at a slower/lower rate than the Motul stuff (which makes it better for long term street use than the Motul, or any of the other racing fluids save for the SRF).

Your experience is that it still boiled out on track less than the RBF 600??

I’ve never had an issue with Type 200. The RBF 600 and I have never gotten along in cars though. I had big issues with it on a short track that has a lot of heavy braking, elevation change and tight corner exits. It cooked in both front calipers twice in the same day after a flush (pre LSD and BBK). Other drivers seem to love it but it doesn’t work for my style I guess. Tires are my braking limitations now.

 

[Jabbit]

You said "if the original pads had the same coefficient of friction" and I took original to mean stock. Then you said "now front pads have a higher coefficient of friction" which means they are upgraded. Then you said "This means....additional braking distance". Just wanted to clarify that the statement as I interpreted it, is not true. I suspect I misinterpreted.