StopTech Level 2 BBK Trackday Review

[VFR750]

Test Results are in: Awesome, but noisy

Conditions: ran 199.9 miles at Lime Rock today with PCA-CVR, 6/25/20 70-85F, dry. (7) 25 minute sessions.

What: StopTech Level 2 Front Kit (STR43 calipers with 282mm x 28mm floating rotors) & ATE "M" (stock) rear, with Hawk HT-10 Pads, Castrol SRF fluid (fresh)

The Good:
1) ]They did not fade. The balance front to rear was fantastic, and best of all it did not change over the course of the day/session. The Braking on lap one (after the pads are properly bedded in) was just as good on lap 25. This is in contrast to the previous experiences where the front start to get a little mushy and the bias shifts the rear, resulting in rear lock up.

2) they really handle the heat better than 24mm wide Carrera Rotors and Wide-A calipers. I was able to increase braking force, for a shorter time (higher heat flux) without any issues. I was able to move my braking point about 50' closer to Big Bend. Lap after lap. Session after session.

3) After sitting for 30-45 minutes, it only took one pump on the brake pedal to bring back a firm pedal. Cooling and "shrinking" of the brake fluid is a common issue, but the amount of shrinkage is dependent upon how hot the fluid got. Must has been less than with the Wide-A pad size I ran two weeks ago. Brakes were firm and grippy immediately.

4) Pad wear seems to be very low. About 2 mm of wear in ~200 miles. This would normally be two days worth. With 20mm thick pads, they should be good for another 4 or more normal 100+ mile days

5) I never had any judder.

6) no overflow of brake fluid. Previously this happened all the time. Every track day. I would get a little puddle of brake fluid from the overflow. Not today.

7) fantastic, straight (w/open differential), controllable deceleration. Awesome.


The slightly Annoying: Light pedal pressure squeal from the HT-10s

1) This may be a trait of the the Hawk HT-10 pads. They do not come with anti-sqeal shims. They squealed loudly under light load after the heated up. Lap 2 till the end. This also happens with HT-10 pads on the stock rotors, but not to this extent. Only with light pressure. Like when you are trailing the brakes into a turn, just as you feather the brakes and go to the gas.

2) I really don't care that they are noisy. Maybe different pad compound would have less/no noise.

3) there is some heat checking on the rotors. Not really surprising considering how hard I was using them. This is more of an observation, as heat checking is common.


Some important points:
1) I broke the HT-10 pads in on the track. I ran the first 4 laps and got some smell. Pulled into the pits and sat for 5 minutes to let them cool. Then went out again for several more laps got some smell. Serendipity; we got black flagged for oil on the track, and that allowed the brakes to really cool down. The extra cool down probably helped as I never had "green fade".

2) I ran all cool down laps with virtually no brakes. And when I did stop I used the hand brake. I avoided pad transfer. by moving the car a little after about 1 minutes in the pits.

Side Note:
I really like Pagid RSL-29 Yellow Pads. They do not offer that compound in the 2205 pad shape. The HT-10 were a stop-gap move. Now that I have the StopTech DR-21 (2205) pads in hand, I am looking at the 2555 shape which is 45mm tall verses 43mm (2205) in RSL-29 compound. Time will tell if the extra 2mm really impact the installation.

Link to Install

[jjeffries]

Great write up.

Do you drive the car to/from the track? If yes, do you install a different set of pads for the drive home?

How “normal” were things at LRP?

Best, John

[VFR750]

I trailer the car in case something goes wrong. Like the grease cap on the front hub. 🙄

HT-10 are not good street pads. So I will swap them for the 309 stoptech pads

If I can get Pagid rsl-29 pads that can fit, then I will leave them in.

Tomorrow is the real test: Thompson. Really hard on brakes!

[Bigtoe32067]

Spray a liberal coat of Copper Coat on the back side of the pads and let them dry overnight before reinstalling. This has worked wonders for me in the past.
Good luck and thanks for sharing your experience with us
Tony

[VFR750]

Track days are fine. Everyone wears a mask. Parking lot is spread out. Signed waivers.

[Locker537]

Originally Posted by VFR750

Track days are fine. Everyone wears a mask. Parking lot is spread out. Signed waivers.

Glad to hear this!

[VFR750]

Thompson speedway track day results: mixed

1st session warm/dry and toyo R888R tires. Brakes worked great. But those HT-10 pads are insanely loud. Screeching in all turns.

2nd session threatening rain, so I installed the G-max a/s tires. Good tire but needed a little less brake pressure to avoid lockup. Screeching pads continued.

3rd session rain. Pads Still screeching But a new issue cropped up. Nonlinear braking.

The HT-10 have a steep coefficient of friction rise. It seems the larger front brakes cooled down more than the rear in the rain. And I found myself chasing brake pedal pressure to avoid lock up. And the pads screeched even when seriously wet.

Could also have been a sketchy track surface, since this was the first rain in weeks.

Either way, it was no longer fun and I came in and packed up. Done.

Ordered a set of Pagid rsl-29 pads. They are the slightly oversized 2555 version. I will figure out how to modify the pad edges to work. That will be a separate post.

I also noted the paint was burned off the large front HT -10 pads. Are they too conductive

The stop tech Brake recovery was excellent. Pedal only needed one pump to bring the pads back.

Conclusion: overall great system. But not with HT-10 pads in the wet

[KTL]

Mike,

Your experiences in improved performance sounds a lot like what we experienced in our local group using a 944T/964 front caliper and '86 944T front rotors. This is the VCI front setup that Doug Arnao has offered for several years now.

The change in bias with the different front calipers and removal of the pressure limiting valve in a Carrera makes a big difference in performance. Pad wear went from substantial each event to minimal. The slightly larger front rotor adds a bit more thermal mass where it's needed and the rearward bias shift balances out the pad wear. All told it's a really good improvement w/out going overkill on the brakes.

I wish I would have seen this sooner because I would have recommended the Raybestos ST43 pad compound. It's been used by a number of people with really good feedback. It's an endurance pad so it's not too aggressive. But still plenty of bite and good wear characteristics.

Lastly, great to see someone still tracking their old 911. I'm looking forward to getting my '86 finished up in the next few months and back on the track. It's been far too long and I miss experiencing what the car was born to do.

[VFR750]

I am definitely interested in different pads.

Yes it is used as intended.



Shawn Pierce Photography took the picture, he gets credit.

[Locker537]

Originally Posted by VFR750

I am definitely interested in different pads.

Yes it is used as intended.



Shawn Pierce Photography took the picture, he gets credit.

Nice picture!

Why do the roof vents appear taped up?

[VFR750]

I tow the car backwards.

Keeps the rain out of the vents and headliner

[gomezoneill]

Been there at Lime Rock many times ( not to drive just watch) lot's of fun.

[Locker537]

Originally Posted by VFR750

I tow the car backwards.

Keeps the rain out of the vents and headliner

Good tip! Thanks!

[Flojo]

Originally Posted by VFR750

I tow the car backwards.

Keeps the rain out of the vents and headliner

and the heavier part of the 911-car (engine at rear) is closer to the hook on the bed.
better tow handling.
regular cars have the engine up front.

[Bill Verburg]

Originally Posted by Flojo

and the heavier part of the 911-car (engine at rear) is closer to the hook on the bed.
better tow handling.
regular cars have the engine up front.

How to set the car on the trailer for best towing depends on where the axles are located, some Trailers like Trailex are specifically set up for car front trailering others w/ different axle location for rear front use

It's far easier to drive on than back on

[Bli8]

In the video below, famous car collector Manny Khoshbin gave negative comments regarding the Stoptech brakes in this 935 EV, so I wonder if he's just not used to the manual brake's high pedal effort or actual braking performance was lacking. Wonder if a power booster would be needed for a heavier than usual 911 (one with electric motor and heavy batteries)?

https://youtu.be/E96Svknrhyc

[kent olsen]

I had a two axle trailer that I towed my 72 911 on. With the car pulled up to the front of the trailer the engine was sitting over the rear trailer axle. I towed it all the way from Florida to Oregon with no issues.

[KTL]

Manny is used to modern supercars and not a 935 work in progress with un-boosted brakes. Un-boosted brakes require a lot more pedal effort than most people are accustomed to feeling. I’d not let his comments about the car having “no brakes” make you think the Stoptech brakes are no good. Bisi himself even comments that he believes he needs to add a brake booster to reduce the effort required to stop

[VFR750]

Originally Posted by Bill Verburg

It's far easier to drive on than back on

Far easier to drive straight off a trailer than backing it off.

I’ve been doing it this way for 12 years. Not a problem. I certainly am not intimidated by it. Just trust that a car goes straight when the steering wheel is centered.

[VFR750]

Originally Posted by KTL

Manny is used to modern supercars and not a 935 work in progress with un-boosted brakes. Un-boosted brakes require a lot more pedal effort than most people are accustomed to feeling. I’d not let his comments about the car having “no brakes” make you think the Stoptech brakes are no good. Bisi himself even comments that he believes he needs to add a brake booster to reduce the effort required to stop

Pad choice also comes into the equation depending on how fast they gain friction with temperature.

The HT-10s don’t grip very well when cold. Hence they are a bad street pad.