Professor Helmüt Tester

I beg to differ - they can be asked...but they usually won't agree to it.

Pretty much agree with the consensus...trail-braking is a wonderful technique, IF you know you are doing it, and IF you know HOW to do it.

Cue up my traditional lecture on "the unconscious trail-braker"...sometimes your brain and hands don't know what your feet are up to, and only your heinie gets the message. Beware. Trail-braking should initially be a conscious decision, slowly transitioning to a reflexive instinct. Trying to push the speed of the learning curve will generally have ugly results.

(Edit) Everybody that I race with (myownsef included) trail-brakes the crap out of SRFs. The little boats push so bad on-power that the only real way to get them rotated early is to do it with your feet. Of course, I trail-brake the crap out of all the other race cars in the fleet, too.

Some of my favorite corners are ones where I can trail-brake "joyously-stupid", stand the bitch on its nose and rotate the rear anywhere I want - Left Hook at VIR (2nd part of Oak Tree, too), T13 at Nelson, 5b at Mosport, blah blah blah...

srf506

The SRF has so much weight in the back, ~64%, and is so HP challenged, ~ 100 +/- a few it takes a delicate touch to keep the nose pointing in the right direction. Massive TTO when you lift (which means it'll take another whole lap to get back to speed because of the small amount of HP), as previously mentioned a real pusher under power in the turn, all the weight's in the back remember). So, You'd set the car up as loose as you dared and used trail braking was a way to get around the problem.

In the original car, the Spec Renault, we were even more horse-power challenged. That was like driving a go-kart as you really just left your right foot planted and used the left foot to set the chassis for the turns. It was a whole new ballgame when we got those Fords.

Mahler9th

More:

I first became interested in cars and racing in 1983 or so, and in '84 bought the Bondurant book and read about trail braking. My only car then was an MGB. No Ax, no track events in that thing. A work colleague went to Skip Barber at LRP in '86, and bought the video a short time later. I watched the video with him and another colleague into motorcycle racing. In '87 I bought a 944 and joined PCA. Very soon thereafter I signed up for DE at LRP as my first driving event of any kind. I dubbed the video and watched it a bunch of times before I arrived at LRP. It was really helpful, and I still recommend it to all of my students. I also watch it 2-3 times each year with my wife. It includes a great description of trail braking as well as some of the other things mentioned by the original poster.

As for working on the eyes and hands, in car video is extremely helpful. As posted many times here and elsewhere. It is very helpful to have a red light that is in the camera FOV that comes on with the brakes. It is easy to rig this up, and you can watch yourself naturally trail brake. It is also helpful to have a WOT light. A little more tricky to rig up, but can be worth it. These things really helped me working with my best student (the wife).

Mahler9th

By the way, I had a very well set up 951 for a number of years and I believe that trail braking was just as important if not more in that car as my current 911. My wife has had the same experience. My personal belief on the TB technique is that it has a place, and it is car, corner and driver specific. It is an arrow in our quiver.

Barfly

I trailbrake in my SRF quite a bit as well, especially in low speed, late apex corners.

I find that I have to trailbrake more early during a race as I will have a mild push, and back off late, when the rear loosens up.

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Jason

38D

Watch any pro race and you'll see they all trail brake regardless of engine placement or even which wheels drive. Assuming you are braking more than a touch, you basically have to trail brake to be fast on entry.

Barfly

I think it also comes down to the difference in a dynamic brake release and performing a trailbraking maneuver. You can't treat the brake as an "on" or "off" switch or you will be losing time (not maximizing grip under the friction circle).

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Jason

race911

Some of my worst memories in anything automotive were Eagle GT equipped SR experiences circa 1984. How did you use your left foot to do anything but clutch when they had a BAR preventing moving your left foot over to the brake pedal? Or maybe common sense prevailed at some point and they allowed its removal?

PedroNole

+1

ausgeflippt951

^^^ Exactly.

Case in point: http://youtube.com/watch?v=A8-zbfdPfRg&feature=related

Note the high-performance driving shoes.

Red!

I'd agree - I think there a difference between carrying the brakes up to the Apex and just coming off the brakes smoothly later after turn in. In the end its measured by lap times and more importantly, the driver feeling comfortable and SAFE.

ervtx

Yes, they do focus on trail braking as their specialty, but since their threshold braking exercises requires you to watch the front tires for that lock up threshold, any rear bias isn't enough to overcome the ability to lock up the front tires, especially with the weight transfer going towards the front.

In fact, SB teaches that tires deliver 100% of their braking traction when they are rotating 15% slower than the actual rolling speed of the car. So 100% of what the car can do is more like 12/10 mentally!

What I found very helpful with the SB approach is that they stage the trail braking exercises right after the threshold braking exercises. So the end-to-end lesson is to take entry braking to the threshold of adhesion (brake late, brake hard, load up the suspension for the trail braking to follow, then release smoothly), and then use the unloading of the suspension during brake release to more effectively rotate the car.

They don't teach it for the purpose of carrying more speed into the entry, or for a save after a missed braking zone, etc., although it's obviously used for that purpose and more. They specifically emphasize that there is not much to gain in terms of lap times by focusing on higher entry speeds. In terms of their specialty, it's about using the suspension to effect the turn. Too little trail braking, and you've missed the point about using the brake pedal for something other than slowing down. Too much trail braking, and you sacrifice exit speed.

Since the DE programs with which I'm familiar don't teach that level of suspension dynamics until you get to the advanced run groups, it's easy to see how people discover or go out to learn trail braking under very different circumstances and applications. Having learned the more narrowly focused SB trail braking approach in a Formula Mazda first (the aforementioned Laguna Turn 3), and then applying it in my own car at a DE last, I think I always braked later and harder, and rotated my car quicker than average while in the green and blue run groups. Now that I'm in an advanced group where more people are mastering it, I can't say that the SB approach makes me any faster than average, but I'm sure it makes me faster amongst similarly weighted / balanced cars because I've learned the technique for the purpose of getting the most out of my suspension (you should see me turn that C4 Cab as though it were a C2 Coupe!)

sechsgang

I learned trail-braking the first time I was on the track...but that was VIR+Oaktree+oh wow, little too fast (didnt have anyone in front of me) off the throttle rather abruptly and presto, my *** was out and I was alright! Ok...I guess I experienced it then...I learned how to utilize TB at a Skip racing school at Limerock with IMHO the BEST corner EVER to learn trailbraking...turn 3 (the left hander). Place was great to inspire confidence and really help me into the trait as a speed/time advantage. Now, it feels like second nature. That said, all it takes to wake up is that one time you let stuff slip out a bit too far (like at the end of an enduro say...haha)...things definitely can get interesting...haha

mpaton

A lot of useful advice here, and as an instructor to the advanced run groups in texas, it's quite possible I'll end up having ervtx and caygirl showing me how well they do it. But a word of caution for those with PSM in their Porsches.

I'm told that the 997 PSM is better than the 996, and I'm very familiar with the 996. One of the components of 996 PSM is something called "Yaw Stability under Braking". Of the 5 components of 996 PSM, this is one of the 2 that are NOT disabled with the PSM OFF switch. It's function is to keep the car straight under braking. In other words, it doesn't want you to get rotation when you trail brake.

All of these PSM functions are described in the owners manual, and all Porsche drivers with PSM who are tracking their cars should read it and make sure they understand it, especially in the advanced groups. Currently there isn't a high probability that your instructor will understand it.

So a PSM equipped car (on or off) would rather you didn't get rotation under braking, but it will let you have some. how much you get is quite usable in the 996, although you might like more. If you demand more and the car doesn't want to let you have it, you should certainly notice the brakes pulsing and see the orange dash light telling you PSM is working.

However my purpose in this post is to warn you that if you ask yet more of the car, as in trail braking and threshold braking combined, and allowing more than a little rotation under braking, then a 996 will at some point decide it's had enough of this, and it will not only pulse the brakes to straighten the car, but it will (mine did anyway) push back on the brake pedal with a force I'd estimate at around 50 lbs.

This will surprise you, it will make you think the car has broken, and it will make you wonder what you should do, and it will add to your stress level at a time when you are depending on threshold braking and trail braking to keep you on the track. I pushed much harder back on the pedal and we only just stayed on the track.

While I believe that in general 997 (and hence Cayman) PSM are more track friendly, Yaw Stability under Braking must keep a lot of bad drivers on the road, so I wouldn't be confident that the car's ultimate reaction would be much different. So please be ready if this happens to you. This reaction by the car is NOT in the 996 manual.

Happy trail braking!

Michael

Professor Helmüt Tester

One of the most monumentally stupid things ever put in a race car. WTF were they thinking ? Luckily, LONG GONE.

Having driven both, Renaults had better overall "balance", although nobody bitched about the hp increase, and the loss of that "carb" thing, when the class went to Ford. 5th gear came in pretty handy, too. And the steel floor-pan, so you don't have to play Fred Flintstone after a major off-track adventure.