BRNGT4

So during the last track day i had the privligae of getting one of the pro Porsche GT3 Cup drivers to drive my car with me in it and also him alone with my Aim Solo DL running. The feedback I got was amazing and has totally changed the way i drive the car. I know i have listed my setup many times before but for those who have not read my previous posts here is the setup:

Tires:
Dunlop Race Maxx set at 22/26 cold and maintained at around 30/32 hot during the track day.
Hard parts:
RSS rear toe links with toe adjuster lock out plates.
15mm per side front spacers
Front and rear shims to adjust camber
Settings:
Front: Camber -2.1 degrees Toe 0
Rear : Camber -1.75 degrees Toe 9" on each side
Sway bars: Front on middle / Rear on stiff

So i have to say i am not a slow driver and that i race professionally in our local 2000cc championship. I have worked over the last few months with my fellow GT4 owners to reach this setup which has proven to be much faster than stock GT4 setups and that is reflected in the many many time sheets where we have evidence of stock vs our modified setups and the gaps are anywhere from 1-3 seconds.

Ok on to the subject of the Pro driver. As soon as he got into the car (after getting his crew chief to check tire pressures and give the car a look over) he switched off all traction control and we were off. His warm up lap i could see he was testing brakes and getting a feel for gear ratios. Then he went for it. His feed back was as follows:
- The car is well balanced however it could use more rear end grip
- The gearing is too long and the car would be much quicker with shorter final so that the LSD can be made to work better
- The Spring rate is a bit too soft however he felt for a dual use car its fine
- Mentioned that the car needs another 100hp and that the chassis can handle it
- He said the brakes were good and that he would want just a slight better initial bite which could be done with pads.

After that he went and did several laps in the car alone and i got the datalogs. He was about 1.5 seconds quicker than me. The key areas where he was quicker were committing to entry speed into the esses (he was several mph faster going in) and on the last turn he had faster avg speed in the turn. Other than that the datalogs were near identical so i am very very happy with myself. I have to say though that i came to within 1.5 seconds of him after he taught me how to do the braking right and before that i was 3 seconds slower than him. 1.5 seconds gained is a huge improvement for me!!!

So to explain what he taught me in braking. First when he was driving there was ZERO understeer and i asked him how that can be when i almost always have some understeer. The response was that during trailbraking, the release of the brakes is very imporatant and it has to be smooth and end right at the point when the car has rotated. What i was doing wrong was that i was trailbraking but completing my braking release before the point of full rotation so when i got on the throttle the car would understeer. Next time around i tried delaying my brake release and like magic the car rotated and i was full on gas with ZERO understeer. Now that i know this i reflect back to all the front tires i killed trying to plow through corners and i believe that the majority of GT4 drivers who complain about understeer have the exact same issue.

MarcD147

that's a pretty cool observation

and an amazing improvement... 1.5s is an eternity...

fishing

That's a great point on trail braking. Thanks for sharing. I haven't tracked my stock car that much and it hasn't seen an alignment shop, but I have noticed on track it turns in and rotates real nice under trailbraking.

jphughan

Interesting! I've only got 3 track days in this car now, but compared to my E92 M3 I've already found myself naturally trail braking much longer in several corners in the GT4 than I did in the M3, and I was wondering this weekend what everyone was complaining about with understeer because I didn't have any. I figured maybe it was just me being new to the car and therefore not going as fast as more experienced others here (which may still be at least partially responsible), but then again I seem to remember people saying that Caymans don't require a lot of trail braking, so maybe they also weren't doing as much as they should. My alignment is -2.5 camber and 0 toe up front and -2 and 10' toe in the rear, fwiw.

Congrats on that 1.5s improvement though for sure! And don't feel too bad about those early front tires, since the longer, higher cornering forces from the extra trail braking will take their toll on the outside edges too.

matttheboatman

Thanks for the great report, BRNGT4.

Brake release critical - I am now at a point in my driving skill where brake release is a remaining critical component for me to reducing time. As a rookie, I was taught the safe but slow techniques of getting off the brakes while turning the car. Now I need to learn a new habit of rolling a bit more into the turn, and super smooth trail braking.

mrd_spy

great to get a pro to drive it, are you going to make any changes to the set up now ?

he stated needs more rear grip even with 295 on the back, so are you going to put the rear ARB back to the middle ? or keep it as is ?


I will be on track soon and it's always great to get a nice set up 1st off, rather than waste 4 track days swearing at the car lol.

I have atm 8mm shims to go on the front and tarret rear toe links with locking plates, just deciding what to ask my Shop for geo wise now.

I est 8mm would give me -2.3 up front ish if I had good top mount adjustment. and was going to go for -1.8 on the rear with stiff rear ARB.

Knolow

Good thread. Subscribed. I like the lessons learned. When I get my car I wanna skip the learning curve duration.

vantage

Looks like you got a neutral setup with less camber than others.

When a pro coached me in my Lotus, I could not believe how deep he wanted me to trail brake into the turns. Pretty much all the way to apex. Literally second third turn of my lap, he goes "you are getting a touch of understeer there because you released the brake too quickly".

2WheelsRBetter

Thank you for the insightful post and congrats on the improved lap time. Can you try to describe for me that moment when full rotation has been achieved and you can discontinue trail braking?

Manifold

Good thread.

My approach is to trailbrake as much as needed to increase corner entry speed and smoothly transfer load from the front to the side of car while also inducing some rotation of the car. I do it routinely with every car I drive, even on the road. Being able to get on the power too much, too soon in a corner is sometimes a sign of not trailbraking enough.

Skip to 4:00 and check this out:

Yargk

Obligatory Andretti quote:

“It is amazing how many drivers, even at the formula one level, think that the brakes are for slowing the car down.”

CAlexio

Really enjoyed reading the feedback on trailbraking, makes so much sense. Thank you for sharing.

bk_911

What a great experience and equally great write up. I have noticed this car tells you right away if you are on the gas too early. It's actually telling you a lot of information but you have to tune yourself to listen. I drove routinely on a pretty tight back road near my work and I can tell when I've done a corner properly. Obviously I'm not going track speeds like 7/10s or higher but you really know quickly if you blow a corner in this car. If will understeer and right before understeer in the softest pasm setting it sorta starts to pitch a bit. You can literally feather the throttle and feel the car hitting that limit.

Alternatively if I'm braking really deep enough to set the car up properly as explained by your post the car just digs in and goes.

This a great car. Best I've owned. I'm enjoying the crap out of it. I can't wait to get on track.

4th911

Great post..thanks for sharing.!

RealityGT

Very much appreciate your input.. Thank you,