fc-racer

Hi there,

I'm trying to determine what deceleration G forces you're are seeing with your GT3's at the track. With the AIM EVO4 DAS, I'm seeing max 0.9g on decel. This seems low given that I'm getting constant 1.1-1.2g in cornering forces and peak readings of 1.3-1.4g.

When I read magazine articles, I've read of cars hitting 1.1-1.3g on decel, but I'm nowhere near close. Is there something wrong with my car, my technique, tires, etc? What G forces are you seeing?

Thanks!

JarmoL

I am seeing -1.24 G's as a maximum deceleration value on my latest datalog. Car is 996 Mk1 GT3 with r888 tires. Data was logged with Aim Solo.

TRAKCAR

On fast laps and hard brake points, I am between 1.2 and 1.55G at max braking..

JarmoL

Checked again and the actual maximum decel value was -1.33 G's. The one I posted earlier was just from the fastest lap of the session..

utkinpol

well, i would say it is most likely a direct correlation to see 0.9G max braking force at the fastest lap.
i see same in my car - properly executed deceleration is about of 1-1.1G max. less g-force means less disbalance for the car, so, if entry speed was kept as it should have been for the corner no one cares what longitudinal force was, alone.

do 2 math channels in AiM -
G_Force = sqrt((Lateral_acc^2)+(Longitudinal_a^2))
Diff_Lateral=GPS_LatAcc-Lateral_acc

for Diff_Lateral you may need to adjust GPS_LatAcc value as (*-1) as it may be inverted.

then check how those metrics show up in the 'GPS Data' view - negative Diff_lateral goes for understeer, positive for oversteer conditions.
Look at G_Force channel together with throttle and brake positions. It also is very visual on the GPS map view.

fc-racer

Thanks guys for the insight; this is great info.

Utkinpol, I setup the G_Force (or AIMGSUM) math channel and it's very interesting. It appears I'm not maximizing the corner entry traction available because the line builds up to 1.34g and holds that until the car straightens out. I would expect corner entry should also show GSUM of 1.34g?

I tried to test the braking g's with full ABS braking from 180km/h and still only got -1.0g. Maybe it's the RA1's?

gstahl

Just some fun data from a cup car (recorded via Motec ADL2 with hard mounted accelerometers).

Max braking: 1.62 G
Max accel: 0.72 G
Max lateral: 1.8 G

TRAKCAR

I get 1.55 G on ra1

MarkD

clearly due to your FLATOUT driving...

fc-racer

Thanks Trakcar, I think I need to be more flat-out!

I went through all of my data and these are the highest sustained g's (not peak, but sustained):

Max braking: 1.16 G
Max accel: 0.70 G
Max lateral: 1.32 G

utkinpol

in what gear do you get 0.70G acceleration? that is nice. my modest 3.6L M96 pulls only 0.30G in 3rd gear as it seems.

my braking is kinda same in 1.06G in fast laps, max one when i messed up and stomped pedal down it went to 1.14G. I need new pads with better bite. Lateral max was 1.44G, it is from last WGI session.

also make sure you calibrated your unit - connect racesturio directly to unit, go to 'online' while car is parked on flat ground and see if accelerometers show 0 or not, if not - click 'device calibration' and calibrate it.

TRAKCAR

Sorry, my number is peak. I don't see for how long it is on my data, but I can't imagine it's that far off..

BBMGT3

I think its quite varies - tire condition, track condition, alignment, shocks, brakes, lot goes into it

But as a rule if you're going hard you should be doing higher lateral G than decel G.

TRAKCAR

Agreed, decel always the highest number or something is wrong

fc-racer

Here's a data trace if it helps: http://www.fcracer.com/gt3/datatracetmp.png

utkinpol, I pull 0.7g coming out of a second gear corner at 88km/h and 5,700rpm. It progressively trails off to 0.50g at 8,200rpm before shifting to third.