Manipulate the Weight Bias (Original Thread)

[Fit4aking]

I tend to bias my cars to keep the handling in line and then adjust to get the front and rear tire temps to come up relatively the same time.  It takes a bit longer to tune and I know each is a trade off between absolute balance and good tire heating but I prefer the consistancy of equal tires than the overall speed of the car after a couple of warm up laps.  To me that is the biggest difference between a race setup and a hotlap setup.

[R2P TALIESIN]

I think the bigest difference between a hot lap setup and a race setup is that the hot lap set up is closer to the absolute edge of what you as a driver can handle to get a fast lap so as a consequence its closer to the edge of spinning out all the timeie wbr at 49/50%. However I feel that as a hot lapper for want of a better expression there are a lot of guys out there who can drive far closer to the edge of control than I can and as a consequence are also far better racers than I will ever be as a racer.

[fndrbndr]

There's definitely overlap.

[Fit4aking]

I like to think I'm a far better racer than hotlapper.  I'd prefer to have my name in lights and on top of the leaderboards but I'm a ways off of that.  I can run pretty fast but mostly consistant lap times.  When I first started using the Blooze Toon I was very impressed and didn't stray too far from the 54.5% bias.  As I paid more and more attention to the tire temps I noticed that the car was very stable but that the rear tires took a full lap or two, on the short tracks, to get up to temp.  I added aero to keep the car inline but I was only covering a symptom not curing the cause.  As I began biasing non-aero cars I found that if I shifted the weight over the back just a touch, usually 52.5%, the back tires heated up faster and stayed in the sweet spot over a decent number of laps.

However I ran an endurance race with the hottest slicks I could buy and they wore out evenly and I was on rollerskates.  To make the car stay faster longer I knocked back the tires I was choosing to go a longer distance.  I had to adjust more than just the settings after that fiasco, several total builds got flushed.  Ultimately the cars got much better and more consistant over a mid length race so I was happy.  The onle car that I spent the most time in is my B-class Trans Am.  I was able to run down and win a drag race on Suzuka Full against a couple of really nice Skylines over 10 laps.  They were faster on the final board but my race time was faster and it was due to consistancy.

To me the consistancy is what wins races.  It helps in longer hotlap sessions but isn't tire wear off in freerun anyway.  I spend a fair amount of time after I set up the alignment rebiasing a car for good even tire heat front to back and it allows me to run confidantly in tight quarters lap after lap because I know its coming down to a mistake.  I don't have to worry about my car going away in the heat of a 5 lap battle, I just hit my marks and know its gonna hold.  I do lose to the fast guys if they get out front or if collisions are off but if they are passing me or are behind be one miralce lap isn't gonna cut it.

[R2P TALIESIN]

I think for what its worth and I am agreeing with you on this is that for a hot lapping car you require a weight bias closer to lets say for arguement 50/50 as you are not looking for consistantcy you are looking for the fastest lap if everything is perfect especially the nut behind the wheel. As the track gets faster you start to knock this ratio back to 51/49.

If you are looking to do say a 5 lap race say the exibition or career mode you require a greater margin of safety so you knock it down further. So in effect I totally agree with your statement the longer the race the safer the bias you want to go.

I think what I was also trying to say very inarticulatly was that there are some drivers out there who can drive a car far closer to the edge consistantly than you or I can, it just that they are able to know better where the limits of the build exist.

[bimmerlovere39]

Most of my cars are in the 51/49 to 48/52 range.  Most are almost exactly 50/50 - which is actually very close to the displayed value for WB on the BMWs (which make up most of my cars...)

The most obvious exception is Porsches - any thoughts on what the WB tuning on those beasts should be?

[Fit4aking]

Bias Tuning A Hit In Forza Motorsports (The Original)

By: Fit4aking

Baltimore, MD.  A local man, authorities only name using the alias Fit4aking, has been spotted pacing nervously in the living room of his home.  Police were notified by a concerned neiborhood watchman after a coffin was delivered to the front door of his residence early this week.  Baltimore County detectives have had Mr. Fit under close surveilance after an interrogation of his wife confirmed his erratic behavior.  Fit4aking was removed from his home shortly after he was spotted jumping up and down on his bed.  Officers on the scene described the actions as self destructive and dangerous.  He was apprehended without incident and has been taken into custody.

"He's not been himself, he stares blankly into the TV, and its turned off.  He holds the remote to his (gaming system) and makes strange noises.  I just want my husband back" Mrs. Fit stated during a press confirence outside of the local precinct.  "He found a copy of (Popular 1st Gen game), and it seemed to get better until tonight, he seemed content"  Detective Smith refused to comment and would niether confirm nor deny any plans to intervene is this destructive behavior.

Police reports indicate that evidence found on the scene point to, what is being described as, Weight Bias Tuning.  A notepad, calculator, and laptop computer were confiscated and no details have been released.  Crime lab technicians confirmed that the objects were in fact used in successful Weight Bias Tuning on the 1st gen gaming system but have no specifics at this time.  Fit4aking has not been available for questioning and there is no indication that he will be released back into the "Next Gen" population for the next 3-4 weeks. 

[Blooze]

Very good!  Goin' BF without the 360 huh?

That is interesting and cool.  It lends credance to the thought that a number of things weren't changed from the first version to the next.  Or at least they weren't modified to the point that it rendered the theory useless.

Thanks for the report and the funny read...

$

[fndrbndr]

Funny read, Fit.  A little scary, but funny...lol

[Blooze]

This is under-going some modification.  I don't know exactly how to explain it.  I am currently calling it...

Minimalist Sychronicity

More on that as it reveals itself to me...

  $

[Stryfe]

I've just finished reading this entire thread. It took coming back to it a few times over the course of a week but I made it.  This discussion has increased my tuning abilities in a huge way.  Before I'd just adjust individual parameters hoping to cure one symptom at a time. Now I understand how everything works together and I've been able to build more and more dialed in cars.

I built three cars over the course of reading this thread, each one better than the last.  The last car I built after finally finishing the thread is the one I'm most proud of, an A class Honda NSX-R. I've always found MR cars tricky to drive, nevermind tune, they just seem to require more concentration than the other drivetrain layouts. This one is a pleasure to drive, it has tons of grip and is easily steered with the throttle.

In interest of contributing to the discussion, below is my NSX-R's setup. It's overall WB is 52.3% with the ARBs at 54% and the Springs/Dampers at 51.5%. I've lowered the SWR some what, at 76% stock is quite stiff, and adjusted the dampers for more grip on corner exit. Give it a try if you like and let me know what you think.

Thank you to everyone who's contributed to this thread, I've learned a lot.


Car: 2005 Honda NSX-R
Class: A850
Engine Parts: Sport Ignition  304hp/236lb-ft
Platform Parts: All Race with Race Weight Reduction   2,201lbs
Tires and Wheels:
     Tires Type:  Avon Race Slicks
     Rim Style:  Motegi Racing "Trak_Lite 2"
     Rim/Tire Size: F: 225/35-18 R: 265/35-18 (Tire Width +1, Rim Diameter +1)
Spoilers and Diffusers: Forza Front Bumper, Forza Spoiler

Tire Pressure: 
     Front: 30psi
     Rear: 32psi
Gearing:
     Final Drive: 3.87
     (1-6): 2.89, 1.95, 1.48, 1.19, 1.02, 0.85
Alignment:
     Camber Front:  -0.9
     Camber Rear:  -0.7
     Toe Front: +0.1
     Toe Rear:  -0.2
     Caster: 5.0
Anti Sway Bars:
     Front:  16.97
     Rear:  20.01
Springs:
     Front:  408.5 lb/in
     Rear:  384.6 lb/in
Ride Height
     Front: 4.5
     Rear: 4.6
Dampers:
     Rebound Front: 8.4
     Rebound Rear:  7.8
     Bound Front:  4.2
     Bound Rear:  4.0
Aero Adjustment:
     Splitter (Ft):  116 lbs
     Spoiler (Rr):  116 lbs
Brake Bias:
     Bias:  48%
     Pressure:  111%
Differential:
     Acceleration:  60%
     Deceleration:  58%

[Blooze]

Now, that is a strong first Post...

A tip of the hat for reading the whole thing, as well.  I went back and re-read the first few pages.  It is interesting to see how the process has evolved.  And, for some reason, it all seems like so long ago when I first proposed the Wb theory over on the Daught Gnet.

I am curious about the process by which you arrived at the three different Bias values for the car.

Oh, and welcome to the forum!

$

[fndrbndr]

Wow.....yeah, very nice first post.  And welcome.  Looks like a good tune.  I may try to run this later, but the only thing that jumps out at me is the tire pressures.

[Stryfe]

Thanks for the welcome guys

Blooze: I started with a WB of 54.5% across the board.  I found the car to be unstable, when turning in the back end would get really loose.  I moved the WB back 0.5% at a time until I got to 52%, at that point the car was much more stable but I'd sacraficed some front end grip.  I've always used the ARBs to fine tune understeer/oversteer so I thought I'd give it a try in this case.  I moved the ARB WB forward slowly until the car felt as balanced as I could get it and ended up moving the Spring/Damper WB back another 0.5% to further stabalize the car.  Finally I made the tweak to the dampers to get that last little bit of front grip on corner exit that I felt was missing.

fndrbndr: I'm stil getting my head around trying to get the tires to heat evenly.  The extra 2psi in the rear was to try and get a little extra heat in the rear tires. I've noticed most people seem to use either equal pressure front to back or at least within 1psi.  I'd appreciate any input as to how to get the rear tires heated up a bit more without the extra pressure.  Or maybe I don't even need to, the rears aren't *that* much cooler on this particular car.

[Detrick]

fndrbndr: I'm stil getting my head around trying to get the tires to heat evenly.  The extra 2psi in the rear was to try and get a little extra heat in the rear tires. I've noticed most people seem to use either equal pressure front to back or at least within 1psi.  I'd appreciate any input as to how to get the rear tires heated up a bit more without the extra pressure.  Or maybe I don't even need to, the rears aren't *that* much cooler on this particular car.

Correct me if I'm wrong but getting the tires to heat "evenly" - that is to say close to the same temp. on the inside, middle, and outside of the tire - has more to do with camber and toe than the overall beginning tire pressures. 

To properly set the beginning pressure you need to run a number of hotlaps to sufficiently warm the tires and then check temperature - for maximum grip the ending pressure should be somewhere in the 33-34 PSI range.  Anything above or below and you are giving up grip.  In my experience, a typical FR/MR setup should include beginning tire pressures of 29F/28R unless the car is a lightweight.  Beginning pressures for a lightweight FR/MR are closer to 29F/29R or even 30F/30R.  For a FF car I've found success with pressures at 28F/30R.