Manipulate the Weight Bias (Original Thread)

[Blooze]

Here's my build on the Dino.  Of note, the car publishes a 42% weight bias but is actually a 41%. 

It is built out to 299 Hp, 237 ftlbs, and 1925 lbs using...

• Race Exhaust
• Race Ignition
• Sport Cam
• Race Block
  
  
• All Race handling except the Drive Line (street)
  
  
• Michelin DOT
• Maximum width (225 mm)
• 18" Rims
• Fiske FM10

Slicks were set aside for DOT to free enough PI to allow engine mods.  The engine has an approx .8 Tq/Hp ratio.

Next, the car's weight bias was set to 54.5%  Telementy studies and test driving ended up adding 14% to the ARBs and 4% to the springs.  The dampers were adjusted 1 tenth for exit grip and and a tenth for transitional understeer as well.  In this configuration the estimated 1/4 mile performance is 10.836 sec & 125.8 mph.  It benches...
3.771; 11.421; 102.7; 277.6; 1.04; 1.02

Setup Table:

Parameter	Front	Rear
Tires	30	30
Camber	-1.1	-0.7
Toe	0.0	-0.2
Caster	5.4
ARB	12.87	10.67
Springs	382.1	319.4
Height	4.1	4.2
Rebound	7.3	5.9
Bump	3.8	3.1
Aero	na	50
Brakes	50	100
Front Diff	na	na
Rear Diff	51	51
Torque	na

I have yet to Dyno the car - the transmission is stock gears with a 4.62 FD.  Also, it hasn't been run through the final tweakage stage.

The car handles pretty nice, I think - I got a 61.338 right out of the box on Mugello, which is pretty good for me.  I am going to finish leveling it up and get a QR on it, then I wll pretty much be done with it for now - many many cars to build before I sleep, and cars to build before I sleep... 

I had figured on building it, testing it, then junking it out.  However I kind of like the little car and think it might do well in B, specially on the shorter tracks.   I think it could be built and do well without the spoiler, also.

Edit: The car has an intitial QR of 182.236, which puts it about a second off my Shelby GT Light... not bad!

$

[Hoplee]

Your upgrade setup is very similar to my FCT Alternate 1.0 except that you went for more weight reduction and less tire. Did you try the heavier build on stickier rubber?

[Blooze]

Oh, I laboured over that one long and hard, almost logic-ing myself into stasis...

I wish that weight reduction and tires did not vie so heavily for PI points.  The reason for having to make the choice in the first place was that the Hp was light for a B class car when both WR and Slicks were present.  One had to go.  Because the G value with the slicks was quite high for the class I figured I had some to give in this area.  The resultant 1.02 G still puts the Dino in the upper eschelon of my B cars for that parameter.  Likewise, because the whole exercise was a scramble for power, I viewed inertia and momentum as serious enemies, and weight as their dominant ally.  And anything I could do to keep weight off the car would only assist the tires. 

Then I flipped a Susan B. Anthony dollar I keep on my desk for such occassions and the WR won best 3 out of 5... 


Were I to approach it again, I would take a serious look at the need for downforce and perhaps get rid of the spoiler.

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[Hoplee]

The nicest unintended consequence of figuring out a great Dino setup is that it doesn't take much tweaking at all for the same setup to work on the 914 or the STRATOS. Try it and I think you'll be pleasantly surprised that you now have 3 competitive foreign classics. Of course, your system postulates that the setup would work on any car with minimal tweaking, so this may or may not be a surprise/useful to you.

[TheTechnobear]

quick question about your setup...

ARBs, are your values correct?
your quoted ones are not  using F=1-WD, you've used F=WD,  by my calcs it  should have been 10.71/12.82
as, the originals would have 11.97/8.67  for 42%, you can see 54.5 would have to have F < R
(of course could be a typo )
intentional?

Rebound - original i had are: 5.5/7.5- which at +4%/54.5 gives me 7.4/6.2,  yours are 7.4/6.5 - which veres to 55.5, similar to where your bump is.
are you adding 'damping agent' to both rebound and bound? and allowing movement away from 54.5?

im just interested in where and our values differ and if its intentional or not


im intrigued by the stratos hoplee, ive found that one tricky to get a handle on
btw, also tried your Elan, which i hit a 60.748 with, but had to have downforce - and the suspension seems to bottom out regardless of what i do with springs and ARBs

[Hoplee]

currently my STRATOS is dedicated to the short tracks because it weighs ~1700 lbs and boasts very little power. I MAY be covering up some of the handling deficiencies with grip by running slicks in such a light car, but the results so far have been pleasantly surprising.

I should note that I am NOT running a wing on the car as only a front wing/splitter is available. I don't think the front needs the help with grip. if there's one thing this car has more than enough of, it's turn-in response!

[TheTechnobear]

yeah, the front is not the issue - with my b700, its the rear trying to overtake the nose at every given opportunity - though perhaps again, my right foot is being a bit heavy.
might have a play with the stratos again, its possibly got some potential
(actually should probably post comments in the FCT garage)

[Blooze]

Heavens!  LoL - you look at 'em pretty tight! 

quick question about your setup...

ARBs, are your values correct?
your quoted ones are not  using F=1-WD, you've used F=WD,  by my calcs it  should have been 10.71/12.82
as, the originals would have 11.97/8.67  for 42%, you can see 54.5 would have to have F < R
(of course could be a typo )
intentional?

True, Forza does set the ARB values to 1-Wb.  If you check the original document, I am fairly certain I stated that I thought that to be part of the ruse.  I never have used the inverse.  The values I show are +14%.

Rebound - original i had are: 5.5/7.5- which at +4%/54.5 gives me 7.4/6.2,  yours are 7.4/6.5 - which veres to 55.5, similar to where your bump is.
are you adding 'damping agent' to both rebound and bound? and allowing movement away from 54.5?

If you check earlier in this thread, you'll find where I said I was going to review my practice of modifying the dampers to match the weight increases of the springs.  This is me reviewing it.  I no longer do that.   And correct, all of my damping agents add two values, front and rear, to either bump or rebound depending on what I want to accomplish.  I published the document from which I established the agents.  If you check that, you will see that most of them modify two values.

[TheTechnobear]

just obsessed with spreadsheets,  chucked your figure into one i have that calculates forward and backwards (and shows me adjustments % etc) and bang the differences were staring at me in the face    

actually, checking and your reply was kind of what i was hoping for - i.e. see see if i was working along the same/similar lines to you.

ARBs, hmm, will need to play with that - i had a theory about the 1-WD, but think i need to review it, as you are getting good results the other way - and i have some issues
(it is odd though, as the setups ive done nearing 50% have been the ones with issues... perhaps the bigger diff springs was helping)

dampers, yeah i remember your post, but misunderstood this conjuction with another post. though, to be honest, ive recently been playing with the balance of the dampers anyway.

seems like im going to have to get the dino out again, then perhaps try some of my troublesome projects.

[Blooze]

I can relate to the Spreadsheet issues... 

I'd be curious to hear what you think of the Dino with my setup on it.

$

[TheTechnobear]

k, will have a go...

just did a couple of quick tests though, and on hopless alt setup, with 54.4 but with ARB set as WD/1-WD
and i thought it had understeer (note: i prefer oversteer) - and i just found i couldnt get the turnin
(my other settings are pretty much the same as yours)

i then tried with -  54.4/+14/+4 was much the same

now what i didnt do, diliberately is alter dampers, as i didnt want to 'tune' out the issues... as i could do that with the ARB either way around.

hmm, so i think i need to try the following:
i)  try your setup exactly, see if i get the same kind of 'feel' ... do i get the perceived understeer?
ii) try the ARB reversed on a couple of other cars, notably the etype and elan, which i think may benefit, they were a bit too lively at the rear

i also have another theory to test, perhaps this ARB is a red herring - if we have good WD on a car, then surely the correct place for the ARB is neutral (50/50) or even just adjust to preference (driver, track and car)
 
update 1: (i) feel was definitely better, but still tendacy to understeer compared to other (but really is a preference on that one, another may argue the other build was tending to oversteer). anyways, i then removed your damper adjustments, and that moved it closer to what i saw before (more understeer), i then reversed the ARB - then got a very similar feel to my wb setup.
interestingly, i then put the arb to 50/50 and it was actually quite a nice compromise.

hmm... unfortunately this doesnt tell me much
i think, im seeing with the dino its a great car and it goes well - and you can adapt easily to how it feels.
btw, like the DOT tyres, i was really pleasantly surprised, i expected to be all over the place
(was get low 61's with pretty much all combos - but i think im not hitting the lines that well tonight, its been a long day.)

so i reckon, on to (ii) they may prove a better test, as the issues were quite clear before.

[JG4tr]

Well guys, I've got to say that so far, I am very impressed with the results of 'Rebiasing'.
Late last week, I built my first MInc spec car, a 69 Z/28. I documented the default specs which were of a 58/42 Wd and began driving, recalculating, adjusting and driving some more. I was able to pick up over a full second on ATLshort by rebiasing to 51/49. Much less tail wag but, still rotating well.

Over the weekend, I took the 'final' percentage changes from the Camaro's ARBs, Springs and dampers and applied the same ratios to a ZR-1 Vette. After a couple of hours to test drive and tweek, I ended up with a 48/52 bias and the additional HP on tap allowed me, even with the extra weight in this particular build-up, to go faster, more consistantly than with the Z/28. I had to really push the Camaro which led to less consistant laptimes.

Just for the heck of it, last night I took my B class WRX to Silverstone, ran it, rebiased it to 50/50 and it was noticeably quicker and easier to handle.

It's been twenty years since I used a calculator this much!

[Blooze]

LOL - next thing you know you'll be looking for that MS Works CD that came with your computer so you can get at the spreadsheet program in there...

This is really cool to see someone having success with other than an types () of bias.  It would appear that your driving style tends toward the more neutral 50/50 car.  Now, I get more tail wagging from cars that are heavier in the back end.

After me and Bear's little discussion I want to ask how you are setting up the ARB, with the inverse value ala Forza, or with the new Bias?

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[JG4tr]

After me and Bear's little discussion I want to ask how you are setting up the ARB, with the inverse value ala Forza, or with the new Bias?

So far, I have been using the reverse of the Wd, like Forza, as a starting point. It's still early days for me and I may find after more cars and more experimentation that something else works better but, for right now it seems to be right on the money. I have just added the same percentage increase to F&R to maintain the bias unless I decide that I want a balance change.

I think that for me, the 'tail wagging' on acceleration is due to the softer rear setup when the bias is forward. Lowering the rear diff accel lockup helps but, by stiffening the rear, I can dial as much out as I want. I like to leave a little in to have in case I need to make a correction on corner exit.

[Hoplee]

I did a little work last night on the Dino comparing setups.

The experiment was set up by building the Dino to Blooze's specs (lighter weight and cheaper tires). I let FORZA automatically adjust my own settings (found in FCT Garage) down to the weight and ran ten laps on Mugello Short. My fastest time with 'Dino-Lite' and my settings was 60.465.

Then, I used the Blooze settings and ran another ten laps. I was behind or dead even with my own settings for the first 9 laps, then, on lap 20 overall, I ran 60.345.

One could surmise that the Blooze settings are therefore worth a tenth of a second, but I'm not ready to make that assumption. For one thing, the application of the Blooze settings reduces grip benchmarks by around 0.02, which doesn't sound like much, but it is significant. For another, I was adjusting my braking points to the new weight for a lot of those 20 laps. There's a chance that by lap 20, I simply knew the car better, thus giving the car that ran second an advantage. As far as lap times go, I consider it a wash until more data is gathered.

Let's compare the times to my baseline

Baseline: Rank #354 Dino 246 GT 59.851 Mugello Short

Both cars are behind my baseline time but interestingly, both cars are just about dead on with what I was seeing when I first began tuning the Dino. My first tunes added predictability while reducing grip and produced a fastest time around Mugello Short of 60.4xx, two tenths behind my then current Toyota 2000GT build. I suspect that the same kind of things may be happening here.

My driving impression of the tune was mostly positive. It no longer rotates mid turn AT ALL. The car dives in, chooses a line and powers out with inputs from steering and throttle locked. With a default tune, this kind of driver input would result in time shedding skids. Normally, when a car handles the way the Blooze Dino does, I add more power. I was impressed with the way it comes over one particular crest of a hill on Mugello Long (Turn 9?), allowing me to run about 3-5 mph faster than I normally do. This was due to the car being MUCH more stable over elevation and gradation changes, not to mention curbing.

Further testing needs to be done, specifically comparing the tunes with the 'Dino-Heavy' build, which is the upgrade setup I used to set my 59 on Mugello Short with. Blooze, can I just let FORZA adjust the settings up to the new weight or will some calcupunching need to be done?