Any hints on how to get the rear tires to heat up quicker without getting too hot in latter laps? The rears on my class A civic are talking about a lap and a half to heat up even on twisty long tracks.

Hmmm,....sort of. but you have to make comprimises in handling.

1.  Set rear toe higher = more resistance = more heat.  But too negative a toe will cause understeer, and too positive a toe will cause instability and oversteer.

2. I recommend a higher rear brake bias.  Your braking distance might get a bit longer, but you'll free up some front end turning traction too.  A good tweak for those who like to trail-brake deep into corners.  I suggest a bias of about 45 or 46% front.  The rear tires will do more work this way, and should pick up a touch more heat. 

Tune tire pressure according to heat build up, and warm pressures, when your done.

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

feuerdog:

You say the car is getting squirrely on the straights?  Or on high speed corners?

Yeah. it gets squirrely in the straights.  The cornering feels great, it takes a sharp tug by me or a fast mash on the gas to get any screeching at all in the corners.  once the car gets to around 135mph I start to see and feel it rocking and eventually the reaer will slide out.

 

I will try all the adjustments you suggested, starting with the toe and moving to the others if that doesn't work.

---

All times are Eastern Standard Time (GMT -5:00), unless otherwise noted.
[Mod edit: Sig size exceeds forum limits, 480x115 pixels max - D]

I agree with the downforce adjustment, I've already been using the camber settings tweaking and -.8 is too much on the rear on my '69 Camaro.  -.7 works best, because with -.6, tire temps are uneven still.  I use 150lbs rear downforce in testing everywhere, with a A850 PI score.

So far, I'm cool with everything in this except dampers, I'm still maybe a bit confused as to why bump damping is a higher value than rebound damping, but when I use it the way the calculator explains, it actually helps performance, so maybe I'm feeling uneasy over nothing!  D-:

---

[RCKT] - RCKT Racing Nova Scotia
Member of SimRacingHD.com's Forums
Open-wheel and sprintcar simulator racer

That's what I'm doing now, but the rears are getting hot and greasy in latter laps... especially on a real twisty track. I'll just keep playing with it. I'm kinda hard on tires since I brake hard into turns and accell right on the edge of control coming out. I kinda figured I was going in the right direction, but I just need to work on it. Thanks again.

Rottenkaze:

CobraRacer,

In my opinion, FM2 seems to use wheel rate rather than spring rate.  Even assuming a pretty generic .5 motion ratio the spring rates get too large in the game to be realistic.  At 2.2 cycles per second on the suspension frequency, for example, the spring rates don't make sense in the game...they are much too large.  I think motion ratio is taken out of the equation and the "sliders" in the game refer to wheel rate.

By the way, is that a Factory Five Spec Racer?  Nice... 

Agree about the wheel rates...  You also bring up another interesting point about frequencies...  Not sure if it would be feasible, or even advantagous to try to calc freqs in this game... but one could probably make some assumptions on unsprug mass at each corner and do some sanity checks. 

Yep, thats a FFR, although not a spec racer.  Its actually one of the first FFR cobras on the road.  Ive owned it for about 10 years now.  Its a classic ;)   

You might like my new project:

Photo Gallery: http://www.gtmbuild.com/galleries/gtm_build/index.htm

If you're interested in checking out the build log where most all the gory details are documented.  See: http://www.ffcobra.com/ubb/ultimatebb.php/ubb/get_topic/f/35/t/000256.html

 

I'll try this on my Mitsu GTO tonight and let you know how it goes. Thanks

teck50023:

This is for the OP.

 

I recently opened up a new website dedicated to tutorials, race and drift setups, and anything else I can find. I would love to post your calculator up on the site. Would you mind? Or anyone else that has an opinion on which one of the numerous ones I’ve seen today mind telling me witch is better? I would like to at least make a link with a little blurb about it on my site. Thank you

Ditto to Feurdog's statment.
Feel free to link to the calculator I built at:
http://www.redshirt1701.com/Forza2/suspensioninput.cfm
All I ask is you give me credit (for the calculator not the brians behind it) and post your link once you are up and running, I need all the help i can Get!

Also, as I try to keep up with Feuerdog's revisions, I'll make multiple copies of the calculator, one for each revision so if people like one but not another, they still have older ones available.

Current Version (and onlyversion) as of 6/12/07 is based on the first set of minor updates feuerdog made from 6/11.

---

Online Forza 2 Suspension Calculator
http://www.redshirt1701.com/Forza2/suspensioninput.cfm
Based on Suspension Guide by Feuerdog
http://forums.forzamotorsport.net/forums/1/256899/ShowThread.aspx

feuerdog:

As for the damper values, i've had similar problems myself.  Not with the calculators, but with justifying the ratio of bump-to-rebound.

In Forza 1 I was settled on the fact that in order to reduce the possible effect of "pack down", I needed to make the rebound resistance lower than the bump resistance.  It makes sense right?

Yes, however, as long as you have the spring and shock to the appropriate ratio, you wont get packing down.  It only happens when you us tooo much rebound on a shock for a given spring.

Well initially I had tuned this calculator the same way,......until I reread my Milliken Racing Car Suspension Dynamics book again on the section about dampers.  Think of the way the suspension is influenced and the way in interacts with the road surface.  Weight transfers, no matter how quick are fairly weak forces, and are primarly influenced by the vehicles weight, CoG, and the counteractive forces of the tires grip.  On the other hand, hitting a curb at 120mph with a stiffly sprung car is going to produce a very high mass shock load to the suspension.  As it turns out, the book mentions these differences as a ratio of 2:1.  Impact loads being roughly double that of suspension rebound loads.  The result is a basic damper value difference of 2:1, with the rebound needing far less damping than the bump damping.

There may be something Im missing about Milliknes text, or theories... However, I havent been exposed to using higher compression than rebound settings in real life.  At least in my case, when I increased the bump, it made the car very skittery and uncontrollable on my car... but its all realitive correct?    The truth is, it only  matters what works, in real life and the game... and formulas are great starting points to get cars in the ball park, and the rest is testing.   I have found your leg work really helps the cars that I've played with thus far.  Since Im limited on time, Its helpful to plug the numbers in and go drive.  Saves a bunch of time!

Now,....you might also notice that I have not stuck with that 2:1 ratio. The Milliken book also mentions successful racing ratios of 2:3 or even 1:1.  So due to bump absorbtion, stabilty, or just plain old "feel",....I like firmer rebound damper ratios too.  So while I typically call my setups soft spring/firm damper, it's basically because thats how they feel to most people.  In reality it's because my rebound damper values are disproportionately high by passenger car standards, but appropriate for racing,................at least according to real world tuning.

As someone who races I know you've felt how stiff a racing suspension can be.

Yes sir... Its a dramatic difference between what works on the track and feels OK on the street.

.....and yeah, cheap racing tires are even expensive these days.  Do you run DOT spec. tires or just prepped racing slicks on your Cobra?

Ive run both Hoosier and Kumho Radial DOT-R tires and now the cobra is on Hoosier Bias Ply slicks.    Interestingly enough, Radial DOT-R tires and slicks generally require much more camber than the game telemetry says is correct.  In most cases, radial tires require between -2.5 and -3ish degrees of camber up front and -1 to -1.5 in the rear.  The game seems to match the requirements of bias slicks as far as camber goes.  Regardless, the telemetry tells us what settings we should use.

One question I have, is that the guide appears to suggest more negative camber than front.  The cars I have tested appear to show the need to for a bit more front camber.  Can you provide some input on this?

Thanks, David

Wickedneoq:

So far, I'm cool with everything in this except dampers, I'm still maybe a bit confused as to why bump damping is a higher value than rebound damping, but when I use it the way the calculator explains, it actually helps performance, so maybe I'm feeling uneasy over nothing!  D-:

After rereading,...... http://www.theoryinpracticeengineering.com/drift_mag/basic_damper.pdf

...it seems I have to eat my previously, retracted statement which was apparently correct in the first place, and replace it with what I have already corrected in my most recent revision and post of said statement. Um,....nevermind.

You are correct and I am confused.

Compression(bump) damper values should be lower than rebound damper values.

My rethink based on what I read in Miliken's suspension dynamics book was somehow inverted and possibly confused with damper velocities, .....or something.

Regardless,.....after some of the damper testing I did last night(max. comp. vs.zero rebound and zero comp. vs. max. rebound), it still seems as though too high a rebound heavy ratio will cause pack-down issues.  However, since Sebring is our only really rough track, and only in one section, the optimal ratio might not be too far off from what we have now.  There is no perfect ratio anyways, thats why we are tuning to begin with.

As far as the calculator is concerned, i'll leave it alone for now.  I'll just have to add this issue into my list of things to test and confirm.  It seems to work ok, so theres no immediate need to change anything just yet just for the sake of realism(It kills me to say that, btw).

I need to reresearch this and double confirm to be sure..

This is the problem with rushing things before they are ready,........my mistake.

 

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

CobraRacer:

feuerdog:

As for the damper values, i've had similar problems myself.  Not with the calculators, but with justifying the ratio of bump-to-rebound.

In Forza 1 I was settled on the fact that in order to reduce the possible effect of "pack down", I needed to make the rebound resistance lower than the bump resistance.  It makes sense right?

Yes, however, as long as you have the spring and shock to the appropriate ratio, you wont get packing down.  It only happens when you us tooo much rebound on a shock for a given spring.

Agreed,.....and it is very road surface dependant as to how early this effect can take place.

Well initially I had tuned this calculator the same way,......until I reread my Milliken Racing Car Suspension Dynamics book again on the section about dampers.  Think of the way the suspension is influenced and the way in interacts with the road surface.  Weight transfers, no matter how quick are fairly weak forces, and are primarly influenced by the vehicles weight, CoG, and the counteractive forces of the tires grip.  On the other hand, hitting a curb at 120mph with a stiffly sprung car is going to produce a very high mass shock load to the suspension.  As it turns out, the book mentions these differences as a ratio of 2:1.  Impact loads being roughly double that of suspension rebound loads.  The result is a basic damper value difference of 2:1, with the rebound needing far less damping than the bump damping.

There may be something Im missing about Milliknes text, or theories... However, I havent been exposed to using higher compression than rebound settings in real life.  At least in my case, when I increased the bump, it made the car very skittery and uncontrollable on my car... but its all realitive correct?    The truth is, it only  matters what works, in real life and the game... and formulas are great starting points to get cars in the ball park, and the rest is testing.   I have found your leg work really helps the cars that I've played with thus far.  Since Im limited on time, Its helpful to plug the numbers in and go drive.  Saves a bunch of time!

See my post above on this very subject.

Now,....you might also notice that I have not stuck with that 2:1 ratio. The Milliken book also mentions successful racing ratios of 2:3 or even 1:1.  So due to bump absorbtion, stabilty, or just plain old "feel",....I like firmer rebound damper ratios too.  So while I typically call my setups soft spring/firm damper, it's basically because thats how they feel to most people.  In reality it's because my rebound damper values are disproportionately high by passenger car standards, but appropriate for racing,................at least according to real world tuning.

As someone who races I know you've felt how stiff a racing suspension can be.

Yes sir... Its a dramatic difference between what works on the track and feels OK on the street.

.....and yeah, cheap racing tires are even expensive these days.  Do you run DOT spec. tires or just prepped racing slicks on your Cobra?

Ive run both Hoosier and Kumho Radial DOT-R tires and now the cobra is on Hoosier Bias Ply slicks.    Interestingly enough, Radial DOT-R tires and slicks generally require much more camber than the game telemetry says is correct.  In most cases, radial tires require between -2.5 and -3ish degrees of camber up front and -1 to -1.5 in the rear.  The game seems to match the requirements of bias slicks as far as camber goes.  Regardless, the telemetry tells us what settings we should use.

One question I have, is that the guide appears to suggest more negative camber than front.  The cars I have tested appear to show the need to for a bit more front camber.  Can you provide some input on this?

I dialed up the caster to compensate for some of this, the rest has to do with front wheel driven drivetrains maintaining a flat contact patch as possible, as well as the addtion of dynamic camber in the front suspension during braking.

For a RWD car, it's close enough for the same reasons that I didn't bother adding a special adjustment for it,....thats all.

 

Thanks, David

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

Good job feuerdog.


It works well with the Proto Motors Spirra...well a strong beginning at least.

EDIT: It actually helped me get top 30 A Class at Silverstone long.


I always enjoyed trying your and Blooze's setups. They always felt right to the junk I always came up with.

---

GT-Helmakr
"Metric?! My car gets five rods to the hogs head, and thats the way we liked it."


I am a Short Bus Racer...where only drool is the fuel.

I like to use the terms tight for when the front end is pushing because the car isnt turning enough, and loose when the back end wants to come around because its turnung too much. But yea Ill use this.

alpizzle:

feuerdog:

You say the car is getting squirrely on the straights?  Or on high speed corners?

Yeah. it gets squirrely in the straights.  The cornering feels great, it takes a sharp tug by me or a fast mash on the gas to get any screeching at all in the corners.  once the car gets to around 135mph I start to see and feel it rocking and eventually the reaer will slide out.

 

I will try all the adjustments you suggested, starting with the toe and moving to the others if that doesn't work.

Another possibility for this oscillation came up,....are you using a wheel by chance?

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

I got a logitech wheel the other day, so in getting used to it, I ran a few laps on Laguna Seca again, with the tuning turned on.  Now, I didn't update my settings, so it's possible that explains why I was having this problem, but I was having a problem.

For turns that were about 90 degrees or less, I would brake into the turn, then attempt to accelerate (perhaps a little too much) out of the turn, and the vehicle would continue to turn until I smacked the wall.  I think it's just really bad oversteer issues, except that I could take sharper turns (like the corkscrew on Laguna Seca) just fine.  When I was softer on the accelerator, I did just fine, but in the end, I lost a lot of time.  It may be that my car is WAY overpowered, moving from D271 or something like that to B700, and firm acceleration out of a turn causes the back wheels to spin, thus losing traction and forcing me into the wall.  If this is the case, and not fixable via tuning, I'll chalk it up to experience and move on with other cars.

Gravity is helping you get out of the Corkscrew fast,....you do have throttle oversteer issues.

Stiffen front springs by 20lbs and increase rear rebound damping by 2. and tell me if that helps on a FLAT track like Silverstone or Sebring.

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

First of all, thanks to feuerdog for the calculator, and for those who set it up on the web. It's been great being able to plug in a few numbers to get a starting point for tuning, and the setups tend to work better than what I can come up with on my own.

So far, the settings have worked beautifully for all of the RWD and AWD cars I've used, but has anyone else run into understeer problems with the FF cars? I figured out how to dial it out of the RWD cars by tuning the diff, but I haven't had the same success with FWD.

How does ride height factor into all of this? If you lower the ride height will it throw off the spring calculations, or should you do all these and then go ahead and lower the ride height as low as you can for a certain track?

---

RevDrew:

has anyone else run into understeer problems with the FF cars? I figured out how to dial it out of the RWD cars by tuning the diff, but I haven't had the same success with FWD.

Throttle understeer, or braking understeer?

Throttle understeer is a fact of life with FWD's......you can cut you diff. settings by 5-10% to help there but watch those tires for spinning.

Braking understeer can be fixed with a touch of brake bias 44-46% front, a +.1 to rear toe, or by raising the rear antiroll bar up a few ticks.  Also try lowering the rear rebound by another .2 or .3

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

feuerdog:

Throttle understeer is a fact of life with FWD's......you can cut you diff. settings by 5-10% to help there but watch those tires for spinning.

Braking understeer can be fixed with a touch of brake bias 44-46% front, a +.1 to rear toe, or by raising the rear antiroll bar up a few ticks.  Also try lowering the rear rebound by another .2 or .3

Mostly deceleration understeer, especially off-throttle, no brakes. I tried all of those so far except the rebound, so I'll give that a shot. Thanks for the help!