Rank: Racing Permit
#1 Posted : Friday, July 31, 2015 6:48:05 AM(UTC)
Morning Forza Lovers,
I am working on FF class A build using the 07 civic type R.
I cannot get the rear tires to get up to temp? in the Tele window rear tires stay blue/green temp at 178 F. and 33.4 psi
The car handles ok, but could be better. it actually has oversteer but on high speed turns rear tends to brake loose? any feedback on tune be great. also watch my replay name is KTOWNPLZ. I tune all cars on Tsukuba full this car runs 1:01 on race tires.
Here is my Tune
Tire Psi 29/29.5
camber -9/-9
toe .2/-.3
caster 5.7
ARB 15/16
Springs 505/510
Ride Height LOW
Rebound 5.5/5.5
Bump 4.4/4.4
Brake 45F 145 pressure
Aero 85/185
Diff 9%/18%
Rank: A-Class Racing License
#2 Posted : Saturday, August 1, 2015 7:52:54 AM(UTC)
With a weight distribution of 60% front bias your always gonna have colder rear tyres relative to the front tyres . The temp of 178 F aint too bad tbh . I will give the car a run out and get back to you . Looking at your tune though , first thing i would change is the spring settings . I personally have settings that are proportional to the 60% weight bias of the car , but thats just me . We all have our own ways of doing things .
Rank: A-Class Racing License
#3 Posted : Saturday, August 1, 2015 8:47:07 AM(UTC)
Your tune was quite stable for me tbh . I got the weight distribution down to 55% front bias using the weight reduction up grades . As i said b4 with a FF car you sre nearly always gonna have colder rear tyres . The colder rear tyres dont seem to affect your tune too much on my build .Its pretty well behaved entering and exiting the corners .
Rank: C-Class Racing License
#4 Posted : Saturday, August 1, 2015 9:08:19 AM(UTC)
Covered this in the fwd tire temp thread in this section

Edited by user Saturday, August 1, 2015 9:09:08 AM(UTC)  | Reason: Not specified

onelapmagic BIGTIME MUSCLE tuner straights are for fast speeds corners are for fast times race hard race clean have fun
Rank: D-Class Racing License
 1 user liked this post.
#5 Posted : Saturday, August 1, 2015 12:17:51 PM(UTC)
There are a number of ways to get the temps up, depending on what direction you want to take with the rest of your tune. No matter what you choose to do, something somewhere will have to compensate for it. Cold rear tires is a very common problem on fwd cars, but it is not a standard that has to be accepted and can be cured.

The first option is to get more weight onto the rear tires somehow. This can be done by changing the build so that as to change the weight balance of the car; your weight reduction will probably have the most effect, but engine parts such as turbos and intercoolers, oil cooling kits, and so on can add weight, further distorting the balance so it may be of some help to focus on performance parts that reduce weight while increasing power. The compensation factor here is obvious; drastic changes to the build, which may drastically change the overall performance.

A second option is to equip a spoiler, however effectiveness may be negligible; a non-adjustable spoiler will not contribute as much as an adjustable one, but will contribute more than no spoiler at all. I cannot say with certainty what contribution a spoiler may or may not have for your Honda, but I can say that on one of my Mitsubishi Evo's a non-adjustable spoiler alone made the difference between understeer and oversteer on corner exit--enough to shave almost two seconds from the overall lap time. The compensation factor here should also be obvious; spoilers can absolutely murder your top end.

A third option, and a much more viable one, is to adjust air pressure. This can be difficult to explain as far as how the effect of heat and heat transfer works (though I'll do my best). The amount of heat generated by any tire on your car is determined by how much weight is applied to that tire. When you change tire pressure, you are changing the size of the contact patch WITHOUT changing the weight of the car; this is important because it means that you're generating the same amount of heat, whether the contact patch gets larger or smaller. If you increase air pressure, the contact patch will decrease in size, thus generating MORE heat per square inch, resulting in a tire that will heat faster, and hold higher temps (because the tire won't cool down as much on the straights). If you decrease tire pressure, the contact patch gets larger and thus generates LESS heat per square inch, resulting a tire that will heat slower, and hold lower temps (because the tire will cool much more on the straights). The compensation factor here is in grip performance; a smaller contact patch will give you better response and temps, but will result in faster losses of grip if/when the car gets unstable requiring more precise driving, whereas a larger contact patch will give you slower response and lower temps, but in return a much steadier loss of grip allowing you more time to maintain and correct the car before ever getting close to losing grip.

The final option, and one of the best in my opinion, is in using the shocks to control applied tire weight. Your shocks affect applied tire weight much more than springs, and have huge effects on tire temperatures. The first rule of thumb, however, is knowing that when it comes to shocks, what you do to one end of the car affects the opposite. In other words, if you want to change the characteristics of the rear tires' applied weight, and thus temps, you'll use your front shocks to do it, and not just the rears. Because this is the lengthiest part to explain, I'll be explaining in short sections.

Corner exit:
Under acceleration, your weight moves to the rear--this transfer is "controlled" by the balance of front rebound and rear bump (front rebound affects how much the front is willing to lift and let the weight go back, and rear bump affects how much weight the rear is willing to take on).
With too little front rebound, too much weight will move to the rear to begin with which may contribute to the front end to have too little weight for steering response, while too much will result in not enough weight moving to the back which may contribute to the tires not having enough weight to generate grip enough for throttle, particularly the inside tire.
With bump, too little will cause the tire to want to bounce up and down more, especially from bumps, thereby reducing and/or limiting how much actual grip you have at the contact patch, while too much will cause the tire to transfer excessive amounts of energy through the suspension instead of absorbing it (which puts more load on the other tires) and can cause the tire to become more airborne more often, whether due to lift caused by weight transfer, or by larger bumps and/or uneven surfaces in the road.
If you don't permit enough weight to the rear under acceleration, the inside tire (which has the least amount of weight) bill begin to slip, and once it does, the outside tire will have an excessive load, will slip thereafter, and then the front end will slide out with it. This all happens within a mere second or two, if that. The effect is as though the rear end wants to walk out on you, almost as if it wanted to oversteer.
On the other hand, permit too much weight and the front end won't have enough weight to maintain proper steering response. The result here will be that as the car continues to accelerate from the apex, steering response will steadily decline and may cause the car to want to heavily push to the outside of the corner, or understeer.

Corner Entry:
Under deceleration, your weight moves to the front--this transfer is "controlled" by the balance of the front bump, and rear rebound (front bump affects how much weight the front is willing to take on, and rear rebound affects how much weight will move to the front).
With too little front bump, too much weight will move to the front and can cause the front end to want to plow through turns despite the extra weight applied to the tires (inertia overpowers the applied weight in this case, but note that the car is still willing to turn), while too much will result in not enough weight applying to the front tires which will also cause the front end to want to plow through turns (though in this case steering response will be deadened, and the car would be reluctant to want to turn at all).
With rear rebound, too little will cause excessive weight to move forward to the front, resulting in the rear end having much less weight on the tires to maintain grip, while too much rear rebound will not permit enough weight to move to the front, thereby deadining steering response as you begin to turn in towards the apex.
If you don't permit enough weight to the front end during deceleration, the front end may not have enough proper grip for ideal steering response and will have negligible effects depending on drivetrain; if you're fwd, you're likely to experience understeer due to insufficient weight on the tires, whereas rwd cars tend to break loose in the rear because the rear end wants to run a tighter circle than the front end can--the difference between the two turning arcs typically causes the rear to break loose first because it has less overall weight.
If you permit too much weight to the front end, the car will likely perform with one of two results; either the front end will want to plow through turns (again, there's a battle between applied tire weight and inertia going on here), or the rear end can become unstable due to the decrease in applied weight and may or may not lose grip. On rwd cars, this can be particularly critical because downshifting may induce spikes of torque (imagine your torque curve backwards--this is how your torque increases and decreases during deceleration) which can cause the tires to lose grip very suddenly, again particularly on the inside tire.

Your Tune:
Having built a handful of Honda's for A class, both fwd and rwd, I must say I'm surprised at how soft your suspension is overall. I've always preferred my Honda chassis's a slight bit tighter than that. From the looks of it, your tune permits quite a bit of body roll, especially in that your sway bars and springs are so soft. That's not necessarily a bad thing though. All it means is that you need to focus more energy on your inside tires BECAUSE there's so much body roll. This is best controlled with your shocks.
You're experiences in high speed turns have a lot to do with your shocks too. What's happening is all in how your weight is transferring, so let's imagine it in slow motion; as the weight is moving to the outside and front end, your front outside corner will take on the most weight and with a bump setting of only 4.4, it's going to bend over and take whatever it's given. This puts a lot of load on that front outside tire, so much in fact that the tire may actually be fighting not to buckle. At the same time, your rear rebound setting is so low that it's allowing the weight to move so fast from the inside that there's nothing to keep weight on it (your springs and sway bars aren't certainly going to fulfill this job at this moment in time).
The result is that the tires are losing weight too suddenly on the inside, particularly the rear, and as I described above, you get your sudden domino effect and grip is lost.

I personally have found it favorable to stiffen the front bump up a bit (my Honda's have always had a setting between 5.2 and 6.4 for front bump). This forces more weight to stay towards the rear, and pushes the center of gravity rearwards, thus stabilizing the car some from the troubles you seem to be experiencing. This means more weight on the rear when it moves forward, and therefore more weight on the inside rear. In addition to this, I would increase rear rebound a bit to help slow the transitional weight as it wants to move forward. This will maintain a steadier amount of weight on the rear as the weight shifts from center to the outside front, then to the outside rear and again back to center. Keep in mind that when you adjust your shocks, you should ALWAYS have rebound settings higher than bump settings; this keeps your shocks from topping out all the time, and allows the car to squat and stand properly.

I could elaborate more, but there should be a good enough bit of info to give you a strong sense of direction with your build and tune. If you need any more info, feel free to hit me up here, PM me, or even hit me up on Xbox. I'd be more than happy to help you any further should you need it.

Cheers,

Hack

Edited by user Saturday, August 1, 2015 12:22:41 PM(UTC)  | Reason: Not specified

Rank: Racing Permit
#6 Posted : Thursday, August 6, 2015 6:52:55 AM(UTC)
Wow thank you for the Lecture I learned a lot. How do I get in contact w u on Xbox? my xbox name is all caps ktownplz. so I should stiffen the springs? and add more front bump?
Rank: S-Class Racing License
#7 Posted : Thursday, October 15, 2015 8:47:01 AM(UTC)
Originally Posted by: SlyMeerkat20301 Go to Quoted Post
Wow thank you for the Lecture I learned a lot. How do I get in contact w u on Xbox? my xbox name is all caps ktownplz. so I should stiffen the springs? and add more front bump?


Put your tune up on the Storefront and I will give you a Tune from the Forza 4 Tuning Calculator.


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