kyoo

iTrader: (29)

they literally wouldn't tell me what the set up is. same fluid as in the cusco, yes.

off throttle may be a little looser, maybe? nothing significant that's for sure. i def can tell it's not locking up hard on power though

Construct

iTrader: (4)

This seems strange. Doesn't the OSG have a relatively large number of plates? I would at least want to know how much more tuning headroom I had available.

kyoo

iTrader: (29)

they do but the ramp angles are relatively mild IMO. I relayed the info to the guy who built the diff, we'll see. I think you do want the diff to be open, but then lock up fairly quickly with power.

Dallas J

iTrader: (1)

So I think you're expecting the diff to induce something its not really going to induce without some odd compromises, you have some cross talk issues with your other diffs, and you probably need to re-sort your suspension for what you have now.

The reason I see for getting the OSG diff is to get better off throttle rotation, if you need more on throttle rotation bar/spring/alignment all can easily fix that. In fact, usually its too much on throttle rotation once you get near a magical setup. To the point people will be happy with everything but that, and run lots of rear toe-in just to manage that.

I've also found, the most aggressive setting on ER map, at least the version I have, seem to cause way too much lockup and really makes the car feel bound up. I only ever use the middle setting now which works well though could probably use a reduction in off throttle lockup .

You can share your setup here (again? I didnt check earlier pages) or private and I'll let you know if I think something is wonky.

kyoo

iTrader: (29)

i'll ping you - the OSG did essentially claim better off-throttle rotation - but I was saying that I did not experience a significant improvement in that aspect over the Cusco

Dallas J

iTrader: (1)

That statement would lead me to think you need more rear spring or maybe front bar (less likely as long as you have stock front bar). The diff freeing up wouldnt induce oversteer it would prevent binding thats trying to keep the car straight which would more likely cause understeer. If you had a fully open diff, sounds like it would do the same thing.

You just need the rear to do more work off throttle, and bar isnt going to get you there. You can either jack up spring or temporarily up tire pressure.

Whats your front/rear ride height? Front roll moment jumps much much faster than rear, so if you a much lower than stock you are shifting that roll axis steeper and steeper.

MrAWD

I have never understood this part - making things acting better off-throttle.

And before I continue, sorry to use your quote here Sam since this has nothing to do with you in particular, but more my general view of things.

We are all trying to make it quicker through the track/course/section and going after things that happen when you are not trying to go faster seems counter intuitive at best! I have read long time ago that the fastest way through the corner is with WOT. Basically, you have to do whatever is needed so you can go WOT asap in that corner. Concentrating on what car is going to do off throttle doesn't fit well into this way of looking at it. I guess, if car is doing strange things when off the throttle or braking, this has to be taken care of. But, tuning for this phase in particular...

kyoo

iTrader: (29)

better off throttle rotation leads to being able to get on the gas faster. If the rear wheels are locked for example, you're not going to turn fast. Turn fast to straighten out faster. Off throttle rotation is improved with, essentially open diffs that let the wheel turn at different speeds. there will be differences with active diffs, so experience from that will not really apply here.

anyway it's kind of moot, as i dont have the means to continue to do AB testing. OSG basically said the diff is right, your setup is wrong. which Dallas more or less echoed. Still doesn't explain why it doesn't behave much differently from the Cusco though

LetsGetThisDone

iTrader: (1)

I've noticed the same with the ER acd tune. For autocross with the tighter corners, the middle setting works well. Open track still likes the full gnar setting.

Dallas J

iTrader: (1)

If you step back and think about how you get through a corner and the end goal, you want to be at the end of the corner facing a different direction. Simple as that really. So you have 2 basic ways of getting there, move the front to pivot the car around the center of the rear axle, and slide the rear around the center of the front axle. I say center but really that point shifts around depending on slip angles and such.

Evo being way front biased, can only get so far with the front grip so we need to combine A & B and thats where yaw comes into play. We want to yaw the car without really sliding it by stretching how much we can get in that rear slip angle. Final effect of this is more deg/sec of rotation combined with the grip of AWD to pull you through the corner once youve hit sufficient angle change.

To your point, you want to be able to get on throttle sooner, well you cant do that till the car is pointed in the right direction.

If you have the capability to log yaw rate, Ive been shooting to get in the 45-50deg/sec range. If you dont log it, that number is meaningless to you but I can say when I feel the car just wont turn, Its usually cause the back wont move and I see 30-40deg/sec. And when the car is real tail happy or I step too far into late braking and have to catch the rear, I'll see closer to 55deg/sec.

MrAWD

Dallas,

Nice description for what is going around the corner! I agree with all the points in there.

Going back to the previous text, I just don't believe that using off the throttle is the best way to achieve all of the rotation that is needed to make it though the turn! The part that I don't like is for even having off throttle section. You get in under heavy braking and as soon as you are done with that part, you are back on throttle - there is no off the throttle section there. For, RWD or FWD perhaps there will be that phase out there especially for longer corners. But, for cars like EVO that have all these gadgets to help with car rotation build in, I don't believe there should be much of the off throttle in there and especially not to tune for it!

kyoo

iTrader: (29)

any braking = off throttle. trail braking, etc. what are you doing with the throttle when you're turning? from your description you're skipping the turning portion. brake-turn-gas for each corner with varying degrees of application as you run through each corner. i am trying to shorten the "turn" portion so gas, any amount of gas. can be applied sooner. i'm not talking about lifting and then just sitting coasting through a turn until the car is straight enough to hit the gas. need the car to be turned to some degree before applying gas.

you got any data logs from any of your runs with brake and throttle application so we can see specifically what you mean?

kaj

iTrader: (60)

"Of throttle" = braking, as said above, possible trail braking, and the rotation you let happen before gently getting back on the gas, then eventual WOT. Nobody goes from braking to WOT, unless you are tail braking super deep/riding the brakes.

CaptainSquirts

iTrader: (3)

Isn't the rear diff pretty much moot when the inner rear wheel is in the air? If so, that's probably why your expectations on throttle oversteer in these low speed turn around situations is, meh . From watching your last autocross video with your new rear diff, the turn around at the 50 second mark, your inner rear wheel is def lifting and if you gas hard it'll just push. I had this same exact thing happen to me when I got my new TRE rear diff. If I was hard into a turn around like that and I gassed early to try to get the rear to oversteer some, it just pushed. If I let the car settle more into the turn around and my streering wheel isn't cranked all the way to one side, then my rear will start to oversteer, then snapoversteer depending how hard I push it. But anywho, if i'm in a situation where I have to force rotation to be wanting to point a certain direction, then I am driving wrong.

p.s I am running 10/12.5k spring 24mm white line RSB on the softest setting. Also I have helper springs in the rear to help keep the tire on the ground, but even this isn't enough. I'm almost/am keeping up with the quickest people with the autocross group I run with so I am content on how it handles. It's still better than restacked oem but it isn't some magical snap oversteer part that you will be able to rotate its *** around whenever you want.

MrAWD

In my case, I am left foot brake guy, so things are not as explicit in that case. Getting into the turn is usually WOT (well, in autoX things are not that black and white, so it is not as easy to describe it) and at one point you have to slam the brakes. Right foot goes up and left one down. When close to end of braking you start to easy of on the left one and right one starts to go down. At the same time (if not even a bit sooner), you start to turn as well. EVOs do amazing job with brake force distribution and even help in this phase with car rotation depending on steering angle. Now, with ending of braking, your are getting more throttle until you are 100%.

Now, as I said, autoX has a lots of curve ***** in there and this can not be applied to every turn that is out there. Sometimes you can't get all the way to the WOT because of perhaps next section being too close, or you don't brake as hard since you didn't have space to accelerate as much. So, take all of that with that in mind.

So, if you guys want to claim "Of throttle == braking", you can see that I don't really see it as such. Lots of things happen during the braking and it is not as clear as that statement. If you want your diff to help you when you braking and trying to tune it for that, I don't think think it is as necessary as you might trying to make it. I would rather tune my diff (or diffs) to allow me to put the power down better and controlling car rotation a bit more.

At the end of the day, there are lots of ways to skin the cat. What I believe is the best way might be far off from some other things that could be done here. Discussion all of this is a direction were I would like this to go as well, so we could all learn something new!!

All the best!

Fedja