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Old 11-08-2006, 11:42 AM   #1
oversteer
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Default "Rake" or no rake for best handling?

Do WRXs and STis like to have some nose-down "rake" for best handling, or do they prefer to be level or even have the ass down? Most chassis work best with one or the other. What have you motorsort guys found in this area?
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Old 11-08-2006, 11:45 AM   #2
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I've "heard" from a few T2 guys that the stis like a little forward rake. They wouldnt tell me how much though.
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Old 11-08-2006, 11:46 AM   #3
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I've found that setting front and rear ride heights is best done in concert with other suspension settings. May I ask for what type of motorsport you're inquiring?
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Old 11-08-2006, 11:56 AM   #4
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I have Cobb Tunings spring set on my car and I know that they adjusted for that larger front wheel wells? (fenders) So my car is dropped 2 inches in the front and 1.5 in the back. I think it looks better, but I'm not sure if it makes that much difference in the way it handles, although I also have front and rear strut tower bars and a rear sway bar that help out.
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Old 11-08-2006, 12:11 PM   #5
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Those springs are hurting your handling more than helping it.
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Old 11-08-2006, 12:15 PM   #6
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Quote:
Originally Posted by fourmicah View Post
I have Cobb Tunings spring set on my car and I know that they adjusted for that larger front wheel wells? (fenders) So my car is dropped 2 inches in the front and 1.5 in the back. I think it looks better, but I'm not sure if it makes that much difference in the way it handles, although I also have front and rear strut tower bars and a rear sway bar that help out.
Most suspensions lose roll resistence as they move lower in their normal travel range. Lowering an axle through it range can sortof be thought of as a "bar" adjustment in this case. Lowering the roll resistence of one axle as compared to the other will encourage weight transfer to that axle when there is an active lateral weight transfer(turning). COBB's lowering springs are most likely designed to encourage this, which in theory reduces understeer.

Rake also is a technique for increasing aero. Lowering the nose will keep high pressure air from getting underneath the car, and lower the pressure of that which does. But this is minor and probably not a detectable effect sub 100mph.

In concert with the fact that it looks awesome, forward rake is generally considered a desirable setup trait(except when taken to extremes)

Chris Lock
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Old 11-08-2006, 01:37 PM   #7
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I don't know how much you can tell in this pic, but I love the rake form my GF210s, 1.5" in front and 1" in back.

LOVE IT, especially since my last car, (integra with eibachs) had HORRIBLE ass sag and looked terrible
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Old 11-08-2006, 02:18 PM   #8
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With the various suspension setups I've tried, I've felt the car always had slower turn-in response and more mid-corner understeer with the front end lower.

Setups Include:
- Stock (meh)
- STI Pinks (good, 14.25" front, 13.75" rear if I remember correctly)
- Tein Flex out-of-box settings (13.2" front, 12.8" rear according to current instructions on tein's site, but I seem to remember it being lower, also bumpstops were not cut and it was heavily into them at static ride height)
- Flex with cut bumpstops at 13.75" front, 13.25" rear (not bad)
- Above + 6gun balljoint extenders (good)
- Above with rear at ~13.75" (not bad)

-Mike
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Old 11-08-2006, 03:04 PM   #9
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I set my rake at an autocross by setting the front to it's "optimal" height of ~14" from center of hub to fender, and setting the rear to 13.5" center of hub to fender. I found myself increasing the rear ride height by 1/10" at a time after every run until I was satisfied with the car's balance.
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Old 11-08-2006, 03:21 PM   #10
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I just make sure the inner side of the CA geometry is slightly higher than the outside, it results in a little bit of a forward rake, lol..
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Old 11-08-2006, 03:24 PM   #11
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for the most part i think most of us are raked, even if its not really noticable. Unless were masybe running coilovers, then im not sure what guys are doing
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Old 11-08-2006, 03:51 PM   #12
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From my autox experience, rake is bad. I have Cusco Zero2R's and I have the car set up as even as possible. The front might be a smidge lower but not by much. If the car is raked too much, it can cause the inside rear wheel to lift at autox events thus killing your lsd. Then again, my setup isn't like everyone's so who knows.
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Old 11-08-2006, 03:59 PM   #13
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Quote:
Originally Posted by grippgoat View Post
With the various suspension setups I've tried, I've felt the car always had slower turn-in response and more mid-corner understeer with the front end lower.

Setups Include:
- Stock (meh)
- STI Pinks (good, 14.25" front, 13.75" rear if I remember correctly)
- Tein Flex out-of-box settings (13.2" front, 12.8" rear according to current instructions on tein's site, but I seem to remember it being lower, also bumpstops were not cut and it was heavily into them at static ride height)
- Flex with cut bumpstops at 13.75" front, 13.25" rear (not bad)
- Above + 6gun balljoint extenders (good)
- Above with rear at ~13.75" (not bad)

-Mike
That would make sense with how lowering the front end affects the camber curves. But if you compensated with the 6Gun Balljoint extender, then I could see how it would be possible to find a much better balance with a raked car.

BTW, it isn't exactly fair to judge handling differences of ride height adjustments when you're also adjusting preload. And on the Tein Flex, there's only one adjustment for ride height and preload together, right?

Last edited by SWortham; 11-08-2006 at 04:08 PM.
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Old 11-08-2006, 05:36 PM   #14
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A big part is just looking at the suspension points like the control arms and the lateral links and seeing if they're past horizontal or not. If anything, I believe the fronts will be horizontal faster than the rears. Thus, you should set teh fronts first and then set the rear at a height slightly higher than the front to achieve that rake.
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Old 11-08-2006, 06:56 PM   #15
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Quote:
Originally Posted by grippgoat View Post
With the various suspension setups I've tried, I've felt the car always had slower turn-in response and more mid-corner understeer with the front end lower.

Setups Include:
- Stock (meh)
- STI Pinks (good, 14.25" front, 13.75" rear if I remember correctly)
- Tein Flex out-of-box settings (13.2" front, 12.8" rear according to current instructions on tein's site, but I seem to remember it being lower, also bumpstops were not cut and it was heavily into them at static ride height)
- Flex with cut bumpstops at 13.75" front, 13.25" rear (not bad)
- Above + 6gun balljoint extenders (good)
- Above with rear at ~13.75" (not bad)

-Mike
Yeah, that is why I said "in theory". In practice you have to make sure you are taking other factors into account as you change something. The big one for the impreza is the camber curve. If I didn't have a way to adjust static camber(or have ball joint extenders as was commented), I would almost always look at sneeking the rear higher rather than dropping the rear. Even though the rake is transfering the weight forward, the side effect of camber loss might be canceling out most or all of that grip depending your setup.

Chris Lock
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Old 11-08-2006, 07:45 PM   #16
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chris, would you mind explaining how rake is tranferring weight forward?

there are two components that affect roll stiffness. that from the geometry and that from the combined resistance of the springs and swaybars. chris covered the aero benefits of positive rake already, so i'll ignore that aspect. everyone should already understand how roll stiffness at each end of the car affects dynamic load transfer and handling dynamics. all that's left is roll stiffness due to suspension geometry.

as you lower a mcstrut car, the roll center moves down faster then the cg does. the further the cg is from the roll center, the more prone to rolling that end of the car is. ie, it resist rolling less. so, just like going softer with the front bar, lowering the front ride height relative to the rear ride height would move the car more towards oversteer because you've reduced front roll stiffness. the same thing happens if you lower the rear of the car relative to the front, except now you're moving the car towards understeer. of course, this all assumes that you can get your ideal static camber setting for each end and that you don't run out of travel or any other number of other things that could alter the results.

going back to my first comment to chris. positive rake is not going to transfer weight forward. it is going to reduce front roll stiffness relative to rear roll stiffness and reduce load transfer across the front axle (up to the point of lifting the inside rear off the ground). static weight on each end of the car won't change. i'm pretty sure chris knows this, so i'm just looking for him to expand on that comment to make sure i didn't miss something else he was trying to say.
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Old 11-08-2006, 07:54 PM   #17
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So in theory, running a big bar up front to keep the suspension in the meat of the camber curve and using rear ride height to adjust handling balance may be the way to go.

Thanks for that explanation solo-x. I understood that by messing with rake you were effectively playing with the car's roll center, but I never considered it in that context.
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Old 11-08-2006, 08:05 PM   #18
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Quote:
Originally Posted by SWortham View Post
BTW, it isn't exactly fair to judge handling differences of ride height adjustments when you're also adjusting preload. And on the Tein Flex, there's only one adjustment for ride height and preload together, right?
Both preload and ride height have their own separate ajdustments on the flex's..
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Old 11-08-2006, 08:26 PM   #19
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Quote:
Originally Posted by slalom274 View Post
Both preload and ride height have their own separate ajdustments on the flex's..
Ah, good to know.
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Old 11-08-2006, 08:31 PM   #20
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Quote:
Originally Posted by Turn in Concepts View Post
Those springs are hurting your handling more than helping it.
Why?

<------Has Cobb Springs.
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Old 11-08-2006, 08:42 PM   #21
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Quote:
Originally Posted by SWortham View Post
Ah, good to know.
you should buy mine..../hijack..
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Old 11-08-2006, 09:15 PM   #22
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Quote:
Originally Posted by DeadPedal View Post
Why?

<------Has Cobb Springs.
Your car is probably riding on it's bumpstops most of the time.
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Old 11-08-2006, 11:33 PM   #23
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my car definately doesn't like the rearward rake I had on it...probably wouldn't have been too bad with a good lsd front diff...most issues cam under acceleration exiting a turn...
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Old 11-09-2006, 08:31 AM   #24
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Quote:
Originally Posted by Mykl View Post
So in theory, running a big bar up front to keep the suspension in the meat of the camber curve and using rear ride height to adjust handling balance may be the way to go.
not really. the change is not a huge one. it's also not a real good idea to crank your rear ride height into the sky along with your cg. think of rake as another track side adjustment at your disposal. lets say you are fighting with an incredibly loose car but disconnecting the rear bar is too much and it's softest setting is not enough. lower the back of the car half an inch and you MIGHT find a good middle ground. alternatively, you could unhook the rear bar and raise the rear ride height. it's just another tool in the toolbox. on my civic, i gain rear camber as a lower the rear ride height. rear ride height is a lot easier to change then the camber and worlds easier to change then the toe and i currently don't have an adjustable rear bar. dropping the rear ride height is a great way for me to tighten the car up on rainy days.
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Old 11-09-2006, 10:08 AM   #25
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Originally Posted by solo-x View Post
not really. the change is not a huge one. it's also not a real good idea to crank your rear ride height into the sky along with your cg. think of rake as another track side adjustment at your disposal. lets say you are fighting with an incredibly loose car but disconnecting the rear bar is too much and it's softest setting is not enough. lower the back of the car half an inch and you MIGHT find a good middle ground. alternatively, you could unhook the rear bar and raise the rear ride height. it's just another tool in the toolbox. on my civic, i gain rear camber as a lower the rear ride height. rear ride height is a lot easier to change then the camber and worlds easier to change then the toe and i currently don't have an adjustable rear bar. dropping the rear ride height is a great way for me to tighten the car up on rainy days.
Well yeah, that's pretty much what I meant, but with fewer words. Obviously you don't want to use ride height as a replacement for a rear swaybar, but just as a supplement to it.

The reason I mention that at all is because a lot of people are pretty fond of running the big Whiteline bar up front, but it tends to not be a good idea to run that big of a bar out back because of the potential three wheel cornering situation it could cause. However, a slightly smaller rear bar in combination with tweaking your rear ride height will likely get the balance you want.
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