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dustinsonger's time attack outback build


dustinsonger

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updates updates updates.

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http://i150.photobucket.com/albums/s89/Dustinz31/20140315_122751_RichtoneHDR_zpsc0a5dee6.jpg

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http://i150.photobucket.com/albums/s89/Dustinz31/20140315_120315_zps9c77d227.jpg

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I hit the earth. I got ran off the road by a semi. Might be trying to fix it or make a new one and cut this one up to make a new diffuser. Idk yet. Im just enjoying the headers at this point haha

 

well that sucks! did the semi stop or you got a plate/picture? make them pay, they usually have really good insurance. :mad:

 

you should be able to bond another layer of carbon fiber (top) and kevlar (bottom) to shore it up. Course you'll lose your top gelcoat.

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I can't see clearly from the pictures, but your rear diffuser looks to be mounted in the wrong place, too far forward and not a steep enough angle. Maybe I did not see it correctly in the picture. At least it's long enough. But as it sits, most likely does nothing. Won't be too hard to correct though.

 

I'm not aware of anyone who has actually ever measured the camber curve or dynamic toe change (bump steer) on a LGT or OBXT (but maybe someone has). So though some of us understand suspension geometry academically, I'm not aware of anyone who has actually checked to see what the range produces with stock mounting points. You can do it VERY roughly pass/fail style by checking whether your control arms ever become flat or even start drooping upwards when fully compressed within the range allowed by your specific coilovers and current height. You can check that VERY roughly with a floor jack under the opposite corner you're looking at, and a block of wood or two under the corner you're looking at just to see if anything jumps out as being way out of range. But if you're serious about time attack, you already know all of this and more, so sorry to waste your time. I like to see people build cars like these that might actually get pushed hard, so more power to you. Please keep updating even if some people are bored and take it out on you.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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I can't see clearly from the pictures, but your rear diffuser looks to be mounted in the wrong place, too far forward and not a steep enough angle. Maybe I did not see it correctly in the picture. At least it's long enough. But as it sits, most likely does nothing. Won't be too hard to correct though.

 

I'm not aware of anyone who has actually ever measured the camber curve or dynamic toe change (bump steer) on a LGT or OBXT (but maybe someone has). So though some of us understand suspension geometry academically, I'm not aware of anyone who has actually checked to see what the range produces with stock mounting points. You can do it VERY roughly pass/fail style by checking whether your control arms ever become flat or even start drooping upwards when fully compressed within the range allowed by your specific coilovers and current height. You can check that VERY roughly with a floor jack under the opposite corner you're looking at, and a block of wood or two under the corner you're looking at just to see if anything jumps out as being way out of range. But if you're serious about time attack, you already know all of this and more, so sorry to waste your time. I like to see people build cars like these that might actually get pushed hard, so more power to you. Please keep updating even if some people are bored and take it out on you.

 

XenonK did 3-d mapping and measuring before creating his epic post on what wheels/tires fit. He may have done dynamic measuring as well, as he was very interested in extremely wide wheels/tires. I doubt he ever published any of that work.

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XenonK did 3-d mapping and measuring before creating his epic post on what wheels/tires fit. He may have done dynamic measuring as well, as he was very interested in extremely wide wheels/tires. I doubt he ever published any of that work.

 

That would be nice, but I doubt he did. Reason being he went to great length to document what wheels / offsets / tires fit and how, after finding out himself. Determining bump steer rate and camber curve requires its own set of measuring equipment (camber being a lot easier than toe, but both requiring a lot of work to do correctly), and to have someone like that then not share his findings would be odd. Ideally someone already did, but I have never seen anything quantified even by the racers.

 

Realistically it's probably not anything drastic on the 4th Gens or one of the racers would have noticed by now. Even though coilovers usually reduce height, they also limit travel. Supposedly if you have kept your bump stops anywhere near stock travel, you're not going to have a problem. But I don't know, I've never measured :lol:

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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The rear diffuser is all wrong haha. Nothing about it is correct to be honest. The big thing with it was just getting under the car and making something, anything really so I could have a better idea of what I had to work with than just laying under there and staring at it all haha.

 

And the camber was really a non issue. If you think about setting up a suspension for traction, you want more in turn camber to maintain traction on the outside tire right? So obviously the best option is to modify caster so just simply turning the wheel increases camber (well actualy decreases because we are looking at the outside tire that you want negative camber on but I digress) but changing caster in a specific manner to match exactly what your looking for requires engineering, fabrication and most importantly, money. Now how else can we get effective in turn camber levels while keeping somewhat desirable out of turn levels? Well as a suspension goes through its range of movement the camber increases more drastically as you reach its limits, so what we can do is design the front spring/dampener combo (coilovers in this case) to take advantage of this. By lowering the car taking into account not simply the cars height but the position of the hub in relation to its movement range we can find a good balance of camber for straight road performance. Then we can look at our left over possible spring travel taking into account spring binding, bump stop and wheel well/tire contact limit and take advantage of as much of that space as possible by choosing a spring rate and dampener valving that will allow the suspension to effectively give us the camber we want when we are mid turn. This is the secondary reason for my spring/dampener/height choice, the primary simply being the funds I have to work with haha. Sorry for the nerd out

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^^^^^

For a road car or for a DD autocross car, using lots of caster and little straight-line camber is fine. But for a time attach car, you're going to want it to sit on a more "race" amount of camber.

Maybe you'll dial it in for time attack later...

I forgot what stock spec is for camber, I think it's out to almost -1.0 front and almost -1.5 rear. You'll probably want more especially up front.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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you'll need custom plates to get that much camber. My BC Racing c/o plates topped at at -2.5. The rear can be done with the Whiteline kit. Be sure to do Johan's trick of moving the mounting point an inch back to recenter the rear wheel in the wheel opening.

 

Vorschlag made/makes plates that have enough adjustability for the fronts. Stoplightassasin had a set for sale awhile back.

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