Sway bar specs... - Page 3

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  1. #21
    CelicaSupra.com Member SupraFiend's Avatar
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    Chad, the difference between the mk2 and the aw11 doesn't so much lie in the spring rate split front to rear, it lies in where the weight is located in the car. And that's why I wouldn't recommend loosing the front swaybar just because it worked in your aw11. There is nothing in the front of your aw11, it has a short low nose and all the weight up there is on the same level as the wheels. But the mk2 has a huge hunk of iron, a giant tall inline 6. Its tendency is to roll up and over its front wheels mid corner (regardless of your cars tendency to oversteer or understeer), and nothing fights rolling like an anti-roll bar. Don't think so much about effective rates at the wheel, think about how a sway bar actually works compared to springs. By connecting the two sides and pushing forces in the opposite direction, those huge lateral roll forces (twist in the forward direction) are resisted by the mass of the car on the opposite side, something individual springs can't do.

    Removing sways in the rear can most certainly be beneficial on front engine rwd cars as their primary mass is up front and keeping the rear tires level with the pavement is key. But again, the mk2 has a lot of mass to fight against and if you combat it with only springs, you can easily end up with rates that make the car completely unlivable on the street. I haven't checked out your build thread yet, its on my list. You haven't yet mentioned here how streetable you want to keep this car or what motorsport your focus for building this thing to be competitive in is (I assume autox).

    I personally have found changes in ride height, and more specifically center of gravity, to be almost more effective on these cars then big changes in spring rate. You mentioned camber brackets, but what are your targets for ride height? One thing so few people realize when messing with older cars like these is that the suspensions in these things were engineered for 1 ride height only, and changing that drastically requires huge modifications well beyond the bolt on nature. Its easy to hide introduced vices from subtle changes in ride height due to the huge benefits of lower CG, but most of us who have changed our ride height have actually compromised the design of our suspension and there is so much to be gained by getting it working the way it was engineered to again. The rear suspension in particular. Once you go lower then an inch and a half, the standard camber bracket fix alone is insufficient for what you have to do to get our IRS working correctly again. This is where I'm spending my time this year, re-engineering all of my pick up points to be correct for my actual ride height. I definitely hit an improvement wall awhile ago, where the last couple rounds of new hard parts effectively made no difference to my track times because I haven't dealt with my geometry problems. Time to correct that sin.
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  3. #22
    CelicaSupra.com Member CLToy's Avatar
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    Suprafiend,

    Thank you for your thoughtful post. You definitely have experience with this chassis. I am for sure going to give the front sway bar a shot as I agree that the weight that lies beyond both, ahead in front and behind in rear, of the axles is of major concern and limited solution.

    I realize that the any weight centered beyond or behind the axles (in front and rear, respectively) will exaggerate the documented MK2 chassis weight distribution of 54%/46%. I am also not trying to say that the AW11 and MA61 chassis can be directly compared, only that the philosophy of tuning without the use of sway bars remains consistent.

    I also do agree that the most important thing to do would be to get the geometry back in line. Once the ride height is set, it is most important to set the height so that the center of gravity aligns with the roll center and that both points are above-ground. Once this is calculated, then the geometry of the suspension should be corrected, then the car should be corner weighed and matched with driver weight included. This, as you know, is a long and arduous process where most people take shortcuts along the way. I am still working on the AW11 platform, especially now that I am moving up from STS to SSM with a 3SGTE swap. So yes, I am concerned at the weight shifted slightly more behind the rear axle with all the intercooler, piping, and approximately 300 more pounds from the engine swap.

    To specifically answer your question, the AW11 will be a dedicated AutoX car with only occasional use at the track (partly because I want to experience the MK1.5 at the track at least once...that has to be fun!) and the MA61 will be more of a track car that can also be used in SM class at AutoX's. I keep my cars running and licensed for road use and do not care if they are necessarily 'comfortable' for street use. Many people's idea of comfort varies, as this is subjective. It personally bugs me to be in a sports car on the street and take a turn only to feel the weight of the body start to sway like a boat...not comfortable to me. This would not be the same idea of comfort when I fire up the Tundra. The spring rates in the AW11 would shock you (maybe pun intended!) but I also enjoy driving it to and from work on occasion. Check out my links and I always appreciate input and comments!
    Chadrick
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  4. #23
    CelicaSupra.com Member Don L.'s Avatar
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    Finally took a peek at your build threads listed. Holy Moly, that's a lot of cars! You work a day job too? I can barely keep one Supra running!

    Don

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  6. #24
    CelicaSupra.com Member CLToy's Avatar
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    Quote Originally Posted by Don L. View Post
    Finally took a peek at your build threads listed. Holy Moly, that's a lot of cars! You work a day job too? I can barely keep one Supra running!

    Don
    Haha, I assume you are talking to me? Well I am seem to stay in a state of stress....high risk/reward job and come home and wrench to try to stay sane and outta trouble. Lol
    Chadrick
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  7. #25
    CelicaSupra.com Member Don L.'s Avatar
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    Yes Chadrick, you

    I thought I had a lot of cars, but you really need a barn sized garage! I'm retired now and still feel like I don't have enough time to wrench on my cars. I guess maybe consistent with my autox driving style....slow

    Don

  8. #26
    CelicaSupra.com Member SupraFiend's Avatar
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    Well spring rate wise for the ma6x, my car is used pretty similarly as yours. But for me, I think 500lbs/ft up front is my limit for for this car. I drive it to race venues and car shows, some of which are in WA state. My koni yellow's are super comfortable though, so much better then my old KYBs, but I am already at a point where my car is just barely tolerable on the street for myself for longish drives, and well past that point for my spouse lol. In fact for our planned trip to SIV and JCCS this fall, I think I'm going to have to detune the suspension for it. Drop in some softer front springs and turn my swaybar down (still running the adjustable whiteline).

    Also keep in mind, Don tows his car to venues The rates he plays with would break spines on the street lol
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  9. #27
    CelicaSupra.com Member Don L.'s Avatar
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    Heck yea, I tow my Supra just to get to the curb

    I unfortunately have to do engine tuning around the neighborhood, so when possible I "detune" the ride by mounting 245/40-17 in front and 295/40-17 in rear. More civilized but still wouldn't take it on a long drive. The thing about crazy hard spring rates is they really require adequate shocks to work well. Most OTS shocks won't handle 800 lb springs very well, and the ride becomes harsh, jittery, bouncy. Good shocks and the ride is more just very firm, not quite harsh, better than a buckboard. Really pretty dramatic.

    I would never suggest more than 500 lbs springs in front for a street car, and likely be less. More than that and lots of compromises!

    Don

  10. #28
    CelicaSupra.com Member SupraFiend's Avatar
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    Some people have had luck with rates in the 600 to 650 range on the street when paired with tender springs. Personally, I don't like them though as the total spring length gets too tall to fit above the wheel and then it cuts into your wheel clearance. Plus I prefer a consistent rate, and I like being able to change my springs without removing the struts.
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