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Discussion Starter · #1 ·
Just want to hear what you guys think is the best suspension set up for the is300??

I was thinking:

Tein RAs (18k up front, 16k back).... proabbly be better with about 20k up front and 18 or so in the back.
Yellow TRD sway bars
All the TOMs stuff (rods, tie bar, braces, rear strut bar)
Area 51 front strut bar
changing out all the stock bushing to poly bushing
225s up front and 255 in the rear

Seems like it would handle like a dream... or be too stiff. What do you guys think?
 

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the RA's would definately be too stiff for me...

try HKS/Zeal/JIC coilovers instead...

TRD, I'd go with Hotchkis or Daizen...

Area 51 Strut bar, I'd go with all the PLP Bars (front and rear) struts...
 

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Discussion Starter · #4 ·
I know that the hotchicks and the other one sways are stiffer then the TRDs, but is having very very stiff sways a good thing? The purpose of sways is to reduse/eliminate body roll right and they do a a great job doing so, but going to stiff on the sways also hurts the handeling, by lifting the tire of the ground in some cases... which is the last thing you want to happen. So instead of going stiff as fuck on the sways, go stiff as fuck on the coilovers and then you wont need the stiff sways and wont have the problem of the tire lifting off the ground... thats y i listed the RAs with the TRD sways which might still be too stiff...

As far as having wider wheels in the back, y not? The is300 has major understeer stock,just like most cars, so having wider tires in the back will allow you to have more grip, and no need for a big ass sway bar in the back to counter the understeer.

I am not arguing, just throwing out ideas, I might be 100% wrong.
 

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I have never had my tires lift up...they'll just slide out...and I've taken my car pretty damn close to the max.

But I would rather have softer spring rates...because I drive the car daily...I don't want to drive a rock around all day long. Sway bars don't affect ride quality on normal day-to-day driving.

Also, wider rear tires WILL increase grip...especially off the line and coming out of turns...but it will increase understeer even more. So setting up a suspension is all about balance.
 

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Discussion Starter · #6 ·
lilaznboi said:
I have never had my tires lift up...they'll just slide out...and I've taken my car pretty damn close to the max.

But I would rather have softer spring rates...because I drive the car daily...I don't want to drive a rock around all day long. Sway bars don't affect ride quality on normal day-to-day driving.

Also, wider rear tires WILL increase grip...especially off the line and coming out of turns...but it will increase understeer even more. So setting up a suspension is all about balance.
Your 100% right for daily driving the RAs are not the best choice.

So wider tires increase understeer and not oversteer? I though since you have more grip in the back the back would come around a turn faster then the front...thus causing oversteer.... which now that i think about it wouldn't make that much sense.

Can you exaplin to me exactly how it adds to the understeer then? Always good to know new stuff.
 

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danielm said:
lilaznboi said:
I have never had my tires lift up...they'll just slide out...and I've taken my car pretty damn close to the max.

But I would rather have softer spring rates...because I drive the car daily...I don't want to drive a rock around all day long. Sway bars don't affect ride quality on normal day-to-day driving.

Also, wider rear tires WILL increase grip...especially off the line and coming out of turns...but it will increase understeer even more. So setting up a suspension is all about balance.
Your 100% right for daily driving the RAs are not the best choice.

So wider tires increase understeer and not oversteer? I though since you have more grip in the back the back would come around a turn faster then the front...thus causing oversteer.... which now that i think about it wouldn't make that much sense.

Can you exaplin to me exactly how it adds to the understeer then? Always good to know new stuff.
Wider tires in the rear would cause more understeer because there's more grip back there and it'll hang on into the turn whereas a narrower tire in the back, less grip would swing out easier (oversteer).
 

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lilaznboi said:
danielm said:
lilaznboi said:
I have never had my tires lift up...they'll just slide out...and I've taken my car pretty damn close to the max.

But I would rather have softer spring rates...because I drive the car daily...I don't want to drive a rock around all day long. Sway bars don't affect ride quality on normal day-to-day driving.

Also, wider rear tires WILL increase grip...especially off the line and coming out of turns...but it will increase understeer even more. So setting up a suspension is all about balance.
Your 100% right for daily driving the RAs are not the best choice.

So wider tires increase understeer and not oversteer? I though since you have more grip in the back the back would come around a turn faster then the front...thus causing oversteer.... which now that i think about it wouldn't make that much sense.

Can you exaplin to me exactly how it adds to the understeer then? Always good to know new stuff.
Wider tires in the rear would cause more understeer because there's more grip back there and it'll hang on into the turn whereas a narrower tire in the back, less grip would swing out easier (oversteer).
bingo, having same tire size front and back will help nuetralize the cars characteristics and maybe even tend to favor oversteer(what most people like i think, at least i do) and the daizen or hotchkis sways aren't so stiff that it will hurt handling, theres kind of a prabolic curve of how stiff the sways should be and how well the car handles, different for every car pending suspension setup, but i feel the hotchkis and daizen are well within these limits of still increasing
 

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Btw, the TRD sways gave my car a more oversteer feel. You might wanna neutral that out.

If the two PLP rears are put in, but none in the front, what type of change will occur??
 

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Until I put the Hotchkis srpings in, my car would always oversteer (tight sways?) - Now, today, I got the first understeer I ever had! Hopefully I can get that dialed back OUT when the PLP bars go in.
 

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how did you have your sways set? since they are adjustable, plp website has a good reference of how to setup suspension either for over steer or understeer. my car acts pretty nuetral as it is, i haven't noticed it one way or the other.

check spring rates on the springs and such if it sems right, then maybe you need to change settings on the sway bars to help adjust the handling characteristics the way you want it to be

heres a link to the handling setup chart thinger

http://www.prolexperformance.com/nav/resources/handling_chart.html
 

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shuggy said:
Btw, the TRD sways gave my car a more oversteer feel. You might wanna neutral that out.

If the two PLP rears are put in, but none in the front, what type of change will occur??
if you stiffened up the back end and left the front soft it will increase over steer
 

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ppl race their Altezza in Japan with some 24-28K spring at a very smooth surface and u telling me u'll put 20K+ spring ont he street?? u must be kidding. :crazy: that setup not only break u car down, it also break ur body down man :lol:
 

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Discussion Starter · #14 ·
Yeah 20K springs will fuck you up on the street, but I never did say that this would be for a street car. I was just asking what would be the best suspension set up period. Meaning what will make the car handle the best, dis regarding comfort or what ever.... So to get the fat ass is300 around corners fast 20K springs might be something it needs, as you said your self they use 24 to 28k springs in the Altezza that weight a lot less.
 

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There's nothing I can make stiffer in the back anymore, so I'll probably move the front sway to the softer setting. I want to wait until I get the PLP bars in however, then see how it is...
 

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by yourself a pyrometer(preferably probe one), and check your contact patch.

no point in investing heavily on suspension, if you arent using available contact pact to the fullest
 

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danielm said:
Just want to hear what you guys think is the best suspension set up for the is300??

I was thinking:

Tein RAs (18k up front, 16k back).... proabbly be better with about 20k up front and 18 or so in the back.
Yellow TRD sway bars
All the TOMs stuff (rods, tie bar, braces, rear strut bar)
Area 51 front strut bar
changing out all the stock bushing to poly bushing
225s up front and 255 in the rear

Seems like it would handle like a dream... or be too stiff. What do you guys think?
I think you've got it pretty close. I wouldn't go staggered though. That setup will give a good balanced, neutral setup with same sized tires all around. I'd actually go l-tunded sways too.
 

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im kinda biased but i like JIC, or maybe even zeal. my buddy's supra with zeal function b6 has 20k's up front and his car is smoother than mine. just because you have a high spring rate, it doesnt mean its going to ride like crap. if the shock assembly can handle the high amounts of pressure the springs will give out, then the car will ride like you want. in all actuallity i used to have 12k up front then upgraded to 14k. my car got smoother because the 12k's werent holding up the front of my car and were almost at full compression, couple that with a short stroke shock, and you are looking at a bad combo. even with my 14's i still hit bumpstops in hard corners. so next bet for me is 16's. the "best" spring rate is not determined by numbers, it determined by your driving style and your ability to handle the certain rate.

i would go with a conservative sway bar like a51 or ltuned, maybe TRD at most in order to allow the sides of the car to move independently. if you want to adjust over/understeer to your preference, you can adjust the coilovers. it is important to note that some lean is good. it means your car is holding. if your car is too flat, then it will tend to come out easier as soon as the tire lifts.

the toms stuff and the poly bushings will provide a much solid feel.

about the staggered idea. i think this also depends on your driving style. if you are understeering you can always soften the front or stiffen the rear. i like staggered because i like a concave/lip look on a rim.. depending on the rim :)

also if you are going to be f/i i would highly suggest staggered as the extra power will kick out your rear much easier. however if staying n/a staggered may not really help out as much.

and judging from .net reactions i would get the PLP bars as they seem to provide the most bracing power for the towers.

and when setting up your car, dont forget about tires! are we looking at DOT tires? or anything under the sun? having a race car running on continentals wont get you anywhere :lol:

btw... why do you ask? or is there a secret project underway? :chill:
 

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having sway bars that are too stiff is NOT a good thing. If the sway is too stiff, it will not allow the car to utilize its camber to give the best contact with the road, and while being too stif will cause the car to slide. it is ALWAYS best to have a LESS stiff sway in the rear. I am pretty sure on this. If the front is stiffer, it will correct the oversteering this car have. Also, having a sway in the front will also reduce the weight transfer the car experiences under hard cornering, and helping eliminate the understeer. Like someone above said, balance is best, but just because a sway bar is stiffer, doesnt make it better. Tein RA's are good coilovers, but strictly for track use. A better coilover that will give a slightly softer ride on the street will be the Tein RS damper. Still harsh as HELL, but softer than RA.
 

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Ok for all you people who say stiffer sway isn't necessarily better...this might be true to a certain extent. But I can tell you I have both my Hotchkis sways on the firm setting, and it's perfect for my driving style. The rear end doesn't come out as easy as everyone thinks...i'm still on shit tires (RE040). You'll be warned before the rear comes out...very easy to feel for the car and it's limits. Slight lean is good for our cars...yes...but only cuz our tires just can't grip when there's no lean.

Also, as to spring rates...a Supra's spring rates will be completely different than the IS, due to different weight distributions. But I understand your point that higher spring rates doesn't necessarily mean a shitty ride. You need a good match between spring and shock for a good ride.
 
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