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Discussion Starter · #1 ·
I am one on the many unfortunate IS owners with a non-LSD pumpkin, and at first it didn't bother me. However, after upgrading to Hotchkis sway bars and Tein HA coilovers, rear traction has become much more of an apparent issue.

Contrary to when I had stock suspension, I can lose traction EASILY if give it too much gas from a stop... the problem is that it is always the right/passenger wheel that loses traction, never the left. Whenever its raining I have to baby it of the line and accelerating out of right turns is proving to be a problem as well. Of course the first thing I thought was 'right turns are always tighter than left turns, taking more weight off of the right wheels... and the stiffer suspension setup just makes matters worse.' However, even when making hard left u-turns and flooring it, I have difficulty loosing traction, and when i finally do, usually both wheels usually break loose.

I've ignored this problem for a while now, and its really not an issue daily driving but I thought I would bring it up and get some input. Has anyone else experienced anything like this?
 

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After getting your coilovers and stuff... are your alignment values okay?

Having too stiff of sway bars would likely cause oversteer... but probably won't affect straight-line traction.
 

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My car is the same way... To remedy the problem I just rip the ebrake pre-turn in order to make it slide more. haha
 

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Discussion Starter · #5 ·
After getting your coilovers and stuff... are your alignment values okay?

Having too stiff of sway bars would likely cause oversteer... but probably won't affect straight-line traction.
i know my alignment isn't the problem, i get it realigned every couple months because of these damn socal roads... and i installed the hotchkis sways to the leasts stiff setting because i wanted to reduce the chance oversteer.

still, if i floor it from a stop i can burn rubber all the way up until about 20mph... which probably looks bad ass if your looking at my car from the passenger side, but if your on the drivers side you'de be like "what crazy car on the other side of that lexus is peeling out?!!"
 

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soften the rear shocks, it will help.

with super stiff suspension the weight can't transfer as easily to the rear wheels.

i never had a problem with straight line traction until i was boosted - so my gues is theres somethign wrong, crappy tires, crappy alignment, crappy suspension setup.. whatever..
 

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Even if you get an alignment often... they may not be able to get it within the stock tolerances if you are lowered alot. I'm lowered just over an inch... and my rear camber is out of factory spec... not by much but it's still out. So considering I have one of the slightest drops possible... if you guys have an even bigger drop... I'd assume you're even more out of spec?

But yeah... you should not be able to be constantly spinning the wheels in a straight line that much on perfectly dry pavement with a NON-turbo car.

Beyond suspension specs... how are your tires? How stiff is your suspension set up overall? Do you think the alignment + stiffer suspension could cause your tires to not make proper contact with the road?

Just trying to throw out some ideas....
 
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Discussion Starter · #8 ·
I would definitely bet that its the stiffer suspension... I guess I was looking for a different answer but the truth is that the traction issues were definitely more apparent once the Tein HA's were installed now that I think about it.

Tread contact isn't an issue, and I've been rollin on Yokohama AVS's lately so I'm confident that its not the tires.

I'll click the rear shocks down a couple steps tomorrow and see what happens... thanks for your input, have some rep!
 

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Even if you get an alignment often... they may not be able to get it within the stock tolerances if you are lowered alot. I'm lowered just over an inch... and my rear camber is out of factory spec... not by much but it's still out. So considering I have one of the slightest drops possible... if you guys have an even bigger drop... I'd assume you're even more out of spec?

But yeah... you should not be able to be constantly spinning the wheels in a straight line that much on perfectly dry pavement with a NON-turbo car.

Beyond suspension specs... how are your tires? How stiff is your suspension set up overall? Do you think the alignment + stiffer suspension could cause your tires to not make proper contact with the road?

Just trying to throw out some ideas....
i can proudly say my front is within OEM specs and my rear camber is only off by 1.5 degrees

weheeeeeeeee
 

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he called it in his own post....


It is the lack of LSD in the car... the rear of this car is always loose even when fully stock,... tightening the suspension only makes it worse & especially compared to one W/ an LSD...


you can look into ALL the stuff mentioned above.. .but hte bottom line is you have non LSD on a car that is notorious for a loose rearend even WITH LSD & you have lowered tighter stiffer suspension.. which makes it worse....


this is a perefectly natural characteristic of the IS in that condition.





bottom line: LSD simply Rules for a DRIVERs car... you just can't live without it...
 

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I had your setup...

Few things at work:
1) Tein HA's had too much spring rate in the rear. 12/12. The IS needs a softer spring rate in the rear relative to the Altezza. Does your car tend to "buck" under power?
2) How low are you? This is a direct contributor to lack of straight line traction due to camber. The lower you go, the more camber you have. You will run out of stock camber correction to fix it completely without aftermarket solutions. Camber is good for cornering but not straight line traction.
3) You can try to dial out more dampening to get more compliance, but the HA's really need the dampening in the back due to #1.
4) Less compliance = easier to overshoot your traction circle.

I disliked the Tein HAs for this very reason. They were good in the corners and removed all understeer, but the rear end was much less able to put solid power down. I'm able to dial out understeer via my hotchkis sways without the compromises of doing via too much relative rear spring rate.

I LOVE my Greddy Type-S's.
 
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Discussion Starter · #12 ·
greddy type-s huh... hows the ride quality compared to the HA? ...like floating through heaven im sure!

bottom line: LSD simply Rules for a DRIVERs car... you just can't live without it...
so true... a Non-LSD pumpkin was second on my list of things i knew i would regret when I bought my IS, right below "E-Shift transmission"... :(
 

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Discussion Starter · #13 ·
so any ideas on why its always the passenger side that breaks free first? i know IS is naturally lower on the driver's side... could that have anything to do with it?
 

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if you are this worried about handling and traction, i would try and find an lsd, or an lsd rearend to put in before buying other coilovers.
 

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My drivers side tends to kick out sometimes but I have a LSD. I noticed when I first got my Tein SS they were too stiff an I ALOT of oversteer to the point every corner I got on it was a power slide. Just lighten up the rear a check your tire wear an alignment. You should be fine after that.
 

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Discussion Starter · #16 · (Edited)
if you are this worried about handling and traction, i would try and find an lsd, or an lsd rearend to put in before buying other coilovers.
im not very worried... like i said, its not a problem daily driving because im not usually on the gas that hard. lsd is def something i would like to install at some point, as well as wider wheels and tires to compliment the power of a turbo that will find its way under my hood sooner or later. as for coilovers, if and when i do swap my HA's out for something new, it will not be because of traction issues...
 

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so any ideas on why its always the passenger side that breaks free first? i know IS is naturally lower on the driver's side... could that have anything to do with it?
I'm surprised no one has answered this question. In a nutshell, it's Newton third law at work. For every action force, there is reaction force. Most engines spin clockwise. The spinning action of the engine puts a reaction load on the chassis and this spinning action tends to unload the chassis and bias its weight toward the drivers side hence raising the passenger side slightly. This alone is the cause of why most Front engine RWD cars will spin the passenger side wheel when not equiped with LSD.

Use a drill and you hand will feel this affect.

In addition the IS300 is heavier on the driver's side so that does not help.
 
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so does explain why my drivers side of the car is lower than the passenger side? i thought i had a bad rear shock.
 

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those with coilovers... have you gotten your ride corner balanced??? i have and its amazing! (but im not that low, tho i am sure my rear bump steer is still a factor) the ability to corner balance my car is half the reason why i went with coilovers.

valving should also be considered as well as spring rates when deciding which coilovers will suit your need. my JIC w/ 14/10 kg/mm spring rates dont feel anywhere as hash as my 2100# corolla w/ 7.5/5.1 rates. its all in the valving!
 

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so does explain why my drivers side of the car is lower than the passenger side? i thought i had a bad rear shock.
Left side is heavier than the right.
 
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