lobuxracer

iTrader: (2)

When I saw the ball joint mount, that was my first thought to lower the car without a lot of issues and retain the OEM travel, spring preload, etc.

But I didn't run the numbers to determine the change. It should actually lower roll center a little, but without running both arms through their arcs and calculating, it's hard to say what's happening with instant center. It could also increase camber gain if the arm is parallel with the ground plane at neutral.

Yeah, I thought about all this stuff as soon as I saw the block and the two bolts. There are other Toyotas using this same approach - needless to say, I think it's a lot easier to play with ride height on these if you have a selection of blocks.

FWIW, I think progressive rate springs generally suck. They really don't do anything well because you have to make so many less than good compromises to make them work at all.

carchitect

iTrader: (1)

I also think that guys who have sport suspension equipeed IS models should reconsider installing any spring kit. IMO, the drop in height is not worth loosing the overall balance of the vehicle. Sport suspension equipped vehicle would have better gains with a HQ coilover kit like the JIC-Maigc, HKS Hypermax or the Carrozeria Ohlins from Japan. If you know your suspensions a set of Motons would really make a difference for a track prepped vehicle. And none of them are progressive rate springs either.

Lobux, I often wondered how the heck do they get a shock to work well with a variable spring rate? Isn't the valving in the shock paired with the spring rate?

lobuxracer

iTrader: (2)

You hit the nail on the head for why progressive springs don't ever work well. There is no such thing as progressive damping to match the progressive spring. They'll work OK, but never the way you'd really like them to work.

FiveOhNine

Don't some of those new fluid magnetic shocks (Bose, etc) allow an almost infinite level of damping?

lobuxracer

iTrader: (2)

Not dynamically the way you'd need it.

VikH

iTrader: (5)

So you guys are saying that the sport suspension equipped IS will perform better than the F-Sport spring equipped IS?

I still have not gotten an answer from carchitect about the F-Sports giving more body roll than the Sports. I have ridden in both and it is apparent that the sport suspension rolls much more.

lobuxracer

iTrader: (2)

Most performance mods need a watch and timed course to demonstrate actual improvement. Few deliver the advertised claims. Many are actually worse than stock. The best performance mods are made to the driver.

Without a watch and a timed course, you really can't say anything except how it feels which may have nothing at all to do with how it performs.

carchitect

iTrader: (1)

Those electronic controlled systems have never track tested for either their performance, durability, or dependability. Neither have they ever compared with the weight from the entire system vs a quality suspension system (either kit or complete custom) and/or its performance. One thing for sure they have yet to test it out of any perofrmance application that is known for out of the box stock great handling vehicles like the S2000, JZA80 Supra, Porsche GT3, Z06, Miatas, etc..

I still feel these systems being very gimmicky. They are using electronic servos to control the suspension support (aka spring) . I do predict that with a worn bushing, its height level sensors could compensate to hurt the handling. Not to mention that these systems depend on most of the control from electronics and it could be an issue if the main ecu were to fail. Not to mention what about the system power requirements. I predict it takes a lot of current to support a vehicle using non-motorized servos.

I know that there are other suspension systems like the ones used is a few caddys that use a fluid that could vary its viscocity within the shoock with current control. I often have to question about the valve control within them. I seriously doubt they use a high speed valve within since the electronic control does the job for it. But what about the delay. I feel these electronic systems would counter attact vs a mechanical system that works immediately.

It could very well be the reason why we still use cam driven valvetrain even today. While electronic control seems like its right around the corner. The precise timing required for consistency w/o a single malfunction is so difficult to achieve that a single hickup could be a disaster.

carchitect

iTrader: (1)

I think the roll on the f-sport seems like its lesser since the vehicle is lower and thus feeling like its flatter. Also a lowered car would have a lower center of gravity which further helps reduce roll. The sport may exibit more roll but it is much more predictable when it gets to the limit. I do drive the car to the ragged limits and I'd like to "feel" as I'm getting there, gotten there and pushing past it. The sport gives me that sort of feedback. The f-sport to me feels more like a cross between the asthetics, a slight improvement in performance, and value. It doesn't give any sort of impression to me that its ready for a road course after the springs and shocks are thrown on there.

I used to run Eibach progressive springs on the Integra. I had a couple of guys in the auto-x run circles around me with the same car riding higher. I could swear they had more body roll but they kept moving thru the course faster than I could ever. We switched cars and drove and they came to conclusion it was the springs. I switched to linear rate with a matched shock. Same specs as the HKS hypermax for that vehicle (9 kg (500 lbs)ft and 7 kg (400 lbs)rr). The vehicle sits higher and has more body roll but it hugs the road and handles a lot better than it was before. It taught me a thing or two about body roll doesn't necessarily mean poor handling. I've found a lot of cars today have their rear suspensions designed to use the body roll to shift the suspension goemetry and point the tire towards the turn and help balance it out.

lobuxracer

iTrader: (2)

So many guys today who never compete don't get this. Nor do they get it isn't all car. I know a guy who consistently beats me karting despite being my height and weight, and he consistently beats guys 50 lbs lighter. I've seen him drive a FWD faster than many, many people can drive RWD. I have another friend who just consistently beats people no matter what he's driving. It's really embarassing when a guy in a totally stock car just drives around you in a turn while you're "at the limit" in your fully modded car. It really gives perspective to what you consider "the limit."

So much of performance has nothing to do with feel and everything to do with control. Just another reason I don't rate BMW highly - feel is nothing, and feeling good doesn't mean it will get around a track faster in the hands of a truly skilled driver. FWIW, I've not met a magazine writer who was a truly skilled driver.

mrsardar

I have a IS 350 w/sport suspension and I am thinking of going with F-Sports sway bar kit do reduce the body roll instead of changing the F-Sports spring/shock which i am learning that i won't notice much of difference.

Please let me know if the sway bar kit would be a better solution here?

FiveOhNine

Now that I believe....but to their credit, as much as they sniff the BMW jock, they do tend to give props to cars that can really fly through the turns (lotus, porsche, etc). Strangely enough, as the lux/sport makers add bulk and gadgets and butt massagers...the lotus et. al. keep weight down and keep getting better. funny that.

VikH

iTrader: (5)

I just wanted to clear up the statement you made regarding the F-Sports having more body roll. In regards to the handling of the F-Sports vs. Sport, to quote lobux, unless you can actually produce some data you can't really make judgment.

carchitect

iTrader: (1)

Why can't I make a judgement on it? It is what I've experienced and I'm sharing it. I never mentioned the F-sport having more body roll. The sport suspension does have marginally more body roll. However, its much more predictable when taken to the limit. If the predictability of the vehicle is insignificant every IS350 would be riding on the 250's brakes from factory (I know there are more reasons than just that). I could use a lap timer and drive my car at the track but I won't be able to take the customer's cars to the track and have then be comfortable with me driving the hell out of their cars. I'm not planning on using these springs on my vehicle just to have me take them back off after the track. Nor do I see myself using track analysis to determine improvements from either of my prevois runs. The "feeling" is all I have to judge with.

The point of me posting through out this entire thread is the springs used in the F-sport are not what I would consider to take the vehicle to the sport level. Its more or less there for lowering the vehicle and having a comfortable ride. Its the drawbacks of a progressive rate spring.

VikH

iTrader: (5)

Let me preface this post by saying, that you have been a great value to this forum. I have read some of your posts and they have been informative because you can give us (consumers) a different perspective since you are a Lexus Tech.

You did. Multiple times:

• Quote:

  Originally Posted by carchitect

  The F-sport springs give you more body roll since the progressive rate springs are good at doing so. Linear rate springs like the sport suspension keep the body roll to a minimum.
• Quote:

  Originally Posted by carchitect

  The ride will be more bouncier with the f-sport springs instead of the sport springs. The car will have more body roll as well.

Your opinion is based off your knowledge of progressive rate springs vs. linear springs and the fact that your old Integra had progressive springs. In my field, that is what we would call a theory. Unless you show me hard facts between the two specific cars I won't believe it and neither should the other members on this board.

You may be right. You have more mechanical knowledge about the 2IS than I do, but we still need the proof. You are obviously biased towards the sports springs because your car is equipped with sports. Yes, you may have put F-Sports on a customers car and test drove it, but you don't have significant time behind the wheel nor did you take it to the limit (I hope for the dealers sake).

With that said, I don't believe our cars were meant for the track. I daily drive my car and I love it.