Deanrcf

iTrader: (1)

For you guys that went to full coilover vice springs, what did you do with your OEM parts? Are they compatible with other Lexus; IS, GS, RC? MIne are just collecting dust in the garage.

lobuxracer

iTrader: (2)

There are no other Lexus cars with separate coils and springs like the late model RC and GS models. One of the reasons I balked at the RC F over the IS F - it was hard to justify buying an 1950's Chevrolet style set up when no other modern performance cars are without concentric springs and shocks. After feeling the GS F wallow in the rear on a hard turn with a bump, I was pretty convinced what Lexus did wasn't all that great.

Deanrcf

iTrader: (1)

Not to push any wrong buttons on this site, but it's important to point out that the new M3/M4 has separate coils and springs in rear as well as Audis S and RS lines and at least the Mercedes C63. Again, not trying to start an argument, quite the contrary. Just need info.

lobuxracer

iTrader: (2)

And the Germans love McPherson struts too. I learned a whole lot about chassis design and setup when I did suspension work on mini sprint team. I'll take coil over shock whenever I can because it's a whole lot easier to get the damping and spring rates working together. When they are separated, it's a lot harder, and worse than that, it's a whole lot harder to find aftermarket pieces to fit. Again, no serious racing vehicle runs anything less than double wishbone fronts and 5 link rears if the rules permit it. Not to say economy setups like a McStrut don't work, they just don't work as well as double wishbones, and they're not even in the same league when it comes to being able to successfully modify the geometry for another purpose. I understand why the new fashion is to separate the spring and shock because it makes more trunk space available - just look inside the trunk of any 2IS, then look in the RC and GS models with the new setup. There is no comparison for how much more roomy the new cars are.

But so many things get compromised for the oddest of reasons. The five link on the previous generation of GS is the same as the five link on the 2IS. It seems the new generation of GS is getting spread across the line as well (3IS, 4GS, RC). It's a good way to amortize the design cost, and Lexus/Toyota/Scion (RIP) had a mandate in 2000 to reduce the parts count of every vehicle dramatically. Part of that is using the same configurations across model lines. The other part of it is why small parts are more and more difficult to purchase separately. Neither makes it great for us except at the time of vehicle purchase.

Deanrcf

iTrader: (1)

Very well explained. Thank you. I guess it all boils down to cost. We may think $80k gets you the best of everything, but in the eyes of the manufacturer mass production and cost savings take priority. I just wanted to know if I could sell the setup rather than it sitting in my garage. I wonder if the RC would benefit? Would the RCF's setup give them a decent drop and better dampening?

lobuxracer

iTrader: (2)

It's really hard to say. Some of the other models are lighter, and the RC F's spring rates might actually make it sit higher than stock. I did a quick check in EPC and the RC F has different springs for the conventional diff and the TVD, but these springs are not used on any other Lexus. It's possible a collection of 3IS, RC, and 4GS springs could offer different ride heights and spring rates on a single platform because they are likely all different lengths and rates. But without doing the necessary homework, it's very difficult to say if the RC F springs would help (or hurt) a different model.

ISFPOWER

iTrader: (20)

i wonder how you feel about the c6 z06 leaf springs, since thats what old trucks use as well. I'm guessing a stock ISF handles better than the c6 z05 as well?

lobuxracer

iTrader: (2)

What do you mean about leaf springs? A spring is a spring is a spring. A coil spring is a torsion bar wound in a circle - if you don't want to believe that, just shorten it and see what happens to the spring rate. Doesn't matter how you use it, it's just a spring. If the Corvette had two leaf springs with shackles on a solid axle the way my dad's '57 Chevy circle track car did when I was a kid, yeah, I'd say it's pretty archaic. But the way Chevrolet uses a composite leaf spring in the Corvettes works just fine for what they do, and the only Lexus to give a Corvette a run for its money on a track day would be the LFA, and by Lightning Lap numbers, the next best challenger would be an IS F, but I already know what happens on a track day when I have Corvettes in my run group. I get ready to point by.

That said, I wouldn't want to run the numbers on the Corvette suspension - it's going to be a lot harder to calculate wheel rates and damping rates (because they are now independent) than it will be if they were coil over shock, but anything can be made to work.

Not just old trucks. Some pretty brand new tractor trailers still use leaf springs and leaf helper springs. Some technologies make a lot of sense to just keep doing it the way it has always been done. Formula One cars had separate springs and shocks at one point in time. Doesn't mean it will win now, but it did then.