I have new found appreciation for the Lexus IS-F
04-07-10, 02:00 PM
#16
Pole Position
Yep, The ISF body structure is no different that the standard IS. As a matter of fact, it's identical, with no extra bracing or structural rigidity added. I believe BMW and Audi add stiffness to their M and S cars.
04-07-10, 02:06 PM
#17
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"...by endowing the IS F with a highly rigid body structure loaded with high-strength steel and strategic bracing."
The grayed areas on the image are whats different when compared to a regular IS chasis.
Joe Z
04-07-10, 02:16 PM
#18
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I just pulled up the '06 New Car Features for the 2IS and the '08 New Car Features for the IS-F. They are as identical as they can be right down to the text. In fact, it appears they copied the drawing from the 06 to the 08 and did a poor scan of the original because the IS-F drawing is grainy with poor contrast compared to the 06 version.
04-07-10, 02:32 PM
#20
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I just pulled up the '06 New Car Features for the 2IS and the '08 New Car Features for the IS-F. They are as identical as they can be right down to the text. In fact, it appears they copied the drawing from the 06 to the 08 and did a poor scan of the original because the IS-F drawing is grainy with poor contrast compared to the 06 version.
Doesn't make much of a difference with all the FWY driving I do.. LoL
Joe Z
04-07-10, 03:52 PM
#22
weird, i wonder why
back on the isf, i am surprised too, somehow i thought the isf body is strengthened from the isx50, guess not huh? so all the improved handling are purely from suspensions?
04-07-10, 03:58 PM
#23
I read that the IS series was based off the GS chassis which was already designed to support a V8 and its associated power. So there was no need for additional bracing. I must say though, the chassis is not stiff enough. My S2K had less body flexing than the ISF.
04-07-10, 07:53 PM
#25
from what i understand Aluminum is, from a metal standpoint, is stiffer than steel? i could be wrong... but from years of riding motorcycles and bicycles, bikes with steel frames ride much less rigid than aluminum, the steel has a lot more flex to it. this could be different from a car i suppose... but my guess would be that the aluminum in the chassis would price the car a lot more expensive, because it is a little harder to work with, and just more expensive in general. i would guess it would bump the MSRP of the car $10-20k .
Alot of Aluminum was used in the Acura NSX, and at the time was one of the best handling cars ever made.
As far as the chassis being identical as the 250, 350, i dont see how that is possible either, it may not list it, on that lexus chassis sketch. the front end has to be changed quite a bit just to fit that motor in the car I would imagine? Im sure there is extra bracing, ect. somewhere in the car.
Also I could be wrong but it looks like there may be some aluminum susp pieces in there somewhere? I looks like aluminum on the top in the front suspension linkage? maybe someone could post a pic.
Alot of Aluminum was used in the Acura NSX, and at the time was one of the best handling cars ever made.
As far as the chassis being identical as the 250, 350, i dont see how that is possible either, it may not list it, on that lexus chassis sketch. the front end has to be changed quite a bit just to fit that motor in the car I would imagine? Im sure there is extra bracing, ect. somewhere in the car.
Also I could be wrong but it looks like there may be some aluminum susp pieces in there somewhere? I looks like aluminum on the top in the front suspension linkage? maybe someone could post a pic.
04-07-10, 09:02 PM
#26
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Umm, no, aluminum is much softer and more flexible than steel. A few very hard alloys of aluminum aren't exactly soft, but no aluminum alloy has the strength and service life of steel.
Aluminum fatigues and eventually cracks in ALL cases. Steel does not unless you exceed the elastic limits. Aluminum is hardened by stressing it - called work hardening - and hard aluminum alloys have a shorter service life than softer aluminum alloys.
Your experience with bicycles and motorcycles isn't an apples to apples comparison. I rode the original aluminum frames back in the 70's made by Alan. They were crap. Modern aluminum frames take a lot into account for the material. Still, steel frames are stiffer by quite a good margin. And yes, I have the same experience you do - racing bicycles and motorcycles with aluminum and steel frames.
The old Reynolds 531 with old school Campy Super Record:
The new, aluminum & carbon fibre with Dura Ace 9 speed:
Yes this aluminum frame is stiff, but not because it's aluminum. It's stiff because the tubing cross section takes full advantage of aluminum's lightness. The steel bike steers better because it's stiffer for sure.
The only big piece of aluminum on the IS-F is the steering knuckles and the rear suspension knuckles. The rest of the car and suspension is steel, and it's not a bad choice at all for what they're trying to achieve.
Aluminum fatigues and eventually cracks in ALL cases. Steel does not unless you exceed the elastic limits. Aluminum is hardened by stressing it - called work hardening - and hard aluminum alloys have a shorter service life than softer aluminum alloys.
Your experience with bicycles and motorcycles isn't an apples to apples comparison. I rode the original aluminum frames back in the 70's made by Alan. They were crap. Modern aluminum frames take a lot into account for the material. Still, steel frames are stiffer by quite a good margin. And yes, I have the same experience you do - racing bicycles and motorcycles with aluminum and steel frames.
The old Reynolds 531 with old school Campy Super Record:
The new, aluminum & carbon fibre with Dura Ace 9 speed:
Yes this aluminum frame is stiff, but not because it's aluminum. It's stiff because the tubing cross section takes full advantage of aluminum's lightness. The steel bike steers better because it's stiffer for sure.
The only big piece of aluminum on the IS-F is the steering knuckles and the rear suspension knuckles. The rest of the car and suspension is steel, and it's not a bad choice at all for what they're trying to achieve.
04-08-10, 05:11 AM
#28
Pole Position
As far as the chassis being identical as the 250, 350, i dont see how that is possible either, it may not list it, on that lexus chassis sketch. the front end has to be changed quite a bit just to fit that motor in the car I would imagine? Im sure there is extra bracing, ect. somewhere in the car.
04-08-10, 08:23 AM
#29
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Technically speaking from the Firewall back, the IS-F body is identical in dimensions as a regular ISx50..
From the Firewall forward the IS-F Body & Chassis is different.. They did not drop the V8 into a basic 2IS chassis which was original designed for the V6's only in the front.
This is coming from a super reliable source I know in the industry...
Edit:
Also for those of you who didn't know, the rear axles on an IS-F are longer by approx. 1/4 of an inch.......
Which is mainly why a nice aggressive wheel that fits perfectly on the rear of ISx50 (with out fender shaving), does not fit on an IS-F perfectly unless the fender lip is shaved away....
Joe Z
From the Firewall forward the IS-F Body & Chassis is different.. They did not drop the V8 into a basic 2IS chassis which was original designed for the V6's only in the front.
This is coming from a super reliable source I know in the industry...
Edit:
Also for those of you who didn't know, the rear axles on an IS-F are longer by approx. 1/4 of an inch.......
Which is mainly why a nice aggressive wheel that fits perfectly on the rear of ISx50 (with out fender shaving), does not fit on an IS-F perfectly unless the fender lip is shaved away....
Joe Z
Last edited by Joe Z; 04-08-10 at 08:40 AM.
This man speaks the truth. 