[Serious] Why Not Use the 3IS Chassis?
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Pole Position
Joined: Sep 2013
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From: VA
[Serious] Why Not Use the 3IS Chassis?
My apologies if this isn't the right forum for this question - but does anybody know why Lexus chose to use a hybrid 2IS/3IS/4GS chassis for the RC rather than a shortened 3IS?
From all accounts the 3IS chassis is world class. Would it have been a problem fitting the 5.0? Is the track not wide enough?
The transmissions and AWD systems in both cars are identical. I'd find it hard to believe that creating a hybrid chassis from three different sources would have been cheaper than modifying just one. Just something I've been wondering since the RC was announced
From all accounts the 3IS chassis is world class. Would it have been a problem fitting the 5.0? Is the track not wide enough?
The transmissions and AWD systems in both cars are identical. I'd find it hard to believe that creating a hybrid chassis from three different sources would have been cheaper than modifying just one. Just something I've been wondering since the RC was announced
Lexus Champion
Joined: Nov 2013
Posts: 13,258
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From: WA
I just read this explanation in Motor Trend:
http://www.motortrend.com/roadtests/..._f_first_test/
The RC 350 F Sport and RC F are not simply two-door versions of the IS four-door sport sedan. The new coupes are, in the parlance of our times, mashups. The front section is from the wide-body GS, the middle section hails from the previous generation IS C (a convertible), and the rear third is stolen from the current-gen IS. Crazy, no? But why? Why not just make a new platform? Well, friends, I posed that exact question to the RC twins’ engineering team and was told that to achieve the rigidity they wanted the car to have and keep costs down, the Frankencoupe was the best solution, weight be damned. Furthermore, it was explained, the GS section allowed them to fit wider tires than the IS chassis would have, the IS C chunk was already reinforced, and the IS rear end allowed for a shorter overhang. But does it work?
Oh, yes, quite well, it turns out.
Oh, yes, quite well, it turns out.
CL Community Team
Joined: Oct 2002
Posts: 30,277
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From: Canada
They managed to fit the 5.0 in the IS F with a bulging hood for the 2IS, and I raised this question here before , that they should have learnt from the experience in preparing for a RC F / 3IS F, but instead, no 3IS F and a Frankenchassis for the RC F, 
No real answer the last time I asked, I guess only Lexus knows and they won't ever reveal the real reasons ...
No real answer the last time I asked, I guess only Lexus knows and they won't ever reveal the real reasons ...
Pit Crew
Joined: May 2012
Posts: 161
Likes: 11
From: TX
Well they were planning that one convertible LF-C2... This would be the perfect reason for using the middle section for rigidity, but if they canceled the convertibles according to rumors, then the RC is carrying around extra weight for no reason at all now. lol
Even if that was the original plan from the beginning, the RC350 should be on that chassis, not the RCF.
http://media.caranddriver.com/images...s-original.jpg
Even if that was the original plan from the beginning, the RC350 should be on that chassis, not the RCF.
http://media.caranddriver.com/images...s-original.jpg
good luck fitting a V8 in there without making an overbulged hood, theyve already said they wanted the GS front to fit wider tires also. Plus with a longer hood, shorter wheel base, and short rear makes it have more coupe like proportions. Instead of a 3IS chassis with 2 doors chopped off.
the convertible rumor is a pure unsubstantiated rumor from motor trend, no one else reported it. If it was canned then why did the LF-C2 show up in geneva again
the convertible rumor is a pure unsubstantiated rumor from motor trend, no one else reported it. If it was canned then why did the LF-C2 show up in geneva again
Last edited by 4TehNguyen; Mar 4, 2015 at 08:32 PM.
Lexus Champion
Joined: Jun 2007
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From: Aventura, Florida
good luck fitting a V8 in there without making an overbulged hood, theyve already said they wanted the GS front to fit wider tires also. Plus with a longer hood, shorter wheel base, and short rear makes it have more coupe like proportions. Instead of a 3IS chassis with 2 doors chopped off.
the convertible rumor is a pure unsubstantiated rumor from motor trend, no one else reported it. If it was canned then why did the LF-C2 show up in geneva again
the convertible rumor is a pure unsubstantiated rumor from motor trend, no one else reported it. If it was canned then why did the LF-C2 show up in geneva again
I think that the planned convertible is the main reason behind the Frankenstein chassis. It really would suck if the rumors are true and the convertible RCF has been canceled. RCFs haven't been selling well in my area so I can understand why the rumors are circulating...
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E90/92/93 m3 are all based on the same chassis. Yet the e93 is the only one that weighs 400lb more. There is really no reason why the coupe has to be compromised just because of a convertible concept when it wont even sell more to begin with. So that excuse doesn't hold up.
The tire argument is a stretch too imho. If they want to fit wider tires they can always do flares. It works and gives the car a more aggressive look too. Plus as stated members are fitting tires just as wide in the front already.
Dpace is definitely an issue. It is a bad planning if they never kept in mind about fitting a v8 when they designed the 3is. I just feel so unfair that Yaguchi-san had to compromise instead of starting out with a better platform
The tire argument is a stretch too imho. If they want to fit wider tires they can always do flares. It works and gives the car a more aggressive look too. Plus as stated members are fitting tires just as wide in the front already.
Dpace is definitely an issue. It is a bad planning if they never kept in mind about fitting a v8 when they designed the 3is. I just feel so unfair that Yaguchi-san had to compromise instead of starting out with a better platform
The tire argument really doesn't hold water. You can find many 3is' with the same size or larger tires with aftermarket wheels.
I think that the planned convertible is the main reason behind the Frankenstein chassis. It really would suck if the rumors are true and the convertible RCF has been canceled. RCFs haven't been selling well in my area so I can understand why the rumors are circulating...
I think that the planned convertible is the main reason behind the Frankenstein chassis. It really would suck if the rumors are true and the convertible RCF has been canceled. RCFs haven't been selling well in my area so I can understand why the rumors are circulating...
That rumor was only put forth my motor trend and no one else so there is next to no corroboration. If LF-C2 was canned why would it show up to the recent Geneva auto show.
Pit Crew
Joined: Sep 2014
Posts: 134
Likes: 4
From: GA
With 255s in the front with 19" and room to spare? RCF can go even wider on the front and rears if it wanted when I felt around the wheel wells. Easily 275/295 if it wanted. 3IS cant even dream of that. RCF tires arent even squared with the wheels and could accomodate wider tires. Im sure these people with aftermarket wheels or spacers are taking into account scrub radius when changing offsets. Not a fan of spacers or a large change in offset for this reason.
The same could have been done for the 3IS chassis.
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