konichiwa3

Yup, everyone want to complain how heavy the RCF is. Well here is clear evidence why, I would rather take structural integrity over a tin-tin featherweight. I bet you decades from now your RCF will still feel as solid and well put together as from the time it drove out the factory.

05RollaXRS

Agreed. It is something I would say to the naysayers. Doubly reinforcing the rear subframe when Lexus did not need to do that, shows their commitment to heavily over-engineering it for much higher loads. There are so many other items. The 10-point rear chassis brace, increased floor pan thickness using gussets, the reinforcement beams in the door, the doubly thick rocker panels structure/door sills (compared to 3IS), increased front apron panel thickness (compared to the GS), 4-point front suspension/chassis brace etc.

Yri

OH, by subframe I thought you were talking about the diff/suspension subframe (namely why I was talking about the weight on the bushings), not the unibody/chassis of the car. I see what your point is now. They surely didn't cheap out with those mounts, that is good to see. Thanks for the info konichiwa3!

konichiwa3

Do you suspect this is because Lexus had clearly set goals to successfully meet FIA homologation requirements for the RCF platform to competitively race around the world?

The street production RCF would have to meet minimum requirements in chassis development and engine displacement to get the green light from the FIA for what is now the RCF GT3. From my understanding the racing RCF GT3 under body shell is totally stock (exactly the same as street production RCF). It may be over developed for the streets but definitely well equipped to meet the demands for competitive racing.

BMW M3 and subsequent M4 have never needed homologation in past years since this models have not been factory supported in the higher level racing competitions since the 1990's.

Ultimately perhaps the RCF wasn't intended to garner Lexus unprecedented sales records in the segment but as a strategic branding platform for the Lexus name through the racing circuit. The M4 was therefore not what Lexus had in their cross hair but a much broader vision was in place.

05RollaXRS

Yes, that is a big reason. I remember the interview in which Yaguchi said that one of the things with ISF was that he had to start with an existing base IS car and build the ISF as a skunkworks project. With the RCF, he set out to create a chassis for the car as it was pre-planned and he was given a much bigger budget in order to build a car that could be homologated for racing campaign according to FIA requirements. "Frankenstein" chassis was meant to create a chassis with much higher rigidity requirements than what was available in the Lexus platform inventory around 2014.. Hence, the over-engineering. There is also the convertible angle as well that Lexus created a convertible chassis and then welded a roof on it, but Yaguchi's interview confirms the GT3 plan was put in place before they started working on the RCF. I feel convertible RCF was actually an afterthought when they realized they could chop the roof off without losing much of the chassis rigidity, which is why it was short lived. The picture of the doubly strengthened rear subframe is also an indication it was over-engineered for a much more aggressive suspension setup.

Yaguchi san figured out they could build a very highly rigid unibody using existing core of the IS-C and adding more reinforcements then use the 3IS for the rear to make it compact/short overhang and the GS front end to get the long-nose/space/track width for the engine as well as getting the engine placement fore of the axle as much as possible. The IS500 for example has engine placement more aft of the axle because the nose had to be lengthened to fit the engine.

The RCF is actually now being kept alive only to meet the GT3 homologation requirements, which is going to retire in 2023 so the RCF will retire within the next couple of years.