The cars I've seen that high were done in 4th or 5th gear. I've seen as low as mid-300s too.

It's just a thought... lots of factors to consider and I'm no engineer so I'm just guessing pretty much lol

 

The author of this blog has trolled us before, saying Mopar products are better, and things like that. Also, they started spreading a theory that the structure of the IS500 couldn't handle the V-8, suggesting that that's why the front bumper issues have been occurring. So, I typically don't take them or their blog too seriously.

Here's a good video showing the internals of the transmission and the design philosophy behind it. For 2006, this was groundbreaking stuff, and, amazingly, simply built on the 6-speed auto that already existed with minimal changes.

 

I also see that this blog has an opinion on the bumper cover situation. Analysis: The IS500 Bumper Cover Separation Issue

I'm wondering if the chassis brace from RR Racing Chassis Brace would mitigate or slow down the separation.

 

Yeah this is exactly why I don't take that blog seriously. We now have a reasonable amount of signs pointing to the clips themselves being the problem.

 

I mean, he made a lot of good points, hadn’t seen any reasoning like that that made sense to me. The part the got me is that basically every single sedan that normally comes with a v6 that has an optional V8 has a strut tower brace and chassis braces when the v8 is chosen that the v6 doesn’t.

personally I had the clips replaced and still have the issue.

What the writer was getting at I think is that the chassis flexing and twisting is causing the clips to separate and wear.

 

And he’s probably right, all vehicles flex, they have to otherwise they would fracture and fall apart. Guess Lexus underestimated what the bumper clips could withstand on the refreshed bumpers vs the body flexing. It’ll be interesting to see what the ultimate fix will be since new clips don’t appear to work. It might take a whole new redesigned bumper that can absorb the flexing .

 

I understand what the writer's trying to say, but I just don't believe it. The IS F, RC F, and GS F don't have strut tower braces.

My theory has always been that the front bumper was hastily redesigned for accommodating the V-8 and not properly tested. They didn't have clips that could hold the bumper on securely with the new dimensions of the new front end. They likely just used whatever they already had for the other IS models.

 

Yeah that guy's theory seems very well written until you actually think about it logically. He uses a Passat W8 as an example which is a ... transverse engine (rocks front to back, not side to side). The IS chassis was considerably stiffened for 2021 according to Lexus, regardless of the type of metal used. It also got IIHS Top Safety Pick+ for 2022 despite this guy trying to say it's less safe than an old Camry. Finally, perhaps most laughably, he tries to claim that the Subaru BRZ with its tiny 4 cylinder engine is also flexing that car's bespoke chassis so much as to cause bumper separation.

The IS500 probably doesn't have the stiffest chassis in the world but it isn't made of wet spaghetti. The bumpers have bad clips.

 

The B5 generation of Passat (that offers 8-cylinder engine), was indeed using the longitudinal engine layout (not transverse). Yes, FWD based but longitudinal engine. Sounds strange but various VW/Audi models were designed like that.

 

I question how much stock should be put into the body flexing as the main culprit. I just don’t think we know enough.

These were taken last week. I go up to the mountains all the time for extra-spirited driving and I’m currently 45 miles shy of 20k.

 

I can't believe I'm saying this... But is that really so bad?

I might not have even noticed that if it wasn't pointed out. When I was living in the city, that sort of bumper movement was not uncommon to see due to lite bumper contact while parking. Not saying I would contact other peoples bumpers, but if you leave your car parallel parked anywhere, I guarantee you this will happen sooner or later. Maybe a lot.

If the gap gets bigger, yeah that would be a problem. The front cover wont fall off, will it?

 

If you squint hard enough (in person), you can see a piece of the clip on the driver’s side, but nothing on the passenger. Most who have reported the problem have it waaaay worse, but from what I’ve read, the bumper will not fall off.

I’m just saying it can’t all be body flexing or heat.

 

Surely, Lexus can figure out a fix that will keep the bumper cover on? It's not rocket science. In fact, a good body shop can likely fix this one way or another. Though, I would prefer Lexus approved fix and not one involving sheetrock screws.

 

I stand corrected!

 

RCF is the only F cars that have strut brace stock but ISF and GSF don't