RC-F Carbon

[Guest]

I'm carbon fibre trained, ie done courses for manufacture and repair. Hate the stuff. It's a massive health hazard when working with it, for several reasons.

Anyway. I avoided carbon rc-f for price and looks (I like the roof but not the bonnet) but I know some people will like it. I had wondered about UV damage but assumed they must have some filter in the lacquer.

But today looking at manual to double check safe jacking points on the RC I noticed this: 

Quote

As the CFRP parts may change color if they are exposed to ultraviolet rays for extended periods of time, Lexus recommends that your vehicle be stored in a place where it will not be exposed to direct sunlight.

CFRP is Carbon Fibre Re-inforced Plastic (it's full name because that's what it is, plastic resin with carbon re-enforcement - so you have a plastic roof)

I see them all for sale in the sun on dealer forecourts .. Note aircraft wings are painted and tested with ultrasound regularly. They also have a wing on a jig someone where flying ahead of the fleet hours so they know where to look for cracks....... enjoy your holiday haha 

Anyway just sharing for potential buyers. Forewarned is forearmed. 

If you're really interested you could read this: http://me.eng.sunysb.edu/~compmech/downloads/N29.pdf

And you may also be interested in: http://ubir.bolton.ac.uk/381/1/ri_2009-4.pdf

 

 

[rayaans]

Interesting.

Also worth remembering that white and red cars should probably come with that statement in the handbook too - after all, red cars go pink and white cars go yellow if not protected

[Guest]

If you look at the research link.... A 29% reduction in tensile strength over a 1000hr cycle is more concerning.

Let's assume a good scenario - car left outside 2 hrs a day for 10 years. That's approx 7000 hrs. It's not going to be a problem under warranty. But in 10 years how is that plastic roof holding up? Replacement would be uneconomical.

I think the manual understated the issue somewhat. But without having access to lexus paperwork we won't know what epoxy was used etc.

I might email hq and see what they come back with. They will at least take satisfaction that someone is reading the manual ;)



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[Flytvr]

15 hours ago, Comedian said:

Anyway. I avoided carbon rc-f for price and looks (I like the roof but not the bonnet) but I know some people will like it.

 

 

I really don’t like it. Looks Halfords to me.

If I ever go the RCF route, it won’t be a carbon model.

Having said that, each to their own 😄

[Guest]

Just sent them an email with most of the above asking:

Quote

What is the expected lifespan of the carbon roof/bonnet if a car has to be kept outdoors, and also is there any expected reduction in strength due to UV damage?

See what they say......

 

 

[Guest]

Customer Relations ref: CASE0826819

 

 

Dear

Thank you for your email. 

I have spoken to our Technical Department and they have advised the following:

Carbon Parts (Models with Carbon Package) 

CFRP (Carbon Fiber Reinforced Plastic) is used in the hood, roof and rear spoiler to reduce weight. 
A special coating is used to ensure a beautiful appearance due to the pattern of the carbon fibers and to ensure weather ability.

There are no comments regarding the lifespan of the carbon parts, however this also suggests that they should last the lifetime of the vehicle, unless external influences such as stone chips are apparent. If there was a risk to the reduction in strength, the vehicle would also require that these items are changed periodically.

As there are no such comments about replacing the components, this would indicate that they were designed and homologated to last the lifetime of the vehicle.

 

I hope that this helps and thank you for contacting Lexus.

Kind regards

Lexus Customer Services 


They ignored my question about dealers keeping them exposed to sunlight against advice of the owners manual. They make no comment on UV specifically. To me it summarises as:

Not got a clue mate
Kind Regards
Lexus Customer services

Just change the roof 'periodically' ...... :D



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[Linas.P]

As well - life time of the vehicle is a bit of grey area. For manufacturer that is literally warranty period, which for body parts is ~10 years, so I guess that is what they mean.

I personally don't see this becoming issue in UK, but in Spain, California, Middle East... that will definitely be an issue. RC-F carbon always puzzled me - it is more expensive, worse equipped and arguably worse looking than standard one - why somebody woudl buy one?! I am not saying it is bad car, but standard RC-F is all the ways better...

I guess it would have made sense in Lexus would have paired it with carbon brakes, maybe more adjustable dampers/coil-overs, no rear seats, roll cage and significantly reduced weight. Then it would be like M4 Competition package track car...    

What they have done, they made it look like track car (by making it worse) but haven't added (or for that matter removed) something which would have made it better.

[Guest]

It's vague isn't it. But you went off on a bot of a rant there mate :D

I've emailed again as follow:

Thank you for the email. However, I don't feel you addressed my questions fully. The reply read a little like a passage from a brochure at first. 


Is it safe or unsafe to keep carbon models outdoors against the advice in the owners handbook? Like dealers do. 


What is the expected 'lifetime of the car' as mentioned? 


Do dealers have equipment to scan the parts for delamination? 


What is the procedure for inspecting for BVID after a stone hits the bonnet or roof?


While I am emailing; what is the cost to the customer of roof and bonnet replacement outside the warranty period please? 


Kind regards







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[NemesisUK]

23 hours ago, Comedian said:

If there was a risk to the reduction in strength, the vehicle would also require that these items are changed periodically.

Surely this statement answers the questions? 

[Guest]

You missed off

'they should last the lifetime of the vehicle, unless external influences such as stone chips are apparent'

Stone chips..... Common or uncommon?




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[NemesisUK]

Metal panels last the lifetime of the vehicle, unless external influences such as stone chips are apparent?

I think the email answers your concerns

On 12/10/2017 at 7:30 PM, Comedian said:

A special coating is used to ensure a beautiful appearance due to the pattern of the carbon fibers and to ensure weather ability.

By weather ability I believe they mean the coating also includes a protectant  against UV damage but not something that can prevent fading. Something that also affects traditional paint coatings on steel panels.

And no, I don't know the mechanism of fading but equally I would have no qualms regarding the durability of the CF structural integrity 

[Guest]

What are you basing this opinion on?



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[NemesisUK]

4 minutes ago, Comedian said:

What are you basing this opinion on?

What is written in the email and trust in the engineering integrity of a global marque.

Aren't there many examples of exposed CF being used structurally?

[Guest]

Oh I see, that's fair enough. Was just making sure I wasn't talking to a world renowned structural engineer and making a fool of myself (again). Well I have less faith than you - a quick Google of manufacturer safety recalls makes for pretty scary reading. They do make mistakes.

However in this case I'm not criticising lexus build quality or the quality of the carbon. I'm questioning the contradiction between the manual, what the emails states and what dealers and owners are doing. How that will impact the life of the parts. Not to run lexus down but to get the info. It's my feeling that info resides in Japan and lexus UK are handling my email by looking through a document, not finding the info I need and by default saying it's not written here so all is well.

Carbon is very strong in tensile only, that's why it's in epoxy resin for compression strength. What happens when a stone hits is, let's call it cracking, happens sub surface, the force causes invisible delamination you can never see by eye. If water gets in it will track between and break down the epoxy carbon matrix. Just putting a dab of lacquer on might too late. not sure about all applications but on aircraft cfrp is always painted and a vulnerable area like the bonnet would be kevlar which absorbs energy by deforming (see bullet proof vests). If a carbon roof cracked it could be repaired, but the equipment needed is highly specialised and a repair scheme would need to be produced by the design engineers.

If I dipped you in a pool of great white sharks would you like a cfrp or steel cage? You have 10 seconds to decide ;)

With regards UV. Paint is better as it will stop it, the manual implies it's not UV proof. But as well as discolouration the scientific literature notes a reduction in strength due to UV damage. If the roof is 3x stronger than it needs to be we don't have to worry. On a steel roof paint will discolour but we don't lose strength - yet the manual doesn't say to not leave metal cars exposed due to discolouration.


I just think buyers should know what they are dealing with and realise it may need to be treated differently to steel parts. That's all.

I wouldn't buy one though.

And in motorbike world I have seen 10 year old carbon fibre mudguards. They look like they have milk inside them and covered in fine cracks. Although I doubt the quality is lexus standard we are also talking about something that rarely stands outdoors.

Sorry if this reads badly. Typed it all on my phone.

I'm not running lexus themselves down. Im mainly wondering if dealers are intentionally damaging cars through lack of knowledge.

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[Guest]

That should say unintentionally.

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[NemesisUK]

24 minutes ago, Comedian said:

It's my feeling that info resides in Japan and lexus UK are handling my email by looking through a document, not finding the info I need and by default saying it's not written here so all is well.

This I think sums it up very well and by default are giving out the corporate spiel to cover their backs. 

37 minutes ago, Comedian said:

What happens when a stone hits is, let's call it cracking, happens sub surface, the force causes invisible delamination you can never see by eye. If water gets in it will track between and break down the epoxy carbon matrix.

This must be what prompts the line in the email regarding "external influences" affecting the integrity

41 minutes ago, Comedian said:

If I dipped you in a pool of great white sharks would you like a cfrp or steel cage? You have 10 seconds to decide ;)

 can I phone a friend? 

43 minutes ago, Comedian said:

I just think buyers should know what they are dealing with and realise it may need to be treated differently to steel parts. That's all.

Definitely agree but perhaps Lexus are not highlighting this because they believe it's not an issue in normal use?

46 minutes ago, Comedian said:

I wouldn't buy one though.

No, neither would I

52 minutes ago, Comedian said:

I'm not running lexus themselves down. Im mainly wondering if dealers are unintentionally damaging cars through lack of knowledge.

I'd hazard a guess that they know nothing about it at the dealership level but I doubt the cars are exposed long enough to cause significant degradation?

I look forward to reading Lexus' response to your second email 

[rayaans]

Also, hasn't the LFA got a carbon fibre body? Most them that are still alive tend to be ticking around fairly well. Especially that yellow one in the states with over 30k miles on it with nothing apart from normal servicing

[Guest]

65% yes. All painted afaik.

You might see more and more of it. Isn't prius plug in a carbon hatch?

Nasty stuff in an accident.

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[Linas.P]

On 10/15/2017 at 12:08 PM, rayaans said:

Also, hasn't the LFA got a carbon fibre body? Most them that are still alive tend to be ticking around fairly well. Especially that yellow one in the states with over 30k miles on it with nothing apart from normal servicing

There are few in states with well over 100k miles, but LFA is painted in contrast of merely lacquered, so carbon fiber parts are not exposed to UV at all.

On 10/13/2017 at 8:50 PM, NemesisUK said:

Metal panels last the lifetime of the vehicle, unless external influences such as stone chips are apparent?

Except metal parts are not UV sensitive or lose strength when exposed to UV. Equally, any modern lacquer contains UV protection - that is standard thing, because the paint is as well affected by UV. The difference here is that there are no point on RC-F carbon and whereas paint does not add structural integrity, CFRP does.

@Comedian - you right about rant, I guess my point was - "why use CFRP if it does not reduce the weight?!", kind of lose/lose - no upsides, only downsides. I am sure RC-F carbon if great car, the only problem is that standard RC-F is better and for less... 

[Guest]

Lacquers can be UV resistant it's true. So I'll try and explain further.

So we have this industry information: 

Quote

.......that contain an additive that will absorb certain wavelengths of UV with little or no degradation. They are usually added to plastics to retard degradation in fluorescent light or protect whatever may be behind the film from the effects of UV. Because these are bulk additives there will always be some unprotected areas of the plastic that will degrade. A rule of thumb is that resistance to degradation will double with the addition of UV stabilizers which means about a year outdoors at best. To be a true outdoor, weatherable film (5 - 25 year life) it needs to have a surface protection. This can be a highly UV stabilized Tedlar overlaminated film (Makrofol EPC), a film with a UV absorbing coating (LEXAN™ HPxxW) or any product that claims to be weatherable and has a warranty or test results to back up the claim.

The best way to address issues involving UV or weather-ability is to ask what the application requires to determine whether a surface protection is needed or a UV stabiliser will do.

So Lexus could have replied to me: We fit a film that protects the roof for 5-25 years.  (Would you be happy with 5 years? - I don't know)

"As the CFRP parts may change colour if they are exposed to ultraviolet rays for extended periods of time" (From the manual) SUGGESTS that there isn't much UV protection as it is UV that causes it, if they had blocked it..... no problem. I find that concerning because structural damage also occurs along with discolouration, as mentioned before.

They could answer in a straightforward manner without the ambiguity - that's all I am asking them. Am I wrong to want to know? 

[Guest]

They aren't talking to me now - so it's left to us to make our own minds up.

[Linas.P]

I personally don't see this becoming a major issue in UK, definitely not to the level where it would impact safety or even re-sale value of the car. However, in Southern EU, Middle East, Southern US that could even become a valid reason for recall.

[NemesisUK]

Los Angeles has similar average UV levels as those found in Tokyo. I feel Lexus will have had all this factored into their design of the exposed carbon fibre panels.

I'd still like to read what Lexus come back with though

[Guest]

What's your view on the statement in the manual then?






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[NemesisUK]

On 09/10/2017 at 3:54 PM, Comedian said:

As the CFRP parts may change color if they are exposed to ultraviolet rays for extended periods of time, Lexus recommends that your vehicle be stored in a place where it will not be exposed to direct sunlight

Lexus is just commenting on possible changes in the cosmetic appearance, rightly or wrongly. They've made no statement regarding the structural integrity over time.

They couldn't do anything else, otherwise they would be publicly accepting there is a concern. Clearly you believe there is, Lexus may think there is but they cannot say so, or even hint at it, for obvious legal reasons.

Personally I think Lexus/Toyota have designed in sufficient strength redundancy. I've no evidence to support this just my feeling that they are too experienced a global company to leave it to chance and them to litigation?