McLaren MP4/6 Tub – Some Useful Information?

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dr_gn
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McLaren MP4/6 Tub – Some Useful Information?

Post by dr_gn »

All,

This information may be well known, maybe not. I thought I’d share it anyway, since it explains some features evident in many photographs of the MP4/6 tub:

I’m currently building the Tamiya 1:12 McLaren MP4/6, and have seen many methods of replicating the rough surface of its male-moulded tub. I’ve been putting off doing mine for several reasons, including:

• It’s difficult to find photographs which consistently show the surface detail of the real tub.

• Getting the correct colours is tricky, since they vary so much depending on lighting.

• Having rough tub sides exposed under the forward bodywork didn’t seem to ring true with McLaren’s reputation for attention to detail. I’ve seen these cars close-up in the pits in 1991, and others in the MP4/x series at historic racing events, and don’t remember noticing much inconsistency in external finish.

• There is little consistency in how the tub is represented in models.

I’ve recently got some clarifications to these points: I posted a series of my old ‘80’s & ‘90’s F1 photographs on a Facebook group dedicated to F1 Testing. Some of them are duplicated here on F1M, but I’m adding to them as I scan them:

https://www.f1m.com/forum/viewtopic.php?f=18&t=31058

Someone replied to one particular photograph of the MP4/5C, and it turned out to be Matthew Jeffreys. Matthew is a former Senior Design Engineer and Project Leader for chassis design at McLaren International. He was heavily involved in the design and manufacture of the MP4/6 chassis (and other McLaren cars of that era). Obviously I took the opportunity to ask a few questions...

To summarise, as is well known, the tub was formed using a male mould, which gave the distinctive rough/wrinkled outer surfaces. This however isn’t the full story: The vertical forward sides of the tub (those exposed to the airflow), were not rough, but in fact quite smooth. This also applied to the flat surface under the front dampers. These smooth surfaces were achieved by incorporating “caul plates” into the moulding process. The caul plates were sheets of smooth aluminium placed in contact with the outer surfaces of the tub in the appropriate places. Once cured, both the inner and outer surfaces of the tub were therefore smooth in these areas. In some images, reflections, combined with the translucence of the resin can make the sides look rougher than they are in reality.

The radii along the tub edges were rougher, since the caul plates didn’t extend around them. Where the edges of the front bodywork contacted the tub, strips of protective helicopter tape were applied. This gives rise to what at first glance appears to be an overlap of carbon sheets over the edge of the tub.

The caul plates extended to somewhere hidden behind the radiator ducts, because the entire visible area of the rear tub (ie behind the ducts) is rough - i.e. no caul plates.

The tub was made up of a patchwork of layers of unidirectional carbon fibre, and the tub colour is described by Matthew as “Dark Olive Drab”.

The radiator ducts were also male-moulded, but using a lower cure temperature resin. That’s why they are a different colour, described as “Dark Grey”.

The nose box was described as “Black” (I think this may be a plain or twill weave carbon).
When I asked about colours being affected by flash, the colours stated were described as “true colours”.

The following photograph shows some of the features described. It was taken from this thread:

https://www.f1m.com/forum/viewtopic.php?f=26&t=31147

...and kindly reproduced here with permission from the photographer, Flemming Hansen:

Image

Just to confuse matters, some early development tubs had different caul plate arrangements, possibly having additional, locally applied plates on the angled parts of the tub for seating electrical boxes etc., so beware of relying 100% on photographs!

Hopefully the above will be of some use – I know I’m relieved that the amount of textured surfaces that need addressing has vastly reduced, although getting a realistic finish remains a huge challenge. I think if you look at photographs of other male-mould McLarens (eg the MP4/5x), you can, to an extent, work out how they were made and where the caul plates were used.

I'm very grateful to Matthew for taking the time to patiently answer my questions. I'll update this thread, should any further information become available.

Cheers!
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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by daveyman »

Interesting info. I've seen Mathew commenting on that site too. Seems a very friendly guy and happy to chat. Have been able to chat to a number of significant 'names' via Facebook groups, very useful site.
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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by donnieleblanc »

This is great Information! Thank you for researching this and posting what Mr. Jeffreys told you.

Donnie

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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by dr_gn »

daveyman wrote:Interesting info. I've seen Mathew commenting on that site too. Seems a very friendly guy and happy to chat. Have been able to chat to a number of significant 'names' via Facebook groups, very useful site.
Agreed.

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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by dr_gn »

donnieleblanc wrote:This is great Information! Thank you for researching this and posting what Mr. Jeffreys told you.

Donnie
No problem, glad you found it useful.
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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by turboF1 »

I found this very useful. Always great to hear from people online that actually lived my dream of working for an F1 team during that era.
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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by marlborored »

Great information! Thank you for posting.

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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by dr_gn »

marlborored wrote:Great information! Thank you for posting.
No problem.
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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by ouizel »

Very interesting. Thanks!

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Re: McLaren MP4/6 Tub – Some Useful Information?

Post by willster127 »

Very interesting, a great read,

Interestingly the tub isn't flat black, Who woulda thought!!!
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