McLaren M20#73

[Andy R]

Hi Michel/Howard, the Rofgo M20 pics on their site of chassis #3 have been an immense help over the years. Will do something close to that.
Had the Rollhoop welded up by a recognised manufacturer to satisfy the the Motorsports NZ powers.. Resubmitted my Rollcage and Logbook application. We'll see where the front hoop saga goes, as MSNZ regulation states front hoops on sports cars are optional.
Been trying to find an Electroplater that has baths big enough to go thru the 3 step chroming process. May have to powder coat.
Got the wing foils back from sheet metal shop.
Andrew.

 

[Michel]

Hi Andy
Is not advisable to chrome the Roll hoop ; prefered if you find the right guy to have it nickeled with ver specific process and being absolutly sure that all welds are continuaous with leaks at all ( they need to plounge the rool hoop in acid !!! ) so if uou did not drill "thru " holes on the right places to evacuate this acid and then the different bathes they plounge the part ( degrease and then cooper bath and then nickel bath etc you could get bad
issues with after one or two monthes leaks of residual acid or watever rusted water bath !!!
Powder coat is the safer solution ......(when electroplaing have not been organised from start with the plater due to "cavity"problems to solve)
Otherwise there in Europe ; Chrome is forbiden since many years for racing cars ; only Nickel Or Zinc Bichromate ( replacing Cadmium)
Hope this helps
In Period ; Lola , Chevron and many UK builders where using Nickel

 

[colin artus]

Two other possibilites would be zinc nickel plating and Kephos/ Fosgard coating .

 

[Andy R]

I did read somewhere about Chrome plating and Hydrogen embrittlement.
Will investigate more Nickel plating, there's a few places in Auckland that maybe able to handle the dimensions.
Failing that there's bright Chrome powder coating. Has anyone had parts Chrome powder coated. Does the shine last?

 

[Andrew Robertson]

Hi Andy,

My main hoop was integral and powder-coated satin black as part of the whole chassis. I had all my suspension arms and radius rods HPC coated and they came up well, durable and and settles down to a semi-gloss silver/grey over time. What's the MANZ drama about your roll protection? - I thought you'd been through that process. Cheers, Andrew

 

[Neil]

Hi Andy
Is not advisable to chrome the Roll hoop ; prefered if you find the right guy to have it nickeled with ver specific process and being absolutly sure that all welds are continuaous with leaks at all ( they need to plounge the rool hoop in acid !!! ) so if uou did not drill "thru " holes on the right places to evacuate this acid and then the different bathes they plounge the part ( degrease and then cooper bath and then nickel bath etc you could get bad
issues with after one or two monthes leaks of residual acid or watever rusted water bath !!!
Powder coat is the safer solution ......(when electroplaing have not been organised from start with the plater due to "cavity"problems to solve)
Otherwise there in Europe ; Chrome is forbiden since many years for racing cars ; only Nickel Or Zinc Bichromate ( replacing Cadmium)
Hope this helps
In Period ; Lola , Chevron and many UK builders where using Nickel

Chrome plating mild steel is OK, it is high strength steel alloys that suffer from hydrogen embtittlement but even those can be baked out. Electroless nickel is one alternative.

 

[Andy R]

Hi Andrew, Main Hoop will be fine since I’ve gone down the Alternate design/Engineers report route. It’s the front hoop that will be an issue.

 

[Andy R]

MSNZ notified me, my Rollcage and Logbook are approved. Just 1 more step..... a MSNZ scrutineer now has to have eyes on and verify the pictures are the same as the cage. This added step is due to a few bods changing/adding bars etc after homologation process, so I just need to organise that and job done.
Just riveting up rear wing now..

 

[Andy R]

Rear wing completed. Did solid countersunk rivets on the wing top (as many as I could) and Sealed countersunk on the underside. The 1/2” pivot rod lined up pretty well and wing is sitting at 10 degrees angle of attack on the lowest setting.
The solid countersunk rivets are harder to install without marking the cover sheet, than the universal Rivets.
Decided only a single underwing support brace was needed as the ribs are made from 2mm and cover sheet 1.2mm.
I can hang off the rear wing lip without any defection.….onto the front.
Andrew.

 

[Andy R]

A little more done.. Completed the left side front support. The strut unbolts easy. Theres a aluminium bush at the front that can be offset to rise and fall 15mm if needed.
Finally upgraded my TIG Defuser Lens Cup to a Furick. Wish I had thrown away the standard junk 10 years ago.
Onto the drivers side…
Andrew

 

[Leon]

Hi Andy, I had my suspension arms "Electric-less Nickel" plated and it looks great. "Auckland Industrial Hard-Chrome" are the people to do it.
Looking good !!

Cheers Leon

 

[Leon]

Hi Andy, Just reading this again and have to agree with Howard, also you make reference to the M8F having front end grip problems. Keep in mind they are very different cars. and the reason for Dennys back flip wasn't completely the cars fault but a product of circumstance with pulling out from behind the car in front at the precise moment of cresting the brow. I'm just saying don't get too tied up with details that won't be a factor on NZ tracks that don't have the crests and won't have the top end speeds that the big road circuits in the US have. As always I am in awe of what you are doing.

Cheers Leon

 

[Andy R]

A MSNZ scrutineer viewed the Roll hoop and I now have a MSNZ log book and the Roll Hoop is Homologated. Whew…
So after that I polished up the hoop and shipped to Auckland to Bumpers Replacements NZ. To get Copper then Nickel plated. They were the only company that had baths physically big enough. So that just arrived back and is back on the car. Pleased with the look and finish.
The drivers side front strut is completed and the L & R front ply splitters have been Fibreglassed. Currently building the front tunnels, and am happy to install (although not period correct…I have a lot of that already) as the front wheel arches need boxing in anyway and its not much more work. Pretty simple shape just ramping up to a 14 degree incline.
I agree with Howard re a single front splitter and as I’m doing a little tribute to the #73 Wood/Hobbs M20 chassis#1, I will be mostly imitating that.

 

[Brian Kissel]

Very nice Andy!!
Regards Brian

 

[Udo Selter]

Love the roll bar Andy.
Regards, Udo.

 

[Leon]

Hi Andy, The hoop looks great and that finish is awesome. I see you got your homologation did they say anything about a front hoop over the dashboard?? If not it just shows how inconsistent they can be and I find that so frustrating. Do your remember who you delt with at MSNZ.
My car is now in the new CARS INC museum in Trentham, I needed somewhere to store it and they were very happy to have it there.

Have a great Christmas, Leon

 

[Andy R]

Not a whole bunch completed this month, must have worked to much….. made the front ground effect tunnels and glassing in. Don’t know if they’ll do much but I like them.
Leon, no front roll hoop required this time... The scrutineer was happy and so was I.

And to the GT40S community, have a Merry Christmas and all the best for 2024.
Andrew.

 

[Russell]

Not a whole bunch completed this month, must have worked to much….. made the front ground effect tunnels and glassing in. Don’t know if they’ll do much but I like them.
Leon, no front roll hoop required this time... The scrutineer was happy and so was I.

And to the GT40S community, have a Merry Christmas and all the best for 2024.
Andrew.

Andy, great to see progress on what is a MASTER BUILD. I have just done the big downsize and sold the family home, starting out afresh on the other side of town. Not doing any more building as such but have plenty to keep me going in the new house, still got my Formula Junior and the Rambler I bought in from the States. So wishing you a merry Christmas and all that goes with it. Cheers Russell