Body Modifications to the GT40

If this part of the build was on TV it would be called the Itchy and Scratchy episode!

Modification of the GT40's body is key to getting the look of the car right. A lot of time was spent on small details to ensure that this would become a very special looking car.

Here is a snapshot of just a few of the modifications.

Rear Flares

A slightly wider rear flare was required to fit the rim and tire package so it was time to cut of the standard ones and bond on the new ones. The new ones are only about 100mm wider, they are not full gulf flares and were applied to the car to just cover the wheels with about 10mm clearance. A very difficult job to get right. It took me to get it 90 percent right andKaber to get it 100% right after laser scanning the car.

Rear Light Mounting and Le Mans Rear Vent Detail

The rear lights would fit better if a small indentation was added in the rear clip to stop the back of the lights from being sprayed by water. I made a mold from wood to accomplish this.

I then made a few oval type parts and glassed them into the rear of the lights. A cable assembly with a grommet was obtained and this will make a sealed cable connection to the lights. Nutserts have been glassed in to fasten the lights.

Before

After

The holes above the rear lights were in the original cars to vent air from behind the wheels. Probably also to send stones flying into cars behind them at Le Mans! I have not seen many replicas with this detail but I like it.

Door Latches and Door Striker

I decided to use Porsche door latches as I have used them before. I manufactured aluminium plates and mounted them to the doors.

The door striker support on the chassis was manufactured from aluminium and ties in with the roll cage to transmit any side collision loading to the chassis.

Interior Door Boxes

I then looked at making some interior door boxes. They give the occupants some extra elbow room in the car. I really did not like any of the door boxes available so I made my own molds quickly out of MDF as per below.

The door intrusion bar can also be seen below.

The box perimeter was then carefully cut out of the door to make a flange that matched the contour of the doors perfectly. These flanges were added to the box taken of the molds I manufactured. Fasteners are on the inside and the box has a perfectly spaced gap to the door. I like creating these gap lines in preparation for the body work! When they are painted black the gap will not be as visible.

Dashboard

I also did extensive work on the dash area to perfectly match the base of the window. I really do not want to see the fiberglass lip of the spider supporting the lower edge of the front window when I sit in the drivers seat. This is something I have seen in most GT40s. Its not a big issue it just bugs me.

Work was also done to perfectly fit the defrost grille. I cut this area out and remade it to fit the custom defrost grille that resembles the original.

The dash was also cut to have small wedges on the sides. The reason for these is to allow removal of the dash with the roll cage fitted. As you can see without these the dash would be captive in the car.

So after getting a dash and working on the top it was time to look into the gauge and column area. I wanted a custom gauge layout, so time to cut and shut the dash.

Custom Speedhut gauges were made. There are two more gauges than usual as I wanted transaxle temperature and voltage.

Designing, Manufacturing and Assembling a Custom GT40 Braking System

As the vehicle was broken down completely for shipping basic suspension assembly was completed first.

I did not purchase the standard RCR Wilwood brakes as they may not meet the ADR’s (Australian Design Rules) and while they fit in 15” diameter rims they look a little small to me inside the 17” rims. Looks are not everything, but I also wanted the challenge of designing a few alloy caliper brackets and rotor hats. The performance of the standard Wilwood RCR brakes are more than adequate, however this setup will be even better and with a larger disc diameter the pedal effort will be reduced.

I decided to use AP Racing calipers and DBA (local manufacturer) slotted rotors. The sizes I decided on (based on some basic brake balancing calculations) are below:

Front – AP Racing CP5555 6 pot calipers and 343mm (13.5”) x 32mm thick rotors Rear – AP Racing CP5200 4 pot calipers and 330mm (13”) x 28mm thick rotors

The rear rotors are quite large as the rear does a good deal of braking due to the weight in the rear of the car.

I also decided to use the Precision Brake Co. handbrake calipers on the rear. While I was designing the alloy brake components I had the logo changed on the face of the handbrake caliper. I modeled up the entire caliper (image below) with the AP Racing logo and had the original logo machined off and the AP Racing one machined in. The logo was then filled with high temperature gloss yellow paint. It’s a flat out lie but it looks better to me as it matches the main brake calipers!

I designed all the brackets myself on CAD by measuring the RCR parts, wheels etc. very carefully to ensure a perfect fit. I then had the rotor hats and caliper mounts CNC machined up directly from the CAD data here in Australia. For the front brake system no modifications to the RCR uprights were required to mount the upgraded brakes. However the rear brakes required some minor changes to the RCR uprights.

Rear Brakes

Front Brakes

The front brakes were designed in the same way as the rear. however clearances between the caliper and rim were much closer as they are larger.

The front caliper clearance to the rim is as little as 2mm in some areas.

The rotor hats were designed without any holes to aid in cooling. The reason will be clear in a future post on brake cooling ducts.

During assembly I was a bit nervous, it all looked good on CAD but did I make a stuff up? Very happy to say all parts fit perfectly. On the rear I simply milled off the existing Wilwood caliper mount on the RCR upright and tapped some holes and bolted my custom brackets on. I’m also happy I found some great NC machinists to make the alloy parts and they are first quality. They will be used again for more custom machining work for my build.

As always these designs worked great for my car but should not be used by others without first having them checked by a qualified and certified engineer.

Travelling to RCR in Michigan USA

It is like visiting Santa's Workshop, snow and all - Race Car Replicas in Detroit USA!

We have a few locally built GT40 kits here in Australia, however the decision to go with RCR was based on it incorporating an aluminium monocoque chassis. Having the support of a local manufacturer would make things easier, but I was not looking for an easy vehicle to construct. I wanted to create something different.

A visit to RCR in the USA to see the car mid construction was a lot of fun but bloody cold! However Fran and his staff were most accommodating so the visit was great.

These are images of my car during construction at RCR in Detroit.

During the visit it was decided that a Ford GT Supercar transaxle manufactured by Ricardo would be used. Its a very capable transaxle and as it was made for Ford it would be appropriate to use on a GT40.

I had no idea how much work this car was going to be. But it was a great starting point for the car that I wanted.

Here you can see some of the other cars in RCR's shop in Detroit. You can visit their website here. They have a great selection of cars and their chassis and suspension work in particular is top notch.

Months later the chassis and body arrived in Australia and the assembly work started with the design and construction of a custom brake setup.