Skip to main content

Ferrari 360 Front Challenge Grill Frame


I decided to change out the front grills on my Ferrari 360 Spider from the stock to Challenge grills. The Challenge grills have a steel mesh to keep FOD out of the radiator cooling area, vs. the stock grills which just have some fins. 

I managed to find both left and right grills on eBay for about $150 each and thought that would be the end of it. After installing them, it seemed like there was a part missing. 

Checking the parts list, I found there's supposed to be a frame behind the grills (part #'s 66307300 and 66307400) to channel the airflow into the cooling duct for the radiators. Without the frame, air can spill around the duct and cause a loss of cooling flow. It's a large part with a maximum dimension about 15".

I had a choice. Spend over $1000 and purchase new frames, if I could even find them, or make my own.

I found a beat up frame on eBay for $80 and used that as a template. The eBay unit had most of the attachment tabs broken or missing but the frame itself was in good enough shape to use as a model.

The part has some interesting geometry that makes it a tricky part to reproduce. It's not flat and has an organic shape on the mounting side. Luckily, the other side is flat so only one side of the part has a difficult shape. The other side can just be traced onto graph paper.

To get the shape digitized, the part has to be "indexed" or registered properly so that the bottom and the top can be modeled and then built up into a solid part with the correct geometry. I did that by mounting a piece of cardboard with staples to my CNC machine table, then tracing the flat bottom onto that cardboard, then placing graph paper on the cardboard, making registration marks at the zero point and corners, tracing the inner shape again, then removing the graph paper and placing the part back exactly where it was. I secured the part to the cardboard with hot glue.

Here's the flat part traced onto fine graphing paper. I had to tape three sheets together to make a large enough tracing sheet. The cut outs allowed me to position the graph paper precisely on the cardboard to index the position of the base.

The tracing was corrected for spherical aberration in Photoshop, then imported into Fusion 360 as a canvas. Using the spline tool, I traced the outline to digitize the shape. 

Digitizing the part's mounting surface required using a probe placed precisely at the inner edge, around the circumference of the part and recording the 3D position in a spreadsheet. I'm sure there's a way to capture the points using Acorn, but I just typed them into a spreadsheet instead. Out of 200+ points, I made one single error, which is pretty remarkable. Humans usually have about a 10% error rate when manually recording data. The little box to the left of the computer controls the CNC machine and can be used to move the business end with extremely fine control. I measured to 0.01" accuracy. Difficult to do with a tape measure!

This is what I ended up with after importing the points into Fusion 360 as an inner and outer spline. I had to create the mounting tabs myself, which was fairly easy once I had the shape. The mounting surface is a complex organic curve in 3 dimensions. 
The mounting holes were recorded and imported into the model as well.

With the shape digitized, the splines were converted into a solid, meshed, and imported into Prusaslicer to prepare it for printing. Unfortunately, my 3D printer has a maximum dimension of about 9", so I had to scale down the print to fit the printer. I've got a new, much larger professional grade printer (Prusa XL) on order that will print this part full size, but for now, the smaller printer will do for testing the shape.

Note the green under the orange part. The green stuff are supports required because the mounting surface isn't flat. They rip off fairly easily and any rough spots can be sanded. My new printer will have multiple print heads so I can print the supports using a material like PVA which dissolves in water, making the cleanup job much easier.

Here's the finished part. It looks great and will be acceptable for use as a frame when printed at full scale. I should have my new printer in about a month, so at that time I'll take my front bumper off again and mount these frames in place.

Here's the old part with the new reproduction to show the scale. The part is about 15" at the wideset. Easily done with the Prusa XL which has a 14x14x14" print volume.

To make the other side, the part is simply mirrored in the slicing program. Only one model is required for both sides. The miracle of digital technology!


Popular posts from this blog

Capote Elastic Bands Replacement

Virtually every Ferrari 360 and 430 has failing elastic bands in the capote, or soft top. The only cars that don't have these items failed right now have had them replaced in the last five years. My car is no exception and my original 20 year old elastic bands are well past the time they should be replaced. The top has a number of elastic bands that help control how it folds up and how things move. These bands are the same type of material as appears in underwear and stretch pants. As these things age, they wear out. So just like your old underwear, the elastic on the 360/430 top loses it's stretch. One of the things these elastic bands do is control a bar that shapes the headliner and roof line. This bar has to be pulled back and lie flat so the rest of the machinery that constitutes the top can fit into the tiny little space in the back of the car. When the elastic bands give out, the bar doesn't move to the right spot and the frame can impact on that bar as the top folds

Bosch Throttle Body (Holder) Woes

My 360 started going into limp mode a while back. It was subtle at first, with it starting to lose power after 4,000 RPM's and then less subtle when it would barely go above idle. Limp mode protects the car when some vital part has malfunctioned. I know a master Ferrari tech that is nice enough to answer questions for me about the car. He lives more than five hundred miles away and it's like telemedicine.  The codes indicated a problem in the drive-by-wire circuit, likely culprit: One or more TB's or the accelerator potentiometer (AP), which is the foot pedal sensor.  I had a good code reader that could monitor the AP voltages (2) and they appeared to be within specification. That left the TB's, one or both. After a long discussion with the tech, his answer was to replace the throttle bodies (TB). The Ferrari 360 has two TB's. One for each bank of four cylinders. To the Ferrari mentality, replacement could only be with two new TB's: "Ferrari likes replacing

Guide to Removal and Replacement of Heat Exchanger

Ferrari 360 Guide to Remove and Replace Heat Exchanger Lars K. Staack (aka lkstaack) 5/23/2021 Introduction 1. This is a first person account of removing and replacing the heat exchanger from a 2002 Ferrari 360 and is applicable to both the Modena and Spider models. I am a shade tree mechanic with decades of general experience, but only a month of Ferrari experience. This guide may assist a novice mechanic anticipate problems in advance, but expect to encounter issues that this guide does not address. Do not begin this procedure if that makes you uncomfortable. 2. This guide is for entertainment purposes only and is not intended to be official or definitive instructions. Performing these procedures introduces the possibility of personal injury and even death. This guide assumes that the mechanic is familiar with the proper use of personal safety equipment such as eye wear and gloves, safety equipment such as jack stands, and basic tools. I do not assume any responsibility for conse