Cars

Mini Rebuild

Step 18 - Rollcage

Tuesday, October 21, 2008:

I just returned from a nice week-long vacation and found that the rollcage fabricators were done working on my Mini. Below I'll walk you through the work done.

Because my car will be used for driving schools on-track as well as for autocrossing, I thought it best to have a roll cage installed for both protection in case of an accident as well as to help the poor car stay together. For true race cars one or two beams are normally run right through the center of the door openings. Since my car will be driven on the street, I decided against these.

Goodbye rear passengers. I really wanted to retain the back seat in this car but with a cage, there's just no way. Here you can see the diagonals running right where the back seat used to be. You can also see the horizontal bar that I'll attach my harnesses to.

If you look in the back window and follow the outer downtubes, you see that they penetrate the rear bulkhead and tie directly into the rear shock towers. This should assist the handling by keeping chassis flex to a minimum and keeping the suspension aligned properly regardless of load.

Here's a detailed shot of the LH shock tower reinforcement.

Max Biaggi stopped by to check out the cage. He approved of it, but not of my Yamaha powerplant. (Ok, that's actually my good friend Rick.)

You'll remember that a previous owner had cut out a very large hole in the front firewall to accomodate huge carbeuretors. I had them weld this hole back up for now, although I'll likely be drilling one or more holes through it to pass electrical wiring between the engine bay and dashboard.

Here you can see where the cage penetrates the front firewall to tie into the front coilover mounting point.

Beyond just tying the front coilover mounting point into the cage, I also had them reinforce the mounting location for the upper coilover brackets.

Here you can see how the lower door rail ties into the body.

You also notice that the box section on the floor has been removed. This was done to allow mounting the seats lower, keeping occupants' heads away from the cage. Despite having the entire shell sandblasted, the box section hid some rust. I'll have to grind that out to remove the surface rust and then cut out and replace heavily damaged sections.

The seats are a tight fit in the shoulder area.

With the seats mounted this low, there should be plenty of room for all but the tallest passengers.

The switch to coilovers makes the bulk of the standard rear subframe obsolete. I've therefore decided to go with a beam-type rear subframe. This is simpler and lighter but it also concentrates loads into the rear healboards. Here you can see the reinforcement of this area and how it ties into the roll cage.

I commented earlier about the stock shock reinforcement plates being too narrow to accomodate the coilover I'd purchased. These plates are no longer needed and were simply removed. No more conflict!

Now with the seats in place, I can begin to work out the positioning of the various controls. Sitting lower means I will need to sit further back to allow enough legroom to operate the pedals. This will mean that I'll need to add some sort of extension the get the steering wheel a little further rearward (a quick-release will probably do the trick nicely). It also means I might not be able to reach the dash-mounted controls once strapped in. I might have to re-think the entire dash at this point....

...and looking at this cross beam, that would appear to be the end of my dream of having a standard MK1 dash - something I really liked. Oh well.

A shot from inside the car of where the cage passes through the front firewall.

One thing I realized last minute was that any added material above the LH rear shock mounting point in the trunk would conflict directly with the fuel tank. It is made to fit in the space very tightly. Tony simply removed the conflicting area of the tank and welded it back up.

A big thanks to Tony Colicchio and Joe at TC Design in Milpitas, California. Not only did they do a great job on the car, they even listened patiently to all my crazy ideas and kept a straight face. If you're anywhere near the SF area, I highly recommend you give them a call.

Continue to Rebuild Step 19

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