The goal of this post is to provide people with the cheapest possible way of getting into an aluminum profile sim racing chassis and to make the whole ordeal as simple as possible. If you follow this guide you will able to buy, with just a few clicks, all the extrusion pre cut to length and all of the hardware necessary to build a very rigid rig that wont have you wanting for more. You will also have an understanding of how to put the rig together and for those nerdy enough to care...why it is designed the way it is.
What is aluminum extrusion framing?
Before we start we need to discuss what aluminum extrusion profiles are. Extrusion is actually a process where material is heated up and forced under extremely high pressures through a die. This creates a very long bar that could have a very intricate cross section, the process allows for cost effective mass manufacturing of framing materials. There are lots of standards for extrusions, but for sim racing rigs the most common are 40 series and 15 series. 40 Series refers to the metric standard size where the cross sections are available in 40 mm increments. For example 4040, is 40mmx40mm, whereas 4080 is 40mmx80mm and so on. 15 series refers to the imperial standard where extrusion is available is 1.5 inch increments, 1515 or 1530 for example.
Metric vs Imperial
The first design choice we have to make is which standard will we use. 40 series is more common worldwide but after doing some digging I found that 15 series was much cheaper, at least here in the US. I estimate that by using 15 series instead of 40 series we are able to save $150+ in material and shipping cost (15 series is slightly smaller but having built this rig already I can guarantee you it is stiff enough for the purpose of sim racing). On the bright side the 15 series accepts the same hardware used with 40 series. We will be using metric hardware to match the hardware wheelbases and pedals accept and because its more common/cheaper.
Light Weight vs Heavy Duty
The next choice we have to make is whether or not you use solid or light weight profile. Light weight profile has a pocket that runs the length of the extrusion, reducing the amount of material needed for the frame. This saves on material cost and saves on weight. If you click the link at the bottom of this post, you will see that you can choose either option. The light weight version is plenty stiff, that's because most of the rigidity comes from where the material is placed (i.e the shape) not how much material is used. This is known as area moment of inertia, or the shapes tendency to resist bending. Imagine if I asked you to drive to your local hardware store, buy a 2X6 and try to break it over your knee. Which way would you hold it? Almost instinctively its obvious that the material is going to be stiffer in one orientation than the other, the shape matters. For most people I think the light weight version is the way to go, but if you have aspirations for upgrading to a motion setup maybe splurge for the heavy duty version. You will notice though that no matter which option you select, they both use light weight profile for the shifter mounts. This is because the shifter mount is already really rigid for its application and using light weight profile here helps us avoid a ~$40 surcharge on shipping.
More Savings
Speaking of avoiding surcharges, we avoided another shipping surcharge by limiting the length of the floor members to 47". These design choices help big time when it comes to saving cost. Now I'm about 6'1" and have another 2-3 inch height adjustment in the wheel position and maybe another inch or two in length (seat to pedal location). If you are over 6'4" I would consider using a board or some 1515 profile to have the option of mounting your pedals a bit further out.
The final way you can save money with this kit is by using grey/silver extrusion like I did. I do have links for black extrusion if you like that look better, but it is typically more expensive because it is less common.
Build Instructions
Safety Disclaimer: The edges of the extrusion can be very sharp. I strongly suggest using thick gloves while assembling.
Bracket Modifications
The most difficult aspect of this build is modifying the 90 degree aluminum brackets. There are a few reasons why I picked these brackets. First and foremost they are gusseted, which adds a ton of rigidity to a joint. Second they have a slotted hole, this allows us to get clever with how we mount the wheel base and saves us money by not having to get special wheel base brackets. Third, they seem to be the most readily available. The down side of these brackets is that they have four tabs on them which limit how they can be used. Note: If anyone is able to source similar brackets without these protrusions let me know and I will gladly update the links.
The tabs are designed to fit in the channel and help with locating a 90 degree joint. The down side is that they severely limit how the joint can be made, the channels have to be lined up for this bracket to work. So unfortunately we will need to modify these. However, because these seem to be die cast aluminum they are extremely soft. I used a Dremel to cut off the tabs but I did attempt to use a file and I was able to file off four protrusions in 5 minutes (with a Dremel or a grinder it takes seconds).
The good news is we don't have to remove every tab. In some areas, like the seat mount they are actually extremely useful and add strength. Figure 3 summarizes the three types of 90 degree brackets we will end up with, type 1, type 2 and type 3 and they are color coded to help distinguish where they are needed. Note type 3 brackets are only needed if you intend to mount your wheelbase as I did.
Frame Assembly
The image below show a 3D model of the sim rig assembly. The callouts for the individual components correspond to the descriptions in the spreadsheet with the material links.
We are going to start with the rectangular base. This consist of two base rails, two pedal mounts, two seat mounts and four type 1 90 degree brackets.
Generally speaking its best to prep brackets with the screws and t-nuts first, then slide them into rails from the side. Its just slightly easier in most cases. This is what a "prepped bracket should look like.
Then prep the four pedal/seat mounts with brackets and t-nuts as shown. I prefer to use the "slide-in" t-nuts for this just to save drop in t-nuts for later. You want the edge of the bracket lined up perfectly with the edge of the extrusion. You can tighten these screws. NOTE: Later on we will mount our seats and pedals to these rails so make sure you slide two t-nuts into each of the seat rails and however many you think you need for your pedal set.
Then begin sliding them into the Base Rails. The seat brackets go in the top t-slot with the brackets facing the front. Pedal mounts go into the bottom t-slot with the brackets facing the center, refer to the assembly image above for. Once everything is in the approximate location you think you need, snug them up just slightly, you will need to shift these around later.
Next is the wheel base uprights. To start we need to prep the tee joining plate as shown.
I like to just start every nut with a couple of threads, again use the slide-in t-nuts if you can. Slide these into the outside of the base rail. Snug up a few of the bolts ever so slightly to have the bracket sit flush with the base rail, this helps sliding the wheel base uprights into place from the top. It should look like this.
Slide the wheel base uprights onto the four t-nuts from the top. Once the wheel base uprights are snug loosen the screws that you previously tightened in the Base Rails so that the assembly can slide back and forth on the Base Rail. You need this to help line up the uprights so that you can install the wheel base mount.
Securing the wheel base mount to the uprights requires four of the type 2 brackets. If you determined you can mount your wheel base the same way I have done here you will also need four of the type 3 brackets. Prep the wheel base mount as shown here. The tabs of the type 2 brackets should sit in the t-slot and the brackets should be flush with the edge of the extrusion. You can tighten these bolts.
You will definitely need a second set of hands for this next part as you try to slide both side of the wheel base mount into the uprights while sliding the uprights back and forth to line everything up. Both of the t-nuts should slide into the slot closes to the pedal mounts as shown here.
Once the wheel base mount is inserted you will notice that it really likes to swing and rotate. This is because of the freedom that the slot in the bracket and the lack of tabs on the type 2 bracket create. This is a major benefit to use because it allows us to angle the wheel base up to 15 degrees without needing some special made brackets. Place this in roughly where you think it will end up and snug up the bolts for the wheel base mount and wheel base uprights.
At this point we have not installed the shifter yet but its a good idea to setup your seat, wheel base, and pedal location. I like to start with the seat. I place the first seat bracket flush with the ends of the base rail. This will be our datum and we can set the positions of everything moving forward from this point. Measure out the distance between mounting holes for your seat rails and position the next seat rail accordingly. NOTE: If you are using a car seat like I am make sure that the holes for the seat rail are in line with each other and that the bottom of the seat rails are flat. This makes it way easier to mount directly to the aluminum extrusion, otherwise you might find yourself doing some drilling, cutting and bending to make it work. FYI if you forgot to slide in the t-nuts when you prepped the seat mounts before, this is a good time for those drop in T-nuts.
Once you have your seat positioned you can set up your pedals. I like to mount the pedals to the pedal mounts first and then slide the whole assembly back and forth to a comfortable position. As far as I can tell most pedal sets are designed to be mounted directly to aluminum profile extrusion so they have holes ready for our m8 bolts. That was the case with the Moza pedals that I am using.
To locate the wheel base uprights we will want to install the wheelbase and wheel first. For the Moza r12 that I use I was able to do this simply by using the type 3 brackets. You should be able to do this with most wheelbases but this is one point where you might need to get creative. If you absolutely need to, most wheelbase manufactures sell adjustable mounts to mate their wheelbase to an aluminum profile rig. Once the wheel base is set in place you can adjust the angle and height of the wheel base mount. Then adjust the location of the wheel base uprights by sliding them forward or back on the base rails until you are comfortable.
With everything in place this is a good time to go through the entire rig and tighten all the bolts that were previously just snug. Take at least two passes at this, sometimes tightening one bolt loosens up another.
With all that out of the way we can install our shifter mount. Some people don't use a shifter but I would advise installing the mount anyway as there are other benefits. Because the mount is triangulated back to the base rails instead of cantilevered out on its own it does add rigidity. It also acts as a hand rail for getting in and out of the rig which I find helpful. Lastly it makes a good place to mount other auxiliary equipment like a moue pad for example.
Installation is pretty straight forward. Two type 1 brackets secure the 3030 shifter mount to the upright. A type 1 bracket is used to secure the shifter upright to the shifter mount and then a type 2 bracket is used to secure the shifter upright to the base rails. Tighten all of these bolts as hard as you can. I found that these like to loosen up the quickest with the loads they take form shifting and from using it as a hand rail.
NOTE: I strongly suggest doing a bolt check after a few hours of gameplay and another one a week or two later. Also I recommend using plastic endcaps to protect against the sharp edges. There is a link for these in the spread sheet but I also provided free STL files in case you want to print your own.
All that's left is to enjoy the rig. If you found this useful and you would like to support P1Labs there are a few ways you can do that. Firstly share this post with your friends.. Secondly please use the links to buy anything you might need, full transparency here they are affiliate links and I do make a small commission, at no cost to you, every time a purchase is made using those links. And finally please take a look around the website for anything sim racing or car related that might fit your needs!
Link to the materials spreadsheet to buy everything that you need, all aluminum cut to the necessary length:
If you have any questions or suggestions for design changes/better sources for parts contact us by clicking here.
