Independent Rear Suspension for your vehicle

You may have seen the website. Team321 LLC is the parent company of TruckIRS. We design and manufacture custom suspension products as well as adapter brackets for a variety of classic Ford and Chevy trucks. The adapter brackets allow the home builder an inexpensive, straightforward way to install an independent rear suspension in their vehicle. The adapter brackets are designed to mount Ford Thunderbird, Mercury Cougar and Lincoln Mark 8 independent rear suspension subframes to the truck frames. While the brackets work for a wide variety of trucks, we continue to receive inquiries for other vehicles. The adapter brackets are best suited for a body-on-frame style vehicle (vs. a unibody vehicle). CALL (321)960-5945 for more information.

If you would like a set of adapter brackets for your vehicle, follow the steps below. The frame shown in the example below is a mid-50s Chevy Truck. Not sure of the exact year, but the steps taken to extract the information are the same regardless of make & model or whether it is a car or a truck. You will likely have then entire vehicle, and may even have a body, bed, rear axle or something else that will make access a bit difficult. Do the best that you can and work around any obstacles.

Step 1 : Setting the frame at desired ride height

It is important to set the frame at the desired ride height. this may be a bit difficult if you have removed weight from the vehicle (like removing the bed from a truck). Keep this in mind when setting the ride height.

Step 2 : Leveling the frame

Once the ride height is established, level the frame. The photo below shows ample use of levels and angle finders.

Step 3 : marking the rear Axle centerline

All measurements are taken relative to the axle centerline. A soapstone was used to mark the frame along with a straight edge. A sharpie pen will likely work as well.

Step 4 : drawing a horizontal line along the frame rail

Measurements will be taken along this horizontal line. The frame has an arc to it, so choose a line that runs horizontal from at least 21 inches behind and 21 inches ahead of the axle centerline. I found a convenient place for a horizontal line that was 20 inches above the ground. I measured 20 inches above ground in a few places and made preliminary marks on the frame. Next, I held a level against the frame rail and drew the horizontal line.

Step 5 : preparing to mark the horizontal line

I added a piece of masking tape to the horizontal line on the frame to make measurements easier. Also, I found that the soapstone line was prone to being rubbed off when I touched it with sweaty hands (it was about 95 degrees with 90% humidity when I did this).

Step 6 : measuring along the horizontal line

With the piece of masking tape along the horizontal line, add a tickmark every three inches, starting with the axle centerline. You will have a mark at 3, 6, 9, 12, 15, 18 and 21 inches ahead of the axle centerline as well as 3, 6, 9, 12, 15, 18 and 21 inches behind the axle centerline.

Step 6 : continued

It may be difficult to see the tickmarks along the masking tape in the image above, so here is a zoomed in shot.

Step 7 : recording the measurements

Using a tape measure or calipers, measure the distance from the horizontal line to the top of the frame, at each 3 inch tickmark. The image below shows red lines showing the measurements upwards of the horizontal line to the top of the frame rail and green lines downward from the horizontal line to the bottom of the frame rail.

Step 7 : recording the measurements

Email the measurements of the lengths of the lines indicated by the red and green lines in the image above, and I will put them into a CAD program to generate a profile view of your frame rail.

Step 8 : Frame rail separation

The last measurements I need are the inside to inside and outside to outside measurement of the frame rails as indicated in the image below.

Step 9 : Generating the 3D drawing

The remaining steps are up to me, but I will show them below to drive the point home. I have invested a significant amount of $ and time in a 3D CAD package to accurately generate drawings of new brackets, if the preceding steps are followed. The last remaining measurement necessary is the tire diameter. The tire diameter determines the location of the spindle, and the frame rail height relative to the ground determines the placement of the IRS subframe. The tire track width shown is based on factory Thunderbird / Lincoln mark 8 wheels / tires.

A second view of the 3D drawing