The most Frequently Asked Question is - How do I know if your Rear Suspension will fit in my Car or Truck?

In order to adapt this rear suspension to a variety of vehicles, we take the following approach:

  1. Customer sends measurements of his frame and required track width. These measurements are taken from a common point of reference, like the center of the differential. ( Below is an example of the relative measurements necessary to fit an IRS into an existing frame). a & b represent distances measured from the center of the differential.   c & d represent the length / width of the frame member itself




  1. Team321 creates a 2D or 3D computer model to fit the proposed IRS configuration to the customer's existing frame... using the customer's measurements.


  1. Often, adjustments have to be made to fit the IRS - and depending on the interference ( if any ) the IRS design or frame may have to be modified. The image above illustates the necessary increase in track width and points out the interference between the customer's frame and the IRS components.
  2. Team321 designs around the interference and provides a solution to fit the IRS to the customer's frame... In this case, the customer was open to relocating the interfering frame member to clear the suspension components.
The image below shows the proposed IRS suspension in it's nominal ride height, full movement up and full movement down... showing there is no interference with the frame member.


  1. At this point, we are ready to proceed. The customer can either choose to purchase the design for their car by paying Team321 in full or pay Team321 a $500 deposit to create a lightweight center section for a test fit.
  2. If the customer chooses to pay a deposit for a lightweight model for test fitting, Team321 makes a lightweight model out of 1/4" thick masonite - not steel... This is just a mock-up used to model the steel IRS unit. It is far easier and cheaper to manufacture such a lightweight, custom piece... not to mention how much cheaper it is to ship the lightweight model.
  3. Customer modifies the lightweight center section to fit and sends it back to me. Since this is made of masonite, it is easily cut, marked, etc... no need for a grinder, welding, etc.
  4. Once Team321 receives the customer's modified piece, steel parts are made - based on the customer's updated design - the $500 deposit is applied to the total cost of the IRS and Team321 ships the final IRS design.
 To be clear, the "Center Section" is the part of the IRS assembly that locates the Differential, mounts the upper and lower control arms and the coilover shocks. My IRS unit is modular in design and allows for using the same Upper and Lower control arms, Spindles, Brakes, etc.. for design to design... Since the Center Section mounts to the Car's ( or Truck's ) frame... it is fairly obvious that this must change from application to application... Mounting my IRS in a Trike will be quite different from mounting the IRS in a Pickup Truck or a T-Bucket, etc...

For more information email dave@team321.com



CLICK HERE FOR A  STEP - BY - STEP  EXAMPLE OF HOW TO UTILIZE THE LIGHTWEIGHT MODEL TO CREATE AN IRS ASSEMBLY UTILIZING FRAME RAILS