Ultimate IRS – Supra Tubular Subframe Cradle Grannas Racing

This is a complete bolt-in rear tubular subframe for the MKIV Supra (JZA80 – MKIV) chassis. This is 100% chromoly, so it is not only lightweight but extremely strong. The bare stock stamped steel subframe is around 65.2 lbs, this bare subframe is 29.2 lbs lighter, weighing it at only 36 lbs. Combined with lightweight chromoly suspension arms, the overall weight savings will be substantial if you are going to use my entire Ultimate IRS system.

This will make the entire IRS suspension more rigid. Removing the play and twist from IRS suspension systems is key in making it work better.

The subframe cradle uses all the factory mounting locations to the chassis and  stock locations for all suspension arms. So, you technically could run all stock arms, or re-use the arms you currently are running with no fuss! This is also designed to work with the factory spindle. 

For the differential, it also uses the stock mounting locations, so you can use stock differential or any of the aftermarket rear end kits. For example, you can see my Driveshaft Shop 9″ kit in the pictures.

A major advantage to this setup when using my Ultimate IRS suspension system is that it allows the use of running a common through-bolt shock combination, so no longer are you limited to the HKS Drag or other aftermarket supra specific suspension systems. This opens the door to a wide array of coilover/shock options! This is a new innovation in the supra world, which is made possible with the Grannas Racing ultimate IRS lower control arm, and upper strut perch combination.

The subframe is available as a full kit with our adjustable lower control arms, upper hat mounts, and coilovers of choice. There are three coilover options currently. The base kit uses Strange brand double adjustables. The middle tier kit uses double adjustable Penske based coilovers setup specific for the Supra by Precision Racing Suspension. The top of the line coilover is again a Penske based strut but with an additional canister which allows for finer tuning of the suspension. 

A lot of people ask how would these compare to HKS Drag coilovers… well, the difference is night and day. You are talking about 20 year old technology based on a factory mounted strut compared to current racing technology. All of the coilovers I offer are double adjustable. HKS Drags are only single adjustable. The double adjustability (rebound control) allows you to control the speed at which the shock “rebounds” from a squat. That is key when it comes to IRS and keeping the car planted going down the track. This is especially helpful in a manual transmission car, where the car will unload and come out of squat on every shift. The double adjustability allows you to tune the suspension to keep the car planted on shifts.