Project SC300 Road Racer: Part 30 – Sometimes You Finish Where You Should’ve Started
using a MAP torch to heat a bushing carrier with a bushing removal tool bolted around it
Interestingly, a 99-04 Ford Mustang Cobra independent rear suspension uses subframe bushings similar in size and shape to the SC300.

Bart does a lot of Mustang work. That means he has a lot of Mustang-specific tools. Maximum Motorsports makes a subframe bushing removal tool specific to that generation Mustang IRS, and it just happens to work here, too!

The rear bushing that attaches the subframe to the car bolts to the post (previously pictured) and connects to the chassis with four small bolts. We had to apply a little bit of heat with a MAP torch, and then the bushing removal tool was able to pull the bushing most of the way out of the housing.

 

wearing heavy welding gloves and using an air hammer to remove bushing held in vise
The housing was then placed into a vise and, between an air hammer and a regular hammer, the bushing was removed the rest of the way.

Once you start using a torch, you should be extremely careful when touching anything, as it’s likely to be dangerously hot. Don’t guess. Wear protective gloves.

 

close up of two large metal encased blue polyurethane bushings on a table with metal washers, a grease packet, etc
Here are the two Superpro Supra/SC300 bushings that go on those rear posts.

I did not use any solid bushings, and FIGS does not recommend them. Lots of people run to the solid bushing store #becauseracecar. The subframe is exposed to very high shock loads from all kinds of places, especially from the drivetrain. For high-powered torque-y drift cars where you are clutch kicking, the subframe and differential bushings provide some relief for these shock loads to go somewhere.

Did you ever wonder why drift cars tend to blow up axles or transmission input/output shafts? It’s because they have solid mounted everything, and the shock loads are transferred directly into these parts that were never designed to see them.

The polyurethane that Superpro uses for their bushings is extremely hard, but it’s not solid. Just that little bit of give drastically reduces shock loading and provides a longer life span for all of the components in the torque path: the transmission, the driveshaft, the differential, and the axles.

Think about it this way: Would you rather replace a poly bushing after a while, or replace a transmission because you blew up the input shaft?

The little tube contains grease. You will need to liberally apply it to the metal housing of the bushing. The washers go on either side of the bushing before attaching it to the subframe.

 

using a hydraulic press to insert a bushing into a carrier
You will want to use a press to get this bushing into the housing.

You could probably do it with the IRS bushing removal tool, but it would be a ghetto hack job. You could probably do a lot of sketchy things to get the bushing into the housing, but the press is the best tool to do the job safely and quickly.

2 comments

  1. At this point, I’m more interested in hearing about you getting your money’s worth out of this thing than more upgrades. That’s not to say the work recently posted isn’t first class, but if it can’t run the times it’s for naught. I’m genuinely curious how fast this thing is as is.

    1. You and me both — curious how it’ll do. I got some lap times at Grid Life Road Atlanta last season and they were alright. Off the pace for NASA ST2 times but respectable considering I still didn’t even have a baseline for the car. Heck, I’m still figuring out starting tire pressure.

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