EPAS Almost Done

After coming to grips with the idea that my new electric assist power steering setup in my 1986 Mustang SVO would lose the collapse functionality of the stock steering column, I created my own collapsible steering shaft in front of the column to make up for it. This isn’t as difficult as you might think. You just need the right combination of off-the-shelf tubing and universal joints, but when you tell people you’re making a custom steering shaft for your car, they tend to look at you like you’re crazy.

Custom steering shaft seen from under the car

I’ve ordered a rubber boot that will hopefully fit nicely between the u-joints. The shaft has grease on the sliding mechanism, so I want to protect it from dust and debris. Under normal circumstances, the shaft shouldn’t slide at all, but I wouldn’t be surprised if chassis flex caused it to slide a bit.

I need to finish and clean up the wiring, put thread locker on all the set screws, and figure out how to tighten a bracket that is nearly impossible to reach. After that, I should (finally!) be on the road again, just in time for winter storage.

I’m going to drive it a while as-is before I add speed sensitive assist. I’ve been having some trouble with an analog input getting interference from the vehicle speed sensor that I might touch on in a future post.

 

Electric Power Steering Progress Pics

As is tradition, I have an automotive project going much slower than expected. I thought I’d share my progress anyway. This is the installation of electric assist power steering in my 1986 Ford Mustang SVO.

Here is the steering column coming out after removing all the trim pieces and unplugging all the electrical connectors. Unplugging 30+ year old connectors without breaking the tabs off is no easy feat, but I managed to do it. It’s difficult, frustrating work at times.

Pulling the steering column

With everything laid out on the bench, it’s time to go past the point of no return and cut the original steering column. The outer part of the column is just a hollow steel tube. There’s nothing too special about it, but when you cut enough of it to allow room for the electric motor, you also have to cut off a fairly beefy support bracket that helps locate the steering column. This reduction in support is addressed by a new firewall support bearing and a bracket that holds the electric motor at the correct angle. It’s acceptable, but maybe not as stout as the factory setup.

Ready to cut the steering column

Inside the hollow part of the column, there is a standard 3/4″ DD-shaped steering shaft. It has to be shortened, and then notched. The DD shaft inserts into a coupler that is pre-welded to the shaft of the electric motor. Two set screws go through the coupler and fit into the notched section of the steering shaft. The set screws have to screw down almost flush with the coupler, because the outer steering column tube slides over this whole assembly.

I had some trouble fitting everything together, and I also managed to strip the set screw threads on the coupler. I ended up tapping the hole to a larger size, and everything worked out. In general, when you strip the threads in a hole, if it was a metric size to begin with, you can go to an SAE size thread that is just a bit larger, and if it was an SAE hole to begin with, switch to a metric size thread that is a bit larger. This lets you tap out a larger hole without increasing the size too much.

Column reassembled with the motor installed

Time to test fit the assembly in the car. I was worried the motor might be too close to the brake or clutch pedal, but it’s not. Your foot has no reason to be that high on the pedal assembly, and the assembly itself doesn’t interfere with the motor either. This is going to come together just fine.

Installing the column in the car

The biggest problem I have with this kit is that this assembly takes the place of what used to be the collapsible part of the steering column. I am going to address this by building a custom collapsible steering shaft on the engine side of the firewall. This is pretty easy to do with 1″ DD tubing that slides over the standard 3/4″ DD shafts. The collapsible steering shaft in combination with extra couplers and joints between the steering rack and steering wheel makes me reasonably satisfied that a hard crash won’t send the steering wheel through the driver’s seat. This is something I’m going to put more thought into.

I’m waiting for more steering shaft parts to arrive, and I also have all the electrical work to do, and I will post again when that is all done.

Mustang 2018 Update 2

I got my ’86 Mustang SVO all put together, but it’s already time to take it apart again. Here’s what’s going on lately.

Airbox

I don’t even want to know how many hours it took to trim and fit the silicone hoses required to fit my new air box, but it’s done! If you know about SVOs, you can immediately tell it’s not a stock airbox, but to the casual observer, it looks like it could be stock, and that was the idea. I’m happy to have less noise from the engine compartment, a fully functional charcoal canister, and it still flows plenty of air. My intake temps will likely go down a bit, as well.

Never mind the power steering pump bracket, with no power steering pump.

The quieter intake really underscores just how loud the blowoff valve is. I recently ditched my Forge blowoff valve in favor of an APR bypass valve set up in a blowoff configuration. That quieted things down a bit, but I wanted more. I decided to use a valve cover breather on the “exhaust” side of the valve to act as a muffler. It doesn’t make it quiet, but it helps.

If it looks stupid, but it works, it’s not stupid.

Short throw shifter

The MGW shifter feels great. The longest shift handle they sell (“comfort”) is borderline too short for this car. I guess people are looking for the shortest throw possible, ergonomics be damned. The new shifter is transmitting more noise from the transmission than I’m used to. I might add a layer of Dynamat under the boot to help with this. Overall, a good purchase.

Steering rack

With the Flaming River 15:1 quick ratio manual steering rack coupled with the aluminum steering rack bushings, I have the best steering feel and feedback I’ve ever experienced in a fox body Mustang. Turning the wheel at a dead stop is a real chore, though, and it’s difficult to make quick transitions at low speeds. I am going to move forward with an electric assist power steering project. More on that below.

What’s Next

  • I am building an Arudino-based performance computer to fit in the lower console, replacing the factory clock. It will measure things like g-forces, 0-60 time, etc. It might use the same microcontroller and codebase as my Meguinauge project.
  • The electronic assist power steering kit is on its way.
  • I acquired parts to add a speed sensor output from the transmission. I will use the speed data for the performance computer mentioned above, and also a “middleware” controller to add speed sensitive assist to the power steering ECU. It will essentially take the VSS input from the transmission and spit out an output through a digital potentiometer. I’m still working out the details.
  • My budget is tapped out at the moment, but at some point I want to start acquiring 8.8″ rear end parts to swap the rear before doing some suspension upgrades.

Mustang 2018 Update 1

I’m finally getting to the point where I can get a lot of work done on my 1986 Ford Mustang SVO. I have a few long term projects in the planning stages, but I’m finishing up some smaller projects to be done this summer.

First, I am replacing the failing power steering pump and rack with a quick ratio manual steering rack, along with upgraded aluminum rack bushings. Mustangs had the option for manual steering as recently as 1984, and my 1986 SVO is just about the same weight as the factory manual steering cars. I think that steering effort will be just fine with the manual rack, but I have another upgrade planned for 2019 – electric assist power steering! There are kits available to add electric assist to fox body Mustangs, and some people also use parts from Saturns to fabricate their own electric assist units. I will probably be getting the kit, but with a twist: I’m going to use an Arduino (or similar board) to make the power steering speed-sensitive. It’s going to take some work just to get a speed sensor in my car and get it talking to the main ECU. I’ll have more updates on this when the project is in full swing.

Another project that I’m finishing up is the intake and airbox. When SVO owners remove the VAM (vane air meter), they typically put a conical air filter on the end of the intake tube. That’s what I had done, but there’s a problem with that: the charcoal canister vent line goes to the airbox, and without the airbox, that vent line has nowhere to terminate. March Performance makes a “Ram Air” kit for fox body Mustangs, and you can buy the airbox as a standalone item. I bought one of these and added a fitting that would accept the charcoal canister vent line. I also fabricated a bracket out of sheet aluminum to physically mount the charcoal canister in a new location. From there, I am finishing up a custom silicone intake tube that goes from the airbox to the turbo inlet. This is more complicated than you’d think because the airbox outlet is several inches higher than the turbo inlet, and space to maneuver is tight.

Custom bracketry for the charcoal canister

These projects are turning out to be more complicated than anticipated, so I did something else I’ve been meaning to do that is much more straightforward. I removed the factory Hurst shifter and replaced it with a MGW shifter. This is said to be the best shifter on the market for the T-5 transmission, and the build quality is excellent. I used their “comfort” handle, which is the longest one they offer. No regrets on that decision, because it is still shorter than a factory shifter and remains in easy reach while driving.

Factory Hurst shifter
MGW shifter with MGW gripper ball

Other than that, I’ve been working on minor maintenance and restoration tasks. I’m not done with this year’s projects yet, but I’m already planning my next steps. I’m going to upgrade my MegaSquirt ECU and finalize my Meguinauge project, and move on to another Arduino project for this car. It involves CAN-BUS communication and a 3-axis accelerometer. Stay tuned.