Electric Power Steering Conversion – Part 4

HAHAHAHAHAHAAAAA!
Man, it’s so good. The adjustments are pretty darn sensitive. We spent the first 6 or so runs dialing out a little bit at a time until we got to the point where the previous spot was better and dialed it back up that notch.
Video won’t show much, but being able to make fine adjustments was a nice change of pace… it went from having to be muscled around the course to finally being able to have soft hands on the wheel.

All in all: if your class allows it, or if you’ve got a street car without PS, this is a great bit of kit 😀

Video:

Advertisements

Electric Power Steering Conversion – Part 3

Continued from Part 2.

Deech came over to help out with the wiring (which is to say: do the wiring) so that it would actually be done properly.

20170930_142403

I decided that as much as possible would go into the switch panel box, just to keep everything out of the weather. The controller was secured to the box, then wired to switched power & ground through the switch box panel. We connected to the rheostat, and we were able to use a pair of unused wires for the clutch pedal switch that were already wired into the switch box (but not used) to carry the power and CANBUS signal to the ECU on the steering column.  We tapped into those wires near the column and spliced the connector on.

20170929_182018

Before tidying up the wiring completely, we went ahead and did a systems test to make sure everything worked. Much to my surprise (because I worked on it…) it worked properly the first time.

“Like a kid at Christmas” is a pretty accurate descriptor. The fact that the steering turns easily without the lever-arm of the steering wheel attached was astonishing. What else can you say other than it just works, as advertised. I ended up needing to turn it down to about 1/3 power on the rheostat just so that there would be some heft in the steering system, even with the tiny steering wheel.

A proper test is coming up at this weekend’s autocross, where we’ll spend some time tuning it in to where it’s happy on course, and happy-enough everywhere else.

Continued in Part 4

Electric Power Steering Conversion – Part 2

Continued from Part 1.

With the column completed, I could get it mounted in the car. Woohoo, it fits! And SOMEHOW, the steering wheel spline size is the same for both the GM and stock columns. My quick release bolted right on.

20170925_105018

While tiedown straps are nice and simple, they’re not exactly sturdy enough for keeping a steering column in place, so it’s time to break out the cutting and welding tools.

The Miata and GM column mounts are not parallel, so it took a little creativity to get everything lined up correctly. After a little bit of measuring, I realized I could cut the shapes I needed out of a drop of 2″ square tube. Everything looks parallel in the picture, but there’s about a 1/4″ slope on 1 side of each bracket to fix the difference in angle between the stock pickup and the GM mount.

20170925_205501

The stock column mounting-plate made a good datum & base to fabricate from. The brackets are bolted to the GM break-away tabs as they would in the donor vehicle, retaining all of the safety features built in to the new column.

20170925_212314

I added a couple gussets to stiffen things up, as there will be a fair deal of torque put on this mount during competition.

20170926_103624

I hacked the lower mounts off of the sacrificial column, and used the stock firewall mount points as the basis for the new lower mounts. The left-side mount was by far the most difficult. It took quite a bit of jiggery-pokery to get all of the angles correct so that there was ample clearance for the brake pedal.

20170926_153948

20170926_161257

There was far more room to work with on the right-hand side.

20170926_203244

I’d been working with the motor disconnected, as it is big and heavy, and would make things far more difficult in this stage. The time has come to put it back on. Plenty of clearance in the footwell.

20170926_212654

Also, check it! I can get about 1″ of tilt on the column (nearly the full stroke in the mounts)! I was fairly convinced that the tilt wouldn’t work with my install, but here we are. Finally, an NA Miata with the oft-advertised but never before actually seen tilting steering column!

20170926_212710

The tilting column adjuster handle is VERY much in the way when climbing around the column getting in and out of the car, so that needed to be modified to tuck it out of the way:

20170927_152108

I also went ahead and installed a smaller steering wheel. I went from a ~14″ / 350mm wheel to a 11″ / 280mm wheel. This effectively reduces the arc length that the driver’s hands need to travel to put in the same steering angle by about 25%.

20170927_153104

With all of the hardware complete, I could get a start on the electrics. I ran and terminated all of the large-gauge wires that carry power to the motor (that are connected directly to the battery with a 60 amp fuse in line), and started modifying the switch panel to accept the potentiometer. I should be able to put the controller in there as well, to keep it out of the box, and tap into a couple of spare pins in the harness going out of the box to run the controller output to the motor, making for a nice, clean install.

20170926_214512

Continued on Part 3

Electric Power Steering Conversion – Part 1

If I have one complaint about the race car it’s that the steering wheel is fairly brutal on the driver. With aero and 9″ slicks going through a Manual rack there’s a ton of feedback. Too much feedback. And because of how heavy it is even with the Manual rack (again, 9″ slicks), I haven’t even wanted to run a depowered PS rack.

Of course, power steering would fix this, but it’s heavy, often messy when they boil over, and saps power from the engine. I already don’t have nearly enough power, so that’s out.

However, I found out recently about a GM electric steering column that’s been seeing heavy use in Rally and other offroad racing disciplines, along with a company that sells a controller that spoofs the CanBus signal, and allows you to adjust the amount of steering assist. I’ve been toying with the idea for a while now, but an autox buddy had one installed in his Ecotec powered Lotus 7 clone and frigging loves it. With some direct experience and some research in the bag, the time came to start building.

So here’s the plan:
-Snag a steering column & controller
-Fabricate mounts and an intermediate “adapter” to go between the end of the GM rack and the input of the Miata’s intermediate shaft. I want to keep it as bolt-in as possible in case something breaks and I need to swap stock parts in.
-De-Power and refurb the PS rack I’ve had sitting on the shelf for ages now waiting for its moment to shine. With the power steering, adding in the faster rack would be good. I’m going to pair this with a smaller steering wheel to lower the distance my hands will need to travel on the wheel for a given angle of input.
-Add steering rack travel limiters to prevent the 15x10s rubbing on the sway-bar in paddock / grid / during big spins.

The steering column in question is out of the Saturn Vue & Chevy Equinox, and is a little over 3″ shorter than the stock NA steering column. I went to the local Pull A Part and snagged one out of the yard, along with the full wiring harness. The nice thing about this column is that they’re built for far heavier cars than what I’m putting it into, so it should be plenty. This system has seen extensive use in the offroad racing community, and I’ve seen them installed in things between ride-on lawnmowers and Unimogs. It appears to be insanely versatile.

20170825_131406

To get everything lined up in the right place took a lot of careful measurement. It doesn’t need to be micron-perfect, but within 1/8″ or so is the goal.

20170912_204103

20170912_204437

The mounts are within an inch or so of where the Miata’s mounts are, so I’ll be able to use the stock upper mounts points (using a modified stock column mount), and will need to re-engineer the lower mounts. The plan is to weld brackets onto a stock upper column mount, and cut the lower mounts off of a sacrificial stock column.

Overall, the GM column is about 3″ shorter than the stock Miata column. This is a good thing as it will allow me to get the steering wheel in a stock location without having to modify the intermediate shaft that runs between the column and rack.

After disassembling the sacrificial stock Miata steering column, I discovered, much to my amazement, that the lower section (where it bolts to the intermediate shaft) is 3/4″ diameter. And just about every aftermarket steering component out there is 3/4″. Due to that size being ubiquitous, EPowerSteering.com sells a 16mm spline to 3/4″ shaft adapter.  I’ll use that and a section of the stock steering column to build a small adapter that will spline / bolt onto the bottom of the GM column, and spline / bolt into the stock intermediate shaft.

I took the parts to a buddy’s shop where we cut the stock steering column down to length, and TIG welded the parts together. It could have been MIGed, but with the threads and fine splines, I wanted to avoid spatter at all costs.

After it was welded, I drilled and tapped through the adapter and spline stub to run a bolt to serve as a failsafe in the event the weld breaks, as that weld essentially is a single-point-of-failure in the steering system.

20170924_122953

20170924_144130

With the column setup complete, it was time to start fabbing the mounts in the car.

 

Continued in Part 2

Setup Stand Build Plans

First off:

warning2

Now that the legal jargon is out of the way:

The response I got from the setup stand build has been tremendous. Several folks have suggested that they’d like plans be made available so they can build their own set, and that they’d be happy to throw a few bucks my way for the time that went into developing them. I’m staggered, because I thought I’d make a couple sets for buddies and that would be it, and that would be that.

 

The directions include a materials list, a cut list, some 3D modeling and photographs of the stands.

Chances are that, having built a few sets now, I may have left out a few things that seem intuitive to me just from having done it several times. Let me know if you have any questions and I’ll do my best to answer them.

 

If you’d like the plans, e-mail me at amaff5@gmail.com and I’ll send a .PDF with the plans.

 

This is very much a hobby for me, not a business, and these are super useful tools for “us people”. I’d rather more of my racing buddies have access to them than not, so I’m making the plans available for free. Hell, if we had money to burn we’d just spend $2,000 on the commercially available options and be done with it.

That said, I have put a great deal of time and sweat (omg so much sweat you guys) developing these. If you feel that these were worth it and / or want to throw a few bucks in the hat / Tire Fund for the R&D done on these, you can do so here:

Donate with PayPal

Setup Stands Part 3 – Setup Setup Setup

Now that the fabrication work is done on the setup pads, it’s time to set up the setup pads so that the setup pads can be use to set up the car.

Setup.

First thing’s first: Paint. It’s always paint.

20170612_160013

20170613_095521

Step 2 is…more paint, oddly enough. I picked a fairly central location in the shop for the setup pads, then got them on the car so that they could be squared up, so that their locations can be marked. This is so that each pad goes in the same spot, in the same orientation each time, that way once they’re leveled, they remain consistent.

I made up a stencil to use for marking the floor, put the foot of each corner on the circle in the middle, then marked out the perimeter with tape.

20170614_211658

That done, the stands came out from under the car, the car was moved out of the shop, and each spot was marked:

20170615_103302

20170615_153653

Next it was time to level the full set. I started off by setting the feet to their highest setting so that I could find the lowest corner, and then adjust the rest of the pads to meet that corner.

CUE THE LASERS!!!

20170616_204525

I used a couple of my big fabrication squares, made white backgrounds (to better see the laser) and then made a mark on each at the same level. Get the lines on the squares to meet the laser at both the front and rear of each pad, and you’ve got it level.

20170616_205211

20170616_205238

20170616_214140

With the setup of the setup pads done, it was time to…. do some setup on the scales. Specifically, I was sick of dealing with the rats nest each time I unspooled the cables, so I made left- and right-side “harnesses” to keep things tidy. They’ll run under the car down the middle so that they’re out of the way of jacks and what not.

20170617_133630

And with that, somehow, miraculously, despite taking what felt like most of my life, they’re complete and in service! They look great and will work great. Having now used them exactly once, they were already worth the effort. Being able to get and keep a consistent setup on the car (and help friends with their cars) can only be a good thing.

20170618_143411

 

Now to make 2 more sets…

 

Part 1
Part 2

Setup Stands Part 2 – Roll Out!

Roll off pads are very useful for setup, allowing a place to make alignment changes, to zero the scales, and to allow the tire to roll to undo any bind that setting changes may have introduced. They are also the thing that adds a TON of cost to the commercial setup stand options.

Since I’m fully committed at this point, might as well go big.

The pad itself will be a pieces of 1/8″ aluminum sheet, supported on both sides and in the middle.

The side supports are made of 3/16″ steel bar with 3 holes per side drilled and a nut welded to the back side on each to secure the plate. The bars are supported on 3 sides, sitting on the frame on the short sides and 1 long side. Those bars on top of the frame puts the floor just a shade lower than the scale pads, allowing space for some thin grease plates to do alignments.

The center support is a length of 1″ bar with 3 holes through it. 1/4″ on one side for the bolts, and just about 1″ on the bottom to allow a 10mm socket with an M6 nut to be inserted from the bottom.

20170425_111651

20170530_215901

20170531_134710

Once the 2 sides were done, the next challenge was fitting up the middle support tube such that it was dead level with the 2 sides so the floor is perfectly flat. To do that, I flipped the entire frame so that the side-supports were flat against the welding table, then placed the tube in to get tacked up so that the welding table top became the reference surface for the whole setup.

20170425_181245

20170425_184036

With the frames completed, it was time to fab up the floor. After rough-cutting it, clamped it to the frame and drilled the 3 central holes as they can be accessed from underneath. The challenge, however, was to get the position of the 6 holes on the sides that were covered up by the angle iron.

This is where a DILYSI Dave hot tip came in incredibly handy. Long ago when I was building the new Seat Mounts, he suggested making some blind transfer punches out of some bolts. I made up a few more so I’d have a full set for this job. I threaded them into the holes, then bolted down the 3 central bolts so that the floor would be in the correct place, then gave each location a sharp whack with a rubber mallet to mark its location on the aluminum sheet for drilling.

20170425_214112

20170425_214112

20170425_215455

With the prototype nearly complete, I wanted to do some strength testing (ie: dropping the car on it vigorously a few times) to make sure there weren’t any glaring issues:

20170425_220310

And since I was painting the new Saw Stand, I figured I might as well hit this one with a coat of paint. This, it would turn out, would be a mistake.

20170505_180015

The keen eyed will notice 2 glaring omissions at this point (the point at which I thought I was done with this…). 1. There is no provision for the cable for the scales to pass through, and 2. There are no wheel stops. The commercial ones don’t usually have wheel stops, but they’re much shorter so were you to roll the car off of them, the likelyhood of them damaging the car is fairly low. These are very tall, and VERY strong. As such, should the car roll off of these, it would be ugly.  I’ll address these next.

First up is a notch for the cable. Attempt number 1 was…. well… fugly. I tried doing it with and angle grinder and the results were bad.

20170521_153950

It was at this point that the true value of a welder came into play. That was ugly enough that I decided to un-cut steel.

20170521_203640

After a rethink and some consultation, I decided to use a hole saw instead. Normally this wouldn’t be a problem, however at this point, with the frame fully assembled, it was a bit late in the game. This is by far the dumbest thing I’ve ever chucked up in the drill press, but damn if it didn’t work!

(I’ve no idea why this photo shows up sidewards. Click the picture for the right-side-up image)

20170522_085952

Thankfully the results were most excellent. After a little cleanup of the sharp edges and corners with a flap disk, I was very happy.

20170522_090728 Now that I know where the notch needs to go, subsequent cuts were FAR easier. 20170522_130536

On to the tire stops. After a bit of figuring and evolutionary engineering, I ended up with an easy to fabricate, dead simple solution that will 1) stop the car rolling off the ends, and 2) still allow the stands to stack together to minimize the space they take in the shop.

Part the first is a 2″ length of 1/2″ OD tube welded in the center of each end of the frame:

20170531_175720

Next is a 6″ length of 3/8″ steel rod, with a bend around the 2″ mark and a bullet nose ground in on each end. The bend is so that they won’t just fall through the tube, and it leaves a ~4″ step that would take an immense amount of force to get the tires over. If you figure out a way to do that, you do your alignments far more aggressively than I.

20170603_143414

The short side / long side has an added advantage that I wish I could take credit for but in reality was a complete, but happy, accident. Up front, that long post interferes with the splitter when rolling the car back and forth between the scale and the roll off pad.

20170617_140137

With it flipped upside down, there’s still plenty of a step to stop the car (plus the taller sides are still up at the rear), and the splitter clears easily. I love it when a plan, accidental or otherwise, comes together!

20170617_140226

Now to just do all that 3 more times.

To be continued!

 

Part 1
Part 3