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.

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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.

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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.

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

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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.

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

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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.

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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!

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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:

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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%.

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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.

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Continued on Part 3

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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.

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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.

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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.

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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 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.

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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.

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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.

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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:

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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.

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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.

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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.

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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)

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

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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:

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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.

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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.

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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!

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Now to just do all that 3 more times.

To be continued!

 

Part 1
Part 3

Setup Stands Part 1 – The Frame Job

Many moons ago, a buddy posted a few pictures to Facebook of his car on some setup / alignment pads. My curiosity piqued, I reached out and got a bit more info from him, as something similar would be phenomenally useful. I’d looked at commercial options for these, but they are prohibitively expensive, and John’s homebuilt pads looked pretty close to what I wanted for a lot less money.

After a great deal of figuring and bouncing ideas off of engineer friends, it became clear that a set could be made that would also incorporate setup scales, for relatively little cash (and a great deal of time….so, so much time). Initial designs were drawn up and steel ordered.

What follows is going to be a boatload of photos of various stages of the build. It was a very very long process of evolutionary engineering and problem solving, but now that I know how to build them, additional sets will be made relatively (and it is very relative, because they’re a ton of work) easily.

First step: getting a bunch of steel home. I had various pieces cut more or less to length, as I didn’t know exactly how they would go together but had a general feel for at least what the long legs needed to be. The rest were cut to fit in the back of the truckster to get it home.

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Lots of measuring (way more than twice), cutting, coping and beveling later, and the first frame was roughed out.

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The scales will sit on the side with “floor” on all 4 edges, and the rolloff pads will go opposite them.

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Cutting 45 degree miter joints would have been far easier from a fab standpoint. However coping the joints has 2 very big advantages: it leaves nice, flat areas on each end of the “long” side of the frame for the legs to sit on, and with that, there is a lot less strain on the welds and puts everything in compression, with the welds mostly holding the pieces together, and not supporting the weight of the car.

It’s not that I don’t trust my welds, but with something that needs to hold the weight of a car from crushing me to death, I will take every bit of added strength I can get.

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A quick test fit was very encouraging. My measuring a dozen times lead to a fit that allows the scale pads to rock in and out easily, but not enough that they can move around too much.

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Mocking up the legs:

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Got the rest of the gussets and the horizontal supports done.

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A design requirement was to have feet at each corner that will allow the full set to be leveled. The first step of that are these that make the bottom of the legs, with the threaded nut inside the leg. So, weld the nut to the washer, then weld that assembly to the leg.

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The rest of the parts stackup.

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This once again goes into the strength of the thing. Once the jam nut is tightened up, all of the load is on the big washers at the bottom of the legs and the bolt, and virtually none of the operating load is on the tack welds securing the nut on the inside of the legs.

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With the basic design roughed out, we’ll work on the roll off pads in Part 2.

To be continued….

 

Part 2
Part 3

Saws and Welders and Stands, oh my!

Workshop update! I’ve made a few tooling changes and upgrades 😀

The biggie is a welder upgrade. The old, tired Harbor Freight 180 amp welder has now been replaced with a Millermatic 211. It’s a massive, “the last MIG welder I’ll ever need” level upgrade, but with the projects going on in the shop (including a few that will be getting sold), it really was time to get something better and more consistent.

Miller had a rebate going on, so everything sort of lined up for it. I’m still getting used to what it likes & setting it up right, and unlearning a bunch of bad habits, but man this thing is nice. The old HF box didn’t much care how your technique was, it was going to weld the same way (mediocrely) regardless. On this one, small things make big differences and you can really tune everything in.

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Next, I really needed something that could fairly easily & effectively notch heavy angle iron to build some frames for a project or three that I’m working on. An angle grinder will do the job, but it’s slow, hot, messy and not nearly as accurate as I wanted for this. A vertical band saw is the correct answer, but is also way out of the budget. Some poking around lead me to SWAG Offroad, which sells laser-cut and pre-bent kits for converting a portable band saw into a benchtop upright bandsaw, and there are enough glowing reviews out there that it seemed worth it to try. Turns out, they were correct!

I opted for the optional foot pedal as well (so that the machine can have the trigger locked on, but you can easily control its stop and start and keep your hands free), which I highly recommend if you do pick one up.

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I put a good metal-cutting blade in it (though from what I’ve read, that’s not necessary but will last longer), and man, this thing gets the job done. It’s not crazy fast, but it’s accurate, makes clean  cuts and doesn’t get the steel scalding hot in the process.

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Finally, I got sick of picking up my miter saw and having to find a place in / around the shop to run it, and of not having a good way to support the stock on it. I pulled together a few scrap bits and bobs and threw together a rolling stand for it that can be moved out of the way / out of the shop for the messy work (since race tires and steel chips don’t really get along). I wanted something that would work as a base for the metal cutting saw, and also serve as storage for assorted grinding & cutting wheels, and my 14″ chop saw that, until now, lived on the floor in a corner.

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Grinding wheel, flap disk, cutoff & wire wheel storage, to get them out from the bottom drawer of my toolbox:

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And with it at that height, it’s not only at a super comfortable height for me, but I can put 1 or 2 of those roller stands nearby and quickly have long stock support. And, as with all of these things, it should make life a lot easier.

That is, generally speaking, the whole point of tools.

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Big-Boy Welding Table

I have a few projects coming up that really need a decently flat surface to build on. While it’s served me well, the flimsy $30 Harbor Freight welding table just wasn’t cutting it in the long run (it has since been donated to a friend’s son who’s going to school as a welder).

Enter WeldTables.com and their CertiFlat tables. After pricing material (since I don’t have that much scrap laying around), I realized I wouldn’t be able to build a table for the price of one of theirs. I went for the 2 x 4′. Big enough to do what I need, but small enough (and on wheels…) that I can stuff it in the corner of my workshop, or in the driveway, should I need the space.

It came in far quicker than their advertised 7-10 day lead time, and once it did I set about cleaning all the parts with Acetone in preparation for welding it together. It really is a man-sized erector set 😀

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We did hit a slight snag that, in retrospect is obvious from the photo above, but we didn’t catch it until we were doing the final assembly. It turns out that they sent leg stringers for a 2×3 foot table, so the short sides were fine, but the long sides were about a foot short:

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A quick call to  WeldTables.com and they shipped the correct parts out straight away. The mistake was annoying, but their Customer Service in correcting it was outstanding.

With the correct parts in hand, I completed assembly and welding. I then flipped it over, did a little grinding of the few spots where the weld went higher than the slots, cleaned up the surface with a polycarbide wheel and sprayed it down with some WD40 to prevent rust from building up.

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I also ordered a couple of their 6×6 FabSquares and broke the new table in by putting those together. These will be super useful in the future.

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What with the Atlantic separating us most of the year, I don’t get to do too many fun projects like this with my Dad. Because of that, so I put a little something together to document it.