Mike7447 Posted August 18 Report Share Posted August 18 (edited) The Prius EPAS unit arrived yesterday, and I dove right into making it work. This is another mod that requires yet another set of irreversible hacks to a fairly expensive factory part on the car, and when you start, there ain’t no turning back. MOF, not only are you gonna butcher the steering column, you have to butcher the Prius PS assembly before you even have a prayer of getting the thing in there. The steering wheel has to come off, and the column removed and gutted.It has to be cut short, leaving only about 1.5” to extend past the tilt mount point. The factory brake light switch is in the way, it has to be eliminated. For me, and acceptable sacrifice. I intend to put an adjustable brake proportioning valve that has a pressure sensing brake light switch in instead. When you remove the steering shaft from the Mitsubishi column, you’ll see the factory “crumple zone” built into its length. The purpose being to help minimize the chance that the steering column becomes a spear that impales you in a front end collision. When you do this mod, the shaft becomes so short the factory crumple zone is completely cut away. The factory steering column steering shaft is originally like 36” long, but after the butchery, the remaining “ factory” part of the shaft will end up at 12” or less. All this has to happen because you gotta fit this thing up under the dash..Hopefully all of the required u joints required to make this thing hook up, eliminates the “ column thru your sternum” thingy. I got this pic from the Ranger Station. The guy that did that write up should be your go to if you aren’t scared away from doing this. The info, options and detail he provides far eclipses anything I intend to do here. I’m just letting you know what you’re gonna run into when, and if you decide to do this. Anyway……I cut the above Prius contraption about 1.5” to the right of the motor. Inside is a splined shaft with a male/female thing going on inside. It will slide apart. At the far right end there is a clip that allows the shaft to be removed from the outer tube. you can remove and get rid of the outer, it’ll serve you no purpose. You keep the shaft. When you cut the mitsu column 1.5” beyond the tilt mount plate, it is conveniently the same size as the Prius outer….it will slide over the remaining stub coming off the Prius assembly. From there, it’d be so easy if you could just weld the Mitsubishi column to the Prius motor,…….but there’s plastic, and electrical thingys on the Prius assembly that cant be removed to safely weld the thing together. So things get ugly from here. I made a plate to bolt to the motor so I could build tabs that would allow me to bolt the two sections together. It still requires tack welding in order to get the thing lined up well enough so when you remove the plate and column you can weld it securely, and no heat gets transferred to the plastic inside the motor assembly. If that little torque sensor processor thingy ( that you can’t remove) doesn’t tolerate any kind of welding current even be it tack welding, I won’t know until after I try it out. For now the ugly little btch can be bolted together. I have to cut and weld the inner shaft, and splice the Mitsubishi shaft to the Prius shaft as a still left to do… after that I’ll hang the assembly and make the shaft that connects the 17mm splined output of the motor to a 3/4 double d shaft that’ll allow me to mate it to the manual charger rack. Thatll be two weeks from today though. Edited August 19 by Mike7447 1 Link to comment Share on other sites More sharing options...
tux Posted August 19 Report Share Posted August 19 Before you go too far, I did see someone who put the Prius epas unit under the hood of their car instead of in the dash. Was a different car, but an idea. Link to comment Share on other sites More sharing options...
Mike7447 Posted August 19 Author Report Share Posted August 19 8 minutes ago, tux said: Before you go too far, I did see someone who put the Prius epas unit under the hood of their car instead of in the dash. Was a different car, but an idea. No room. The steering angle has to turn immediately as soon as it exits the firewall. And besides,……I’m already there, it fits under the dash. Just waiting for two weeks from now so I can finish it. Link to comment Share on other sites More sharing options...
tux Posted August 19 Report Share Posted August 19 Gotcha Link to comment Share on other sites More sharing options...
LizardKing Posted August 20 Report Share Posted August 20 Progress is looking good! Link to comment Share on other sites More sharing options...
psu_Crash Posted August 20 Report Share Posted August 20 Very interested to see all the details on this! Link to comment Share on other sites More sharing options...
Mike7447 Posted August 21 Author Report Share Posted August 21 I lied. It’s not gonna be two weeks before I update this thread. I was able to get my machine shop to get the inner shafts machined so they could be pressed together. That all happened today. This morning I started with this: The Prius shaft is on the left, where the area in front of black arrow at the top can be seen was cut off, and the remaining stub was machined down to fit into the CQ shaft on the right. Upon picking it up, and by the power vested in me by my machinist, I proudly made the two pieces one. You’re looking at it preweld. This was pressed together, and probably was enough, but where steering is concerned, it got welded. The top goes through the factory column, and the bottom slides over the splined input shaft on the motor, and over the stub standing off the Prius motor assembly. What got left at the alter was the remaining Starion factory shaft w/the crumple zone. I will not be using this in any part of the remaining mod. to avoid the steering column impaling me in a front end collision, I’ve decided to just wear a 1/4” thick plate the size of a 14” pizza pan around my neck. It only weighs 53 pounds. The butchered Starion column looks like this now that I’ve added 3 legs so that it can be bolted to the motor. So,…. Three little pig legs that bolt to a plate that bolts to the motor. Only 2 bolts on the motor hold the plate, so I used 3/16” plate and made two overlapping sections that stack on top of each other in an attempt to make it strong enough. I slid the inner into the the column upper and secured it with the snap ring. Then slid the column over the Prius motor assembly, and bolted it up. If you’ve ever had one of these columns out, you should now be able to visualize where this thing hangs……….. Directly in front of the brake pedal. It was at this time ( for whatever reason) I decided to check that everything spun normally. Cept, nothing spun. It was like it was welded solid. Fear set in, what if the minimal welding I had done had fused something?…..I took everything back apart . For no reason. It all came down to a bolt that was 1/4” too long. This bolt MOF. After finding an appropriately short enough bolt, everything spun as it should…. Crisis averted. I bolted everything back together. That brings up the what if thingy that’s should be floating around in you head about now…….What if the “electric” part of this thing fails? Ever driven a car that was supposed to have hydraulic power steering with the belt off? Same. So…. what do you need to finish Mike? Im glad you asked. The output shaft of the Prius motor is 17mm x36 spline. There is a solid coupler on order for that that will secure a 3/4” DD steering shaft to it. I will put another 3/4” rod end at the firewall to hold the column at the right angle as it exits through the firewall. Something like this: ( Done to one of my 3 previous cars that had a Prius P.S. conversion.) Which brings me to my “ hands tied” conclusion. I will not be here to complete this this weekend. What I’ll need will be here though. Soooo….2 weeks? Link to comment Share on other sites More sharing options...
psu_Crash Posted August 22 Report Share Posted August 22 Great stuff Mike! What bolt was too long? Hard to tell from the picture. Add this to the list of reasons I need a lathe. Safety 1st! 😄 "I will not be using this in any part of the remaining mod. to avoid the steering column impaling me in a front end collision, I’ve decided to just wear a 1/4” thick plate the size of a 14” pizza pan around my neck." Link to comment Share on other sites More sharing options...
tux Posted August 22 Report Share Posted August 22 I thought it was safety third Link to comment Share on other sites More sharing options...
Mike7447 Posted August 22 Author Report Share Posted August 22 3 hours ago, psu_Crash said: Great stuff Mike! What bolt was too long? Hard to tell from the picture. Add this to the list of reasons I need a lathe. Safety 1st! 😄 "I will not be using this in any part of the remaining mod. to avoid the steering column impaling me in a front end collision, I’ve decided to just wear a 1/4” thick plate the size of a 14” pizza pan around my neck." since the plate was only secured with two bolts on the input side, I made an “L” bkt that bolted to the output shaft side. That bolt threaded in, and didn’t feel like it was hitting anything, but clearly it did. I’ve been considering repurposing the crush shaft and welding short sections of the double d steering shaft on each end. That way it will still bolt up, and bend or crush if I ever needed it to. * Now I gotta figure out what the hell im gonna do with this giant disc of 1/4” plate now…🤔 Link to comment Share on other sites More sharing options...
psu_Crash Posted August 23 Report Share Posted August 23 16 hours ago, Mike7447 said: I’ve been considering repurposing the crush shaft and welding short sections of the double d steering shaft on each end. That way it will still bolt up, and bend or crush if I ever needed it to. * Now I gotta figure out what the hell im gonna do with this giant disc of 1/4” plate now…🤔 I don't think I'd bother with the re-purposed crush section. It's an 80s car. Reminiscent of a time when we just died like men. Joking aside, if we hit something that hard head on it probably won't matter anyways. 1/4" plate makes for decent target practice Link to comment Share on other sites More sharing options...
Mike7447 Posted August 24 Author Report Share Posted August 24 (edited) 12 hours ago, psu_Crash said: I don't think I'd bother with the re-purposed crush section. It's an 80s car. Reminiscent of a time when we just died like men. Joking aside, if we hit something that hard head on it probably won't matter anyways. 1/4" plate makes for decent target practice When I can get back to it, I’ll look at it. On one hand, the fact that there are 3 u joints between the steering shaft, and the steering rack input shaft, there really isn’t a “ straight” shot from the steering to my chest anyway. And as you stated, a head on collision hard enough to worry about any of this is probably moot Edited August 24 by Mike7447 Link to comment Share on other sites More sharing options...
Mike7447 Posted September 2 Author Report Share Posted September 2 (edited) Well I’m gonna say the column is done. It’s mounted, but unwired. All that’s required to do that is a 10 ga. 12v constant, and 10 ga. gnd, and a switched 12v to make it operate in failsafe. At the bottom of the column, I had to put another rod end to hold the column at the proper angle. ( gave me a chance to try out my new riv-nut tool)👍 I had to re-do the exit coupling on the engine bay side, as I had placed the rack too far forward, it had to be moved back about an 1.25-1.50”, which made the old setup no worky. Painted just enough of the bay to get that all placed… on to the reinforcement of the steering rack mounts Edited September 2 by Mike7447 Link to comment Share on other sites More sharing options...
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