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411 Rack & Pinion Prototype


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Hey, gang,


I don't recall whether I posted about it here, but I recently test fit a 1999/2000 Miata engine in my wagon and was happy to find that it fits really well. In 1999, they took the giant cam sensor off the back of the engine, allowing about 2-1/2" of addition space in front without cutting the firewall, which is always the challenge with swapping into the 411 engine bay.


Anyways, the only modification necessary would be to clearance the oil pan for the steering cross link. But, the more I measured that out, the less happy that approach made me. I really had to shove the engine against the firewall to clear the front face of the transmission, and cutting and welding that highly-engineered cast aluminum oil pan just seemed rude.


So, I returned to an old idea of converting the car to rack and pinion. In very little time, I was able to mock something up that is pretty easy to do and appears to out-perform the stock system in most respects using the 411 steering arms (swapped side to side and flipped to be front steer with proper Ackerman) and an MG Midget/AH Sprite steering rack (unmodified).


Stock steering radius: 16.4 feet

R&P steering radius: 15.7 feet (calculated)


Stock turns, lock to lock: 2.5

R&P turns, lock to lock: 3.0 (I believe there is a faster MG steering rack out there)


R&P Ackerman: More or less the same

R&P bump steer: Almost none, much less than stock (mathematically, I am a few shims away from zero bump steer, but we'll see)


R&P wheel fitment: Requires 14" or more (my 14" Riken mesh wheels clear the flipped arms, but just barely)


R&P anti-sway bar fitment: Fits


R&P lowered suspension clearance: I believe this will work with Roadster springs, but haven't tried, yet.










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This project got put on the back burner for a bit, and then it took me a while to figure out how to mount the rack so that it would be adjustable, removable and allow the crossmember to be boxed in again. But, it's all mounted, now, and I'm moving on this week to making a bracket to hold the lower end of the steering column in place, where the steering box used to be.







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By flipping the steering arms did you give yourself anti-Ackerman?   That’s how the photo looks.  I could be wrong.  Besides that sounds like a win, win!!!  


We put a degree wheel on the steering wheel and on the rack input to make sure the u-joint phasing was correct.  


Are uou sure the stock steering is 2.5?  Usually it’s around 3.5-4.  



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The Ackerman is correct; the orientation of the first photo is front of the car towards the top, and it's steering a bit to the left.


I hadn't thought about the u-joint phasing, thanks for bringing that up!


I indexed to a crack in my steering wheel and turned lock to lock a few times and got 2.5 each time, which did seem fast to me....


I think I'm putting this project on hold again to do a quick engine swap into my '68 Toyota Corona coupe, but I'll be back around to this, as I want the wagon back on the road....



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