RX7 FC steering rack in S31z

[s30kid]

Alot of people are always asking what steering racks fit in the Z to convert to power steering. I know there is a thread about using a subaru rack however I could not get my hands on a RHD subaru rack, Instead I have an RX7 FC rack which is also a front steer car.

 

 

The issue is that the steering rack comes in contact with the motor mount. Now this install is on a RHD Z but the crossmember is pretty symmetrical So i think that If anyone else tried this install they would run into the same problems. 

 

Also, the RX7 FC rack is 53 1/4" from tierod bolt to tierod bolt and the stock z rack is 46 1/8" (just a quick measurement, probably not dead on accurate)

 

I plan to take the inner tie rods off and have them machined with threads down the majority of the body, measure and cut the inner tie rods to fit with enough adjustment for alignments. Easy peasy.

 

The only other issue is figuring out a way to make the neck (or whatever its called) to clear the motor mount. I have 2 options. Mount the neck upwards and use a few u-joints to make the ~90* bend or C-notch under the motor mount and run the neck so that its a straight shot to the steering column. And of course finding a u-joint that fits the splines of the RX7 neck and making a custom steering shaft to the steering column at the firewall.

[260DET]

Might be an idea to check what your'e proposing for a potential bump steer problem. It's pretty easy to get involved in solving fitting problems and forgetting to also check that it's going to be compatible with the rest of the car.

[s30kid]

So If any of you fallow me on Instagram (@s30kid) you will know that what I ended up doing was extending the lower control arms to match the width of the new steering rack. The reason I did this was because I wanted to widen the track of the car and keep the increased steering angle of the new steering rack.

 

The steering rack was roughly 3 inches longer on each side then the stock rack so that was my base number. The reason I did not go with any of the many aftermarket control arms is they do not extend long enough. I need at least 3 inches on each side to compensate for the new rack so I decided to make my own. 

 

I started by measuring the stock lower control arm and cutting the inner end off, So that I can adjust the rod end all the way in which would be stock length. 

 

 

Cut

 

I then had to cut and make room for the new Rod End. Summit Racing part number TMI-4116260.

 

With the rod end in place I measured and began tac welding the new sides of the control arm into place.

I then added a top piece

 

With everything tac welded in place I was able to test and make sure the rod end was able to fully turn in and out from stock length, all the way to 4" longer then stock.

 

I then test mounted everything to the car.

 

And here is the car on the ground with 2 rather large friends in the engine bay to roughly equal engine weight and get the car to the proper ride height.

 

As you can see the new control arms add quite a bit of camber to the wheels but I wanted the added camber for better steering angle, occasional drifting and looks (I know I know please keep the hate to yourselves) But someday when I get coilovers and camber plates the camber can be corrected.

 

And here is the new steering angle

 

And under view as well

 

Now, the only problems left are to figure out new sway bar mounts and tension rods. With the strut now 3 inches further out the stock tension rod, 1, The threaded end doesn't reach the frame. And 2, The angle on the head of the tension rod where it bolts to the lower control arm is too shallow. I need to heat up and bend the tension rods in more towards the frame to have the correct angle on them and then modify them to be length adjustable as well.

 

This was a very fun weekend project and great for anyone looking for dramatically increased track width of the car. I plan to someday lengthen the rear as well but for now I think i'll just run deeper offset wheels in the rear. 

 

All the pictures show the control arms only tac welded together. After I test mounted everything I took the control arms off and took them to a professional welder who opened up the control arm and welded everything form the inside and out. Mainly because I just don't trust myself with welding a crucial suspension part. 

[1969honda]

Interesting approach to things, love to hear how it handles when all is said and done

[s30kid]

Also, Once I get my steering shaft connected to the column I can install the motor and start driving the car again and I will let everyone know of any possible bump steer issues or any issues for that matter. Obviously with the camber where it is there is going to be a loose feeling or maybe a wobble on the freeway. But what I am trying to accomplish here is to show everyone that is IS possible to run an RX7 FC rack in a Z. Weather you section your inner tie rods, or greatly extend the lower control arms. Either way Its possible.

[tube80z]

You need to reinforce the nut you used.  A threaded bushing could have been used, which would have more weld area.  And a rod end would give you much more room to raise the inner control arm if you need to.  The large bearing you have looks like it would contact the top of the crossmember.  Just a few things to think about.

 

Cary

[s30kid]

I got the steering fully finished and working perfect I used needle bearing eyelts for mounting the rod to the fenderwell.

 

Also finished installing the control arms and rolled the car outside. I just need tension rods now.