For my FC subframe install into my FB, I want to keep the interior stock feeling and to do that I need to adapt the FB steering shaft/column to for on the FC steering rack.

like this, a pic of the FC lower column and lower shaft.





so I have mocked up the lower steering column from the FC to where it needs to be roughly to hold the lower steering shaft in position as seen above. I'm looking at possible mounting ideas for holding the bottom of this column stable near the firewall.




My plan (subject to the measure and mock up at least twice, then cut once rule) is to cut the FB steering column where the wrench is laying across it, and to cut the FC lower column where the other wrench is laying across. Fit the FC lower inside the FB upper with appropriate grinding and some way of attaching. I'm thinking of using pop-rivets to secure the two columns together so I can easily drill them out and disassemble in the future, vice welding.


you can see the at the bottom of this pic the Upper FB steering shaft above the lower FC shaft. They do fit together very snug, and I'm going to drill a pair of 3/32" holes and use brass shear pins to lock them together, but retain the collapsing function of the shaft for safety.

To summarise the point of this post, I'm asking for anybody who did this to please post pictures of the firewall mount, and anything else they learned the hard way to help me decide how I'm going to finish this.

Thanks.

 

you might want to look at miatea columns too, it might be a more compatible length.

 

Miata is basically a short FC. I have all three columns. No go for the same reasons the FC column is a no go.

I made my own steering shaft, but I found that a NA steering shaft is almost exactly the same length.

SO: Use a NA Miata steering shaft, and a power steering FB column, and it will be a bolt together affair.

 

I'm working on the FC subframe swap for my GSL-SE right now... you're saying I can get any NA miata column and bolt it straight to my current GSL-SE column, without any cutting or other modification? It's the right length and everything? This is the first I've heard of this but it'll save me a ton of time and effort if it works

 

How did you secure the bottom of the column? Or is your column only held together with the two bolts near the keyswitch?

 

Bottom of columb WOULD be secured by the column bracket/collar that power steering cars had... but I forgot to get it out of the parts car. I just welded a tab and bolted it up to the pedal box.

YOU DO NOT USE MIATA COLUMN. You use Miata steering shaft. You use POWER STEERING column from Series 3 RX-7. These are rare since people throw them away and convert to manual steering because they like really slow vague steering or something. They fit FB (obviously) and are the same 36 spline joint on the end as Miata, FC. probably everything Mazda made. It is infuriatingly close to 5/8-36 but not enough to work.

I'll post pictures tomorrow night of the dimensional differences between NA and FC columns.

 

pretty sure that is correct. if there are exceptions, it would be the Mazda 3 and 93-2013 626/6's.

 

I just finished this for my car. I used the very end of the FC column only so the collapsible function of the FB column was retained. The lower FC column does slip over the FB column but not snug enough to just leave it so I welded the end on. As far as mounting the end I used the stock firewall mount for the rubber seal, cut a plate to fit inside and drilled that to match the FB lower column. The trick here is it has to be put over the column before welding the FC end on, since the FC end is larger. I though about making a two piece end to bolt to the firewall by cutting the flange I made in half and making a larger mounting surface to meet the column. But now that its bolted up it is very solid on the firewall.