Something doesn't quite look right, here
glad to see that the FC subframe came together!
02-18-10, 10:24 AM
#7
Old [Sch|F]ool
Thread Starter
I still can't believe how simple it was.
Two inch-tall boxes need to be fabricated for the rear subframe mounts. I chose to oval the forward subframe mounts inward (and trim the sides a little) and use the stock forward subframe studs, which makes the front wheels sit an inch or so further forward than normal. If I didn't want that, I could have just redrilled the subframe. I have to cut the fenders, but the fenders needed cutting for other reasons, so I don't mind.
FC steering column needs to be used, the FB power steering column is the right spline but is not long enough.
I used Escort ZX2 strut mounts (strut hole needs to be filed a little, chassis needs to be drilled for the 10mm studs vs. stock 8mm) and I'm going to modify the FC spring hats for use with 2 1/2" coilovers. KYB AGXs are still on backorder. FB strut mounts cannot be easily modified for FC struts, the through-hole would need to be .050" larger in diameter. Ever try to machine a bearing that can spin?
Other than that, everything all bolts up. Now I can use anything that an FC can use suspension-wise, except of course for the strut tops. I was feeling too lazy to cut the strut towers from the parts car and weld them on the FB. (Plus then I couldn't use my strut tower brace)
Oh, and I have no idea how I will mount the engine. I do have an FC engine in the car, but I can't use the passenger side mount because that area of the center housing is broken off and siliconed in place to keep it from leaking oil. Mazda went to the center mounts, because there's no good way to have a front-steer rack and a front engine mount.
Two inch-tall boxes need to be fabricated for the rear subframe mounts. I chose to oval the forward subframe mounts inward (and trim the sides a little) and use the stock forward subframe studs, which makes the front wheels sit an inch or so further forward than normal. If I didn't want that, I could have just redrilled the subframe. I have to cut the fenders, but the fenders needed cutting for other reasons, so I don't mind.
FC steering column needs to be used, the FB power steering column is the right spline but is not long enough.
I used Escort ZX2 strut mounts (strut hole needs to be filed a little, chassis needs to be drilled for the 10mm studs vs. stock 8mm) and I'm going to modify the FC spring hats for use with 2 1/2" coilovers. KYB AGXs are still on backorder. FB strut mounts cannot be easily modified for FC struts, the through-hole would need to be .050" larger in diameter. Ever try to machine a bearing that can spin?
Other than that, everything all bolts up. Now I can use anything that an FC can use suspension-wise, except of course for the strut tops. I was feeling too lazy to cut the strut towers from the parts car and weld them on the FB. (Plus then I couldn't use my strut tower brace)
Oh, and I have no idea how I will mount the engine. I do have an FC engine in the car, but I can't use the passenger side mount because that area of the center housing is broken off and siliconed in place to keep it from leaking oil. Mazda went to the center mounts, because there's no good way to have a front-steer rack and a front engine mount.
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02-18-10, 02:08 PM
#8
Old [Sch|F]ool
Thread Starter
Okay never mind.
The FC column, like the FC struts, are just a tiny bit larger everywhere.
I basically destroyed the column trying to get it small enough for the FB multifunction switch to go on. This, after modifying the snot out of the column bracket just so the column would bolt in to the FB dashboard. And grinding out my FB ignition lock unit. The FC column outside diameter is about .050-.070 larger in diameter so nothing fits.
Back to Plan C - FB power column and extended FC steering shaft. That gives me the heebie-jeebies but not as bad as the hacked up FC column.
The FC column, like the FC struts, are just a tiny bit larger everywhere.
I basically destroyed the column trying to get it small enough for the FB multifunction switch to go on. This, after modifying the snot out of the column bracket just so the column would bolt in to the FB dashboard. And grinding out my FB ignition lock unit. The FC column outside diameter is about .050-.070 larger in diameter so nothing fits.
Back to Plan C - FB power column and extended FC steering shaft. That gives me the heebie-jeebies but not as bad as the hacked up FC column.
02-18-10, 03:21 PM
#10
Old [Sch|F]ool
Thread Starter
I am nowhere near the first person to do this. From what I am told, a significant portion of the RX-7s stage rallying in the US (possibly elsewhere?) have FC front suspension.
Andrew Havas's awesome orange RX-7 uses FC struts but still has FB steering.
My main reason for doing it is my steering box is trashed beyond belief (it's not the play, it's the horrible clunking noises it makes) and the rest of the front end is in disrepair to one degree or another and I need to find another set of spindles because I bent another snout and I'm just fed up with it all.
When I'm done, it will be an FC that has headroom and good styling like an FB and a real rearend instead of an Inferior Rear Suspension.
Andrew Havas's awesome orange RX-7 uses FC struts but still has FB steering.
My main reason for doing it is my steering box is trashed beyond belief (it's not the play, it's the horrible clunking noises it makes) and the rest of the front end is in disrepair to one degree or another and I need to find another set of spindles because I bent another snout and I'm just fed up with it all.
When I'm done, it will be an FC that has headroom and good styling like an FB and a real rearend instead of an Inferior Rear Suspension.
02-19-10, 09:51 PM
#12
Old [Sch|F]ool
Thread Starter
Extending the FC steering shaft to use with the FB power column turned out to be silly easy. I used a piece of rear suspension link for the tubing.
I also had to fab a small end support for the column, since it's no longer being held up by the box at the firewall end.
All assembled, and it is STRANGE to have zero play anywhere in the steering. After playing with 1st-gens for twelve years, this just feels wrong somehow
I also had to fab a small end support for the column, since it's no longer being held up by the box at the firewall end.
All assembled, and it is STRANGE to have zero play anywhere in the steering. After playing with 1st-gens for twelve years, this just feels wrong somehow
02-23-10, 08:17 PM
#15
Old [Sch|F]ool
Thread Starter
No idea. I got mine with a seriously used-up car around it. (Blown engine, shredded transmission, cracked glass, every body panel dinged/dented... a real winner )
The way I mounted the subframe is going to require massive clearancing of the inner fender in order to prevent the tires (185/65-15) from hitting at full bump if the steering is at all turned. Long story short, I have to lose my headlight motors, since that whole area has to go.
If I'd mounted the subframe in stock FB location, then I'd only have to clearance a little bit. An inch forward, and a lot more things get in the way.
That's fine with me. I like having pop-ups, but I like saving weight even more. For now, I will just remove the motors and linkage and make two simple strut rods to hold the buckets up. Later, I'd like to do a smooth light setup, but time is critical right now.
I still don't have the engine held in yet, either. I found a way to do it, but to do it "right" I will need to reinforce the body rails. So, the current order of operation is: clearance inner fenders, reinstall the fenders and cut them for tire clearance, remove subframe, reinforce body rails, make engine mounts, install KYB struts (which are here... finally!), loop the power rack's lines together, reinforce the rear subframe boxes I made (paranoid worry), bolt it all back together, and start worrying about the rear suspension.
And then start tuning the engine.
This would have been a LOT easier if I mounted the subframe in the stock location and used an FC engine mount setup. Most of my problems are due to the subframe shift and my insisting on using the front cover to mount the engine.
)The way I mounted the subframe is going to require massive clearancing of the inner fender in order to prevent the tires (185/65-15) from hitting at full bump if the steering is at all turned. Long story short, I have to lose my headlight motors, since that whole area has to go.
If I'd mounted the subframe in stock FB location, then I'd only have to clearance a little bit. An inch forward, and a lot more things get in the way.
That's fine with me. I like having pop-ups, but I like saving weight even more. For now, I will just remove the motors and linkage and make two simple strut rods to hold the buckets up. Later, I'd like to do a smooth light setup, but time is critical right now.
I still don't have the engine held in yet, either. I found a way to do it, but to do it "right" I will need to reinforce the body rails. So, the current order of operation is: clearance inner fenders, reinstall the fenders and cut them for tire clearance, remove subframe, reinforce body rails, make engine mounts, install KYB struts (which are here... finally!), loop the power rack's lines together, reinforce the rear subframe boxes I made (paranoid worry), bolt it all back together, and start worrying about the rear suspension.
And then start tuning the engine.
This would have been a LOT easier if I mounted the subframe in the stock location and used an FC engine mount setup. Most of my problems are due to the subframe shift and my insisting on using the front cover to mount the engine.
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