Now that progress has finally started on my FC RX-7/LS1 project car, I need some advice. I imagine there will be many more posts along this line. 
As background, the car is meant to be a track car for HPDE/TT/auto-x use, with very occasional street use for fun. The interior is stripped, it will have race seats, harnesses, roll bar, etc. Estimated RWHP is 380-390 with a curb weight of ~2500 lbs. It is a 5 lug car.
What I need help on at this point is suspension and brakes. We tore down the front of the car this week and removed the rotors, calipers, brake lines, hubs, control arms, tie rods, sway bars and springs/shocks.
I have coilovers to install but have other questions.
- Can the ball joints in the control arms be replaced? Or do I have to buy new control arms?
- Will stock, remanufactured calipers be sufficient?
- What type of bushings should I go with (I plan to eliminate the DTSS in the rear)?
- Sway bar recommendations?
Any other thoughts would be appreciated!
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According to Mazdatrix's website, 86-88 (also called S4) ball joints can be replaced. On 89-91 (S5), you must replace the entire control arm.
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If they are the single-piston front calipers/solid rear rotors, no. If they are the 4-piston front calipers/vented rear rotors, then yes as long as you upgrade the pads and rotors. The 4-piston setup was so good, Mazda retained it for the 93-95 models and some FD owners have kept that setup while making stupid amounts of power. You can find the 4-piston calipers on GXL and turbo models. They'll swap onto the stock knuckles with no problems. Also replace the stock lines with stainless-steel braided lines. I have Corksport lines on my FC, but Mazdatrix and Racing Beat have them too.
If there is one thing my FC can do very well, it's stop. My setup is Hawk HPS pads, Brembo OEM rotors, ATE Blue fluid, and the aforementioned Corksport lines. Very firm pedal and very little fade. The pads and rotors may not be aggressive enough for the power your planning, though.
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Mazdatrix, Mazdaspeed Motorsports, Racing Beat, and Corksport all sell DTSS eliminators. Mazdatrix has an FAQ on their website on how to install them.
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I have the Racing Beat front bar on mine. They make very high-quality stuff. Suspension Techniques also makes FC sway bars, and the front for the S4 is actually adjustible, but I have heard of some owners having to modify the brackets to make them fit. You should replace the end links with adjustable units while you're at it; RB and Mazdatrix make those.
Finally, here are the URLs for the sites I mentioned:
http://www.mazdatrix.com
http://www.corksport.com
http://www.racingbeat.com
Have you spent any time over at www.v8rx7forum.com?
I used to spend a good bit of time over there when I had my 5.0L FB. Good group of guys.
Something else I forgot to mention: Get Koni shocks and better springs. The stock shocks are a weak point on the FC's handling. IIRC, yours are busted anyways, so might as well upgrade those while you're at it. I haven't heard many good things about Tokico's offerings for the FC. I've heard nothing about KYBs or the JDM stuff (Tein, etc.) for track/auto-x use. Mazdaspeed Motorsports has coilovers, but they are basically Koni shocks/GC springs. Save the fronts; the Konis are cartridges up front and you'll need to gut some parts from the old front shocks to install them.
Mazdatrix has a chart with spring rates for the stock springs as well as some of the better aftermarket offerings, like Racing Beat and Eibach. Ground Control can make springs with spring rates to your specifications. Check out the site JWD mentioned as well as the V-8 conversion forums on RX7club.com and RotaryCarClub.com, they'll give you some more specific feedback on what type of spring rates you should use on an LS1-powered FC.
I have some used Konis on the way. I can let you know what I think of them once I have them mounted up.
RexSeven wrote:
1. According to Mazdatrix's website, 86-88 (also called S4) ball joints can be replaced. On 89-91 (S5), you must replace the entire control arm.
2. If they are the single-piston front calipers/solid rear rotors, no. If they are the 4-piston front calipers/vented rear rotors, then yes as long as you upgrade the pads and rotors. The 4-piston setup was so good, Mazda retained it for the 93-95 models and some FD owners have kept that setup while making stupid amounts of power. You can find the 4-piston calipers on GXL and turbo models. They'll swap onto the stock knuckles with no problems. Also replace the stock lines with stainless-steel braided lines. I have Corksport lines on my FC, but Mazdatrix and Racing Beat have them too.
If there is one thing my FC can do very well, it's stop. My setup is Hawk HPS pads, Brembo OEM rotors, ATE Blue fluid, and the aforementioned Corksport lines. Very firm pedal and very little fade. The pads and rotors may not be aggressive enough for the power your planning, though.
3. Mazdatrix, Mazdaspeed Motorsports, Racing Beat, and Corksport all sell DTSS eliminators. Mazdatrix has an FAQ on their website on how to install them.
4. I have the Racing Beat front bar on mine. They make very high-quality stuff. Suspension Techniques also makes FC sway bars, and the front for the S4 is actually adjustible, but I have heard of some owners having to modify the brackets to make them fit. You should replace the end links with adjustable units while you're at it; RB and Mazdatrix make those.
Finally, here are the URLs for the sites I mentioned:
http://www.mazdatrix.com
http://www.corksport.com
http://www.racingbeat.com
Excellent information. Thank you. I'm not home this week, and can't verify, but I think the chassis is an '86. I recall seeing single piston calipers (
) when we took them off, but don't recall the front bar being adjustable. I'm definitely planning on going with stainless steel brake lines too.
RexSeven wrote:
Something else I forgot to mention: Get Koni shocks and better springs. The stock shocks are a weak point on the FC's handling. IIRC, yours are busted anyways, so might as well upgrade those while you're at it. I haven't heard many good things about Tokico's offerings for the FC. I've heard nothing about KYBs or the JDM stuff (Tein, etc.) for track/auto-x use. Mazdaspeed Motorsports has coilovers, but they are basically Koni shocks/GC springs. Save the fronts; the Konis are cartridges up front and you'll need to gut some parts from the old front shocks to install them.
Mazdatrix has a chart with spring rates for the stock springs as well as some of the better aftermarket offerings, like Racing Beat and Eibach. Ground Control can make springs with spring rates to your specifications. Check out the site JWD mentioned as well as the V-8 conversion forums on RX7club.com and RotaryCarClub.com, they'll give you some more specific feedback on what type of spring rates you should use on an LS1-powered FC.
I have some used Konis on the way. I can let you know what I think of them once I have them mounted up.
I'm set on this front, as I have these waiting to go on.
dyintorace wrote:
Excellent information. Thank you. I'm not home this week, and can't verify, but I think the chassis is an '86. I recall seeing single piston calipers () when we took them off, but don't recall the front bar being adjustable. I'm definitely planning on going with stainless steel brake lines too.
The stock front bar isn't adjustable, but the Suspension Techniques S4 front bar is.
Since your car is already a 5-lug model, swapping the 4-piston brake setup is easy since you don't need to swap the hubs. You'll need the front and rear calipers, pads, rotors, mounting hardware, and SSBLs specifically made for the 4-piston setup. On 4-piston setups, the rear brake rotor is the same diameter as the single-piston setup, but the rotor is vented. The rear caliper is a single-piston sliding caliper on both types, but the one for the vented rotor is set wider apart.
D'oh, I forgot about the Bilsteins! Always a good choice. I was thinking of adjustables only, since that is what I'm going with.
An S4 with 5-lugs SHOULD have the 4-pot brakes. The S5s could come with either.
Actually, yeah, I'm willing to bet you've got the 4-pots.
I think your questions have all been covered, but something else to think about is that if you don't have the vented rear brakes there's not a huge reason to swap them to the vented version. The pads are identical between the vented and non-vented (only the part of the caliper that goes over the rotor is different). The biggest pain is that the rear calipers are not cheap...I swapped mine but later regretted the extra clams that it took to do so.
Some will say that you need to go to the larger 15/16" MC, but I never had any complaints about the 7/8" MC on my '89 with swapped-in four pots. As with RexSeven, the pedal feel and modulation on my '89 FC was the best of any car I've ever had.
jwdmotorsports wrote:
Have you spent any time over at www.v8rx7forum.com?
I used to spend a good bit of time over there when I had my 5.0L FB. Good group of guys.
Sorry...forgot to answer this. Yes I have. I've been lurking for some time, but am more comfortable with you guys!
I did make an intro post there recently and will start asking more questions.
Osterkraut wrote:
An S4 with 5-lugs SHOULD have the 4-pot brakes. The S5s could come with either.
Actually, yeah, I'm willing to bet you've got the 4-pots.
I'll check. It would be nice if they are!
RexSeven wrote:
The stock front bar isn't adjustable, but the Suspension Techniques S4 front bar is.
Ahh...that makes more sense. Thanks!
I'm resurrecting this topic as I was just stupid enough to bid on an LS1/T56 combo on Ebay whilst flying to LA last week (damn in-flight wifi). Soooo I will have a new project soon wedging the combo into my '88 vert which has been sitting with a blown housing seal for about a year or more (who counts this E36 M3, other than my wife).
Today's question:
Seller will reprogram the PCM for me to delete trouble codes not wanted. Has anyone done this swap before and has familiarity with this? I'd actually like to talk with someone briefly to help me decide my direction on this so I can get this info to the seller so he can get this done and ship the drivetrain.
If you think you can help can you drop me a PM? Thanks!
Damn. I hardly remember even writing these posts! Too many projects coming and going I guess. 
You should hook up with Greg Voth. He's swapping an LS1/T56 into an FB. Not exactly the same, but he's a damn smart cat when it comes to this stuff.
BTW, I'm eying that FC/5.0 combo again. It's calling me.
I may not be the go to person but I can usually find someone that is. I recently met a local guy who has a 5.3 / T-5 combo in his FC. He tuned it himself using HP Tuners and I believe it costs $100 for each additional vehicle.
Shoot me an email with the specific trouble codes he is talking about deleting and I can run it by him.
Tucker, You dont still have those coilovers, do you? Im trying to convince some people we need that 5.0 FC in our lives as well.
Greg Voth wrote:
Tucker, You dont still have those coilovers, do you? Im trying to convince some people we need that 5.0 FC in our lives as well.
I wish. I sold them once I sold that car. Should have kept them, given how rare coilovers are for the FC.
dyintorace wrote:
Greg Voth wrote:
Tucker, You dont still have those coilovers, do you? Im trying to convince some people we need that 5.0 FC in our lives as well.
I wish. I sold them once I sold that car. Should have kept them, given how rare coilovers are for the FC.
I have a set but they're going on mine.
Greg Voth wrote:
I may not be the go to person but I can usually find someone that is. I recently met a local guy who has a 5.3 / T-5 combo in his FC. He tuned it himself using HP Tuners and I believe it costs $100 for each additional vehicle.
Shoot me an email with the specific trouble codes he is talking about deleting and I can run it by him.
Tucker, You dont still have those coilovers, do you? Im trying to convince some people we need that 5.0 FC in our lives as well.
Email sent with form attached. Let me know if you don't get it.
And the goodness has arrived....
Out of curiosity, Hobie, what did you give for that LS/T56 setup? This thread is suddenly relevant to my interests given the RX7 I'm about to buy.
Glad to see this project moving forward hobie. You are on your way to a supercar killer. The FC is a phenomenal chassis for an LSx swap.
I am a rotary fanboi. I have had 7 or so rotary engined cars. I have owned 1 V8 powered car.
I WANT LS RX!!!!!! It could be called the LX17
Carry on.
In reply to wvumtnbkr:
I'm saving a LSx swap for an s13 (I used to own one with the 2.4L)
I have a friend who has a 3 rotor FC and a LS1 w/ 100 shot FC, except the v8 one is in bad shape because he rolled it...
