Lighter = Faster (RX-7 Build #2)

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'86 RX-7 Base, '79 RX-7 GS
For information regarding my previous build see here.

Picture log from previous build here.

Picture log for this build forward here.

Picked up a pretty clean '86 Base model RX-7 yesterday. Quick photo while stopped to refuel:



Moved into storage for the time being:







This build will pick up where the first left off. I'll be swapping all the parts from the red car to the silver car and going from there. Because I prefer the look of the S5 cars I'll be swapping as many cosmetic parts as possible as well. Why go with the S4? Why a base model? No power windows, no power locks, no power mirrors, no rear wiper, no sunroof, no security system, no automatic seatbelts, and a fully loaded curb weight of slightly over 2600 lb. Compare that to the 2800+ lb curb weight, fully loaded '89 GXL.
 
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THE Phen

Phenda Bear
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2013 Abarth, 2004 MSM - FM, '74 BMW Bavaria, 97 Civic EX B18C1
I can totally understand your reasoning. Looking forward to following this!
 

o0n8

Still have noob questions
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74 Schwinn Varsity, 75 Camaro (Project), 04 6 Wagon
Looks good! Let me know if you need to borrow the fender roller again.
 
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'86 RX-7 Base, '79 RX-7 GS
No pictures as there's nothing to show. The subframes on the silver car are rusty so I'm swapping those from the red car. I got the rear subframe and suspension removed from the red car and everything is loose on the silver car. I broke one bolt on the silver car: one that holes the rear swaybar bracket to chassis. When the silver car is in my garage I'll drill and tap it. I've removed the braided fuel lines from the red car because it's easier to install them with the rear subframe out.
 
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'86 RX-7 Base, '79 RX-7 GS
I decided to clean up the subframe and differential from the red car a little.





Compare that to the subframe and rear differential out of the silver car:



I also got all the fuel lines out of the silver car. I did find a few other issues on the silver car I need to address before the swap can be completed. The vapor line from the fuel tank to the charcoal cannister was rotted through in a few places so I'll swap that over as well. The parking brake is also in pretty bad shape so I may swap that too.
 
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'86 RX-7 Base, '79 RX-7 GS
Since I can't work on the silver car I got bored last night and started tearing apart the red car. Got through a good amount of the rear of the car.



Started a pile of parts I know I will swap over:



Need to take out the steering wheel, seat, and roll bar before I can make much more progress.

On a side note does anyone know where to get those plastic, threaded plugs that come with new master cylinders. I need to cap mine off to remove the brake lines and I can only find 1/3 of my plugs. M10x1.0 thread, inverted flare, I believe.
 

o0n8

Still have noob questions
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74 Schwinn Varsity, 75 Camaro (Project), 04 6 Wagon
so what's the plans with the red shell? scrap it?
 
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'86 RX-7 Base, '79 RX-7 GS
so what's the plans with the red shell? scrap it?
It'll probably be scrapped but I need to figure out how to go about doing that. Do I put the '86 subframes on the '89 and tow it to a scrap yard or leave it bare and cut it to pieces? Anyone want to lend a hand?

Speaking of the red car I did more teardown last night. The rear end is completely bare: no suspension, no brakes, and no drivetrain:



It's been slower going on the inside but I did have to remove the seat and center console to get to the parking brake handle.

 
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1979 Mazda RX-7 base modified for solo/trackdays
if you don't have a truck, cut up the car with torches or a sawzall. then go rent a Uhaul truck or the Home depot truck and take it to the scrap yard.
 
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'86 RX-7 Base, '79 RX-7 GS
if you don't have a truck, cut up the car with torches or a sawzall. then go rent a Uhaul truck or the Home depot truck and take it to the scrap yard.
This is most likely what is going to happen. I'm still going to put the whole thing on CL to see if someone will take it away.

Took a half day on Friday to get some work in knowing I wouldn't be able to over the weekend. Started by pulling all the brake stuff off including the parking brake handle:



For giggles here's a comparison between the S4 (top) and S5 (bottom) handles.



The differences are only cosmetic and I like the S5 handle better so that's what went into the car:



And with that the brakes and rear suspension from the red car are now in the silver car:



I would have made more progress but I forgot my bag of M6x1.0 nuts and torque wrenches at home so I had to call it a day around 5 PM. I just have to route in the new fuel lines and it'll be ready for the donor subframe and differential.
 
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'86 RX-7 Base, '79 RX-7 GS
More carnage on the red car. The rear hatch area is completely gutted and has now become the storage area for parts I'm not going to resuse:



Started to attack the front of the interior:



Removed rear defroster, power door lock relay, rear hatch lighting, driver's side auto seatbelt, power mirror, rear anti-theft, and rear speaker wiring:



...and the pile of parts to reuse slowly grows larger:



I also found a solution for my new speedometer setup:



A company called Speedometer Solutions out of WI makes this little mechanical-digital signal converter. It threads right onto the stock mechanical speedometer takeoff point on the transmission and generates a digital square wave signal with 16 pulses per revolution. Perfect!
 
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'86 RX-7 Base, '79 RX-7 GS
Slow progress on the silver car. Got the rear suspension and drivetrain fully bolted in.





Somewhere in the process I misplaced the stub shaft nuts so the axles aren't completely bolted in. I'll get some new M8x1.25 nuts and finish that next weekend. Before the subframe went in I ran the new SS fuel lines. Under the car:



I think my phone's camera is dying. In the engine bay:



Last night I realized the fuel lines are reversed. The feed should be on the inside and the return on the outside. Shouldn't be too hard to correct.
 

Lewis7789

Evan aka "Lady Hands"
Contributor
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1995 MX-5, 2006 MZ5, 2001 Yamaha R1
Sub again. The red color was faster but I'm sure the silver will clean up nicely. Not that you were really too interested in looks anyway. ;)

Why not just keep the manual rack? Wouldn't the ratio be better than the de-powered rack? (I'm the lab coat dog meme right now, just curious is all)
 
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'86 RX-7 Base, '79 RX-7 GS
Sub again. The red color was faster but I'm sure the silver will clean up nicely. Not that you were really too interested in looks anyway. ;)

Why not just keep the manual rack? Wouldn't the ratio be better than the de-powered rack? (I'm the lab coat dog meme right now, just curious is all)
The manual rack is "slower" than the power rack. IIRC, the manual rack ratio is 20:1 (i.e. 20 degrees on steering wheel = 1 degree at the tires) and the power rack is 17:1 (vehicle speed sensing PS) or 15:1 (engine speed sensing PS). So the only advantage using a depowered rack is less steering input for a given turn radius. I imagine this is useful for autox and tight road coarses. That and my depowered rack is nice and shiny now that it's been repainted. Not that I can't do that with the manual one as well though. I'll probably clean up the manual one, test each out for feel, and go with the one I like best.
 
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