So I took the FD to a local rotary shop to get formal compression test numbers with a Mazda tool to compare to my DIY tester numbers.
rotor 1: 6.7/6.7/6.9 at 264 RPM
rotor 2: 6.1/6.3/6.4 at 265 RPM
So it looks like my #2 rotor is only marginally in spec -- I guess that's sort of expected for the 58K miles that are on the car.
I need to sit down and crunch some numbers to work out conversion factors for my DIY tester to the factory one.
Lately the FD has been behaving a bit like an old british car, the feeper that warns you about door open is really quiet -- until you turn the headlights on, then it gets back to normal volume. The seat belt warning light is on when the headlights are on, off when the headlights are off, and the redline buzzer has stopped working.
Did some googling, sounds like there's a common problem on "CPU #2", which is apparently a box full of analog components that drives all of this stuff (no actual micro controller in it). Sounds like the capacitors like to dry out and then the board does all kinds of wonky things, so I guess it's time to go at it with a soldering iron.
Hm, haven't posted much here lately, mostly because I haven't done all that much with the FD worth posting out. I did take it autocrossing today for the first time, though.
I used to autocross my Miata regularly (for about 5 years), but when the club that I ran with disappeared I stopped going and started doing more track days with the Miata instead. A few weeks ago the Miata broke the power steering at the track, I replaced the pressure hose, but decided it would be smart to give it a test run before the next day at Laguna Seca in a few weeks. Since it's not currently registered, doing that shakedown on the street wasn't really feasily and there was an autox this weekend, so I decided to use that.
Then, yesterday, I took a hard look at the pressure line that I'd taken off the car, and found the leak. So with that confirmed I decided to be lazy and not mess with the trailer. Since I'd already registered & paid for the autox, I took the FD instead!
I ran it in ASP because the wheels are too wide for AS. Other than that it's street-class legal, stock suspension, muffler, RE-71Rs. So it's wildly uncompetitive, but hey, this was round 9 and I didn't go to 1-8, so clearly I don't care about points, right?
So how did I do with it? Not as well as I would have liked (isn't that always the case?). Most of the cars in that run group were very different prep levels (like that orange Fiesta with a V8 in the second shot). There were some B Street Focus RSes, I was about 1-1.5 seconds off their times. I've got a big list of excuses though :) First time autoxing this car, it's been 4-5 years so I'm rusty, and the front upper control arm bushings need to be replaced. The course also wasn't playing to the FD's power band, I spent a lot of time below the boost threshold in 2nd, but really too fast to be downshifting into 1st.
I've got the replacement bushings waiting to go in, but I've also got some coilovers on order and so I'm waiting until those show up to take everything apart. That way I only have to align it again once.
Is that Fiesta wearing tires or new asphalt rollers?
That Cayman behind you looks familiar. Where you the one to convince him to start posting? 
Matt B wrote: That Cayman behind you looks familiar. Where you the one to convince him to start posting?
Does Grant have a build thread on here?
I mounted the GoPro on a suction cup below the rear hatch, but forgot to bring the external mic with me (it's mounted in the Miata) and the audio is terrible. Lots of boomy bass in it.
He should fit in great around here, but I think we have different ideas about what a budget build is.
Picked up some new toys for the FD today...
Ooooooo - nice!
Once their installed someone should take a picture of your expression mid-corner. It would be your Ohlins-face. 
Sorry, I'll leave now.
Matt B wrote: Sorry, I'll leave now.
:-)
I was hoping to install these this weekend, but it's supposed to be 110 here tomorrow so I don't know if that will happen. I did have to open the box to fondle them though. Ohlins packages these much more carefully than any shock I've ever bought before!
Holy shiny awesomeness Batman. 
Yikes. So that is what a gajillion bucks worth of suspension looks like. Excited to hear how it feels when you get it setup.
Saturday and Sunday were miserable, 110+ outside. The new garage has some decent insulation but it isn't actually air conditioned so it was still 90+ in there. Monday was much more reasonable as far as temperature goes, only high 80s outside and 80-ish in the garage, so with help from a friend the Ohlins went in.
We started with the front, I forgot to take a "before" picture, but ah well. This is the front passenger side, and the basic shock replacement procedure is similar to a Miata although actually somewhat less of a pain. There's a TSB out for failing upper control arm bushings that mine is exhibiting, where you get a fairly loud clunk when transitioning from acceleration to braking or forward to reverse. So normally you just need to remove the two inner bolts for the upper control arm, but for the passenger side I pulled the ball joint out as well. Unlike the Miata's castle nut, the FD has a pinch bolt in the aluminum upright. After taking that out, a few taps on the bottom of the ball joint stud got it out much more easily than the Miata's.
After loosening the sway bar, the shock assembly basically falls out. One OEM FD front shock, 60K miles and 25 years old. Vintage!
The only part that Ohlins doesn't supply is the thin plastic upper gasket thingey. I've been transferring these things between upper perches on the Miata for years -- anyone know what they actually do?
Upper control arm with failed bushings. The ball joint appears fine, which is good. As with the Miata they aren't replaceable, and new FD control arms are a lot more expensive than Miata ones.
Bushings is visibly mangled:
To make it easier to press them out, I cut all the flanges off the bushings. The old ones were pretty hard and dried out, not surprising for 25 years old. In retrospect, I probably should have bought bushings for both sides, but I didn't. List price on them is something like $80 each!
Discarded bushing flanges:
Pressing them out. This actually started ripping the sleeve out of the rubber, so I stuck a washer on top after I took the photo. The HF shop press handles this easily.
Dead bushings:
Control arm minus bushings:
New bushings!
New bushings installed. They press in easily.
(continued in next post).
Off to assemble the Ohlins. Each shock has a bumpstop, upper washer, boot, spacer, spring, upper perch, insert spacer, locknut, and adjuster. They come with the bumpstops, upper washers, and adjusters installed, the rest of the parts are separate in the box. The spacers come in 2 bags, each with 2 straight and 2 insert spacers, but it's critical to note that one bag is for the front shocks and the other is for the rears, and they are NOT THE SAME. Nor are they marked. So it's very easy to put it together with the rear spacers on the front shocks -- guess how I know?
Shock, spring, bumpstop, washer, and (wrong size) spacer:
Fronts assembled:
Installed on the car. Getting the upper A-arm bolts to align was moderately a pain. I still need to go back and retorque them with the weight on the wheels.
Assembled, the fronts wound up with very little droop travel, the adjuster sticking way up into the engine bay, and the front being VERY low. The instructions say to set it up with 2mm of preload on the spring and 10 clicks back from full stiff on the damper (adjustment is for both rebound and compression, although it changes rebound somewhat more). That's supposed to give about a 3/4" to 1" drop from stock -- this was WAY lower than that. The rears are still stock in this photo, which is why it looks jacked up like a drag racer, but the front is much too low. We hadn't figured out why yet.
So on to the rears. The FD's rear suspension is pretty different than the Miata's. No lower A-arm, so the shocks mount to the upper arm instead. This makes them pretty short. This time I got a "before" shot:
Basic idea is to pull the single bolt holding the lower mount and the 3 bolts up top (along with the rear shock tower brace) and it falls out. For some reason my passenger side one didn't want to come out, so we pulled the bolt attaching the upper arm to the upright as well, and then it was easy.
When it came time to assemble the rear Ohlins, we figured out what was wrong because the longer spacers meant that there weren't enough threads to get the adjuster on. So we had to go back and take the fronts apart, although not all the way. Rather than pulling them all the way out, we set the dampers to full stiff, removed the top nut while it was still in the car, and then one person pried the shaft down while the other swapped the spacers. Not something you could easily do without a friend, though. With those swapped, all the problems I mentioned above went away.
Car is back on its wheels, no more drag racer look!
By this point it was 9PM, so we took it to grab some dinner.
So how does it drive? Well, I didn't take it around real corners because it needs an alignment -- lowering it added about half a degree of negative camber at both ends, and the rear is now toed in. I'm very pleased with the ride though, I was initially concerned that the supplied spring rates would be too high (they're about 3-4x stock rates), but it's actually really reasonable. You can definitely tell that it's got higher rates, but it's not painful at all. Body roll, dive and squat are obviously much reduced, and it feels much more alive. I like it a lot.
Unfortunately the guy I usually take it to for alignments is in Nebraska for Nationals right now, so it may take a couple weeks til I can take it up to the mountains.
(BTW, springs are also different front-to-rear, but they're marked and the instructions say which is which. Long ones go in the front, FWIW.)
Also, I'm not completely sure what those holes in the rear perches are for. They're labelled left and right, and there's a small bump in the unibody that seems to roughly fit, so we lined it up with that.
Did you get the alignment yet?? I thought you weren't going to mod much. Pleased to see the DFVs going on.
Great to see this project. One of these is on my bucket list but as more of a track car. Currently have the S13 and pondering a GT-R, S30, NSX someday too.
Well, I'm mentally classifying the stuff that's on the car at the moment as being replacing parts that were broken/worn out, just using parts that are moderately improved over the base versions, rather than being outright "mods". Yeah, it's a slippery slope, but that's how I justify it to myself. :)
Wheels -- tires were dead, there are no decent 16" tires that fit, and stock wheels are known to crack.
Radiator -- stock rad was leaking.
Muffler -- stock one had rusted through.
Suspension -- stock shocks were worn out.
So before I did the suspension, the car was clunking when changing directions between forward and reverse and other parking lot maneuvers. I traced this to the front upper control arm bushings sliding forwards and backwards, which turns out to have a TSB out from Mazda on it. At the time, only the passenger side was doing it, and since MSRP on these bushings is like $100 each, I decided just to do those two. All was quiet for a week or two, then it started doing it again on the driver's side. Doh! So I ordered another pair and swapped those over the weekend. No photos of that, it looks just the same as the passenger side.
Anyway, yes, today I took it for the alignment! I had checked it in my garage with hand tools and confirmed that it was close enough to not be dangerous (or eat tires), so it wasn't *super* urgent. I also had to go to Boston for a wedding, and then get my schedule to match with that of my friend with access to the alignment rig, but it's done!
It comes in at 2869 pounds, empty, with a full tank of gas. For an FD that's fairly heavy -- mine is a touring package so it's got the leather seats, Bose subwoofer, sunroof, etc. I haven't done much in the way of weight-reduction to it either, the Ohlins are somewhat lighter than stock, as is the Racing Beat muffler, but the 6ULs are slightly heavier than the stock wheels (which are shockingly light at 13 pounds, and which explains why they tend to crack), and the oversize Koyo radiator adds more coolant, which adds weight too.
F/R balance is almost perfect, it's a bit left-heavy and gets more so with a driver in it. Apparently, though, if you have a single person on the other side, it becomes almost perfect left/right -- almost as if it was designed to be RHD... :)
I went to the dyno today, primarily to check on the effects of the new valve springs in the Miata, but I talked a friend into driving the FD over as well so that I could baseline it at the same time.
I ran the FD first, because it just needed a couple of runs. Since it's stock aside from the muffler, I'm just looking to make sure it's working properly.
It did 230 whp, 200 torque, which is about what I was hoping for. Looks like the marginal compression on rotor #2 isn't hurting power all that much. Just a quick cell phone shot of the plot, because they updated the dyno software and I haven't got the new run viewer installed yet.
Pretty strong considering those were rated at 255 crank hp brand new...
Yeah, especially considering the reputation these things have I'd say it's doing great!
<insert tired apex seal meme here>
I've always loved the looks of this final generation RX-7, and your's is a really nice one. Very well maintained. Enjoy!
As long as it starts without an issue when hot and makes power, I wouldn't worry about the actual compression numbers.
Yeah, 230 at the wheels vs a nominal 255 at the crank is higher than I'd expect for a RWD car. The muffler is helping some there, the stock one is quite restrictive and rotaries really don't like that.
Mine starts when hot, but if it's heat soaked (say it's driven for 20 minutes, then parked for 10 and restarted) it has some issues with idling until it circulates enough coolant around.
Gratuitous dyno video. :)
I dropped 20kg moving from the stock B4's to Ohlins R/T, which I wasn't expecting but was a pleasant surprise
In reply to codrus :
For better or worse seeing that video and there not being big fire or sound (like so
)is a pleasant change, but also kinda sad too, looking great though.
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