1987 RX7 LS1 Swap

Time for another update.

By pure luck, I managed to snag a piece of 1x2 rectangular tubing in the perfect length for my seat mount that one of our maintenance guys at work was scrapping the day after my last post for $free.50. That then became the outboard drivers side seat mount:

Driver's seat is now mounted.

Moving on to the passenger side, there's a big hump in the floor pan protruding out from the trans tunnel that was obviously going to need some surgery. I presume this space at one time housed the catalytic converter or something, which is funny because the donor Camaro has a similar feature, but there's nothing in the way there now. So I broke out the angle grinder again and made some cardboard templates to fill the space.

Cut some more .120 sheet and welded it in place (sorry for the crappy pic, this side of the garage has bad lighting at night.)

On the outside, I just welded a piece of 1/8" flat stock between the stock mounts, drilled some holes, and welded nuts on the backside. I had to cut a relief in the rear hump for one of the nuts.

Overall I didn't put as much effort into getting the passenger side as low as possible, so it sits a bit higher than the drivers side. I'm still comfortable without a helmet, but with it's just a bit snug. The driver's side is a much better seating position for me with a helmet on than before. Better support from the seat and better leverage on the steering wheel should make it a lot easier to drive.

I had really hoped my roll bar would be ready for pickup last week so I could get going on it this weekend, but no such luck. So yesterday I looked at mounting the factory oil cooler instead.

I had decided to attach my lower radiator mounts where the factory mounts for the oil cooler would go, so I had to engineer some new ones to fit the cooler to the opposite side of that same bracket. This will all make a lot more sense once I put it together 

While waiting for the paint to dry, I hacked apart my Y-pipe to weld in some flex couplings. I don't know why I never did this in the first place, but there was a slight misalignment between the v-band flanges at the headers that caused one of the clamps to come loose and mangle itself a bit. I'll wait until new v-band clamps get here before I finish welding it.

I've been feeling ambitious his week, so lots to update.

The oil cooler is on. Mounts turned out really well, it sits right where I want it and they're solid as hell. Still need to plumb it, and I might flip it over since it's upside down how I have it now, with the inlet/outlet on the drivers side. That would put the drain plug on the bottom where it should be, but also makes for somewhat longer and trickier routing for the lines.

With that settled and nothing better to do, I tore the sunroof out.

Now why would I do that? Because I am going to attempt to make a carbon fiber filler panel to replace it. I've got some other projects in mind down the line and have been looking for an excuse to try messing with composites, so I figure now is the time to deal with the sunroof, before I weld a roll bar in the way. Should save 20+ lbs way up high.

The stock sunroof panel was in pretty good shape, aside from this one gnarly little dent.

I started sanding down the panel and filled the dent with Bondo while contemplating how to construct a plug from it.

I want to construct a flange and utilize the mounts for the sunroof "chassis" for mounting. They're the two brackets shown here with four studs hanging down.

I bought a sheet of that coated particle board stuff and cut a 3'x4' section to build the plug on.

The sunroof brackets sit about 7/8"-1" below the lip of the roof, so I blocked up the edges of the sunroof panel with some scrap trim boards I had laying around to put the lip about 1"-1.125" off the particle board. The mounts actually have some vertical adjustment built in, but I still wanted the flange to err on the long side so I could shim it down if necessary.

I agonized for a few days over how best to attach the panel and fill the gaps at the front and back and eventually landed on expanding foam as my best solution. I had some reservations as to how well it would stick and whether the expanding action might actually lift the panel out of place or distort it, but it actually seems to have worked exceedingly well. Still, I'm pretty much committed to getting some level of success out of this project now, as I don't think the stock panel will be easily recoverable if I berkeley it up.

Next came several tedious hours of trimming the foam roughly to shape with a razor blade and sanding it smooth.

Then I laid down the first layer of Bondo.

After several applications and rounds of sanding, I've got a pretty good surface and draft angle starting to build. One or two more goes and I should be there, then it's sand, prime, and sand, sand, sand some more.

Meanwhile, I got the call that my roll bar was ready for pickup at S&W, so Friday I was able to take a ride out there and pick it up. Sorry for the crappy pics, but if you're following along that's par for the course 

Yesterday I worked on feet for the main hoop. .120" plate tied into the b pillar and rear wheel arch a little bit. There's a ton of structure in this area, so i think it should be pretty well supported.

And that's where I'm at. Lots more to come this week, I have a ton of E36 M3 to do and the weather is getting nice, so i'm thrashing hard to get back on the road!

Work is crazy busy right now, but I'm still finding time to work on the car. Caffeine is my friend.

Sunroof plug is now in primer. LOTS of sanding ahead before I can start to lay the mold, but hoping to get there by the weekend.

Got a box of goodies from Summit. You know you're spending too much on the race car when they start throwing in free swag . 

Roll bar is all fit-up and tacked together. Coping tubes with an angle grinder sucks, but does give good fitment. Plan is to weld what i can in the car and maybe put some tack bars on to hold everything in place, then cut the tacks on the main hoop and down tubes loose so I can weld the hard to reach parts outside the car. Also makes painting infinitely easier.

Fitment of the main hoop is awesome!

Lot's of work these last few week, I'm just behind in updates.

First, the roll bar. With everything tacked together, it was time to finish weld, and if I must admit, I was a bit nervous about this step. This is definitely the most structurally critical piece I've ever welded, and while I'm well practiced lately and reasonably confident in my skills, I do sometimes struggle a bit welding out of position, which was clearly going to comprise a lot of this project.

But, I took my time finding reasonably comfortable positions beforehand, traced my path with the torch ahead of time until I found a smooth movement and proper torch angle through the path, and got my settings dialed in on some scrap tubes. There were a couple places I ended up grinding out and rewelding, but overall I'm pretty happy with my work.

With the welding complete, it was time to prep for paint on both the roll bar and the floors. I went back and forth on the color for the floors, but figuring that the OE matched paint was too expensive and an alternate red would just clash, I went with the classic race car look of Rust-O smoke gray. I got the stuff in a can, thinned it slightly with acetone, and brushed it on. I'm really pleased with how flat it laid down, having never brushed Rustoleum before. 

On the bar, I went with Rust-O High Performance satin black, and also hit a good portion of the undercarriage with POR-15. There were just a couple of crusty spots that needed to be addressed with a wire wheel, but this should keep the tin worm at bay for a while. 

I almost hate to cover it up, but carpet is going back in. More on that later.

Meanwhile, on the sunroof front, I spent a LOT of hours wet sanding the plug up to 2500 grit, then buffed it with some polishing compound,  and hit it with 5-6 coats of mold release wax. I thought I had some pics of this stage, but they seem to have disappeared. I also screwed down some aluminum angle to create a flange on the outside of the mold for stiffness.

Then it was time to prep for the mold layup. I had planned this around an unusually warm spell, where overnight lows were expected to remain above 60, the recommended working temp for the gelcoat and fiberglass resin. The downfall of this plan was that humidity was ridiculous when I went to apply the PVA mold release compound, causing it to take WAY too long to cure and also bunch up into streaks and globs. 

It was a bit of a mess, so I peeled it off the top surface of the sunroof and reapplied. Came out somewhat better the second time around under more favorable conditions.

Next, it was time to brush the gelcoat on, which was allowed to cure overnight.

I had three yards each of 1.0 and 1.5 oz. chopped strand mat, which I laid over the cured gelcoat and cut roughly to size, yielding three layers of each. 

Now it was time for the lay up. No pics here, as it got really messy really quickly and I was working feverishly to get everything laid down flat within the working time of the Bondo resin. I'll admit, this was not the least bit fun and I wasn't super pleased with the results. The first layer went on ok and stayed pretty flat to the gelcoat, but subsequent layers kept gradually developing more and more bubbles and creases, and I struggled to keep it flat to the contours of the plug, especially the sharp corners at the outside flanges.

I let it sit for a week and cure. When it came time to pop it off the plug yesterday, I wasn't sure what to expect, but fortunately it came off pretty easily and turned out great, asside from a few spots in the corners. This was a massive relief, as this project has already far exceeded the amount of time and money I had hoped to commit.

Some lessons learned thus far for next time:

-Spraying the PVA and gelcoat would have probably yielded a better surface finish. Didn't turn out bad, but it will need a little work.

-Get a resin with a longer working time. 

-Working with smaller sections of mat rather than trying to lay one big, continuous layer, would have been way easier and probably yielded better results.

-The outside flanges should have been spaced farther out and I should have added clay or something to create a fillet in the corners.

-This is an expensive pain in the ass and if the part is commercially available you should just buy it 

Planning on the actual CF layup this week and the goal is to have the car back on the road and operational by the end of next weekend.

Nice work!

I'm really interested in trying to make some carbon stuff, so watching this is really interesting.

In reply to Run_Away :

Thanks! It's my first attempt at any sort of fiberglass or carbon fiber layup, so I'm not promising the best results, but it's been an interesting (albeit expensive and time consuming) learning process. 

So this week I got as much of the interior back together as I could before the sunroof is finished.

In spite of my best efforts to clean and die the original carpet last year, it was still looking pretty nasty, and with my spiffy new seats going in I didn't really want to put it back in the car. With all the rubber and foam backing, the factory carpet is also surprisingly heavy, so I figured this might also be an opportunity for some weight savings, as I am desperately trying to offset the weight of the roll bar and then some. I bought a roll of this stuff to replace it: https://www.yourautotrim.com/ozitemediumgray.html

I roughed out the shape laying it on top of the old carpet, then spent all of Sunday afternoon trimming and fitting it inside the car. Some strategically placed adhesive backed velcro helps hold it in place, along with the seat mounts and eye bolts for the harness.

Looks a E36 M3 ton better and no joke probaly saves 20+ lbs easily. 

Today I'm getting ready to do the sunroof layup. 

Monday is my birthday, so that's my self-imposed deadline to have it back on the road. Lot's of work to do this weekend! 

The sunroof lay up went down last weekend.

In the last pic of the post above, you can see me trimming the cloth in the mold, as well as the Divinycell foam mat. I did three layers of carbon, Divinycell in the middle and an extra two layers of cloth at the flanges, then another two layers on the backside. I didn't alternate directions on any of my layers, because I realized only after I had started cutting that I'm an idiot and didn't order enough material to cut a couple layers at 45 degrees and still get enough thickness, but fortunately the end product turned out to be stiff enough. I stacked all my layers in sequence, along with the vacuum bagging materials, and set them aside for the time being.

I picked up this vacuum pump for around $80 on Amazon, along with a cheap vacuum gauge.

A trip to Home Depot for some fittings and some vacuum tubing I had laying around yielded this:

I went with FiberGlast 2000 epoxy, with their longest pot life 120 minute hardener.

As noted previously, the mold had a few defects in it where the gelcoat was not adequately supported and started cracking. I first made an attempt to fill these with Bondo, however it seemed like the more I sanded, the more defects I opened up. So I had the lazyman's idea to just cover over these spots with packing tape before I made  matters any worse. I then wet sanded what will be the top portion of the plug out to 2500 grit and hit the whole thing with 5 layers of mold release wax. No PVA this time because I didn't think it would yield a good enough surface finish.

Finally ready to do the lay up! I put the laminate down in the order described above, then peel ply, breather cloth, and vacuum bag. Hooked up the vacuum pump and it held ~23 in Hg once I had a couple minor leaks sorted out.

The resin called for a 24-36 hour cure time, so I figured I'd let it go to the long side since temperatures were marginal. The vacuum pump held up for right around 23 hours of continuous use before it crapped out, which was disappointing, but luckily the resin had pretty well set by then so i don't think it affected the part.

Time to de-mold! I pulled the peel ply/breather cloth/vacuum bag mass off first. Looking good from the back side.

It took quite a bit of delicate work to get the part out of the mold, but after about an hour I got it loose without damaging it. 

I'd call it a mixed result, overall. It's perfectly functional and looks ok from about 10 feet, but it's got some obvious defects. 

Here you can see a corner where the vacuum bag apparently didn't have enough slack and the cloth also didn't fully wet out. There's also a spot of gelcoat that transferred, and the parts where I covered the mold with packing tape came out much glossier, as seen on the flange here.

The above are pretty much common themes throughout. 

Trimmed it with a jig saw and drilled holes for mounting. Fits pretty well, though in hindsight I might have added about 1/8" all the way around to close up the gaps a bit. Forgot to get any pics on the car and it's back off today for a dose of polishing compound.

Overall, I would have liked it to turn out a bit better and I think I could yield a much better result if I did it again. I'll hang on to the mold and maybe try that sometime down the road, but for now I'm not spending the money to build another one. I'll polish this up as best I can, and maybe even use some strategically placed stickers to hide the worst of the defects, and call it good enough for now. The important part is that it's functional and, oh by the way, it weighs nothing!

I did get to drive the RX7 on my birthday - for about 1/4 mile up the road before I realized:

A) I forgot to fully tighten the lug nuts

B) I never topped off the tranny fluid after the last time I dropped the subframe and the driveshaft slip yoke came out of the trans

And C) the radiator had sprung a leak again.

Not that any of that was all that big a deal,  but this is the second time the radiator has leaked because of the stupid design of my radiator and electric fan mounts, so it's time for that to go. The Thunderbird fan, or whatever it came from, has always been uncomfortably close to the serpentine belt anyways, and a PITA for serviceability to boot, so this had been on my agenda already.

I even bought the fan already at Spring Carlisle a few weeks ago.

Still waiting on the sheet metal I ordered for the shroud and new mounts to show up, which is annoying. I'm planning on autocrossing at the Carlisle Import and Performance show next week, so I need to get this stuff wrapped up ASAP.

Well this thread is long overdue for an update.

First things first, I guess I never wrapped up these projects a couple years ago. The radiator shroud and new upper mounts turned out really well. Super solid, looks good, the fan has a much easier time keeping up at idle speeds, and there's way more clearance to the accessory drive.

I think I pretty well highlighted the flaws in the sunroof plug above. It looks fine from 20 feet, but certainly not a show piece. Oh well, it's a race car.

And that's pretty much how I've run it these past couple years. It has its quirks, like the wipers that haven't wanted to turn off since an event at Pocono last year, but the critical systems have all been rock solid reliable. I'd guesstimate it's up to somewhere around 5-6k street miles since the swap.

More to come soon...

Very cool.  I LS'd my e36 at about the same time you did this car.  Just re-read your whole thread and our cars are very similar in prep despite being different chassis.  Mine's been a lot of reliable fun too.  Nice work!  I didn't see anywhere in here that you've needed any more hp - did you ever upgrade the cam or valvetrain at all?  I have not, I've been very satisfied with the stock output.

In reply to Lof8 - Andy :

Thanks! My choice for chassis was down to the FC and E36 before this car popped up in the for sale section here and I jumped on it. I'm sure I would have been very happy with a Bimmer as well, I had an E36 previously and it's still one of my favorite cars I've owned. Glad to hear you like it.

Still haven't done any cam or head work or anything like that. Auto x is my primary interest with this car and, frankly, more power is pretty far down the list of things it needs for that right now. Plus, it's still running the stock N/A RX7 diff and it's a miracle it's lived this long at the current power level.

That being said, I think I've finally hit the point where more would be nice. I had a blast putting together a 5.3 with a mild cam and 243 heads for my truck and that experience has me itching to do something a little more spicy for this thing one of these days...

Dibs on that rear end if you get rid of it!

This car has benefitted to a couple of favorable changes to SCCA auto x classing over the course of its development. At the time I started the build, I'd planned on getting stuck in whatever mod class it would land in, but just took the attitude of of "screw it, I'm just going to build what I want and run it wherever it fits."

But just as I was finishing the car up prior to the 2017 season, a change to SSM was announced to permit cross brand engine swaps, with a small weight penalty. So that allowed me to run a much better populated class where I was theoretically able to be competitive, but as I had no plans of running Hoosiers anytime soon I was left competing for mid-pack finishes with the other guys on 200tw rubber. 

2020 brought about the advent of XSA (or XA as I guess it will be called this year), which is essentially the "import CAM" people have been begging for. The 200tw tire limitation and overall ruleset actually gave me some hope of being competitive, so I made the jump. Turned out to be a great season long, three way battle between me, an LS swapped Miata, and a newer turbo Civic SI. Every event, the three of us were within a few tenths of each other and there was no telling who would come out on top. Ultimately, I ended up with the short straw in the season point standings, but this was still the most fun season of autocross I've had to date. I was motivated to come back hard with a few tricks up my sleeve for 2021...

Some action shots (photo credit Tom Hamm Photography):

In reply to wvumtnbkr :

Deal! Hopefully next winter I'll get around to doing the Ronin Ford 8.8 IRS swap, but that's a chunk of change...

So about that "rock solid reliable" remark...

This was our ride home from yesterday's auto cross. Or rather it was the car's ride home, since due to COVID, AAA doesn't currently permit you to ride in the tow truck. So SWMBO had to come rescue me and got to share most of the 3+ hour wait time. I definitely owe her big time for this one.

What happened was a classic Exxon-Valdez incident.

The AN hose running to my recently installed oil cooler started leaking badly at the hose end during my first fun run at the end of the day's event. I spun it once early in the run and thought  'ok just cold tires,' but shortly after I got going again it became clear that something was wrong, the rear end felt like it was on ice. Spun again, then tip toed all the way to the finish, oiling down the whole course in the process, before anyone realized I was leaking fluids. We called it a day after that and I had the joy of helping our very gracious organizers scrub down the whole course with dish soap, push brooms, and water distributed via wheeled coolers. Following the trail of oil, it must have started right off the line at launch.

This was the first spin. Note the heavy oil trail.

In hindsight, I really should have pulled off course as soon as I knew something wasn't right, although leaking fluids never crossed my mind at the time. That particular oil line had been a concern of mine, however, as the 90 fitting going to the cooler is far too low and vulnerable for such a critical component. I'd been planning to mount the cooler higher and redo the lines, I just ran out of time to deal with it before the first event. The low clearance wasn't the issue though, I think it was probably a combination of lack of strain relief on the hose and a faulty install of the fitting.

With the added capacity of the oil cooler, it had around 7.5-8 qts in it to begin with, and I'd guesstimate it lost 3-4. Motor seemed to be fine and luckily nothing caught fire, and at least we got through all the competition runs before SOMEONE ruined the fun .

Now chronologically we've gotten a little bit out of order here, so let's just back up a step. 
 

This spring I had a few more upgrades for the car on tap. First up was the aforementioned oil cooler, the stock FC piece that came with the car. For those not familiar, they're actually a pretty nice piece, generously sized with a built in thermostat. 
 

First things first, I gave it a thorough cleaning using the power washer and various solvents. The thermostat assembly was removed and replaced with a plastic dowel for this process to hold the bypass valve shut and ensure the whole cooler got flushed. 

I'd actually bought the hose, fittings, and Improved Racing oil cooler adapter quite some time ago, as well as built the mounts, so I threw some lines together...

...and mounted it up.

I pretty much immediately looked at it and thought that needs to go about 3-4" higher, but I had a lot more to do before this season's first event so that would have to wait.

Next on the list was a brake job. I wanted some pads with a little more bite, so I picked up some Hawk HPS 5.0 pads and Centric rotors. I soon discovered though that the DS rear caliper was seized, so rebuild kits were ordered for both rears. Figured I may as well give them a coat of paint while I was at it.

Before:

After:

The fronts were functioning fine so they just got a coat of paint. Cleaned them up real nice with the old cheek poker first.

Next up were the AWR spherical bearings for the rear trailing arms. First we employed my favorite method of bushing removal to get the old stock rubber bits out.

The AWR pieces:

They're a light press fit into the trailing arms. The directions then call for four tack welds on each side to hold the shells in place.

And a coat of paint on the trailing arms while they were off the car.

I also installed some solid aluminum bushings in the rear upper attachment point to the spindle. Not sure why I didn't do this at the same time as the DTSS bushings.

Added some Ronin camber links as well. They're just solid pieces available in three progressively shorter lengths to allow camber adjustment, rather than using some sort of threaded feature as most others do. Simple and robust.

Back together, and I spent about 5 minutes just sitting there moving things up and down, amazed at the smoothness with which it glides. There is like zero resistance. The whole rear end is now on either delrin or aluminum bushings or spherical bearings.

Alright, I'm going to try to finish getting things up to date so all two of you reading this thread can follow along in real time with this season's hot auto cross action.
 

Should probably fix these pics too, seems to be an issue posting from my phone. Sorry bout that 

The big ticket item for this winter's round of modifications were the Redshift Motorsports coilovers.

My setup on the car since day 1 has been springs, sways, and KYBs with a 225/255 staggered tire setup. While I'd learned to drive it well enough, there were several fundamental issues that were really holding it back, namely:

-Lack of front camber

-Lack of front tire clearance

-Lack of spring rate all around

-Too large rear sway bar

In addition, I think the strut mounts were getting pretty tired and causing the front end to sag. 

The end result of all of this was a car that would roll right over onto the bumpstops on corner entry, plow its way into the middle of the turn, rotate under trail braking with the big rear sway, and exit sideways with the power down. Entertaining at times, but not the quickest way around the course.

Coilovers solve pretty much all of those issues and for a few years now I've been listening to the NEPA region guys gushing over these Redshift units, so I finally bit the bullet and ordered a set in 9k/7k spring rates. For those who may not be familiar, Redshift takes off the shelf BC dampers, guts them, and stuffs them full of their own custom race valved goodness for less than half the cost of a set of  MCS or Penskes. So far, I'll just say these things have completely recalibrated my definition of what a good damper is.

On the car and all buttoned up with the new brakes:

Here are the shocks and springs that came off of the car. The front springs are the big, beehive shaped ones and really limit tire clearance on the inside.

I couldn't let all that additional real estate up front go to waste,  so a pair of 17x9 et22  Enkeis and four 255/40 17s were ordered. Unfortunately, because I'm a procrastinator by nature and waited until March to order tires, the RT660, Rivals, and Yokosuka were all back ordered until May or beyond. With the first points event on May 1, I decided to roll the dice on the Kumho V730 instead, which were only out until mid April. Still not in time for the season opening non points event, but I didn't mind sand bagging a bit anyway 

Eventually they did show up.

They fit great, not a hint of rub.

Unfortunately, the bigger rubbers forced the hard decision to swap to power steering. The car came with a depowered rack, done the right way, and the feel and feedback was one of my favorite things about the car. Once rolling, the effort was fine, but at parking lot speeds I could foresee the 255s being a problem, and during auto cross it could also be easy to get caught out if I got behind in my steering inputs. 

So the decision was made to swap to a power rack, although I'm hanging onto the old one in case I ever change my mind. Still had the fancy Turn 1 pump from my Camaro. Had to move the coolant overflow bottle to accommodate it and whipped up a quick bracket to attach to some existing studs for that purpose.

I used a kit from Sikky intended for an FD chassis RX7 for the lines, as this was going on right after the Exxon Valdez incident detailed above and I was thoroughly disgusted with AN lines by that point. It mostly worked, nice quality parts but the high pressure line was just a hair too short and the adapter fitting for the high pressure port on the rack wasn't quite long enough. After several iterations, I landed on a 12mm to 6AN banjo fitting adapter, M 12x1.5 banjo bolt, a 90 degree -6 elbow, and a 45 -6 elbow. It works.