I remembered an older article in Grassroots Motorsports about Burns Stainless mufflers. They're supposedly very high quality and in GRM's tests they offered both better power and sound suppression than a competitor. I haven't found any examples of them being used on a rotary though. Price is comparable to the XR-1's.

I like your thinking with the miata trans. What kind of rear end are you going to run? Also what gear ratio? 4.1, 3.9, 4.3 ?

Sticking with the n/a rear end. I've got the 4.30:1 ring and pinion out of a GTUs and torsion LSD out of a Miata. I would've gone with a higher gearing but I still wanted to have an accurate speedometer for the time being.

Awesome set up! I am loving the build so far. Keep up the good work!

just read from page 1 up to now. AMAZING, man. loving the heck out of it!

Thanks guys. I've run into a bit of a snag with the 929 MC/booster swap. I made a post in the wheels/tire/brakes section to see if anyone has any ideas. Basically I've bled the crap out of the MC and the lines but I'm still getting a spongy pedal. It's not acting like normal air in the line though because pumping the pedal does nothing and the pedal doesn't fade with brake pressure. Could this be the result of having a bad/nonexistent check valve in the booster line (no real engine in the car)?

Could the problem be lead back to not bench priming the MC before putting it in the car? When I swapped clutch MC on my 7, you could pressure bleed it, but you had to sit there and prime the pedal for a good half an hour to get fluid in and bubbles out of the master cylinder.

Okay so I've been away from RCC for a bit and gotten little done on the car. Too much traveling and family stuff in the summer :)

I finally got the brake issue sorted out. I'm not sure it was something with the Raybestos MC but I ended up replacing it with a Centric MC, bled that, and reinstalled:

https://lh3.googleusercontent.com/-H...630_200101.jpg

Pedal feel is better, but still not perfect. Either way, time to move on and I'll deal with again when the car is running so I can judge the feel with the booster working. Only new plan at this point is to make a MC brace and a pedal assembly brace as I can see both of them moving a little when bearing down hard.

The next task is getting the fiberglass fan shroud made. After some iterating I came up with a design I liked and get the frame made:

https://lh6.googleusercontent.com/-z...630_195843.jpg

The fan mounting flange is actually on an angle:

https://lh5.googleusercontent.com/-e...630_195931.jpg

The current plan is to have the taller end at the bottom of the radiator in an attempt to exhaust the air through the hood vent. I wanted to duct it but it looks like the water pump pulley and upper radiator hose are going to be in the way. If I run into other interference issues (front swaybar) I can always flip the shroud for more horizontal flow over the engine.

The next step is to stretch, glue, and staple fleece over the frame. I'll be turning this into a mold or "buck" so the fleece won't be integral to the final part. I'm thinking two or three layers of FG for most of the shroud with the mounting areas reinforced with another. I'm also looking into DIY vacuum forming for a stronger/lighter finished product.

whats the advantage to the 929 mc/master. also did it require modification to the firewall?

1" bore MC versus 7/8" on the N/A MC and 15/16" on the TII MC. The idea is less pedal travel for a given amount of braking. No modification to the firewall but the N/A booster can't be used. I've read the TII booster can be used but I got the 929 MC and booster together so I used it. Just had to switch over the clevis for the brake pedal and modify the proportioning valve bracket a bit. IIRC, the N/A booster is a 8" single diaphragm, the TII is a 7-8" dual diaphragm, and the 929 is 8-9" dual diaphragm.

well, you might just have some wicked air bubbles still. ive had that before from bleeding from 100% dry.

also the firewall flexes.... a lot. that can be fixed with a bracket and a bolt pushing against the MC

Ugh, I hope there aren't still bubbles in the MC. I bled and bled and bled that thing in my vice until I couldn't see even the smallest bubble. I even cracked the brake line fittings at the MC and BPV after everything was installed (with the MC under pressure so no air could come in). It may just be firewall/pedal flex at this point. I've got some ideas for braces.

I haven't been able to dedicate much time to the car. I've been busy doing stuff around the house, possibly preparing for a move, and doing a lot of traveling. It's also the time of year when it's 90+ degrees outside with dewpoints over 70 degrees so the heat index is 100+ and I just don't like working in that. I spent maybe an hour this weekend doing this:

Decided I didn't need windshield wiper sprayers. The car will likely not be driven (willingly) in the rain so I figured that can go.

https://lh3.googleusercontent.com/-w...720_112445.jpg

https://lh5.googleusercontent.com/-W...720_112457.jpg

I left all the provisions for the system in place just in case I live to regret this decision. In a bit of boredom I stretched the fleece over the frame for my fan shroud.

https://lh5.googleusercontent.com/-s...721_220119.jpg

The flat stock is holding the fleece down where I sprayed adhesive to make the "flange" for the shroud.

After much debate I said screw it and I decided to turn everything into a mold so my shroud will be completely fiberglass. I became convinced either the spray adhesive would prevent me from removing the resin-soaked fleece from the frame or it would just dissolve when the resin was applied ruining the shape. I stapled the crap out of the border of the shroud and flange to maintain the shape. Everything is ready for resin now:

https://lh6.googleusercontent.com/-N...722_194754.jpg

https://lh4.googleusercontent.com/--...722_194809.jpg

After a couple coats of resin I'll apply filler to the areas with the staples to prevent the "dimples" from transferring to the fiberglass. Plan is to resin, fill, sand, clear, wax, and coat with PVA before laying the fiberglass.

First layer of resin applied to the fleece:

https://lh3.googleusercontent.com/-x...724_211714.jpg

https://lh4.googleusercontent.com/-x...724_211737.jpg

It's a little thin in a few places (3/4 of the flange and on top) but I went through most of the quart of resin I had and all the hardener. I'll pick up some more tonight and after another good coat everything should be ready for sanding.

Also, to address a question I asked previously I think I'm going to break down and go with a Racing Beat pre-silencer/muffler combination for the exhaust. Hopefully this will keeps things quiet enough.

Another thing, I've got a bunch of stock crap still lying around I'd like to get off my hands. It's taking up too much space in the garage and I'd rather see it go to another 7 owner than to a scrap yard. Off the top of my head:

-Steel N/A hood
-GTUs viscous LSD
-S5 N/A rear end minus cover
-S5 N/A transmission (complete)
-S5 N/A transmission (minus housings)
-New AWR rear camber bar
-S5 N/A oil pump
-S5 N/A injectors
-Front/rear stationary gears
-Black cargo cover

are you talking about the RB universal straight through ones?

Assuming you have the 4-piston brake calipers, have you bled both bleed screws on the rear caliper? Also, if you bleed brakes much at all, a Motive pressure bleeder is a great tool to have. No need to waste time and make a mess bench bleeding. Just put the system together and let the bleeder go to work.

Yeah, the universal ones because my exhaust is completely custom. By "quiet enough" I mean quiet enough so I don't get black flagged. Something like <=100 dB or so.

Yep, I have the 4-piston front calipers with slotted rotors in the back. The rear calipers do have two bleeder screws but I thought the bottom one was only used if the caliper was dry, which mine never were. I thought about bleeding through the lower screw anyway but I couldn't see a way to do it without unbolting the caliper from the hub. Also, by "pressure bleeding" I mean I am using the Motive tool. The MC resevoir adaptor is a little annoying but otherwise it's a nice tool to have.

i ran both mufflers your talking about. Car was loud as shit on a naturally aspirated car with a header.

That's what I was afraid of. Are the 12A's and 13B's on the FB's just that much quieter or are the mufflers for those systems different from the universal ones? They seem to get away with a single pre-silncer/muffler combination. I'm really trying to avoid dual outlet exhaust due to weight and I only have room for two supressors in the single-outlet configuration.

the issue is there are no bafflees. Its just a giant straight through thing with packing.

When we had the roadrace car, we had a not quite right pedal for two years. Someone suggested bleeding through the bottom bleeder and it solved the pedal issue.

So do their direct-replacement mufflers and pre-silencers have baffles? Has anyone run something with a baffle that hasn't robbed power? A while back I was talking to the Burns' Stainless guys and they seemed to think two of their mufflers in-line would be sufficient. Though from what I've read online that seems unrealistic.

How'd you access that bleeder screw? I assume you removed it from the hub. I'll have to try that when I get closer to having the car running.

It's not so bad to do mounted on the car. Might need a shorty wrench and small hands. I tend to bleed both when I am feeling frisky. I can take pictures later today of a caliper I have removed to give you an idea.

I recall talking to a friend about mufflers and exhaust tuning. In his 2 stroke motorcycle racing days, they managed to get their bike to be dead quiet. To the point where you just heard resonance from the air cooling fins on the block. And with no power loss. Its all about how its done I suppose.

Plus, if its so loud you don't want to go WOT, then you in effect DO have powerloss.

Leaving the caliper in place it appears to require a deep-well socket, which would prevent me from attaching a hose to the bleeder screw and make a mess in general. I assume you can bleed these off the hub pretty easily.

No doubt with a lot of iteration. I'm certain there's a perfect combination of sound suppression and power out there. Another idea concocted was to run the exhaust to a muffler on one side of the car and then have it loop around and run to the other side of the car where it goes through another muffler.

The car being loud won't bother me. I just know some tracks have sound intensity requirements as low as 92 dB.

I've been running dual 32" straight thru mufflers in front of dual spin techs (about like a straight thru sound wise) on a NA 13B. They are too loud for what you're looking for. About 91db idle to 118db peak at WOT external measurement.

I plan to try the Rocky Mountain Performance Quiet Riot exhaust baffles when I get it back on the road. Hopefully it helps as it is louder than I want as well.

http://ts4.mm.bing.net/th?id=H.45922...96507&pid=15.1

I don't remember. Probably a box end wrench. On any bleed screw you need a hose draining into a clear bottle that has brake fluid already in it. The end of the hose needs to be submerged in the fluid in the bottle. This way, when bubbles come out, you see them rise through the fluid in the bottle. Pump until you see no bubbles. You also need to start at the caliper furthest from the mc and work to the closest. Stock prop valves can also cause issues with getting all the air out if the back half of the system.

That's basically exactly how I bled the system (minus the lower bleed screw on the rear calipers). I was wondering if the proportioning valve could be causing issues. Is there any trick to bleeding that? When I hooked up the MC and applied pressure I broke all the proportioning connections until only fluid came out. Regarding the rear caliper lower bleed screw I guess I'll have to take another look. I didn't think I could fix a box wrench down there.

The second (heavy) coat of resin is on so now it's sanding time. The plan is to work on that tomorrow.

Otherwise, I'm having impure thoughts about ditching the RX-7 chassis and dumping everything into a NA Miata. Lighter chassis and better suspension and all.

I have a real nice roller NA I might part with.

Haha, very tempting! Details?

Spent a lot of time on the shroud this weekend. Applied the second layer of resin Thursday night:

https://lh4.googleusercontent.com/-Z...727_111427.jpg

Spent most of the day Saturday sanding:

https://lh3.googleusercontent.com/-j...727_141550.jpg

Applied filler and sanded Saturday night and Sunday morning:

https://lh4.googleusercontent.com/-a...728_192945.jpg

Sprayed primer last night:

https://lh4.googleusercontent.com/-1...728_201517.jpg

The plan is to sand again and apply several layers of high-gloss clear. Once that's done I'll apply several layers of mold-release wax and then I can lay the fiberglass. The mold isn't perfect but I'm operating under the assumption the fiberglass and resin of the final product won't take every small imperfection into form.

Sanded the mold again last night:

https://lh6.googleusercontent.com/-f...729_211537.jpg

I think my total sanding time is in the double-digits. This is turning into one of the more labor-intensive projects I've worked on during this build. Next step is clear followed by lots and lots of mold release wax.

Finished up the clear on the mold last night:

https://lh3.googleusercontent.com/-p...731_203346.jpg

It doesn't look particularly glossy in the photo but it's got like 10 layers of clear on it. If I get some time tonight I'll start building up the layers of mold release (just like wax). Going to a wedding this weekend in Seattle so I'm not going to get much done.

I've also started working on my radiator/oil cooler ducting. I've moved the front harness from the oil cooler support bar to underneath the upper radiator support. My plan is to cut off everyting from the oil cooler support bar except the oil cooler brackets to reduce the number of airflow obstructions. It should also make the ducting a little simpler but it's still going to be a PITA to get around the bar itself and the oil cooler lines.

Finally decided and bought some exhaust stuffs:

https://lh6.googleusercontent.com/-6...808_205829.jpg

Gonna try to go with Racing Beat stuff and see how it turns out. Singl 2.5" pre-silencer and muffler. Also going to try some thicker-walled tube. It's going to be heavier than I originally wanted but it's probably the best compromise between weight and sound supression.

Got 5 coats of wax on the mold. I'll probably do two more for the maximum recommendation of 7. I'd still like to find some aerosol PVA or something similar. Can you tell I'm worried the fiberglass shroud is going to stick to the mold? In between coats of wax I started screwing with the front of the car in more preparation for the ducting.

https://lh6.googleusercontent.com/--...811_201254.jpg

The hood latch and cable have been completely removed. I've got a set of Aerocatch hood pins on the way to replace everything. I've also cut off all the random brackets on the oil cooler support bar for better airflow to the radiator. I still need to smooth down the cuts.

7 coats of wax on the mold. I also picked up some PVA I'm going to try to apply with a spray bottle as I don't have a spray gun. Hopefully tomorrow I'll be laying fiberglass. The plan is for at least two layers of mat with another layer in the corners and flanges for support.

In between coats of wax I've been busy grinding down the remains of the brackets on the oil cooler support. The radiator/oil cooler inlet is as free of obstructions as I can possibly make it with the stock setup:

https://lh4.googleusercontent.com/-S...815_205817.jpg

And in order to deal with the no hood latch thing my Aerocatch hood pins came in a whole 5 days ahead of schedule:

https://lh3.googleusercontent.com/-5...815_211532.jpg

I'm waiting on some 2.5" SS flanges for the exhaust and then the car gets taken to a local shop to have to exhaust fabbed up. I'm going to have to deal with crush-bent pipe for a little while since no one around here has a mandrel bender. Diameter reduction shouldn't be too bad as I'm trying to keep the bends to 15 degrees or less. I also need to remember to install the aluminum driveshaft and rear swaybar to avoid and potential surprises when putting the car back together.

I got the fiberglass laid over the weekend:

https://lh4.googleusercontent.com/-c...818_194255.jpg

As it's my first attempt it's nowhere near perfect but it should still work. I ended up using only two layers because I bought heavier mat. It just has to be able to hold the fan anyway. It was hard getting bubbles out because after laying about 1/2 the first layer my roller fouled up with resin and was pushing the mat around. If I did it all again I'd cut larger pieces of mat and do whole sections at once. Tonight I'll start trimming and sanding. If it turns out crap I'll just try again.

Actually looks like a good job!
Yeah, I think you're getting a little paranoid about the mold release...
We went with the minimum 2 - 3 coats of wax and then a layer of PVA.
The release went OK.
I don't think you should have any problems.
Bubbles are due to the complex shape, so either cut the fiberglass mat smaller (not in your case) or use thinner, lighter weight mat - which would be the better option here and just run more layers.
Experience will tell you what you can and cannot get away with.
It comes down to getting corners and nooks / crannies to transition as smoothly as possible.


-Ted

Awesome! So rare to see monster builds like this to learn from. I appreciate you taking the time to make such a detailed thread for us. Subscribed, keep it up! :)

Where did you get the aluminum driveshaft made and the cost if you don't mind.

Thanks! Yeah, 7 layers of wax was probably unnecessary when I used PVA in the end. That stuff helped out big time. It's fun to pull off too. A lighter mat would have probably been better. I'm not sure what weight mat I used but it's intended for boat repair so I imagine it's pretty heavy. I'll definitely use lighter stuff next time for complex parts like this.

Thanks! When this is all said and done I'd like to make a few how-to threads. I'm using a lot of parts from other Mazda models and while the information is out there on the internet it would be useful to collect it all here. I still need to make my transmission rebuild thread...

I got mine straight through Mazdatrix so you can check the price on their website. If you're looking for a custom application you'd have to ask them who they use.