infernosg's S5 N/A Build

[infernosg]

Originally Posted by WE3RX7

Personally, I don't care for the XR-1 muffler. Lately, everything has been magnaflow with no issues and lifetime warranties. Use a thicker 14ga exhaust tubing with an RB presilencer and good magnaflow performance muffler and it should be plenty quiet for track officials. I know the 14ga is heavier, but an NA rotary with thin exhaust is going to get noticed...


Everything else looks great BTW.... should be a great ride when your done.

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.

[Rotary#10]

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 ?

[infernosg]

Originally Posted by Rotary#10

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.

[Rotary#10]

Originally Posted by infernosg

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!

[RedR1]

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

[infernosg]

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)?

[tweiss3]

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.

[infernosg]

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:



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:



The fan mounting flange is actually on an angle:



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.

[Whizbang]

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

[infernosg]

Originally Posted by Whizbang

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.

[Whizbang]

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

[infernosg]

Originally Posted by Whizbang

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.





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.



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:





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.

[infernosg]

First layer of resin applied to the fleece:





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

[Whizbang]

are you talking about the RB universal straight through ones?

[C. Ludwig]

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.