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[How To]: 1" BMC Upgrade for S1-S3 RX-7
This will be my first installment of many for redesigning and updating my 1983 RX-7 Project Car deemed "Project Mickey" by the previous owner. The more criticism and input I get from you guys, the better I can make the next ones.
Goals: Adjustable Brake Bias 13/16" to 1" BMC to accommodate for larger S5 brakes in the future Better Pedal Pressure What You Will Need: Wilwood Brake Proportioning Valve 260-11179 (2 Inlet, 3 Outlet, and Brake Bias Adjuster) Wilwood Brake Proportioning Valves 260-11179 - SummitRacing.com 1993 Mazda 929 1" Non-ABS Brake Master Cylinder (Raybestos Part #MC390112) More Information for RAYBESTOS MC390112 2003 Mazda Protege ABS Power Brake Booster (A-1 Cardone Part #532517) Product Detail Vacuum Hose to the Power Brake Booster Terms BMC = Brake Master Cylinder PBB = Power Brake Booster Brake Bias/Distribution Block = Where two brake lines come in directly off of the BMC Procedure 1. Place Rags Everywhere. Underneath the BMC/Booster area, around the fenders, etc. Brake fluid does not play nice with paint and WILL eat it up if left for an extended period. 2. Disconnect brake lines from the BMC using a 10mm flare nut wrench (or just an open wrench, but be careful not to strip these. They only need 15ft-lb and I would suggest using teflon tape when reinstalling the fittings.) 3. Remove the brake bias/distribution block off of the BMC(10mm socket wrench) and slightly bend the lines up and over to the passenger side of the vehicle to allow for the BMC and PBB to be removed. 4. Remove the two BMC bolts (12mm open end and 12mm socket wrench were used) 5. Use a standard (flathead) screwdriver to lightly pry in the tabs of your brake fluid level sensor and slide it out of the BMC reservoir. Disconnect this. You'll be using it in the new 929 BMC. 6. Carefully shimmy the BMC off of the two integrated bolts of the PBB with a rag in hand. Do NOT allow any fluid to touch your paint. Put this BMC into an oil pan or bucket, you might need it later. 7. Prepare your new 929 BMC and install the brake fluid level sensor you just removed from the car. https://sphotos-a.xx.fbcdn.net/hphot...35029819_n.jpg 8. Using a set of pliers, slide up the clamps on the PBB for the vacuum line. Next use those same pliers, grab the middle of the hose, and gently rotate back and forth until the seal from years of use breaks. Slide the hose off of both ends, you're going to need a new one. 9. Hop in the car, head under the pedals, and locate four long bolts where the brake pedal assembly bolts to the PBB. They will need a 12mm deep socket wrench and possibly an extension depending on the year of your RX-7 and reach. Remove those 4 nuts on the bolts. 10. There is a "pedal shaft lock pin" located at the end of the PBB rod connecting to the brake pedal arm. This will be simply removed using a set of pliers to grab the locking pin and sliding the small rod out. If this gives you any grief, try jostling the brake pedal as you do it. 11. Press the brake pedal in slowly and giggle the PBB 3/4 of the way out. Go back to the engine bay and remove it completely. https://sphotos-a.xx.fbcdn.net/hphot...63868363_n.jpg Have you noticed yet that the designs of your new BMC and PBB are different? MOST Mazdas have the older RX-7 style BMC, but this design looks to be much more reliable. ***Saving this for now, I'll update the walkthrough later.*** |
Check out the mounting piston design comparison
https://sphotos-b.xx.fbcdn.net/hphot...14580435_n.jpg See how the four holes in the firewall are farther apart in the horizontal direction? Notice how the old BMC bolts were vertical and the new are horizontal? This is the mounting orientation according to your firewall holes. https://sphotos-b.xx.fbcdn.net/hphot...69377320_o.jpg 12. Swap over RX7 pushrod arm to the new 03 Protege PBB. https://sphotos-b.xx.fbcdn.net/hphot...61657891_n.jpg 13. Install the same way you took everything out using gutentite torque ratings. Keep the brake lines disconnected until your brake proportioning valve is installed and mocked up. Ideally, we want to keep the original lines. Oh Hey, remember that brake fluid level indicator I was talking about? Here are those tabs to remove it. https://sphotos-b.xx.fbcdn.net/hphot...15663627_o.jpg Here's why you need a new piece of vacuum hose for the Protege PBB. https://sphotos-a.xx.fbcdn.net/hphot...74844748_o.jpg Installed with included plastic tabs to prevent leaking. https://sphotos-a.xx.fbcdn.net/hphot...27143949_o.jpg https://sphotos-b.xx.fbcdn.net/hphot...61040904_n.jpg https://sphotos-b.xx.fbcdn.net/hphot...37325918_o.jpg I'll come back and post the rest once my Wilwood Prop Valve/Distribution Block comes in |
Interesting... but S5 calipers have the same volume displacement as SA/FB/FC single pot. The main advantage is that they are lighter.
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Oh well, hahaha. I would have figured that out once I purchased my S5 front clip. I plan on doing a 5 lug conversion and Ford 8.8 rear end with 5x114.3mm bolt pattern. Full S5 electronics and running gear of course. Probably going to design my own rear suspension with Solidworks too.
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I'll update this soon with pics, but the Wilwood Prop Valve/Distribution Block came in and the lines are all rebent for proper fitment.
I reused the old distribution block mounting bracket and bent it to my liking for the new Wilwood unit. With this mod, you'll need a double flare tool and have to cut the stock ends off of the lines and use the new 3/8"-24 fittings. You SHOULD ALWAYS USE TEFLON TAPE on brake lines. I tested mine as a mockup without it while using the elcheap-o Autozone double flare kit, and 5 out of 7 fittings leaked. Ouch. |
You will need about a foot and a half of 3/8" ID, 5/8" OD rubber vacuum hose to adapt to the new '03 Protege PBB.
Make sure you slice open and remove the old one way valve from the old line and push it into the new piece. I believe the smaller end of that fitting is towards the engine. The bulbous side goes towards the PBB. Press in the valve with a screwdriver about an inch and attach to the engine vacuum line which will then push it further back. Don't forget your hose clamps! :D |
Originally Posted by SirLaughsALot
(Post 11323945)
You SHOULD ALWAYS USE TEFLON TAPE on brake lines. I tested mine as a mockup without it while using the elcheap-o Autozone double flare kit, and 5 out of 7 fittings leaked. Ouch.
If they were leaking, it was due to poorly made flares, plain and simple. OTOH, when I get a car in where tube nuts have teflon tape or sealant goo on them, I know that everything on the car needs to be gone through with a fine-toothed comb because whoever put it together was mistaken on some very basic concepts. |
Seems like an interesting enough idea, but I'll stick to the 4x110 with standard brakes until I get a car worth doing an entire swap in.
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we knew Mazda used the same brake booster bolt pattern from 77?-now, but we have just learned that Honda does too.
the reason the booster matters so much is because the FD/S5 T2 boosters are so rare, but you can use the Protege, tribute, Rx8, basically anything made after 89, BUT since honda boosters fit, it may be easier to just use one of those, and they came stock with a 1" master. |
Thank you Peejay, I wasn't entirely sure where the leak was from. I'll rent out another tool and see if I can widen the second flare. Or maybe it was too wide, and that was the problem.
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The 03 Protege is the exact same size as the FB Booster and is thankfully abundant. Either way, the point of this was to show a thorough walk through on what needs to be done.
This is a simple mod for someone considering a larger brake setup or someone who wants an adjustable rear bias. RX7Club has amazing articles, but for the most part they aren't complete, DIY, and step by step walk throughs. The DLIDFIS and Nikki rebuild threads are phenomenal. :D I'll continue doing as many write-ups as I can and try to fill in the gaps. I still need to finish this one...hahaha |
Since the front brake circuit is at the front of the 929 MC, and the front brake circuit is at the rear of the FB MC, you will need to reverse the lines that lead from the MC to your prop valve.
Also, check the fittings in the 929 MC. It looked like some of them came from the factory with a banjo fitting at one of the ports. If so, that port may not have the inverted flare seat that you need to seal against. |
Elwood, those were my thoughts exactly. I'll reroute the lines when I get the chance and pick the banjo bolt parts off of a 929. Since I used another prop valve, my setup works though. I'll post the new pictures.
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Finalized Pictures
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