No braking power!
 

I have been unfortunately experiencing some brake issues at the track on my 1997 track car. For brakes the car is equipped with a 1" Willwood MC, a Supermiata 11" boxmount kit, SS lines, stock 1.8 none sport calipers in the back, Castrol SRF fluid. For pads I am running G-loc, R10 and R8. At the track I am unable to lock my brakes, by the time I put my foot to the floor I bottom out the MC. While I have some stopping power, I am no were close to being able to lock the wheels.

Background Knowledge
For many track days I was running this same setup except with the original Master Cylinder. The pedal felt amazing, brakes bit at the top and had fantastic modulation. Having a track day coming up and not much time I needed to bleed my brakes, I took my brakes to a shop, they bled them but after they had my car the bleeder valves on the Wilwoods were ALL bottomed out. Great job! I ignored this and put about 8 hours of track time till the fluid was cooked.
Right before another day I made the time to bleed them myself and thought it would be a good idea to change all the bleeder valve fittings on the Wilwood calipers. After I changed all of them I bled my brakes in the proper sequence using the 2 person push pedal method. Everything went well until I came to the last front caliper. I had realized that I had forgotten to tighten the bleeder valve on the brass fitting. When I went ahead to bleed this side I was getting endless small bubbles. I went back started from the same sequence with all the bleeders closed and when it got time to bleeding the last caliper I was stilling get endless bubbles. This point I gave up tested to see if the pedal was firm, nope the pedal felt spongy and only started building pressure 1/2 the way down.

Later I took it to my buddies shop and asked them to bleed the brakes, they used a vacuumed type method and the pedal felt better, but no were close to where it was. They believed I broke the MC by pumping the pedal all the way down and destroying the seals. Really not knowing what to do I tried it. I decided I may a well upgrade my MC in the process and so I went with the 1" Wilwood MC kit. I went and purchased the kit from Goodwin racing. Additionally, I decided to get bleeder assemblies for the Wilwoods because I was still getting all those bubbles when bleeding the front-driver caliper. I changed the fittings, and changed the MC. I first bled the MC from the bleed ports, something I noticed was I always got small bubbles when bleeding from the MC after the first 2-3 pumps. I called Wilwood and they said it was normal, I went ahead and bled all the calipers, no bubbles/air coming from a single corner. I took the car for a spin and I noticed that the pedal felt lower compared to the OEM MC. I thought it was a issue related to the small bubbles but it wasn't. Pumping the pedal didn't raise the pedal height either. I then realized there was lots of dead play in the pedal, so I went ahead and adjusted the spindle rod just before the rod would touch the MC. BOOM amazing pedal feel. Car felt ready to go like it used to. Pedal felt firm, wheels would fully lock.
First three track day everything seemed to feel okay but I really wasn't pushing the brakes, however, later on as the days progressed the pedal started getting lower and lower but no sensation of pressure loss. At the end I was bottoming out the pedal. Pedal has no feel until the last 20% then its stiff but wont produce enough pressure to lock the wheels. I contacted Goodwin racing and they sent me a new MC. I bench bled it, swapped it in and boom pedal feel all came back.
Second track day, I go into my first braking zone after warming my car up, bottom out the MC and I cannot lock the wheels. The pedal was stiff and throughout the day it got worse and worse till it got the to same point as the last MC, bottom 20% is the only place where there is pedal feel and it not enough to lock the brakes.
I contacted Supermiata and they got a short story and told me to adjust the pedal and give the MC more dead travel before engaging. They believed my brakes were dragging. It made sense honestly, but I never smelled my brakes. I tried this. My car felt like it had more acceleration, and rolled more when I was on a slope. I bled my brakes went to the track and same issues, no pedal till the last 20%. But the pedal feel never really came back but I had enough to lock the wheels.

My hypothesis
1. Brakes were dragging, bottoming out the MC at the track 24/7 just destroyed the MC.
- While I want to believe this I just can't because a MC shouldn't brake by pushing it all the way, plus there are no leaks, also how would it brake 2, and I never even smelled my braking fading.

2. Calipers are bad cause it happened after screwing with the bleeders. Wilwood support told me to use NPT tape to help seal the bleeder threads, dude on the phone swore by it. Worst advice ever, all that tape just got dissolved by the fluid and filled my calipers with junk. That junk clogged my bleeder valves, smh.
- Calipers broke cause of junk inside and or some kind of invisible leak, idk.
- Maybe the pistons are getting pushed back to far for some odd reason, idk.

3. My rear caliper has a point when I adjust the e-brake allen bolt. It is a little resistant and then it just keeps moving.
- I honestly cant imagine this being a issue cause its something mechanical.

4. Bad wheel bearing? They all felt fine though.


Key Points
Pedal is sponge/none existent until the last 20% of travel.
Pumping pedal does NOT build any more pressure.
Pads are new, properly bedded in.
I checked wheel bearings, with the car jacked up all wheel bearings feel solid. I cannot feel any play when nudging the wheels.
Rear calipers are set correctly for the E-brake.
Cannot see any leaks. Pedal does not feel as if it sinks.
Changing the MC once temporarily fixed the problem, then at the track the problem immediately returns.

I am at the point that I want to renew my entire brake system including the the solid lines running through the chassis. Would love to get some help getting this solved. Excuse typos.

Correction: I never had enough power to lock the brakes after readjusting the pedal rod.

Subscribed. Glad you posted here, lots of sharp people here. Welcome to Miataturbo.net.

Hopefully someone here has an idea other than swaptronics.

Edit: Was talking with Emilio about this more... Car is still NA right? Does the pedal feel change? lack of power locking up the brakes could be an assist issue. Unlikely if the pedal still feels spongy but.... it's an idea. If your booster diaphragm is leaking you'll lose assist/braking power. Not sure how to troubleshoot that but something you can check.

Never use a vacuum bleeder. Teflon tape is impervious to brake fluid. Op-rod needs to have some clearance when the pedal is fully retracted. You may have a leak. The fittings that came with the adjustable proportion valve that I purchased were not threaded deep enough for the tube nuts.

Car is naturally aspirated nothing done with the motor. Just a fresh and health 97 1.8.

With the engine on, the first 50% of the pedal travel is pure mush. It can effortlessly be pressed. The next quarter of the pedal is sponge and the last quarter is hard, like how the top of the pedal should feel. Once I bottom out the MC there is still not enough power to lock the wheels.

https://cimg5.ibsrv.net/gimg/www.mia...60c7147e0a.jpg

I did a whole general check for leaks on all the lines and calipers. Everything was dry. The adjustable prop is from SM/949. Possibly could be a leak with the stupid line I had to use to make Goodwin Racings kit fit with my portioning valve. But no visual leaks.

Is the op rod from the booster to the MC adjusted correctly? Did you remove the check ball and spring (residual valve) from the rear port of the MC?

Before it was a little to close. Now it has lots of dead play. After bleeding the brakes and adjusting brakes are still bad. The residual valve is removed.

If both rods are adjusted correctly and there is no leaks then maybe the booster is bad. I’m not sure what a bad booster would do other then increase the pedal effort.

Booster is fine, I without a doubt feel the master cylinder bottoming out(hitting the end of it). The car also only has 17,000 miles, would be pretty odd for it to break haha.

I had something happen sort of like this but nowhere near as bad. Couldn't get it to bleed properly. What ended up fixing it is doing the traditional two person brake bleed procedure but with the engine running. Person pumping the brakes does not need to stand on the brake pedal, just be firm with it. Start with the corner furthest from the master and end with the closest, also, you're going to need to bleed through a decent amount of fluid (like a quarter liter per corner) so consider maybe something less expensive than SRF for now. I think that since you're getting the added assist of the brake booster using this method, it's much better able to suddenly knock air bubbles out of places you might not have been able to by just bleeding with the engine off. Also, make sure you are closing the bleed screw before the brake pedal reaches the bottom of the throw. Short bursts.

Love the suggestion! However, no air in the lines. We bled 2 liters of Type 200 then we put the SRF in there. No air at all in the lines. If there was air in the lines then pumping pedal would create more pressure. Sadly that's not the case. What added more pressure was changing the MC. After we changed it the pedal immediately came back then at the track it immediately left.

Okay then don't try it. Best of luck. 🤞

A bad booster would not increase stroke, it would only increase effort.

https://cimg4.ibsrv.net/gimg/www.mia...45c903d0d0.jpg

This S-bend into the prop valve looks like a huge potential air trap. Try bleeding at the connection into the valve to push all air out of that local high spot.

Decided to give this a shot, no luck. Pedal feels exactly the same.

Agreed, I don't know why Goodwin racing didn't decide to just add an option to send 2 of the same brake lines to avoid this junction. You would think that most people with a 1" MC will also have a brake kit and will also probably have a portioning valve. I ordered SM's new kit as it will remove that point entirely. If I can find a shop that will flare some solid lines with the correct fittings Id prefer to do that but I do not even think that would make a noticeable difference in pedal feel. Anyone could chime in on that question?

I've added taking a dead blow hammer and tapping lightly on the calipers to ensure there are no stubborn bubbles trapped in the system. I was surprised to see stragglers come out.
have you thought about making your own power bleeder? How much pedal free play is reccomended for this MC setup?

Man I'm still leaning towards booster.

The fact that the car is low mileage means very little. It's 25 years old.

From what the op has said so far it has to be the MC. Most likely if you put the previous mc back on they will work. The only causes are a bad mc, it’s not installed correctly or there is a leak. When I replace an mc regardless if it’s a factory part or aftermarket I measure from the inside of the piston to the mounting flange and compare it to the previous unit. I think last time I used a short piece of round stock, maybe 6-8mm in dia that I put a radius on one end. Then with dial calipers I compared both mc’s. There has only been a few times that I have been able to r&r an mc with out having to make an adjustment. It’s been a year since I swapped mine and I’m 2days into a dance the omicron so please excuse my writing. Just trying to help.

The mallet has always been my tool of choice for bleeding. That thing gets some suckers out after the first tap. I have thought about getting a motive power bleeder, just not sure if its compatible with the wilwood MC.

Ya true, the car is still a s**t box. This brake issue has been making me question why I turned a perfect 10,000 miles NA into my racecar rather than selling it making double the profit and purchasing a new BRZ. I saw you guys make Xidas for those things. After I saw that I really got depressed. :confused:

Anyways, Ill ignore the idea that I feel that I am hitting the bottom of the MC. Maybe that's when the booster doesn't provide sufficient power to aid me in the pedal effort anymore. If you can answer this question, fabulous. How low can you press the brake pedal before bottoming it out with this MC? On my car its just a little bit lower the the level of the gas pedal. But I got to say I really do feel like I am hitting the bottom of it, like I feel like the pedal is hitting a solid wall.

Your comment had me thinking this. I will go in a little bit more detail here.

I ran my first Wildwood MC for 2 track days at Sonoma. I did set the pushrod on the pedal pretty close to the MC for a very aggressive brake pedal feel. There was still a little play but it was less than .2 inches. I had caught covid and lost my sense of taste/smell for weeks. So I could not smell if my brakes were fading. I was getting some pad knockback and being stupid and not thinking I decided to adjust the rod even closer so it would be easier to heal toe. I only ran it like that for one session. Then I went to Laguna Seca, at Laguna Seca that is when I felt that the pedal go soft and I was hitting the bottom of the MC and getting horrible braking. My friend did not smell any brakes. I went home, bled my brakes with the engine running. Pedal still spongy, then I checked wheel bearings, everything was good. I checked my brake pads, no difference.

Contacted Goodwinracing, they sent me a new MC. I bench bled it, threw it on. I didn't even bother bleeding the lines. Pedal came back everything felt good. I went to Buttonwillow pedal felt real solid first session but there was no bite. I thought maybe I need to bed the new pads in. I did that let the car sit for an hour and went out. Second session I was real hard on the brakes and the pedal just started getting lower and lower. Till it felt like the first MC.

Supermiata got the story and told me to add more dead play with the push rod and the MC. I went ahead and gave the pedal lots of dead play. I went for a drive on the street with race rubber and while the pedal was really low, it was enough to lock the wheels. I noticed the car was rolling back on hills more easily and the car required less gas on the highway. I do trailer a 4x4 paddock trailer though so my feelings may be off. However, when I was at the track I noticed something. When I was driving around the paddock my brakes were making the faint brake rubbing noise every rotation that it always used to when everything used to work right. Then during the sessions the pedal felt like shit but I was able to lock them a couple times. But I was mostly bottoming it out.

So I am thinking maybe the pushrod was dragging and that caused the MC to break. What you all think? I hope you have a smooth recovery LeoNA.

I’m running the gloc pads as well and they make a bit of noise when driving slowly. They are just moving around and contacting the rotor. The smaller pistons in the multi-piston calipers don’t retract much. It is determined by the cross section area of the square piston seal. I think we’re talking about two different op-rod adjustments.

https://cimg9.ibsrv.net/gimg/www.mia...4ea2da670.jpeg

Yes and I never heard that noise until I gave the rod more dead play with the MC. It used to always make that sound before I installed the MC and adjusted the rod to be more aggressive. I now am more convinced that the brakes were dragging but I still never smelled cooked brakes. So it possibly could me the MC is bad but I still have my doubts.

Looks like we are talking about two separate adjustment points. However both essentially do the same thing. If you adjust the rod at the pedals underneath the dash it effectively changes the rod length when the brake pedal is fully released.

Their two different rods. They are separated by the booster. The booster has a neutral position when energized. It can apply pressure to the piston in the mc even if the peddle op rod has clearance. In your case I don’t think it’s enough to keep the calipers applied but enough to not expose a port or ports to allow fluid to flow into the piston of the mc. If the calipers were not releasing you would not make one lap a Laguna. Your rotors would be cooked. I went to Laguna to dial in my system, had 1/2 a turn to much bias to the rear and the rotors were dead by the end of the day. Grooved and blue.

Huh, I never new that. Maybe its a good idea to install a MC when the booster has sufficient vacuum.

Grooved and blue? These were my rotors after laguna.
https://cimg5.ibsrv.net/gimg/www.mia...d160b36f8.jpeg

My rear rotors were much worse. Although pictures don’t really show depth well, but they do look like they were working hard. What do the rear rotors look like?

No good photos. Just a one a while after the day of buttonwillow. Excuse the mud, I went off bad at buttonwillow and there had to be a mud pit. ha!
https://cimg7.ibsrv.net/gimg/www.mia...c26c4df079.jpg

Trying to be analytical.

Brakes don't lock even with high pedal force, possible causes:
- Insufficient booster assist? Leaking vacuum check valve or booster? But that would make pedal harder, not softer. Rule out anything booster related. It's hydraulic.
- Fade? Every symptom and condition points to fade, despite having R10/R8 BX11 on a stock power HPDE Miata which should be enough pad. Laguna Seca is hard on brakes. He'd have to be an advanced driver on 225/45 Super200's to find the limits of that hardware. So that's possible.
If the pedal comes back firm after they cool off, but then sinks as they get hot, that's fade. In such case, I'd find a way to get some 3" duct hoses to the gap under the calipers.
- Hydraulic failure? The pedal height would be erratic, not the gradual sinking with heat. Not outright failure.
- Incomplete bleeding? It would start mushy and stay mushy. Wouldn't be affected by heat. It's probably bled fine.
- Issue with pushrod preload not letting calipers and/or master reset properly. Symptoms point to this to some extent. A test would be to back off pushrod and pedal adjustment, run a session and see if brake maintain enough bite to lock wheels.

That's it, I'm out of ideas.

Forgot to ask, is this car ABS or non ABS?

Car does not have ABS.

Ill consider your points in the same order:
- Confident the booster is not the issue, so agreed.
- Yes, it feels like fade. Going into the first several braking zones, the pedal is nice and hard but the pads feel like they are rubbing but not biting. This is fade. Couple sessions later, the pedal begins to feel like mush. It does not come back after everything has cooled. Pedal continuous to feels like mush even after a full-bleed. Pedal only came back after replacing MC.
- Pedal height does just drop for the first 75% of travel. Then the last 25% builds some pressure. I could take my pinky finger and push down the pedal until I hit that last 25%. Little to no hydraulic pressure is built during that 75%. So maybe something hydraulic is going wrong but as a symptom of a constantly engaged pedal???
- I know how to bleed brakes. So yes, we can rule that out.
- I ran 2 days without fading issues with this setup, but I was not that hard on the brakes. I adjusted the rod on the last session on my second day at Sonoma, then took it to Laguna and immediately got the fade/pedal-mush symptoms. Changed the MC, felt fine. Went to Buttonwillow at first the pedal felt good but was fading during the first session. The pedal then became as I describe at point 3. Went home and then I backed off the pedal pushrod. I was able to lock the wheels driving around the street on the race rubber. But at Thunderhill 5 mile, it wasn't locking. Though, I only had the bottom 25% of the pedal. I then bled the car between sessions and the pedal didn't change. Possibly the hydraulics in the MC could have broken.

Now saying that the issue is in fact the MC is constantly engaging causing drag still leaves us wondering why I have little to no pressure gain for 75% of the pedal after several sessions. Bleeding doesn't fix it either. Possibly the seals of the MC got damaged because they constantly rested on the ports of the MC.

If no other suggestions come up, once I get my new MC kit from SM. I will install it and make sure there is enough clearance with the pedal and the booster pushrod.

Have you throughly inspected your hard lines for kinks, dents, or blockages? How is the pedal feel in each corner with the one bleeder open?

I don't understand how you all are so confident the booster is not an issue. This sounds like booster to me. Stiff pedal, no braking power. Sounds like unboosted brakes.

I gave a entire inspection of all the brake lines. No kinks everything looks good. My brake pedal slave(dude who pumps the pedal) says everything feels normal.

I don't think its the booster for the following reasons:
- After turning the car off I have about 2-3 pumps before the pedal starts stiffening up. Even if I leave the car for couple days.
- If I apply constant and equal pressure to the brake pedal while the car is off and then turn the car on the pedal will sink normally as soon as the engine starts.
- If I relieve all pressure from the booster and try to brute force the pedal, the pedal actually still feels like it has little pressure for the first 50%. Still a lot harder to press.

I should be more clear with my explanation. When I say the pedal is stiff, I mean its stiff as a good brake system feels when everything is working well. Its not like I cant push further. I can, the pedal just bottoms out. I believe I think I am hitting the bottom of the MC. I even hear it hitting it if I listen closely. If I had another car with the same MC it would be nice cause I could compare pedal travel distance. Not sure if your car has the same MC, but if so, we can compare. My pedal will bottom out little bit below the level of the gas pedal.

Ill try to look for any leaks next time I see the car.

Perhaps the check valve going to the booster? But yes all your tests indicate a properly working booster.

Ed

The last time you bled the system did you see any air come out? Bleeding can be a challenge especially on the clutch system on these cars. For that reason I recently purchased a motive kit to test out. Not a huge fan of the fact that it does not separate the pressurized air and fluid but thought since their made in Gilroy I would try it.

Here is my process and system specs. I will usually do a slight bleed before every track day and a full flush once a year so I do it a fair amount. My system is a home brew because when I put it together the SPM box mount kit was not out yet. Surely the way to go and would have saved me a bunch of time. I’m using the 4 piston dynapro, r10 pads with the aluminum hat 11” wilwood disc’s and their adjustable proportioning valve. Rear brakes are the na8/nb1 with powerstop track day pads. The MC is a rabestos Na6 replacement, not the bestos part and that’s what originally drew me to this thread. Fluid is just pentosin dot 4. Currently the system works good has run in the 1:40’s at laguna with me driving 400mi round trip to the track.

I use the two person method but have had to shore up it’s short comings to make it consistent. The worst issue is closing late and air being introduced around the threads of the bleeder screws. First fix is to Teflon tape the threads of the bleed screws. It should not be below the threads, not over the ports or the conical sealing surface. It doesn’t last long before the tape is ineffective. The little willwood bleeders do wear but are relatively inexpensive. The bleeding hoses get hard over time so I use new ones often. I secure them with safety wire.

I open the proportioning valve all the way when I bleed on new fills. Here is a little disclaimer about this because a mis-adjust PPV is one of the fastest ways to get you killed on the track. Make sure you can and do return it to it’s proper location. Mark the knob and count the turns from closed first. With the reservoir caps off I will slightly overfill the res with fluid. Make sure there are no air bubbles in the res from the pour. A little finger tap for good measure. I set the car up on stands usually level or with the back a touch higher. I used to just go corner to corner with the tools but now I install a wrench at each corner with a hose that is safety wired on the bleeder screw running into a clear jar.

Start at the corner which is furthest from the MC which is the driver side rear. I have the operator pump the pedal 2-3 times between bleeds to make sure fluid is entering the system from the reservoirs. Many pedal jockeys are erratic with the pedal movement which should be smooth with a light to medium pressure and the screw should be closed before the pedal bottoms. If the screw is not open enough the fluid speed in the lines can be too low. Open too far and you will not be able to close it in time. A tap tap from a small dead blow before hand is always a good idea and pay attention to the ambient temp. Cold temps make bleeding harder. I always inspect everything visually and check mounting fasteners at this time. If your MC has an internal leak you will not be able to bleed out the air and it will be obvious. There may also be fluid leaking down the booster. Good luck.

I started investigating on the car itself. If I remove the Master cylinder and connect my old one without it being connected to any hydraulics the pedal has so much more travel, like we’re talking 3x the travel.

so either bad booster/or kink or clogged lines.

edit: well actually if a line was kinked then any other caliper would lock its wheels. I’m leaning towards bad booster. I will check it rn.

Or bad adjustment of the pushrod just as LeoNA suggested. A quick test for this is to see whether you can easily push fluid through the system with a Motive bleeder, since bad pushrod adjustment will block the transfer port.

I believe the rod is fine. I test fit it. Same issue. Pedal just stops at a certain point doesn’t want to go further. Rather then adjusting the rod cause I think it’s fine, just put some spacers between the MC and booster. Same issue pedal just doesn’t want to go further past a certain point.

I think the worry is that bad adjustment broke your MC (it can easily destroy the seals). I would try this after replacing the MC.

That was one of my thoughts. Not that I’m disagreeing, but, I want to know why you say the seals would break. I can only think of it as it’s always resting on open port rather then a smooth surface.

So this is where the car stands:
- Brake travel feels limited to just a little lower then the gas pedal. If I open a bleeder and push the pedal drops a lot lower. If I hookup a MC to the booster without connecting hydraulics the pedal just can drop to the floor.
- With everything connected the pedal just feels extremely difficult or impossible to press passed the gas pedal.
- I did not hear any visual leaks with the booster.
- I turned the engine on and the adjustment rod seems fine. I can easily press the MC against the booster to be flush.

With foot on brake and medium force, engine off, the pedal should be rock hard and high. Without releasing pedal pressure, start engine. Pedal should sink and become a little softer as booster receives vaccuum. If pedal doesn't change at all, stays stiff and high, you have no booster function.

I decided to tackle the issues. Prior to changing the master cylinder with a new one I made sure that the brake booster rod had proper clearance(0.2 inches). After install and bleed, pedal feel did not change. I took it to a performance shop and has them double check everything. They then reinstalled the MC checked the clearance and pedal still is the same. Both of us agreed that the booster is the culprit. It feels that its impossible to push the pedal after a certain distance. When I bleed the brakes the pedal can easily be pushed a lot lower.

Now before I purchase a new booster, I am honestly thinking about just deleting the booster entirely. Couple options available:
Slap the Honed booster delete kit with the 1" MC or a OEM MC. I do believe this would require way to much pedal effort.
Slap on the Fab9 kit, i really don't like the fact that its a 1 way system.
Follow some of the guides on this forum and do a custom duel MC system.
Or just fix the booster and call it a day.

Don't forget mazda used different ratio boosters in different models. I believe the lowest ratio is 1:4. A quick search should tell you which car to source from.

The Honed kit includes a template to drill a new hole in the pedal to improve the pedal ratio, but does not get it to stock (NA8) ratio. Also remember with a bigger master and no booster, it maybe harder to modulate the brakes. A bigger master will mean less pedal travel to modulate the pressure at the calipers.

Ahh so your saying when you switch from boosted to manual brakes, a smaller MC is preferred as the pedal stiffness will be there, its just you want that flexibility of more pedal travel along with the stiff pedal?

What do I win if it's the booster? :hahano:

Basically yes. Too little travel and heal-toe braking becomes an issue.

This weekend I got hold of a working booster & valve and the time to put it in. Sadly.... issue remains the same. The pedal is just sponge until the last 20% of travel and that last bit can't lock race rubber. Running out of ideas here. However....

Something I noticed when reading step 2 in the instructions for the same kit on v8 roaster, "Check to make sure that the rod from the booster is slightly compressing the plunger in the new master at static(no pedal pressure). To check this for engagement use a small piece of molding clay on the tip of the rod. Install the master like normal, then remove and check to make sure the clay is completely compressed. If it is not, the difference in the clay will need to be added to the rod by adding a small amount of weld on the end of the booster rod. If the booster rod is not fully engaging you are only getting partial pressure from the new master." I put that in bold cause it feels like I'm getting partial pressure.

When I swapped in a master cylinder that was dry and not connected to any lines the pedal had so much travel before it bottoms out. If you hook up the lines and only have fluid in the system the pedal travel is limited by 3x, as in if I put all my strength into pushing the pedal I will hit a wall 1/3 of the stroke of the pedal with no lines connected to the MC. Could anyone explain to me why this is? Does a booster just have a maximum amount of that travel that it can build pressure?

Maybe v8 roadsters are right but from what I know a booster should make pressure no matter what, low pedal anything Sigh.... Getting to the point where I may just go back to the OEM MC and get a HOONED booster delete kit. This will just make the whole system even simpler. But part of me is starting to think that the MC or booster isn't the problem. Me and a reputable shop have done throughout inspections of components and nothing looks out of the ordinary. Might be time for swaptronics. :cry:

I would start by measuring the piston to flange distance of the oe mc that works and compare it to the wilwood unit. Its something I always do regardless if the replacement is an aftermarket or oe replacement. The welding of the op rod justs sounds dumb. It the distance is too great the adapter could be milled down. Sometimes when the mc is bolted on you can see if the piston moves though the fluid port holes in the bottom of the reservoirs.

Agreed, there way of fixing sounds really stupid. You could honestly just turn the nut on the rod and it will extend. More safety measure put some Loctite or just add a jam nut. I did measure both MC's. They are within 3 mm of each other. The rod to the MC piston measures 2mm. And they are measured in account for all differences in master cylinder bodies.

I have solved the issue.

I decided to isolate each brake circuit until I could pinpoint an issue. Using only stuff I had in the garage I made some plugs:
https://cimg9.ibsrv.net/gimg/www.mia...4b3ad7b746.jpg



I plugged the rear circuit. Pedal still felt garbage. I then plugged the front circuit with the rear open, the pedal is still garbage. Pugged both and that leaves the MC feeling like garbage. Well, I changed that 3 times. Then that leaves the booster. Ahh, well I changed that too. So then what the **** is wrong?

I decided to listen to V8roadsters instructions: just extend the rod at the booster until it was obvious that the MC was going to be preloaded. I kept repeating while adjusting the rod until the plunger was not being preloaded. And ya, that fixed it. It looks like it was extremely vital to make sure that the rod is adjusted with virtually no gap. I took it up some mountain roads to further test it. Been a while since I've driven the car there, was pretty nostalgic. Anyways...

I am assuming when I first put the MC, the rod was binding on the edges of the MC walls, when I got to the track that bind gave and now the MC was being compressed right. The same thing happened when I put the second MC in.

Overall this whole brake system feels great. Supermiata Boxmount + the 1" Willwood MC is definitely a nice upgrade. My track buddy drives a mustang GT and I was always jealous of how his pedal felt with those Brembo's. Now I am no longer jealous.

If anyone is planning to do a 1" Wilwood Master Cylinder, MAKE SURE THE BOOSTER ROD IS ADJUSTED TO JUST BE TOUCHING THE MASTER CYLINDER. If you just slap it on, odds are it won't work. Looks like Ed was the winner.

I will be probably making a post with install notes on these kits.

Thanks for all the help guys.

Man. So, booster pushrod adjustment huh. Wild. Glad you got it figured out. What a saga.

:likecat: awarded.

I'm glad you figured it out. There are two op-rod adjustments. One from the pedal to the booster and one from the booster to MC. The booster to MC is not an easy dimension to measure. It can have a very small amount of clearance to a small amount of pre-load as long as it does not cause the mc piston to block off the feed port from the reservoir.

This was the difference in length of the rod before I adjusted it. Never would have thought such a small gap could be the difference from garbage brakes to amazing brakes. Well I'll be damned!

https://cimg3.ibsrv.net/gimg/www.mia...7eb16b85f1.jpg

Just spent some time reading through this thread.

What booster has a rod that sticks out that far?

I am attempting to install the 1" wilwood master on a 2001 non abs car and the rod is way too far in booster.

You need a earlier model one. 97 or under I have a extra if you wana pay or shipping.