Brake master cylinder brace, and servo / booster removal
 

I've come across a few threads that mention bracing the master cylinder, but none that go into any detail about removing the servo.

Bracing the brake master cylinder on these cars is very popular here in the UK. I've not heard many people making a big deal of it on MT. Is there anybody who has done such a mod, and anyone who would care to talk about any positive (or negative) affect it had on brake feel?

I've driven one NA that had the servo removed. The brake feel was fantastic; completely solid pedal and very progressive.
When I mentioned my dislike of the free travel at the top of my brake pedal - and my desire to achieve a Caterham-like brake feel - to the person building my car, he immediately suggested removing the servo assistance.
Again, I've not heard much mention of this on MT. Would anyone care to share their thoughts and experience on this matter?

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Outstanding idea!! waiting to hear opinions of those who have done it......

As I said, I've driven a mk.1 with no servo assistance, and it was fantastic. So I know it can work. I'm more interested, to be honest, as to why the racers DON'T run without servo assistance. I can only assume that because it doesn't improve braking power, that the potentially improved subjective feel isn't worth the extra leg effort if you're only looking for the fastest possible lap times.

http://www.norcalroadsters.com/forum...hp?f=33&t=8047

https://www.miataturbo.net/attachmen...ine=1317769852

Not my work, but I do know the guy.

There is also some talk of modifying the shock top mounts off of cheap eBay strut tower bars (STB). There are pics out there but I'm too lazy to look.

The Yankee name for "brake servo" is "brake booster".

I'm looking into removing the booster on my track/race car. Removal of the booster would require a higher pedal ratio and I think to be done correctly, a dual master cylinder. My situation may be different than most, as my engine is naturally-aspirated and I believe my (mild) cams are not providing quite enough vacuum for the servo (booster) to operate to its full potential.

Many, many Miata owners have posted about solid pedals with properly setup brake systems that utilize one of the various stock boosters, so it is probably not worth it to them. Here's some good info about various MX-5 & Mazda master cylinders, boosters, and calipers: Some interesting brake information (tech!)

That said, I know of a car that has stock Miata brakes, stock master, and after market proportioning valve. The car is a Locost built from MX5/Miata parts. The brake system does not include a servo/booster. The car uses a stock Miata pedal box, however the brake pedal was modified to increase pedal ratio. The amount of required pedal force to stop the car increased substantially.

I have a pair of master cylinder/brake booster braces. I tried one like the picture above, except it attached to a non-modified shock tower brace, and though it worked it wasn't great. The shock tower flexed and allowed the master cylinder to continue to move. The brace pictured above seems much more stout.

The two braces I have now work excellently. Best I've seen on any car. Each aluminum brace runs from one of master cylinder bolts to a point on the chassis. These are the two bolts that hold the master cylinder to the booster. One of the chassis points in on the frame and the other is the shock top hat bolt closest to the fender. A friend made them and they were quite cheap. Just a couple of bent pieces of aluminum bar with some bolt holes. With these braces, neither the master cylinder or booster move at all, even under heavy brake pressure.

^^^Pictures, now.

I'm using the modified ebay STB for a MC brace, lemme see if I have a picture...

Nope sorry.

those BMC braces alone work some pretty significant wonders on 300zx's i know. i had looked around for one for the miata with no luck. time to look again

I had been planing to make a thread about all of my brake mods I did this year, but the booster delete pics should fit nicely here.

The configuration of the pedal assy does not allow to just remove the booster, and bolt the master to the firewall. there are standoffs to the plate, I built an elaborate spacer.

https://www.miataturbo.net/attachmen...ine=1317824877

The spacer turns the standoffs into a solid mount to the firewall, and allowed me to install studs to mount the master.

https://www.miataturbo.net/attachmen...ine=1317824877

The whole assy bolts solid to the firewall.

https://www.miataturbo.net/attachmen...ine=1317824877

The master bolts securely, and is a bit more solid than the stock power brake setup.

https://www.miataturbo.net/attachmen...ine=1317824877

I did have to fab a new pushrod for the setup, as the stock one did not work at all, sorry I did not take any pics, but it was basically I used the stock clevis that hooks to the pedal arm, and a long bolt with the head cut off and contured to fit down into the master cylinder piston.

This is a 91 Miata with 1.8 brakes front, and a hybrid 1.8/sport setup rear (sport calipers on 10" rotors, more on that later) Even with larger pistons all around, and the stock power master, the brakes work fantastic! The pedal effort is not huge, the stroke is not long, and the stopping power is easy to modulate, from a tap to set suspension on a corner, to ohhhhh shit I'm in too deep! I will recommend this conversion to race or street drivers, I am very happy with the results.

Edit: Review of my pics, I see the pushrod is actually in the first pic.

I am considering going to larger pistons on the calipers in combination with going Boosterless. I haven’t yet started to calculate what I think it might take. I do have a car now that I have started into a very slow process of building an extreme Autocross XP car which could also be Road Raced in SPO. I plan to go boosterless. Not having to worry about having consistent vacuum in the booster to get consistent braking I consider to be worth it. Especially if you add in a lot of left foot braking, crossing throttle and brake, and blipping throttle on downshifts while braking where the booster will screw with braking response.

Bob

Crappy iPhone pics:

https://www.miataturbo.net/attachmen...6&d=1317856337

https://www.miataturbo.net/attachmen...7&d=1317856337

https://www.miataturbo.net/attachmen...8&d=1317856337

https://www.miataturbo.net/attachmen...9&d=1317856337

Good responses, thanks. I've decided I'm going to go servo/booster-less on my car.

Does anyone know how much the servo/booster unit weighs? I've tried Google, lots.

what does bracing the master cylinder do?

It braces the master cylinder? :fawk:

Pop the hood and get someone to pump the brakes while you watch the master cylinder/booster.

I was about to comment on the Youtube poster's fantastically nerdy voice, until I saw that it was sjmarcy. Comedy.

Thanks :)

Is that bolt threaded into the MC or is it just wedged against it to prevent it from moving

ಠ_ಠ

http://www.norcalroadsters.com/forum...hp?f=33&t=8047

Would you consider upping the piston sizes on the calipers all around if you were to try tweeking the setup a bit? I’m thinking of ditching the E-brake and using Dynalites or something on the rear so I could easily do something different with piston sizes to reduce the required pedal effort a bit after removing the booster.
Bob

Bob

I had already put on the 1.8 brakes all around, and was unhappy with front lockup all the time. My approach was to up the rears a little, with the larger sport caliper.

This was the fix for me, as now instead of the prop valve screwed to all the way more rear, to about 3 turns from the end, and now I can adjust for track conditions. No more flat spotted fronts, much less front pad wear, and now that the rears are actually biting the rotor, the noise is all but gone.

I cannot imagine a front only upgrade being manageable, and I now have another set of sport calipers to put on my street car!

Ron

That is not what I was asking.

My car now has 11.75" front rotors with 1.38" X4 pistons. and 11.44" rear rotors with 1.375" Sport caliper pistons but it still has a booster although it has a 1" Master cylinder.

The bias is great and tunable with this setup via the wilwood adjuster. But sometimes Heal toe and left foot braking the booster really jacks with brake feel and consistancy.

So in getting rid of the booster. it seems I would want to up the mechanical leverage ratio a bit to make up for the lack of boost? There are some options.

1) Go back to a 7/8" master cylinder.

2) Maybe use calipers with 1.5" pistons front and rear. Or maby 1.5" in the front and 4 piston 1.375" in the rear.

Designing the braking system from scratch I do have some options. I might even go to a dual master setup.

Bob

Just my "opinion" but I would think the 1" would be an improvement to mine, less pedal movement. I do not have issue with pedal pressure, but dont think less distace would be an issue.

Willwood tripple master is in my future, with luck this winter. I have good brakes, but with losing the E-Brake, one leak could be serious! The tripple (dual with clutch) would be safer, and more adjustable. I'm also in for less clutch pedal distance.

Bigger rotors are out for me till I can afford to change to 8 larger wheels.

The 1" Tandem wilwood master cylinder has front and rear circuits completely independent. I think if you lost a single brake line on a corner you wouldn’t lose all brakes like with the stock one.

http://www.wilwood.com/MasterCylinde...temno=260-8794

Bob

I am thinki8ng more along the lines of this

https://www.miataturbo.net/attachmen...ine=1320696716

I have been looking at those but not sure the ergonomics could be worked out right. If you look at where the stock location of the brake pedal is it is directly under the steering column. The pedal arm makes a jog to the right to get it there. I think to fit this thing in the brake pedal would end up about 3" further from the gas pedal and you would have to have your leg crossed under the column to operate the brake. It might work but it may not be too simple to get the positions right. .

Bob

Hi,
Would you consider making up one of these adapter plates for me?

Many Thanks,

:David

Try this


https://rover.ebay.com/rover/0/0/0?m...2F141028581231

Thanks stevos555,

That is the sort of thing, but the master cylinder mounts on mine are horizontal rather than vertical, and I want to keep the original Master cylinder set-up.

Regards,

David

I would drill new holes and plug honda vertical ones. Or you can contact Fab9 and they have the miata plate.

That did occur to me, but the plate needs to be at least 200mm thick to house the mounts already welded to the brake pedal bracket. Will look up Fab9.

Yeah - I erred on Fab9. Their kit is using wilwood master.

No problem. I grabbed the photos of the plate I need made up and posted on a few UK Mazda MX5 sites.

Thanks for responding anyway.

Since you are in the UK, check these guys out

https://www.compbrake.com/product/ma...ylinder-kit-b/

Looks like a proper bit of kit, including a bellcrank to get the pedal ratio right, balance bar, dual AP master cylinders etc.

Thanks, will do!!

Hi Guys, just to let you know I got one from someone who made one but never used it. So thanks for responding.

I still have a long way to go on my project, one small step at a time :x:https://cimg6.ibsrv.net/gimg/www.mia...fc7f9de880.jpg

Home made adaptor plate and shortened pushrod