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Old 10-04-2011, 04:28 PM   #1
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Default 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?

Last edited by owenwilliams; 10-05-2011 at 01:12 PM. Reason: clarification of title and text
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Old 10-04-2011, 04:41 PM   #2
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Old 10-04-2011, 06:03 PM   #3
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Outstanding idea!! waiting to hear opinions of those who have done it......
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Old 10-04-2011, 06:10 PM   #4
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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.
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Old 10-04-2011, 08:10 PM   #5
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http://www.norcalroadsters.com/forum...hp?f=33&t=8047



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.
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Old 10-04-2011, 10:42 PM   #6
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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.
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Old 10-05-2011, 12:06 AM   #7
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^^^Pictures, now.

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

Nope sorry.
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Old 10-05-2011, 09:20 AM   #8
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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
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Old 10-05-2011, 11:27 AM   #9
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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.



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



The whole assy bolts solid to the firewall.



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



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 **** 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.
Attached Thumbnails
Brake master cylinder brace, and servo / booster removal-dsc_0689.jpg   Brake master cylinder brace, and servo / booster removal-dsc_0691.jpg   Brake master cylinder brace, and servo / booster removal-dsc_0697.jpg   Brake master cylinder brace, and servo / booster removal-dsc_0698.jpg  
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Old 10-05-2011, 05:30 PM   #10
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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
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Old 10-05-2011, 08:17 PM   #11
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Quote:
Originally Posted by curly View Post
^^^Pictures, now.
Crappy iPhone pics:







Attached Thumbnails
Brake master cylinder brace, and servo / booster removal-brakebrace1_800.jpg   Brake master cylinder brace, and servo / booster removal-brakebrace2_800.jpg   Brake master cylinder brace, and servo / booster removal-brakebrace4_800.jpg   Brake master cylinder brace, and servo / booster removal-brakebrace5_800.jpg  
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Old 10-07-2011, 01:50 PM   #12
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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.
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Old 10-08-2011, 04:51 AM   #13
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what does bracing the master cylinder do?
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Old 10-08-2011, 05:47 AM   #14
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Quote:
Originally Posted by giblets View Post
what does bracing the master cylinder do?
It braces the master cylinder?

Pop the hood and get someone to pump the brakes while you watch the master cylinder/booster.
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Old 10-09-2011, 08:29 AM   #15
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I was about to comment on the Youtube poster's fantastically nerdy voice, until I saw that it was sjmarcy. Comedy.
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Old 10-09-2011, 11:40 PM   #16
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Thanks
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Old 10-10-2011, 01:50 AM   #17
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Quote:
Originally Posted by EO2K View Post
http://www.norcalroadsters.com/forum...hp?f=33&t=8047



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.
Is that bolt threaded into the MC or is it just wedged against it to prevent it from moving
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Old 10-10-2011, 01:24 PM   #18
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Quote:
Originally Posted by Slacker2223 View Post
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
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Old 10-21-2011, 03:18 PM   #19
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Quote:
Originally Posted by Alta_Racer View Post
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.



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



The whole assy bolts solid to the firewall.



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



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 **** 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.
Would you consider upping the piston sizes on the calipers all around if you were to try tweeking the setup a bit? Iím 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
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Old 10-21-2011, 11:24 PM   #20
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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
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