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Discussion Starter #1
I bought a new master cylinder and vacuum booster. The combo is much longer than the original.
[/url]master cyl 1 by Patrick Smith, on Flickr[/IMG]


[/url]master cyl 2 by Patrick Smith, on Flickr[/IMG]

[/url]master cyl 3 by Patrick Smith, on Flickr[/IMG]


Since the assembly is so long it projects to a much higher height. I am afraid it might hit the hood.

[/url]master cyl 4 by Patrick Smith, on Flickr[/IMG]


It has a 17 degree angle which is the what the stock one should measure from the factory.

[/url]master cyl 5 by Patrick Smith, on Flickr[/IMG]

I have read several posts in this forum asking how to reduce the angle to make it more level, but none of them really came up with an answer. Some mention different mounting brackets or adding washers to shim the vacuum booster. I do not have any qualms about cutting and modifying something. I think if I cut the bracket then I will also have to modify the rod that the brake pedal connects to keep the geometry correct.


The hood might close. I do not like the look of the master cylinder looking at the stars.

[/url]master cyl 6 by Patrick Smith, on Flickr[/IMG]


[/url]master cyl 7 by Patrick Smith, on Flickr[/IMG]


[/url]master cyl 8 by Patrick Smith, on Flickr[/IMG]


[/url]master cyl 9 by Patrick Smith, on Flickr[/IMG]


I am wondering if there is an aftermarket part available or has anyone leveled the master cylinder successfully? Any suggestions would be appreciated.
 

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The angle is to prevent side loading for the required pedal ratio. I would not mess with it unless absolutely necessary. Change the booster to a single like the Detroit Speed one if necessary. Those small diameter duals are not great imho...

Don
 

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Looking at the pics your hood should clear no problem.

Don
 

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Discussion Starter #6
Thank you Mr. John and Mr. Don for the suggestions. I agree the master cylinder will clear the hood. The assembly just looks crooked. I did not choose the Detroit Speed master cylinder assembly because the reservoir is made of plastic.

Mr. Simon, I looked at the bracket you found. I might use it as an example to cut my existing brackets and weld them back together. The brake push rod angle will change if I cut the brackets. The rod might bind if I change the angle too much. I could drill a new hole in the brake pedal or maybe use the other one. Moving the push rod to a new hole will affect the pedal ratio. The pedal ratio is one of the factors that determines how much line pressure the brakes can develop. I will have to redo all my calculations if I change the pedal ratio. Nothing is easy. That's why I enjoy this hobby.
 

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Discussion Starter #9
What brake rotor diameter are you going to use this with? You could maybe go with a manual brake system
Two questions will cause me to write an essay. :surprise: :wink2::smile2:

I have purchased the rear brakes. They are Wilwood model 140-10012. They use the thinner 14 inch rotor. The calipers have four pistons. The pistons area is small, 1.98 square inches. The caliper name is Superlite 4R. The bore is the 1.12 inches. Since I am using the small piston size calipers, I am under the impression I need the assistance of the engine vacuum to get enough clamping force. If I knew then what I know now, I would have bought a different kit.

I have not purchased the front brakes. I am planning to buy Wilwood model 140-13766. The brake rotors are 14 inches in diameter and use the same type of caliper as the rears but they have 6 pistons. I do not think I can fit the larger Aero type brakes in the front because I am afraid they will not fit inside my wheel. The piston area is 4.04 square inches. The bore is 1.62, 1.12, 1.12 inches.

Brake pads are BP-10 type.

Master Cylinder is 1.125 inch bore size, tandem type with a proportioning valve.

Vacuum booster is a dual diaphragm eight inch model made by Right Stuff.
 

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I run 6 piston Wilwood fronts and 4 piston rears without boost. Works great and don’t have to worry about vacuum or the angle or clearance for a booster
 

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I had no idea disc brakes could be used without power, I have been struggling with hard peddle from low vacuum and was thinking of getting a vacuum pump.
How can the booster be eliminated? is it the same master?
Sorry to step on this thread but it would also give me more room for the air cleaner on the Procharger.
 

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Move the brake rod to the top pedal hole and use a different bore MC. 1” will work for Disc/Drum and a 15/16” or 7/8” for disc/disc
 

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Thank you, I am 4 wheel disc so I guess the larger the bore the better?
As long as I don't have to stand on the brakes to stop.
Talk to tobin at kore3. He can advise you on bore size and also the best pads to use.
 

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Discussion Starter #16
Thank you so much for the advice.

I decided to go ahead and purchase the DSE bracket that allows the vacuum booster and master cylinder to sit level. I thought about cutting the original bracket and welding it back together. It has cadmium plating and it would be poisonous to inhale the burning fumes. Plus I would have to refinish the bracket after welding.

The bracket forces me to use the manual brake hole in the brake pedal. In my case I do not think it will be a problem. I ran the calculations with the larger brake pedal ratio. The torque to the rotors increased, but now it is in the range where it should be for a good street car (3500 lbs-ft). In the power assisted hole it was in the range of a production car. I think I will be ok.

[/url]brake calculations by Patrick Smith, on Flickr[/IMG]

If anyone sees something wrong with my plan or calculations, let me know. I find it interesting that the high dollar brakes really require some sort of power assist to get them to perform as good street brakes.
 

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I would be concerned about having too much boost with the booster level. I'd ask DSE if the master cyl should be a different diameter with the level booster setup.
We run 14" manual brakes with Baer 6R calipers, I'm not sure how the bore sizes compare to Wilwood. I have driven a manual brake 68 Camaro with Wilwood 6 piston calipers and it was fine. A manual setup is more sensitive to pad type/CF. The big issue with manual brakes is pad knock back which manual systems are more sensitive to. You feel the pedal drop a lot more, and the rear axle will knock the pads back causing a lot of pedal drop, even if it's a Ford type, of which there are two. A full floater rear axle is the only way to reduce it. The front spindles flex and the stock type tapered roller bearings allow knock back too, just less than the rear.
On a manual brake system we ran a 15/16" bore diameter. Brake pedal travel will be higher on a manual system.

I see your spreadsheet lists your bore diameters in sq inches when they should be inches.
 

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Discussion Starter #18
:surprise:You are right... the bore diameter should be in inches not square inches. Stupid Patrick. So you are telling me that when I tap on the brakes, I am going through the windshield? That thought has crossed my mind. The problem with the Wilwood brakes is that they have a small piston area. I am thinking that I need a lot of line pressure to compensate for the small pistons. The pistons need a lot of pressure so they will have enough force to push the pads against the rotors.

This is a street car. I thought power brakes would be nice. On the other hand, manual brakes are so much simpler.

The big unknown for me is the actual amount of vacuum my engine can provide. It is a supercharged LSA engine. GM provides a vacuum line for the booster. I cannot find any data that tells me what a good number would be to put in my spreadsheet. I think 7.9 inches in the spreadsheet is a very high number. I am not sure how GM's supercharged engine produces any vacuum.

The Ford 9 inch rear end is not the full floating type. It does have tapered bearings.

The front subframe was made by Detroit Speed. It has the Corvette C6 type spindles.

I called DSE in the past for other problems. They never shipped the missing bolts for my subframe. My Quadralink rear suspension also had missing parts. I ended up going to the hardware store after another disappointing phone call. I called them gain and tried to ask them about using Wilwood brakes on their subframe. They told me to call Wilwood.


I would be concerned about having too much boost with the booster level. I'd ask DSE if the master cyl should be a different diameter with the level booster setup.
We run 14" manual brakes with Baer 6R calipers, I'm not sure how the bore sizes compare to Wilwood. I have driven a manual brake 68 Camaro with Wilwood 6 piston calipers and it was fine. A manual setup is more sensitive to pad type/CF. The big issue with manual brakes is pad knock back which manual systems are more sensitive to. You feel the pedal drop a lot more, and the rear axle will knock the pads back causing a lot of pedal drop, even if it's a Ford type, of which there are two. A full floater rear axle is the only way to reduce it. The front spindles flex and the stock type tapered roller bearings allow knock back too, just less than the rear.
On a manual brake system we ran a 15/16" bore diameter. Brake pedal travel will be higher on a manual system.

I see your spreadsheet lists your bore diameters in sq inches when they should be inches.
 

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The LSA will still have good vacuum of close to 15".

Boost will give psi but only under boost. Your not boosting and braking at the same time plus the vacuum canister has a check valve where you attach the vacuum hose to hold vacuum.

For power brakes you'll want a 1 1/8" to 1 1/4" MC
 

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:surprise:You are right... the bore diameter should be in inches not square inches. Stupid Patrick. So you are telling me that when I tap on the brakes, I am going through the windshield? That thought has crossed my mind. The problem with the Wilwood brakes is that they have a small piston area. I am thinking that I need a lot of line pressure to compensate for the small pistons. The pistons need a lot of pressure so they will have enough force to push the pads against the rotors.

This is a street car. I thought power brakes would be nice. On the other hand, manual brakes are so much simpler.

The big unknown for me is the actual amount of vacuum my engine can provide. It is a supercharged LSA engine. GM provides a vacuum line for the booster. I cannot find any data that tells me what a good number would be to put in my spreadsheet. I think 7.9 inches in the spreadsheet is a very high number. I am not sure how GM's supercharged engine produces any vacuum.

The Ford 9 inch rear end is not the full floating type. It does have tapered bearings.

The front subframe was made by Detroit Speed. It has the Corvette C6 type spindles.

I called DSE in the past for other problems. They never shipped the missing bolts for my subframe. My Quadralink rear suspension also had missing parts. I ended up going to the hardware store after another disappointing phone call. I called them gain and tried to ask them about using Wilwood brakes on their subframe. They told me to call Wilwood.
DSE customer support is marginal at best. That is why I buy Art Morrison when I can. I even have the email and phone number of the engineer who designed my stuff. Very nice guy and always willing to help.

Don
 
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