Brake Advice Needed

[GreenSnakeDoc]

I just test drove a LA Exotics roadster I'm thinking of buying, and the brakes were really terrible. It took all the leg force my 150 lbs. to generate to do a hard stop: no need for ABS here as there is no way that I could have locked up any wheel on dry pavement. If I buy, what do you recomend for improving stopping power. There is no room to add a power brake booster to the master cylinder, maybe not enough room to add a Ford Mustang Hydroboost device. The front brake disc are from a Mustang II and are all of 9.3" in diameter and need to be increased. I bet somebody makes a conversion kit for these cars with 11" rotors that would fit inside the 15" wheels, so with multipiston calipers do you think stopping power will be greatly increased?:

[convincor]

what's it using for a master cylinder??
change it to a smaller bore.
My car is the same way right now. Smaller bore will give less pedal effort with more stopping power.

[GreenSnakeDoc]

convincor: Approximating the I.D. from the as-cast O.D., I'd say it probably has a .875" bore, 1.0" at the most. Trouble is, if I improve the front calipers to 2-piston floating pin type, I might need the fluid volume displacement of a larger diameter master cylinder.

[CHANMADD]

You can get a remote vacuum booster,BMW,ALFA ROMEO etc,go to a brake shop and ask the guys there.

[mgilbert]

greetings, beware some of the 11" rotors kits move the wheels out i can't remember how much an 1" or so but in my opinion lae & bb wheels are out almost to much to begin with. and yes brakes on my lae suck. that my next project. this coming winter. this weekend my 04 gto is getting the 05-06 brake upgrade. brakes handling power in that order for me. good luck see ya

[bobcowan]

Good braking for these cars is not hard to obtain. They're only about 2200-2500#. All the brake parts we generally use are designed for cars that weigh at least 1/2 a ton more.

So you have tio start by looking at the installed components. Take a sytematic approach. Are they quality parts? Installed and operating correctly? Good pads? Properly bedded in.

Since MGilbert also has poor braking from the same kit maker, I would first be looking as some small design flaw. The first thing that comes to mind is the pedal ratio. For manual brakes, it should be at least 7:1. It's all about leverage.

Measure the distance from the pedal pivot point, to the attachement point of the push rod. Then measure the distance from the push rod to the middle of the foot pad. The second distance should be 7 times the first.

[Madmiles442]

Agreed, Bob,
I contacted Willwood about changing my pads before the All Ford Meet in Tulsa. Told them what I was doing and they recommeded a more agressive pad and suddenly that thing would stop on a dime. Unbelievable. Would really make you woozy and pull your eyeballs outward.
Changing the pads will give you all the stopping power you want. It's up to you to clean the front wheels because those mothers dust!
I also changed the brake fluid to Motul 600, but you've got to be pushing hard to see that difference.

[mickmate]

I just sold an ECI hot rod brakes kit that puts the 11.75 x .810 Vette rotors and Calipers on an MII spindle. There are cheaper ways of sorting it out like cylinder sizing and pads as suggested.

[GreenSnakeDoc]

Thanks guys, it looks klke the fix will be contibutions from several sources:
increased disc diameter, more agressive pads, larger or multiple cylinders, pedal lever ratio. Over on the ffcobra forum, I've found that donor Mustang brake pedals have two pivot holes: one for power brakes and one for manual. There's also an inline booster device that I think can be installed in the line to the front brakes. It supposed to have a stepped piston inside that boosts line pressure 70%. It costs around $160. Then, there's always the consideration of having the proper balance between the front and rear. Never the less, 9.3" rotors on Cobra front wheels is ridiculous. I think the original 427 Cobras had opposed single piston (1.75" dia.?) pressing on solid 11" discs.

[mickmate]

about 11 3/4"

[Bill E]

We have used the geo tracker booster with a GM vet master.This will work well with the brakes you have but will be spongy with larger callipers. You will have to widen the mount holed in the Master and cut a piece of tubing to fit the plunger in the master to the push rod in the booster. You will make a gasket to seal the back of the master. this will give you good peddle feel and just the right amount of boost. I have photos of a finished system if you wont them.

[LMH]

I have 12.19" Wilwood rotors on the rear of my car with 15" Trigo pin drives. It's a close fit but it works, even with a parking brake. Wilwood makes a Mustang II kit for the front that complements the rears with the same size rotors.
However, keep in mind that the whole system needs to work together, not just rotors.
Larry

[Silverback51]

The last post was 3 years ago gentlemen.

[LMH]

Originally Posted by Silverback51

The last post was 3 years ago gentlemen.

That's ok, its good info for those searching for similar current issues.
Larry