The reality is that when you're trying to feed 24 pistons, there are very few masters capable of moving that much fluid in one stroke with the pedal ratio of a stock vehicle. I have 6, 4 piston calipers (dual rear) aerospace calipers on my Chevy II, and its stops just fine. I'm also sure I could stop the car just as well with only 4 of those calipers as well. Its was a poor decision on my part financially, but if you have them, it won't hurt you. In speaking with them, they wanted to see 900 psi at the rear calipers. Locking up the rears? I would verify that you are using the proportioning valve correctly. Many times, the way you THINK you would turn the screw on the valve, in reality is opposite to the way they actually work. That would explain the lockup. You think you're closing it off, when in reality, its wide open.

 

Is there a way to check line pressure on front vs rear to see how that looks?

 

Summit has some single inline gauges that can be used. I ordered (2) - That way I can have one gauge on the front and one on the rear. How should the pressures look on front vs rear?

 

It also allows you to see exactly what happens when you makes changes with your pro valve.

 

You do not need dual calipers on the rear brakes.

 

Do I really need dual calipers when using a T-Brake?

I would not think so unless you will go footbraking or need the stopping power at the end of the track

 

I got my pressure gauges for my front and rear calipers today. I installed the gauges and bled the brakes. The pressures below were from me standing on the brakes pretty hard.

The proportioning valve has just 1 click for the rear.

My issue is that if I press on the brake pedal firmly after a pass, I have problems with the rear tires wanting to lock up.

Is the concensus to remove a caliper on the rear?

Strange Calipers on the front
Dual Aerospace calipers on the rear

Front Pressure: 940 PSI
Rear Pressure: 490 PSI

 

The proportioning valve has just 1 click for the rear.

The proportioning valve should be on the front to reduce the pressure there and have full pressure on the rears.

FAQs - Brakes - Strange Engineering

Recommended brake pressure will normally get you in the ball park, but many factors will play a role in achieving optimal braking. There are all the different elements that exist between front and rear. Weight, tire height, width, compound, pressure, rotor diameter, number of pistons per caliper, piston diameter, brake pad area and compound. Always begin with the manufacture’s recommendation and adjust as needed.

The following suggestions are assuming that this is a Drag Race vehicle and you are using an adjustable proportioning valve, like our B3369, plumbed to the front brakes. To maximize braking, all four tires should want to lock-up at the same time. Many may choose not use this valve, but their braking will never be as good as they possibly could.

Front brakes 550-650 PSI / Rear brakes 1,000-1,200 PSI

These pressures should be achieved with a very hard push on the pedal, like your setting the line-lock. It will give you a comfortable pedal when your stopping the vehicle. If you don’t have pressure test gauge, take a look at the P2360.

Adj Proportioning Valve

 

IMO, No. They can never hurt you. Use the rear proportioning valve to reduce pressure to the rears. You just need to find the balance that works for your set up. You ONLY have the manual proportioning valve correct? Is the stock proportioning valve still in the system as well? When I bought my kit, AE also included very thin washers so you could center the calipers on the rotor. Since they are hard mounted, and don't "float", this is something you need to do every time the caliper is off the car. You need to verify the rotor is on center in the caliper, with the caliper and rotor tight, and the pads removed.

 

With 2 types of manufacturers calipers there are a couple of things are going on here that are not "normal".

Because you have 2 types of calipers you also need to do is look at the size (area) and number of pistons on the front and rear calipers. If you have too much area on the rear calipers (area of each piston x number of pistons) vs the fronts then they may be too powerful even with the proportioning valve fully adjusted. There is a limit to how much bias the proportioning valve can do.

Also, the pads material on the front/rear calipers may be different. With one manufacturers caliper you usually have one type of pad with the same material. Depending on the material, the coefficient of friction will vary as the brakes heat up. One type of pad may be great "cold" but another type may not be nearly as effective.

 

Not to disagree, but like the literature says, you want all the brakes to lock up at the same time. Clearly the rears will have more braking capacity than the fronts, and under braking conditions, it is not uncommon to have somewhat of a nose down/ass up condition, making it even easier to lock up the rears. Scaling bias in the car shows 52% front and 48% rear. I have run this brake set up on my Chevy II for 6 years, using the same aerospace calipers/pads up front as well without issue. I have my pro valve limiting the rears, using the above weight philosophy.

 

Since I have the aerospace rear calipers, I called and talked to Aerospace for about 40 minutes this morning. Per Aerospace, they suggest not running a proportional valve since the master cylinder should be set to be a 60/40 split. They gentleman there that I was speaking with was named Scott. Said he's worked there for 25 years and has his own drag car. He said that it should be 1000 psi on the front and 900 psi on the rear. He as well suggested removing one of the calipers on the rear. I ordered a union to replace the T's in front of the rear calipers. I also ordered a new master cylinder and backing plate just to make sure that I don't have an issue going on there. He also suggested milling off about .010" to 0.15" off of the pads all around to make sure they are not glazed over. Scott said that I should have a minimum of 1000 psi on the brake lines and ideal would be more around 1200 psi. I'll get everything installed tomorrow evening and report back with what I come up with.

 

I have aerospace brakes on all 4 corners. i do not use a proportioning valve. brakes work very good. You dont need very much pedal pressure to stop after a run. I just lightly use my toe on the brake pedal. Too much brake pressure wears the pads unevenly and causes drag. Most of the braking power is on the front wheels.

 

I swapped over to the aerospace master cylinder and their backing plate. Took out the prop valve and removed 1 of the calipers in the back. Then had the brake pads surfaced to take about .012" to 0.15"

I as well removed the brake pedal and drilled the 7/16" hole 2" from the pivot point. That gives the pedal a 7:1 ratio. Going from the pin to the hole with 7/16" fine threaded bolt was a MOFO to get tightened up. About 1/8 of a turn at a time. Too little room even for a 1/4" drive ratchet. I could have maybe got it tightened up quicker if I had help, but it was a solo job with me doing it all.

After I got everythign bled, I was seeing pressure on the front at 1250 psi and right around 1000 psi in the back. I ran up and down the driveway a couple of times. Brakes seem to be pretty strong. I'll find out here in a couple of weeks when I go to the track.

 

When I ran dual aerospace on my car years ago footbraking, I had to put a prop valve on the rear. I could lock the slicks up and slide them at the finish line...

First time I did that turning a guy loose at the stripe was the last. Prop valve was on it the next week.

 

That was my experience as well.

 

There is actually very little braking power at the rear wheels. I had the front brakes fail on one of my street cars and only the back brakes were working. It would just slide the rear tires and barely stop. On a drag car the proportioning valve is so the fronts wont lock up before the rears being we have such a narrow tire on the front. I dont run a proportioning valve on my car. Its fairly heavy and I am light on the brake pedal. I have Aerospace brakes on all 4 corners and have been real happy with them.

 

Different cars need different setups. My car has dual rear Baer brakes and the proportioning valve reduces the pressure to the rear. I regularly stop my 3600lb car from 160-165mph without a chute and my brake setup works just fine at the track and on the street. I've been using this setup for 15 years.