In this video, we talk to Kirk from Tilton Engineering about the importance of creating a perfectly balanced braking system for your motorsport vehicle. He discusses the differences between tandem master cylinders and dual master cylinders, the importance of pedal ratio, and how to size your master cylinders and calipers correctly.
Key takeaways:
- Dual master cylinders are typically used in motorsport vehicles because they provide better brake balance and tunability. - The size of your master cylinders should be based on the piston sizes in your calipers, rotor diameter, tire diameter, vehicle weight, weight distribution, and pedal ratio. - A manual brake system will give you more driver feedback and a firmer pedal feel than a boosted system. - The typical pedal ratio for an OEM vehicle with a brake booster is 4:1. - The typical pedal ratio for a motorsport vehicle with a dual master cylinder is 5:1 to 6.5:1. - The balance bar on a dual master cylinder allows you to make fine adjustments to your brake bias on the track.
Speaker 1:
There's more to performance braking than throwing the biggest brake kit you can on your vehicle. We're here to talk to Kurt from Tilton about creating a perfectly balanced braking system.
Speaker 2:
Welcome to High Performance Academy's Tune In Field Report podcast series. In these special midweek episodes, we look back through our archives to find the best conversations we've had through years worth of attending the best automotive events across the globe. We've pulled the audio from these tech filled interviews with some of the industry's most well known figures and presented it in podcast format for you to enjoy as a quick hit of insider knowledge.
Speaker 1:
So with people starting with a street car or an OEM based car and they're developing up to a performance application or into a motorsport car, a vehicle generally an OEM car will come with a tandem master cylinder for the brakes and a brake booster as well. We don't often see that in motorsport vehicles. Can you explain what we do see and why?
Speaker 3:
Yeah, in motorsport vehicles we typically have a dual master cylinder setup. You have one master cylinder for the front brake circuit, one master cylinder for rear brake circuit with the balance bar that operates both of them. So you're able to achieve better braking balance through size of the master's, appropriately and correctly. And so when we size masters we look in the piston sizes, in the caliper, rotor diameter, tire diameter, vehicle weight, weight distribution. That all gets factored in into determining the sizes of masters to start with, and in pedal ratio. Also. Another benefit is you get 95% of your braking balance through the size of the master's. But then the balance bar enables you with remote adjuster to make adjustments to the braking balance on the track. If fuel loads changes, track conditions changes. You want more front rear brake, you can dial it in with the balance bar, get more by as you want.
Speaker 1:
So it's really based around tuneability. Is there also some benefit to kind of consistency of the brake pedal feel moving to a manual brake system rather than a boosted system?
Speaker 3:
Yes, it's going to provide better driver feedback, for sure. The booster is kind of an artificial. It's more of an artificial feel where this is a you know it's going to be a firmer pedal, get more confidence to the driver on what the brakes are really doing.
Speaker 1:
So, in terms of the manual system that we see in motorsport vehicles with dual master cylinders sizing those two, and then how that's related to the sizing of the calipers, what's the kind of method that you'd work through there? We're figuring out the sizes to get yourself in a decent starting point before you need to make tuning adjustments from there.
Speaker 3:
Well, typically we see we like to see the calipers size where the piston area, the rear caliper, is about 50% of the fronts. Sometimes we have customers, you know, choose, they kind of pick maybe they're not the best option for calipers and so if they go say the calipers and the rear are too big, then we got to kind of compensate that for in the master cylinder sizing and you may see a pretty big spread in the difference between the front and rear master where we try to get them pretty close ideally.
Speaker 1:
So you want to start with them pretty close, just so there's no massive imbalance here, that you've got it in.
Speaker 3:
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Speaker 1:
Moving from an assisted system. What would be the typical pedal ratio that you'd see on like an OEM vehicle with a brake boost?
Speaker 3:
Yeah, seeing in modern cars you're like a four to one ratio. It's kind of what a modern car has and most of the motorsport application. Our pedal boxes are anywhere from about five to one to six and a half to one, and then in that and of course that's factored into the master cylinder sizing also what the pedal ratio is.
Speaker 1:
Yeah, so that gives you a mechanical advantage to make up for the lack of assistance.
Speaker 3:
Correct, yes.
Speaker 1:
Okay, just backing up a little bit to the balance bar, sitting the actual balance bar in the first place, before any adjustments are made using the hand control, the dial. What are we looking for there when we're sitting it up?
Speaker 3:
When you set it up you'll set up the clevises of the balance bar to be on the same center to center distance of the master cylinder mounting studs so that you'll set the clevises you know that that distance. Then you'll thread the push rods of the master cylinders into the clevises equally to kind of set your desired pedal position and then from there you usually make the front master cylinder push rod about a quarter inch longer because you typically use more front brakes, a little more stroke, so you do a little stagger in the setup that way.
Speaker 1:
And then the hand dial allows the driver to make adjustments from there. And what would they need to kind of make those adjustments for changing conditions?
Speaker 3:
Yeah, changing conditions, few load changes. So you know, next, if they're finding they're locking up their rear brakes and they want to dial that out, you know they'll put more bias to the front brakes to, you know, keep the car more balanced under braking.
Speaker 1:
So really, when speaking the size of the master cylinders, the brake cylinders, the entire braking system, it's really a package that you need to consider the whole thing to work the balance together. Or is there a set kind of way of working through, maybe from the caliper size back to the master cylinder size, pedal ratio that you can guess?
Speaker 3:
Yeah, so when we, when customers, you know, ask us what sizes to use, the things we ask them is okay what's the piston sizes in your front and rear? Calipers, rotor diameter, tire diameter, vehicle weight, weight distribution, pedal ratio, and then we factor in a brake pad coefficient, a tire coefficient, into our calculation. So we take all that information, put it into a program and then it predicts what size master is to start with. And then you go to test the vehicle with those size masters you find it may not be ideal, you may have to make some minor adjustments, but it's a good starting point.
Speaker 1:
As a getting into a good starting point and then being able to make the finite adjustments from there with the control.
Speaker 3:
Yeah, at the end of the day, you know math could tell you one thing that you know real world track conditions. You may not match up, so you may have to make some adjustments from there. We'll have to test.
Speaker 1:
Okay, well, thank you for your time. It's been really interesting. If people want to find out more about your product or potentially purchase anything, where can they?
Speaker 3:
go. They go to tiltmoreasingcom.
Speaker 1:
Right, thank you very much. Alright, thank you.
Speaker 2:
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