quote:

Originally posted by TOP38:

So there are a few factors in this whole mess!

First you need to know that your pedal ratio and master cylinder diameter are correct in order to develop adequate line pressure, if this is not right you will have issues with any brake manufacturer.

I have experience with Strange, MW and Lamb. Strange work OK on slower dragsters but once you get into the 170 mph plus range, the pads needed to stop don't last and the rotors turn into stop signs and warp. Lamb's work great but their rotors are cast, which eventually crack. I guess they have a steel rotor too. I have MW on my car now with Ferodo pads, stops great at 196 mph plus and the pads last and the rotors do too! No idea why anyone would need or want more stopping power than these brakes provide!

Add to this that many dragsters come with brake pedals that are too short from the factory to achieve proper pedal ratio. My Undercover car has a short pedal, the ratio is 4-4.5:1 at best. My wife’s Miller car has a real tall pedal, ratio is like 6.5 or 7 if I remember correctly. Her car has MW brakes/ferodo pads with a 3/4” master cylinder and has really nice pedal feel and stopping power. They last a long time, 100+ runs with minimal brake dust stopping from 177+.

When I got my car it had a 1” master cylinder and lamb brakes with the cast rotors and their pads with the aforementioned poor pedal ratio. Man that thing burned up the pads and heat cracked the rotors in 80 runs, lots of brake dust. I put a 7/8 MC on it and another set of lamb rotors. They lasted a little longer and still heat cracked. I then went to a 3/4” MC and Ferodo pads and another set of lamb rotors and all of a sudden pad life is excellent, minimal brake dust, and the rotors look great. On my third set of pads now.

The Ferodo pad must be more aggressive than the Lamb so it’s grabbing the rotor and stopping it instead of making heat. But the Miller car with more pedal ratio definitely has a better feel to it. Maybe one of these years I’ll make a new brake pedal for my car but it works well enough the way it is now.

This message has been edited. Last edited by: 183N,

I have been going back and forth on Moser Stainless or Mark Williams. I have decided to go MW for a couple reasons. Number 1 CUSTOMER SERVICE! #2 I see a lot more Mark Williams on fast dragsters than I do Moser.

My pedal ratio is 4-1 with a 7/8 master cylinder. Travis @ MW said he liked the 7/8 MC but doesn't think I can get to 1200 psi with the 4-1 ratio. I have a gauge coming tomorrow so I'll know for sure how much pressure I actually have. Then if he thinks I should go with a 3/4 MC, I will change them out.

Tony. I would work on pedal ratio..Stroke volume is a factor in this equation, the pedal will feel hard with the smaller bore ,but that doesnt mean your will achieve 1200 psi of line pressure at the caliper on the first hit of the pedal...I think M/W looks for 6:1 or something in that neighborhood....

quote:

Originally posted by S/S Dart:
Tony. I would work on pedal ratio..Stroke volume is a factor in this equation, the pedal will feel hard with the smaller bore ,but that doesnt mean your will achieve 1200 psi of line pressure at the caliper on the first hit of the pedal...I think M/W looks for 6:1 or something in that neighborhood....

I have a feeling that is going to be the case. M/W told me I need to be around 5:1 with the 7/8 MC to get to 1200 psi with reasonable pedal pressure. The only way to get a better ratio would be to go longer on the pedal.

Tilton 7/8" Master cylinder filled with DOT5 silicone brake fluid



on my Undercover dragster, actuating Mark Williams calipers with Ferodo pads

https://www.youtube.com/watch?v=zjC7IUotH0w

1st hit 760psi


2nd hit 860psi


3rd hit, hold the brakes for a moment 1420psi

quote:

Originally posted by 1320racer:
Tilton 7/8" Master cylinder filled with DOT5 silicone brake fluid



on my Undercover dragster, actuating Mark Williams calipers with Ferodo pads

https://www.youtube.com/watch?v=zjC7IUotH0w

1st hit 760psi


2nd hit 860psi


3rd hit, hold the brakes for a moment 1420psi

Do you know what your pedal ratio is Ed?

I don't but I'll find out later this morning.

5.8:1

quote:

Originally posted by 1320racer:
5.8:1

Thanks.
Travis @ M/W told me when Kurt first started building Undercover cars, he was setting them up with 3.5-4:1 ratio by design. M/W explained to him the importance of having a higher ratio. Apparently they were worried about drivers locking the brakes up. My car is a Mullis and I'm sure they had the same thoughts as Undercover.

Kurt started to build cars 30 years ago. My son says he can't lock up the brakes. That said, Bill Frederick Elite Chassis, building Undercover cars tells me he's building his cars with a 6.9:1 ratio.

quote:

Originally posted by 1320racer:
Bill Frederick Elite Chassis, building Undercover cars tells me he's building his cars with a 6.9:1 ratio.

That will make it a lot easier to achieve proper brake pressure.
https://www.markwilliams.com/b...pedalcalculator.html

Pedal ratio means nothing without knowing the MC piston diameter, the two need to be sized to develop adequate line pressure.
Example: 1" MC Piston, with a 4.0 pedal ratio
Assume 300lbs applied

Piston area = .785 in^2
Applied force to MC = 300 x 4 = 1200lbs

Line pressure = 1200/.785 = 1528 PSI

Issues usually occur with too large MC pistons, same example but 1.25" diameter piston
New Piston Area = 1.23in^2
New Line Pressure = 1200/1.23 = 975 PSI

Small increase in piston diameter results in a large different in line pressure!

Also note, the same amount/volume of brake fluid is needed to active the brakes, therefore the smaller the piston diameter is, the further the brake pedal needs to travel and visa versa! So your looking for a good balance between pedal travel and line pressure!

quote:

Originally posted by TOP38:
Pedal ratio means nothing without knowing the MC piston diameter, the two need to be sized to develop adequate line pressure.
Example: 1" MC Piston, with a 4.0 pedal ratio
Assume 300lbs applied

Piston area = .785 in^2
Applied force to MC = 300 x 4 = 1200lbs

Line pressure = 1200/.785 = 1528 PSI

Issues usually occur with too large MC pistons, same example but 1.25" diameter piston
New Piston Area = 1.23in^2
New Line Pressure = 1200/1.23 = 975 PSI

Small increase in piston diameter results in a large different in line pressure!

Also note, the same amount/volume of brake fluid is needed to active the brakes, therefore the smaller the piston diameter is, the further the brake pedal needs to travel and visa versa! So your looking for a good balance between pedal travel and line pressure!

Thanks Top38, the M/W calculator does the same math. The default applied pressure in that calculator is set at 150,300 lbs of pressure seems like a lot or maybe I need to increase my squat and dead lift routines!

This thread has made me educate myself on how our brake systems work. My brakes worked well before stopping at 193 but there were things that I was not happy with, mainly staging and brake drag. The Mark Williams brakes should be a big improvement over the Strange brakes. I am going to use the Ferodo pad initially but may try the TBM pads at some point.

Definitely want lock um up with FERODOS

that's a good thing

A friend is ordering TBM pads for his M/W calipers. What thickness do you order .490 or .625? It doesn't state what thickness the Ferodo pads are on M/W site

quote:

Originally posted by TonyB6255:
A friend is ordering TBM pads for his M/W calipers. What thickness do you order .490 or .625? It doesn't state what thickness the Ferodo pads are on M/W site

.490, I believe they are actually .472 for what its worth

quote:

Originally posted by TonyB6255:
A friend is ordering TBM pads for his M/W calipers. What thickness do you order .490 or .625? It doesn't state what thickness the Ferodo pads are on M/W site

the 625's were to thick for mine

I just measured a brand new Ferodo pad...

.480 with the backing plate
.350 pad only