Wilwood stopping power

[65 drop top]

I have a 65 Chevelle with Wilwood 14" rotors with the forged narrow superlite caliper 6 pistons front and 13" 4 piston rears. 7/8" manual master and bp 10 pads. Car has upgraded bolt-on suspension and 235/255 mm Nitto extreme 555 tires. Normal stopping from stop light to stop light seems ok. But when I stomp on the brakes the car seems to stop ok, but nothing overly impressive. I also can't get them to lock up, front or rear. I feel like I should be getting more stopping power than it is. I'm thinking about trying bp 20's up front to see if that helps any. But I also don't want pads that'll dust up too much I have fully polished billet wheels.

[andrewb70]

No air in the system?

Andrew

[65 drop top]

No air in the system?

Andrew

I don't think so. I just had the master off for the Wilwood recall. I did a bench bleed and then went around the calipers multiple times and I was getting fluid only(after the initial few bubbles). The pedal has a very slight travel then becomes very solid. It doesn't feel overly mushy either considering its a 7/8". I can feel the extra travel, but it does feel firm.

[dontlifttoshift]

If it's not a race car I would put power on it. Stopping force comes from two things, pressure and friction, you need a lot of one if you don't have a lot of the other. A little of both does the job also.

143471

The E pads are so much better but not what I would call "low dust" and they can be "not quiet" sometimes, too. If you look at the chart you will see that 20s will be a step backwards on a street car.

[65 drop top]

I don't want to put a power booster on it, even with the trade off of less braking power. Are there any other aftermarket pads that I could use other than Wilwood's? Something low dusting but more aggressive that the bp 10's?

[dontlifttoshift]

Nothing I can think of. I have had good luck with CarboTech or GLoc but they are definitely not low dust.....Maybe the Carbotech 1521s but I have no experience with them.

[rickpaw]

Is your brake pedal ratio correct? IIRC, there are two holes on the brake pedal. One for manual, one for power brake.

[kevmurray]

I have a 65 Chevelle with Wilwood 14" rotors with the forged narrow superlite caliper 6 pistons front and 13" 4 piston rears. 7/8" manual master and bp 10 pads. Car has upgraded bolt-on suspension and 235/255 mm Nitto extreme 555 tires. Normal stopping from stop light to stop light seems ok. But when I stomp on the brakes the car seems to stop ok, but nothing overly impressive. I also can't get them to lock up, front or rear. I feel like I should be getting more stopping power than it is. I'm thinking about trying bp 20's up front to see if that helps any. But I also don't want pads that'll dust up too much I have fully polished billet wheels.


Which piston sizes for front and rear? They are available in many different sizes. If you can provide the part numbers that is fine.
What are you using for a proportioning valve? How did you come to the current adjustment?
What is the distance from master cylinder rod clevis to the pedal pivot point?
What is the distance from the pedal foot pad to the pedal pivot point?
235/40/18?
255/45/18?
Need to know exact sizes to look up wheel diameter.

[65 drop top]

Which piston sizes for front and rear? They are available in many different sizes. If you can provide the part numbers that is fine.
What are you using for a proportioning valve? How did you come to the current adjustment?
What is the distance from master cylinder rod clevis to the pedal pivot point?
What is the distance from the pedal foot pad to the pedal pivot point?
235/40/18?
255/45/18?
Need to know exact sizes to look up wheel diameter.

4.04 front 1.98 rear piston areas
Baer proportioning valve in rear brake line, fully open
Pedal ratio is stock manual, which is about 6:1. I can't measure it right now, but recall it being normal ratio when I did.
235/35/19 front and 255/35/20 rear

[kevmurray]

These are what I understand your specs to be, correct me if I'm wrong on anything:

Pedal:
Manual position (top)
Ratio 6:1

Booster:
None

Master Cylinder:
Dual pot, 7/8" piston
Area = 0.6in2

Front:
Caliper: FNSL6 (1x 1.62, 2x 1.12 pistons ~4.04in2)
Rotor: 14"
Wheel Dia: 25.5"
Pads: BP10

Rear:
Caliper: FNSL4 (2x 1.12 pistons ~ 1.98in2
Rotor: 13"
Wheel Dia: 26.6"
Pads: BP10

Using a reference leg force of 100lbs this calculates out to 2500lbs total stopping force at the tire patch. According to Ron this equates to the average passenger car so with those upgraded tires I can see why you are unable to achieve lockup. I would never question Ron's wisdom, maybe something was changed from his design or he was given bad info? Those calipers have a very small piston area to go without a booster. The front bias is a nice 70% which should not need much proportioning to be ideal.

[65 drop top]

These are what I understand your specs to be, correct me if I'm wrong on anything:

Pedal:
Manual position (top)
Ratio 6:1

Booster:
None

Master Cylinder:
Dual pot, 7/8" piston
Area = 0.6in2

Front:
Caliper: FNSL6 (1x 1.62, 2x 1.12 pistons ~4.04in2)
Rotor: 14"
Wheel Dia: 25.5"
Pads: BP10

Rear:
Caliper: FNSL4 (2x 1.12 pistons ~ 1.98in2
Rotor: 13"
Wheel Dia: 26.6"
Pads: BP10

Using a reference leg force of 100lbs this calculates out to 2500lbs total stopping force at the tire patch. According to Ron this equates to the average passenger car so with those upgraded tires I can see why you are unable to achieve lockup. I would never question Ron's wisdom, maybe something was changed from his design or he was given bad info? Those calipers have a very small piston area to go without a booster. The front bias is a nice 70% which should not need much proportioning to be ideal.
Yes, I'd agree with them being equal to the average passenger car. They stop ok, not good but not too bad. I guess I was just expecting a little more out of them. At the time, this was the best kit a Wilwood offered for my car. It had the largest piston area too. Now I see Wilwood has an aero6 kit, but I'm not gonna redo the brakes.

What would happen if I went with a 15/16 master? I understand pedal effort would increase, but how much more braking force could I make? And would the 15/16 require too much leg effort to be comfortable on the street?

[kevmurray]

...What would happen if I went with a 15/16 master? I understand pedal effort would increase, but how much more braking force could I make? And would the 15/16 require too much leg effort to be comfortable on the street?

That's actually going the wrong way. It would increase the leg effort and lower the line pressure. Your current setup will provide 2485lbs of brake force at the tire patch. Going to a 15/16 master would put you at 2165lbs while reducing the pedal stroke. If you have the stroke available going to a 0.750" master would bring you up to 3382lbs. I don't think anyone offers a 13/16 but a free option would be to raise the clevis a half inch or so, but would require fabrication. Otherwise it's going to require a booster of some sort. Maybe you could try a dual 7" if space is an issue?

[badolds]

Your brakes are just a hydroboost away from being awesome, just sayin. HIGH DROW BOOST = STOP TIME REDUCED. haha

Dan

[a67]

Just need better pads and a smaller M/C, simple as that. I have the total braking force lower at 2434 pounds. And this is with the pad mu at .45, which the BP-10s don't reach until they are at 700° F. At 100° F the mu is .40 for 2166 pounds of total at the tire stopping power. Not going to stop that well with this set up.

If we change to the E compound, same braking at 100°F, but at 500°F the mu is about .475, into the lower end of the G range. Which provides 2572 pounds of brake force. Better but still not great.

So, keep the E pads and fit a 3/4" bore MC:

At 100°F, a total of 2944 pounds of braking force.

At 500°F, a total of 3496 pounds of braking force.

That will work.

Bob.

[kevmurray]

Just need better pads and a smaller M/C, simple as that. I have the total braking force lower at 2434 pounds. And this is with the pad mu at .45, which the BP-10s don't reach until they are at 700° F. At 100° F the mu is .40 for 2166 pounds of total at the tire stopping power. Not going to stop that well with this set up.

If we change to the E compound, same braking at 100°F, but at 500°F the mu is about .475, into the lower end of the G range. Which provides 2572 pounds of brake force. Better but still not great.

So, keep the E pads and fit a 3/4" bore MC:

At 100°F, a total of 2944 pounds of braking force.

At 500°F, a total of 3496 pounds of braking force.

That will work.

Bob.
Bob,
He doesn't want pads that dust because of his nice wheels. Just curious, what did you use for rolling wheel diameter and effective rotor diameter? I'm wondering where my calculations differed from yours.

[a67]

Bob,
He doesn't want pads that dust because of his nice wheels.

Then he should swap to drum brakes...


Just curious, what did you use for rolling wheel diameter and effective rotor diameter? I'm wondering where my calculations differed from yours.

For the tire diameters I used what is listed.

For the rotor diameter I subtracted 2 inches. This is approximately the center line of the pad (1 inch of radius). Not all of the pad is exerting force at the outer diameter of the rotor, there is more pad at the smaller diameter.

Bob.

[GoodysGotaCuda]

FWIW, I have a similar setup with my 'Cuda using 7/8" bore with 6piston/4piston Wilwoods. However, I have a -very- long stroke and am able to go completely around the Wilwood 1500psi caliper pressure gauge [~3000psi?]. The stroke required is unusable, however. I have it raised ~1" over stock and can nearly get it to the floor. I'm a scrawny 150lb desk-worker, by no means someone with significant leg strength.

I will likely go to a 15/16" or 1" master cylinder this Winter, I will take the higher force/in of pedal travel.

[H8rDave]

Save your money. Starting with the pedal ratio of 6.0 - 1, you stated that the pedal has "very slight travel, then becomes very firm". OK, so, that's hard to modulate, with less feel, and it doesn't stop. Changing the pedal ratio to 7-1 (a 17% total output increase, or even 7.5 - 1 (a 25% total output increase) may be a smarter solution. Remember that these aftermarket brake companies build RACING brakes, and are designed to use RACING pads, with Race Car Drivers pounding away at them. Then, we want docile, smooth, clean and quiet from them. Not going to happen. Yes, you will have more pedal travel, but this = more pedal feel, not such a bad thing. So, pull out your pedal, do the math, and drill a 3/8" hole. If you don't like it, move it back. No loss. BTW, an OE GM full size caliper with a 2 15/16" bore has 6.775 sqin of piston area. This caliper on a 12" rotor, in your same system, would build just over 4000 lbs brake force on the front. I know it's not as flashy, but it stops 5000 lb cop cars with no problem. H8 on.

[Ron Sutton]

These are what I understand your specs to be, correct me if I'm wrong on anything:

Pedal:
Manual position (top)
Ratio 6:1

Booster:
None

Master Cylinder:
Dual pot, 7/8" piston
Area = 0.6in2

Front:
Caliper: FNSL6 (1x 1.62, 2x 1.12 pistons ~4.04in2)
Rotor: 14"
Wheel Dia: 25.5"
Pads: BP10

Rear:
Caliper: FNSL4 (2x 1.12 pistons ~ 1.98in2
Rotor: 13"
Wheel Dia: 26.6"
Pads: BP10

Using a reference leg force of 100lbs this calculates out to 2500lbs total stopping force at the tire patch. According to Ron this equates to the average passenger car so with those upgraded tires I can see why you are unable to achieve lockup. I would never question Ron's wisdom, maybe something was changed from his design or he was given bad info? Those calipers have a very small piston area to go without a booster. The front bias is a nice 70% which should not need much proportioning to be ideal.

Hey Kevin !

I agree with you. This package has too small of piston area for a manual system. FYI ... I didn't design nor sell this system. What he needs is more piston area front & rear. The issue is the Superlite caliper isn't rigid enough to handle more clamping force. The calipers will simply flex. Frankly I don't sell Superlite caliper front brake systems anymore. The Wilwood Aerolite 6 calipers are much better, much more rigid calipers. For manual systems, we increase the piston area to 5.40" with the Aerolite 6. In the rear, we run Superlites with either 2.46" or 3.00" piston area & balance the system with proportioning valve or bias bar. *The Superlite caliper works well with smaller piston areas. It's when it get up around 5" is where we start to see clam shelling of the caliper & mushy pedal.

Now for this particular application, a Aerolite brake kit may not be available from Wilwood. In that case, each of his options comes with negatives:
* Higher CoF brake pads, like BP20s, Hawk HP+, etc will create more braking force, but cost more, wear out quicker, wear rotors quicker, squeal & dust the wheels
* Switching to a power booster will create more braking force, but the calipers will flex & pads will wear uneven.
* A smaller master cylinder will create additional hydraulic force & more braking force, but will make the calipers flex the same as if they had larger pistons.
* With a power booster, the driver probably won't feel the caliper flex & the pedal will feel firm. Not so with smaller master cylinders.

Just my 2¢. :cheers:

[AMC Racer]

Hi Ron,

Sorry for the hijack, but does the extra thickness of the FLSI or FSL4R/FSL6R (... assume the FSL4R/6R have better stiffness than FSLI) give noticeably less deflection than the FNSL4R/FNSL6R (narrow Superlites are in most kits ... assume to more easily fit stock wheels)?

Also, how would you rate a GN6R vs. the narrow-body Aero calipers in most kits? Been considering a GN6R front / FSLI rear combo.

Thanks.

[Ron Sutton]

Hi Ron,

Sorry for the hijack, but does the extra thickness of the FLSI or FSL4R/FSL6R (... assume the FSL4R/6R have better stiffness than FSLI) give noticeably less deflection than the FNSL4R/FNSL6R (narrow Superlites are in most kits ... assume to more easily fit stock wheels)?

Also, how would you rate a GN6R vs. the narrow-body Aero calipers in most kits? Been considering a GN6R front / FSLI rear combo.

Thanks.

Hi Duane,

Good questions. I can not answer either one with data to back it up, as I have not tested the calipers you're asking about on a brake dyno with measurement equipment. All I can give you is my opinion. An educated opinion, but still an opinion.

I think the Forged Superlites are a smidge stronger (more rigid/less caliper flex) than the Forged Narrow Superlites.
* If you were running them in the front, like we do on our Track Toy 11.75" & 12.19" brakes (see HERE (http://www.ronsuttonracetechnology.com/catalog/?page=254)) ... I'd only run the standard width Superlites.
* If you're running them in the rear ... with piston area of 2"-3" ... I don't think it matters. We still use the regular width Superlites in our rear kits HERE (http://www.ronsuttonracetechnology.com/catalog/?page=252)& HERE (http://www.ronsuttonracetechnology.com/catalog/?page=254).

I am certain the Aerolite calipers are stronger (more rigid/less flex) than the Wilwood Grand National 6P caliper. I can't quantify how much, as I have not tested the GN6P on a brake dyno with measurement equipment, like I have with the Aerolite 6. My guess, is the GN6P has about 30-35% more flex at 1000 psi, compared to the Aerolite 6. I like the GN6P for race applications where I can run an aggressive race pad. I wouldn't use it on the street. Stick with the Aerolite 6.
You can see our 11.75" & 12.19" GN6P Track packages HERE (http://www.ronsuttonracetechnology.com/catalog/?page=254), 13" & 14" Aerolite Track packages HERE (http://www.ronsuttonracetechnology.com/catalog/?page=252)& Pro-Touring packages HERE (http://www.ronsuttonracetechnology.com/catalog/?page=104).
* You'll notice an absence of Superlite caliper front packages. There is just no comparison to the Aerolites.

Even though I couldn't provide you with hard data, I hope I was of help.

:cheers:

[65 drop top]

I agree with you. This package has too small of piston area for a manual system. FYI ... I didn't design nor sell this system. What he needs is more piston area front & rear. The issue is the Superlite caliper isn't rigid enough to handle more clamping force. The calipers will simply flex. Frankly I don't sell Superlite caliper front brake systems anymore. The Wilwood Aerolite 6 calipers are much better, much more rigid calipers. For manual systems, we increase the piston area to 5.40" with the Aerolite 6. In the rear, we run Superlites with either 2.46" or 3.00" piston area & balance the system with proportioning valve or bias bar. *The Superlite caliper works well with smaller piston areas. It's when it get up around 5" is where we start to see clam shelling of the caliper & mushy pedal.

Now for this particular application, a Aerolite brake kit may not be available from Wilwood. In that case, each of his options comes with negatives:
* Higher CoF brake pads, like BP20s, Hawk HP+, etc will create more braking force, but cost more, wear out quicker, wear rotors quicker, squeal & dust the wheels
* Switching to a power booster will create more braking force, but the calipers will flex & pads will wear uneven.
* A smaller master cylinder will create additional hydraulic force & more braking force, but will make the calipers flex the same as if they had larger pistons.
* With a power booster, the driver probably won't feel the caliper flex & the pedal will feel firm. Not so with smaller master cylinders.

Just my 2¢. :cheers:





When I bought this kit I was working with Wilwood on the combination. At the time, about 2 years ago or so, this was the biggest, baddest kit they made for my application. I understand the physics now, but I guess I'm just a little disappointed with the final product. Wilwood knew I wanted a manual system. Had they told me I needed a booster to get them to work properly I may have looked at other options. I previously had Baers on the car and they worked great. I had to change because I got new wheels and they didn't clear the Baer hubs.

Hi Ron, is been a couple years now, but you helped my with the brake system for my '55 Chevy. I'm finally getting close to having it on the road. I went with the Aero6 5.40 15" front and Aero4 14" 3.56 rear. Your calc's put me at close to 4000 #'s with a 15/16" manual. Would a hydroboost be overkill? I like the feeling of tapping the brakes and getting a good response, but I also don't want to lock them up just by looking at them.

[dontlifttoshift]

A hydroboost on the 55? That's not going to work very well with those calipers.

On your Chevelle it will work great. We did a 69 with the same brake kits you have and a vacuum booster and it was OK but the 540 didn't make a ton of vacuum. Installed Hydroboost and the car will suck the eyeballs out of your head now....same thing, billet wheels, didn't want dust.

[Ron Sutton]

When I bought this kit I was working with Wilwood on the combination. At the time, about 2 years ago or so, this was the biggest, baddest kit they made for my application. I understand the physics now, but I guess I'm just a little disappointed with the final product. Wilwood knew I wanted a manual system. Had they told me I needed a booster to get them to work properly I may have looked at other options. I previously had Baers on the car and they worked great. I had to change because I got new wheels and they didn't clear the Baer hubs.

Hi Ron, is been a couple years now, but you helped my with the brake system for my '55 Chevy. I'm finally getting close to having it on the road. I went with the Aero6 5.40 15" front and Aero4 14" 3.56 rear. Your calc's put me at close to 4000 #'s with a 15/16" manual. Would a hydroboost be overkill? I like the feeling of tapping the brakes and getting a good response, but I also don't want to lock them up just by looking at them.

Howdy !

I'm on the same page as Donny. You & I configured your '55 Chevy brake package for a manual system. To add a power booster to it would be more than overkill. It would be dangerous to the point of undrivable.

Even though you didn't plan to, you & Wilwood ending up with a system for your '65 Chevelle that really needs to be boosted. This car would benefit from going with a hydroboost, as Donny suggested.

On a different note, not specific to your cars, but applicable anyway ...
I don't think enough car guys are clear on how different manual & power boosted systems should be configured. Back in the 60's the car manufacturers like GM made the front calipers with over 6" of piston area. Combine that with a 6-1 pedal ratio and M/C around 15/16" & you had good passenger brakes producing around 2500# of braking force. When they sold them as power boosted brakes ... with the single, low efficiency boosters of that era ... all that was required was to change the pedal ratio to around 4-1 & they worked good as well. At least for the standards of the 60's.

Today, with modern car designs, the boosters are much more efficient & effective. So they design front calipers with around 4" of piston area & they work good. Producing around 2700-2800# of braking force ... except in Performance cars like Camaros, Mustangs, Vipers & Corvettes ... where they increase the CoF of the pads & engineer the systems to produce around 3000-3200# of total braking force. These modern cars are ALL POWER BOOSTED, typically with a dual vacuum booster or hydroboost.

For autocross & track, I am not a fan of boosted systems for how they affect the quality of braking. Vacuum systems are not consistent. When you brake into turn 6 of WeBeFast Autocross Emporium at point X one lap ... with 14" of vacuum in that instant ... and get X amount of braking force. The next lap you make, for whatever slight difference you did with the throttle, now you have 9" of vacuum and don't have as much brake. Then the next lap you may have 15", etc, etc. In short, vacuum boosted brakes are not consistent on track ... where you the driver need them to be if you 're going to drive at the limits.

Hydroboost brakes are more consistent, but they take away brake pedal feel. Driver's can't modulate the brakes very well with a hydrobooster. They act almost like an on/off switch. Not 100%, but almost. For these reasons, you don't find boosted brakes on professional race cars where the brake systems are $50,000+ & engineered to the nth degree. IMHO, boosted brakes are a luxury item for street cars. They make the car/truck easier to drive on a daily basis. A slight push on the pedal & we're stopping easily at a stoplight. I wouldn't want manual brakes in my daily driver. But manual brakes are the best for our triple duty Pro-Touring cars that see Street, AX & Track.

My suggestion is this:
* Every person should decide for themselves if they want power or manual brakes on their Pro-Touring car .... based on their usage & preferences.
* If it's going to be a manual system, the piston area needs to be around 5.5" or greater, combined with the proper ratio pedal, rotor, M/C size & Pad CoF.
* If it's going to be a boosted system, the piston area needs to be around 4"+/- combined with the proper ratio pedal, rotor, M/C size & Pad CoF.


:cheers:

[65 drop top]

Thanks Donny and Ron. That's what I thought for my '55, I'll stick with the manual system. I just wanted to double check so I don't run into the same problems as the Chevelle.

Again, the Chevelle brakes aren't horrible, they just aren't overly impressive. Is there a way to actually document how well they perform on the car, something like measuring a 60-0 stop? Then I can evaluate how the overall package works. How many feet would be considered a good stop? I was also considering doing a side by side stop vs my moms new Mercedes. If the Chevelle was even close to it, I'd assume the brakes are fairly safe for street duty. Although her Mercedes has massive AMG brakes, I don't think I have a chance.

[dontlifttoshift]

Here is what some really fast cars do 60-0. http://www.motortrend.com/news/20-best-60-to-0-distances-recorded/

A stock big block 69 camaro went 60-0 in 143 feet.....A 69 GT500 took 164 feet......:eek:

[Ron Sutton]

Thanks Donny and Ron. That's what I thought for my '55, I'll stick with the manual system. I just wanted to double check so I don't run into the same problems as the Chevelle.

Again, the Chevelle brakes aren't horrible, they just aren't overly impressive. Is there a way to actually document how well they perform on the car, something like measuring a 60-0 stop? Then I can evaluate how the overall package works. How many feet would be considered a good stop? I was also considering doing a side by side stop vs my moms new Mercedes. If the Chevelle was even close to it, I'd assume the brakes are fairly safe for street duty. Although her Mercedes has massive AMG brakes, I don't think I have a chance.

You're welcome. Glad Donny posted a link. I didn't have that kind of info.
Looks like 100' is a good baseline & C6 is King of the production cars at 90'


:cheers:

[RSX302]

Boy does this thread bring back sore memories. I went through the same pain 10yrs ago. I tried many manual brake combos and the only one that worked to my liking was twin 3/4" masters on a bias bar system with Wilwood H race pads. (13" rotor with Superlite 4"area) Where was Ron Sutton 10yrs ago..lol

Since I couldn't continue to run this system on the street, I switch over to a hydroboost system, 1.12 master and BP20's.

Since you already have your system and you say that it's ok, I would try the BP20's before doing anything else. I don't have any squealing and doesn't seem to wear my rotors any more then the BP10's. It may feel the same as the BP10's when cold, but as soon as you get heat into them, they should be a little better. My 2 pennies

[Ron Sutton]

Boy does this thread bring back sore memories. I went through the same pain 10yrs ago. I tried many manual brake combos and the only one that worked to my liking was twin 3/4" masters on a bias bar system with Wilwood H race pads. (13" rotor with Superlite 4"area)

Where was Ron Sutton 10yrs ago..lol
Running 9 race teams. Haha

Since I couldn't continue to run this system on the street, I switch over to a hydroboost system, 1.12 master and BP20's.

Since you already have your system and you say that it's ok, I would try the BP20's before doing anything else. I don't have any squealing and doesn't seem to wear my rotors any more then the BP10's. It may feel the same as the BP10's when cold, but as soon as you get heat into them, they should be a little better. My 2 pennies


:cheers: