My fantastic wilwood experiance, NOT

[the dan]

So I've had my set up for about 3 years and after 7.5 years building my c10 long bed, I'm extremely dissapointed with everything. I have 14.5" c6 z06 rotors and wilwood 6 piston calipers up front, and c5 front calipers in the rear, after I did the area calculation for the master cylinders I called wilwood to confirm my results. I'm running a 6:1 pedal with 7/8 masters (manual brakes).

Before I even get to the poor performance, let's talk about how the ghetto m10 flair fitting bleeder boss snapped off when I snuggled it after it was leaking out of the box, it has a small 10-32 bleeder centralized on the boss. I had to machine it out, call wilwood to explain my issue, when the guy on tech support tells me I don't have an m10 bleeder. Ironically I had already machined my own using an m10 die since you cannot buy this bleeder boss locally. I sent him pictures as requested and never heard a word from them again

Now to the performance. My mother's land rover stops better with a 20ft boat with no trailer brakes. I've tried all the bar bias adjustment and I can 2 foot stand on this pedal and not even close to locking up the tires.its embarassing that single piston stock calipers are stopping my truck better then 14.5 6 pistons. I have just received a set of 3/4 masters and will be trying those out. Word on the street is the calipers have poor (small) piston area and to go to baers.



Anyone else have this awesome experiance?

[Peter Mc Mahon]

Dan, I don't have the same setup as you but I do have the wilwood super pedal and twin masters. When I first booked it up I had the threaded rod on the masters screwed into the balance bar too far and couldn't get much pressure to the calipers. I unscrewed them a bit and tried again. It took me a couple of times but way better now. Keep at it. Love your truck!

[the dan]

Thanks Pete, The pedals are already pretty far forward but it doesn't hurt to try!. ill do that as soon as I swap over to my 3/4 masters

[parsonsj]

You need to gather some data. What brake line pressures are you seeing at the calipers? How much travel are you seeing with your pedal?

[Apogee]

Given your component mismatch with respect to the front/rear caliper piston areas, I'm surprised you're running the same bore size MC front and rear. Assuming a Wilwood FNSL or Aero 6-piston front caliper with ~4.04 square inches of effective piston area, I'd probably be looking at a .70" front MC and .81 or .88 rear MC, but at least the .75" is a step (26%) in the right direction.

In addition to the items noted by John above, it would help to know what pad compound you're running, and maybe some accurate rotor diameters. You didn't specify the rear rotor diameter and there is no 14.5" C6 Z06 rotor that I'm aware of...but there are 14.00", 14.25" and 15.00" Wilwood upgrades for the C6 Z06.

There are many more variables that should be taken into consideration when spec'ing a dual master cylinder setup, however it basically sounds like you're just not supplying enough pressure to the calipers given your current components.

Tobin
KORE3

[the dan]

14" front, its been a while.
Wilwood FSNL6 - with BP10 Pads

12.6 Rear rotor with 2 piston 40mm caliper pistons so 3.89 in^2 x 2 (since there are 2 rears) of 7.79in^2

[Apogee]

The BP10 pads aren't doing you any favors with respect to brake torque in a manual brake configuration, especially not with a balance beam and oversized MC's. I'd suggest swapping them out for a "GG" friction rated pad, something like an EBC Yellowstuff, Hawk HP Plus, or something comparable.

Next, I'd run the .75/.88 MC's and see how it goes. It think you'll find that the balance bar will be biased towards the front somewhat once you get it sorted, but as long as it's within the range of adjustment, all's good.

Relatively small changes in terms of rotor diameter don't change the overall brake torque much, so that would be the least of my concerns at this point. The factory C5/C6 Corvette base level front rotors (RPO = JL9) are 325x32mm, so 12.79" x 1.26", and the piston diameters are 40.5mm with an effective caliper piston area of ~4 square inches per caliper. You don't typically double it because there are two calipers, but rather use the specs from one front and one rear to determine balance and hydraulic requirements for the system. While you can multiply everything by (2) if you like, it doesn't gain you anything unless you're specifically trying to calculate total brake torque per axle.

Tobin
KORE3

[MonzaRacer]

I have always wondered if the pedal level ok and stopping ability are marginal wouldn't a more aggressive pad be an obvious direction over changing other parts?
Just seems like a obvious swap. Because wouldn't pads be cheaper than a master cylinder?

[the dan]

Rodger because pressure is is even throughout the system

I'll look into changing pads for sure.



As for this.

[the dan]

Rodger because pressure is is even throughout the system

I'll look into changing pads for sure.



As for this.

[andrewb70]

Looks like you over tightened it and broke the fitting.

Andrew

[RobNoLimit]

We see this all the time. The BP-10 is a good pad, if you have power brakes and you are really concerned about low dusting. With the gain in interest towards auto-x and track days, carrying a second set of pads is going to become pretty normal. I run EBC Yellow, Wilwood E, or BP-20 for spirited street, then swap to BP-30 or B pads for short track days. - just clean the wheels ASAP, they will pit and etch the wheel.

As for pressures, lets work it through. Say you push down with 80 lbs of foot pressure (that's pretty hard), on a 6-1 pedal. You get 480 lbs of input force to work with. If your balance bar is 50/50, you have 240 lbs per master cyl. A 3/4" bore master (front brake) has .44 in. surface, with 240 lbs = 545 psi. The 7/8" bore master (rear brake) has .601 in. surface, with 240 lbs = 399 psi. This is a bit simplified, as balance bar systems are dynamic, but you get the idea. Where is the 1200 psi everybody talks about? lol, not happening, not here. If you want the feel, response, and ability to modulate brakes, you have to go manual, and that means lower operating pressures. From here, small changes in bore size, pedal ratio, and pad compound is where you sort it all out.

[the dan]

Thank you rob.

As for overtightening? No. Actually they leaked from the box and whike snugging it to stop the leak it snapped off. Now you take a look at the cross section and there is maybe .020 on brass. Now I'm no engineer.... oh wait. I have two points to be made. If you want a caliper that doesn't require you to buy new fittings even though they're brand new, and you have to buy a 4 pack for $15.94+ shipping after you she'll out $1,000 for new calipers, buy these. If you're also getting someone in the tech support that doesn't know their own product, do the same.

Wilwood only sells 3/4 " masters for their manual brake pedal assembly, so once I install these and push the bias bar to the front as kore says, it should work better. And i guess i need pads too just to feel safe driving it on the street. Dust doesn't bother me because my wheels are black anyways. But this isn't just a weekend truck it's actually still being used as a truck

[the dan]

This also states that I have two 7/8 masters for sale

[andrewb70]

I do agree with a point made by The Dan. Why would Wilwood do a bleeder inside a bleeder design? What's the point of the brass fitting and then having the tiny little bleeder inside that? Seems to me that a more robust design would be to simply have a proper steel bleeder inside the caliper and call it a day. Maybe they are using the brass fitting as a safety so that an overly enthusiastic racer doesn't over tighten a large thread steel bleeder and strip out the aluminum caliper? That's the only reason I can think of to do it the way they did.

Andrew

[dontlifttoshift]

Because the brass piece is easily and cheaply replaced and the caliper is not.

[kevmurray]

I'm guessing the same. The brass fitting is being used like a Heli Coil since it's harder than aluminum, has larger thread diameter (than the actual bleeder), and is soft enough to still be sacrificial. It is odd that it was leaking though. Maybe it was damaged during assembly by Wilwood. That would explain the leaking and why it broke so easily.

[the dan]

The reason is because they needed a way to make lefts and rights the same casting, so the crossover tube fits both sides

[parsonsj]

they needed a way to make lefts and rights the same casting

Probably. BOM reduction reduces costs.

[the dan]

they needed a way to make lefts and rights the same casting

Probably. BOM reduction reduces costs.

Rodger, I'm a manufacturing engineer at a investment casting (lost wax) for aerospace components. We have one casting that does 3 different castings of lefts, rights and one differently machined one. The investment fixture was ~$180k and the straightening fixture was ~ $100k.

I put the .750 master cylinders in last night and there is an improvement but not enough. I'm going to adjust the bias bar a little but I don't think it will improve much because the rears were not locking up under hard braking. I think I will have to buy some better pads.