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I understand what you're saying, but if your really want them to pay attention, you should start by spelling their name correctly.
W I L W O O D
I hesitated on that as well. Highly unlikely that they will change a design that has long been in production. Seems clear to me that this plumbing was done for their convenience, not ours. They may never even have thought about it, although one look at the originals is a damn big clue.
It is irritating, but once properly bled, it lasts for years, provided of course that you have no runout whatsoever.
I just looked at some pictures of Brembos and they don't look any more friendly.
Other than saving weight the stock brakes work just as good as any aftermarket 4 piston brakes. After all they were 4 piston brake calipers before 4 piston brake calipers were cool. My '71 will still out stop anything in my garage. Just saying.................
fwiw ... at end of MT article are source credits ...guess who's credited ?... wilwood. Every stock car chassis I've worked on (including scratch built tube w/aftermarket race calipers) ... fronts do trail & rears do lead.
now, they Do handle differently; so, what's the better of these two and why ? ... front steer (tie rods forward of spindles) or rear steer (tie rods aft of spindles) ?
fwiw ... at end of MT article are source credits ...guess who's credited ?... wilwood. Every stock car chassis I've worked on (including scratch built tube w/aftermarket race calipers) ... fronts do trail & rears do lead.
now, they Do handle differently; so, what's the better of these two and why ? ... front steer (tie rods forward of spindles) or rear steer (tie rods aft of spindles) ?
Where the caliper is clocked has zero effect on braking..it's ease of assembly on the line, packaging, ease of service, and finally performance. The calipers can be placed inside the wheelbase for a slight decrease in the polar moment of inertia, or at the bottom for a slight decrease in the vertical center of gravity, or in the front for a slight advantage in cooling.
front steer has diminished deflection oversteer
Last edited by Pegan2261; Aug 10, 2021 at 02:20 AM.
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Jebby: Here is the geometry for our cars. The blue tape is the correct diameter and likely placement of the caliper piston and cylinder. The inked line is the likely path of the bleeding. Wilwood probably drills it out, maybe it is cast, I don't know. If you drew a horizontal line across the cylinder, there would be an air pocket, technically a secant, above the line in all four cylinders that can't be bled in the stock position. To properly bleed it you need to unfasten the caliper and hold it vertical, much as your Demon picture shows a more vertical mounting position.
At least that is how I and others see the situation
Jebby: Here is the geometry for our cars. The blue tape is the correct diameter and likely placement of the caliper piston and cylinder. The inked line is the likely path of the bleeding. Wilwood probably drills it out, maybe it is cast, I don't know. If you drew a horizontal line across the cylinder, there would be an air pocket, technically a secant, above the line in all four cylinders that can't be bled in the stock position. To properly bleed it you need to unfasten the caliper and hold it vertical, much as your Demon picture shows a more vertical mounting position.
At least that is how I and others see the situation
I was speaking more about the OP’s link in post one…..in the article, the Wilwood kit is a leading caliper…..
The calipers on the Demon bled awesome in 30 minutes with a gravity bleed…..
Jebby
Last edited by Jebbysan; Aug 10, 2021 at 01:02 PM.
Jebby: Here is the geometry for our cars. The blue tape is the correct diameter and likely placement of the caliper piston and cylinder. The inked line is the likely path of the bleeding. Wilwood probably drills it out, maybe it is cast, I don't know. If you drew a horizontal line across the cylinder, there would be an air pocket, technically a secant, above the line in all four cylinders that can't be bled in the stock position. To properly bleed it you need to unfasten the caliper and hold it vertical, much as your Demon picture shows a more vertical mounting position.
At least that is how I and others see the situation
I don't understand the drawn line. I believe the fluid level line in the caliper cylinder would be horizontal. Perhaps I am missing some peculiar detail?
I don't understand the drawn line. I believe the fluid level line in the caliper cylinder would be horizontal. Perhaps I am missing some peculiar detail?
I'm going to give you the benefit of the doubt and believe you just looked at the picture.. So let's try it again this time in bold!
Jebby: Here is the geometry for our cars. The blue tape is the correct diameter and likely placement of the caliper piston and cylinder. The inked line is the likely path of the bleeding. Wilwood probably drills it out, maybe it is cast, I don't know. If you drew a horizontal line across the cylinder, there would be an air pocket, technically a secant, above the line in all four cylinders that can't be bled in the stock position. To properly bleed it you need to unfasten the caliper and hold it vertical, much as your Demon picture shows a more vertical mounting position.
One thing the artical didn't quite get correct was production car caliper placement could have been dumbed down a bit. Caliper placement is relative to steering placement. Rear streer (firewall mount) requires Front mount calipers and Front steer (rack under the rad) Rear mount calipers. There may be 'some' exception to that but for the most part its rather obvious why this is- there's only so much room on the knuckle.
As for the layed over bleeding above- won't work. Once you get past about 15 degrees the bleed passages don't have enough under cut remaining to not trap air. I put this drawing up years ago to explain what is going on inside your caliper and how angles effect the bleeding. Multi piston calipers have a port passing through all three (ex) piston locations. But due to the staggered location they may not always intersect the crown of the circle. For that reason an undercuat is milled into the crown to force air to channel into the port.
__________________ TCE
Your one stop...for Wilwood Brakes! 480.967.7901
Just to be sure I understand your picture Todd, the "undercuts" are straight cuts tangential to, and divergent from continuation of the circle. And yes it seems they allow a little trapped air to squeak out.
Guess I missed this picture back went we went around on this subject the first time. Curious if this is reflected in the directions shipped with the product these days?
Just to be sure I understand your picture Todd, the "undercuts" are straight cuts tangential to, and divergent from continuation of the circle. And yes it seems they allow a little trapped air to squeak out.
Guess I missed this picture back went we went around on this subject the first time. Curious if this is reflected in the directions shipped with the product these days?
I'm not in a position to provide extensive pics or descriptions really beyond what I have now. But yes, many if not all, staggered bore calipers have (likely) some sort of relieft cut at the top of the fluid passage to account for the angle or even offset of bleed passages. If not you'd end up with the trapped air all the time. I'd guess each mfg does some sort of that but it could vary by idea. Somehow you need to vent the circle. *I have not seen them be more than mayb .100" in height- they don't run the length of the bore, just at the base.
I don't know that there is a defintive stated angle but kits with calipers mounted at extreme angles are often suggested to be removed and held vertical for a more pure bleed- like the D4s.
Last edited by Todd TCE; Aug 13, 2021 at 03:11 PM.
I'm not in a position to provide extensive pics or descriptions really beyond what I have now. But yes, many if not all, staggered bore calipers have (likely) some sort of relieft cut at the top of the fluid passage to account for the angle or even offset of bleed passages. If not you'd end up with the trapped air all the time. I'd guess each mfg does some sort of that but it could vary by idea. Somehow you need to vent the circle. *I have not seen them be more than mayb .100" in height- they don't run the length of the bore, just at the base.
I don't know that there is a defintive stated angle but kits with calipers mounted at extreme angles are often suggested to be removed and held vertical for a more pure bleed- like the D4s.
That's interesting. Because I bought rear Willwood callipers for my C3, and fooled around for days trying to get the rear brakes to do their share, and get a fairly high and firm pedal.There was nothing in the box in the way of instructions as far as holding them vertical while bleeding.
I finally came to the idea, and reverse bled them, with the callipers dismounted and held in a vertical position, and by Jove, air came out, and I had a high and firm pedal, and rear brakes that actually heated up when the car was driven.
Why don't you admit that this is a design flaw that the buyer has to work around? The callipers are mounted at this angle, and at this angle, THEY WILL NOT BLEED PROPERLY!
There was nothing in the box in the way of instructions as far as holding them vertical while bleeding.
Why don't you admit that this is a design flaw that the buyer has to work around? The callipers are mounted at this angle, and at this angle, THEY WILL NOT BLEED PROPERLY!
There's no design flaw, simply a lack of knowledge and understanding. To which I'm offering to help with. Call them and complain about it, makes sense to me.
Not a design flaw, but an user installation manual flaw. Wilwood needs to add to the installation instructions that the rear calipers need to be held vertical to bleed properly before mounting. I'm sure they could also source the correct length bolts so as not to have the supplied bolts lock the rotor without shimming. Redesigning the caliper to get a proper bleed in the installed position is also an option. If GM did it, why not Wilwood?
