Bleeding Wilwood Calipers
Thread Starter
Racer
Joined: Aug 2014
Posts: 479
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From: Tennessee
Bleeding Wilwood Calipers
I have a new set of Wilwood D8-4 calipers and drilled/slotted Wilwood rotors finally installed with minimum runout on my 76. I have researched and studied many articles on how to bleed these Wilwood's and there seems to be conflict regarding procedures that work. I would like to read what you did that worked for you on getting the Wilwood's bled and acquiring a nice firm brake pedal. Also, which brake fluid do you use?
Last edited by ykf7b0; May 9, 2019 at 09:24 AM.
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
Considering that you did not mention the master cylinder I'm presuming that it did not get changed, then you want to use the same type of brake fluid that was in the system as before. I have Wilwood rotors and the D8 aluminum calipers on my blue car. As far as bleeding I first used a 'Motive bleeder' bleeding the bottom first then the top, starting with the furthest away caliper and so on. Got a fair pedal took it out for a test ride and just beat on the brakes. Solicited some help and rebleed the brakes using a heavy foot on the pedal, now have excellent pedal height and it's rock hard with straight even braking. Also mine is a manual brake application. T
Supporting Vendor
Joined: Jun 2008
Posts: 2,195
Likes: 119
From: tempe Arizona
I feel the need to step in here already.
There is no such thing as "bleeding the bottom". The calipers are built with bleed screws top and bottom for a universal mount design. ALL bleeding on any caliper is from the TOP ONLY. In fact you can plug the bottom ports and save the removed bleeder for future use if you choose. Just about any opening of the "bottom bleeder" will result in the introduction of air in the system.
In the rear, because of the mount angle, you'll want to remove the caliper and bleed it in the most vertical manner possible. This will require a temporary "something" fit between the pads so they don't push out with the pistons as you apply pressure.
This is clearly stated on page 4 of the PDF
There is no such thing as "bleeding the bottom". The calipers are built with bleed screws top and bottom for a universal mount design. ALL bleeding on any caliper is from the TOP ONLY. In fact you can plug the bottom ports and save the removed bleeder for future use if you choose. Just about any opening of the "bottom bleeder" will result in the introduction of air in the system.
In the rear, because of the mount angle, you'll want to remove the caliper and bleed it in the most vertical manner possible. This will require a temporary "something" fit between the pads so they don't push out with the pistons as you apply pressure.
This is clearly stated on page 4 of the PDF
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
I feel the need to step in here already.
There is no such thing as "bleeding the bottom". The calipers are built with bleed screws top and bottom for a universal mount design. ALL bleeding on any caliper is from the TOP ONLY. In fact you can plug the bottom ports and save the removed bleeder for future use if you choose. Just about any opening of the "bottom bleeder" will result in the introduction of air in the system.
In the rear, because of the mount angle, you'll want to remove the caliper and bleed it in the most vertical manner possible. This will require a temporary "something" fit between the pads so they don't push out with the pistons as you apply pressure.
This is clearly stated on page 4 of the PDF
There is no such thing as "bleeding the bottom". The calipers are built with bleed screws top and bottom for a universal mount design. ALL bleeding on any caliper is from the TOP ONLY. In fact you can plug the bottom ports and save the removed bleeder for future use if you choose. Just about any opening of the "bottom bleeder" will result in the introduction of air in the system.
In the rear, because of the mount angle, you'll want to remove the caliper and bleed it in the most vertical manner possible. This will require a temporary "something" fit between the pads so they don't push out with the pistons as you apply pressure.
This is clearly stated on page 4 of the PDF
But why doesn't Wilwood revise the rear caliper bleeder location to match the stock calipers so they can be bled mounted to the bracket? Seems like it would be a simple programming change when machining the calipers.
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
I would imagine as said above the calipers are meant for a universal design. They are not Corvette specific. why do they not make Corvette specific? probably due to the low volume of them that would be made and these work fine if bleed properly as said above. Just my .02. I have them on my Vette and my Cobra and they stop very well with a firm pedal.
Supporting Vendor
Joined: Jun 2008
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From: tempe Arizona
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
I would imagine as said above the calipers are meant for a universal design. They are not Corvette specific. why do they not make Corvette specific? probably due to the low volume of them that would be made and these work fine if bleed properly as said above. Just my .02. I have them on my Vette and my Cobra and they stop very well with a firm pedal.
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Burning Brakes
Joined: Feb 1999
Posts: 1,052
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From: Woodinville WA
Actually, they are Corvette specific. D8-4 Calipers ". . .are a direct bolt-on replacement for the OE factory calipers on all 1965-82 Corvettes"
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
Bleeding Wilwood direct replacement rear brakes "Do you think someone just pulled numbers out of thin air to produce these parts? They were of course copied from oe parts or those supplied to them for that purpose. These entire kits came about by the request of a very large Corvette parts supplier who is also a vendor here.
Did they supply Wilwood incorrect parts? How would either of us know. But they were 'signed off' being correct by that vendor who had a somewhat exclusive on them for a bit of time."
The "very large Corvette parts supplier who is also a vendor here" is Van Steel. VS just missed the bleeder location problem when they signed off on the design.
Did they supply Wilwood incorrect parts? How would either of us know. But they were 'signed off' being correct by that vendor who had a somewhat exclusive on them for a bit of time."
The "very large Corvette parts supplier who is also a vendor here" is Van Steel. VS just missed the bleeder location problem when they signed off on the design.
Safety Car
Joined: May 2004
Posts: 4,340
Likes: 1,565
From: los altos hills california
Bleeding Wilwood direct replacement rear brakes "Do you think someone just pulled numbers out of thin air to produce these parts? They were of course copied from oe parts or those supplied to them for that purpose.
Todd: Any possibility that some sort of adapter could be fab'd to have the bleeders point straight up somehow? My pedal has gotten a little soft after five years and bleeding the fronts didn't fix it. I am really looking forward to getting the car back in the air, dismounting the calipers, putting in some pieces of wood to replace the rotor, bleeding the brakes, and then retorquing things.
Maybe while I'm in there I'll think about that.
Supporting Vendor
Joined: Jun 2008
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From: tempe Arizona
Mechanical drawings of the Willwood calipers are available from their website. Piston diameters and mounting positions conform almost identically to the OEM parts.
Todd: Any possibility that some sort of adapter could be fab'd to have the bleeders point straight up somehow? My pedal has gotten a little soft after five years and bleeding the fronts didn't fix it. I am really looking forward to getting the car back in the air, dismounting the calipers, putting in some pieces of wood to replace the rotor, bleeding the brakes, and then retorquing things. Maybe while I'm in there I'll think about that.
Todd: Any possibility that some sort of adapter could be fab'd to have the bleeders point straight up somehow? My pedal has gotten a little soft after five years and bleeding the fronts didn't fix it. I am really looking forward to getting the car back in the air, dismounting the calipers, putting in some pieces of wood to replace the rotor, bleeding the brakes, and then retorquing things.
Maybe while I'm in there I'll think about that.I don't see an easy way to make it work without a messy deal. You'd end up with four bleed screws per caliper.
Safety Car
Joined: May 2004
Posts: 4,340
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From: los altos hills california
I'm sorry I wasn't quite clear. The idea would be to have the mounting flange rotate it some to be more vertical. It's all GM's fault. The calipers should all be inboard anyway to minimize the moment of inertia.
Supporting Vendor
Joined: Jun 2008
Posts: 2,195
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From: tempe Arizona
*Looking at this I'm not sure where you'd put them.
https://www.wilwood.com/Images/Brake...651_IPB-lg.jpg
Even the BBKs have the same issue:http://www.tceperformanceproducts.co...ll%2010471.jpg
Last edited by Todd TCE; May 10, 2019 at 09:48 PM.
Thread Starter
Racer
Joined: Aug 2014
Posts: 479
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From: Tennessee
The rear calipers are a total mess to get bled. Removing them and positioning them completely vertical is an inconvenience but the brake fluid shooting straight up and running down the calipers and rotors is down right nasty. Smaller tubing would have helped a little without as much of a mess but I still don't like it.
Thread Starter
Racer
Joined: Aug 2014
Posts: 479
Likes: 93
From: Tennessee
I cannot seem to get good pedal height or a firm pedal with these Wilwoods and neither did I ever have a good pedal with the factory calipers. What am I missing with these Corvette brakes?
Safety Car
Joined: May 2004
Posts: 4,340
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From: los altos hills california
What I have observed, and I can't say why, is, after getting the best pedal I can, I go out and drive them a bit hard, and they get better. That has often included new pads.
Last edited by ignatz; May 14, 2019 at 11:55 PM.
Melting Slicks
Joined: Jun 2011
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https://www.corvetteforum.com/forums...-cylinder.html
Once you feel all is good at the MC then pressure bleed the calipers.
This is how I pressure bleed. Use about 20 PSI
The first time bleeding the rears I did bleed with the calipers removed and set vertical. Since then I bleed while on the car.
Last edited by cagotzmann; May 15, 2019 at 09:49 AM.
Thread Starter
Racer
Joined: Aug 2014
Posts: 479
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From: Tennessee
I have bench bled the master and have also removed the new rear Wilwood calipers, used woodern blocks to keep the pistons in, and positioned them vertically. I have a Motive power bleeder then used 15 psi and have bled each caliper 5 times already. As suggested, I bled using the top most 2 bleeders on each caliper and I submerged the bleeder tube in brake fluid to prevent the possibility of drawing in any air. As recommended by Wilwood, I started at the left rear outside bleeder then, right rear, front left, and finally right front.
Melting Slicks
Joined: Jun 2011
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