C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

Wilwood Brakes for my 1974

 
Old 03-15-2019, 12:51 PM
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shurst
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Default Wilwood Brakes for my 1974

I hope I'm not beating a dead horse, but here it goes;
I just noticed that my front calipers are beginning to leak in my 1974 convertible and I am contemplating the best repair path. I noticed that Wilwood has a very nice kit that is quite lightweight, assumed to be high quality, and comes with the pads and SS lines for about $500. My question is, has anyone else used the Wilwoods, and are they worth the extra money, or am I better off going with something else? Of course, I would value any other suggestions as well.

Thanks in advance!
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Old 03-15-2019, 01:18 PM
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Peterbuilt
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Just go to your local auto parts store and get the rebuilt calipers they offer.
Get new rubber hoses too.


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Old 03-15-2019, 01:25 PM
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I installed the wilwood front and rears with braided hose about ~6.5 years ago from a group sale on this forum then. They have been wonderful. I recommend them. Have NOT had a brake issue since.
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Old 03-15-2019, 01:50 PM
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I rebuilt my existing calipers and in the process had them powdercoated and threw in a set of Willwood Rotors just for show! .. I guess if I was racing the car I would think about maybe the upgrade would be possibly needed but for the street use i get out of it it's just what I need!



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Old 03-15-2019, 01:58 PM
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I just installed D8-4 Wilwoods on my 74, front and rear, I'm happy with them. Light weight, SS pistons, o ring seals. They are expensive, time will tell if the investment pays off for me. You may have to shim the rear calipers with the supplied washers and you WILL need to bleed the rears dismounted - I found it to be no big deal. I'm clear it will cost you double the replacement cost of stock calipers. Just my .02.
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Old 03-15-2019, 02:05 PM
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Those look great!
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Old 03-15-2019, 02:15 PM
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I personally would not go willwood for a street driven C3 unless you go 6 piston front calipers and bigger rotors. Willwood 4 pistons calipers will NOT stop your car any faster than the stock delcos BUT are lighter being aluminum. If you plan to keep it basically stock, I would rebuild your current calipers if they are already stainless steel sleeved OR buy rebuilt stainless steel calipers from one of the vendors. You can also buy NEW cast iron calipers in either regular lip seals or o ring. Some folks swear by o ring calipers BUT I have had SS Delco calipers with lip seals on my C3 since 1985 and the car is hardly driven so I don't buy the longevity theory with O ring seals. Change you brake fluid every 4-5 years is the best insurance for leaking calipers.

Last edited by jb78L-82; 03-15-2019 at 02:17 PM.
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Old 03-15-2019, 02:19 PM
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I like them. Much lighter than stock.
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Old 03-15-2019, 03:23 PM
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Here's a good read- this was done by fellow member "427Hotrod"

Stock versus the Wilwood-

http://www.amosauto.com/corvette-braking-test/

Stock
151 ft., 2 in. – Nice quick stop to get an idea of how hard I could push it on that surface.

•123 ft., 7 in. – Worked it much harder. No brake lockup or drama.

•118 ft., 3 in. – Back to back. Now I knew I could work it harder.

•109 ft., 5 in. – Hit it hard and kept it right on the edge of lockup. Never could repeat it.

•135 ft., 1 in. – Real hard and locked up front wheels early and rears near the end.

•111 ft., 4 in. – Very similar to test four.

•113 ft., 2 in. – Another good one!



Wilwood
•130 ft., 9 in. – Good feel but sliding at the end.

•129 ft., 6 in. – Nearly identical.

•115 ft., 5 in. – Finding the “sweet spot”.

•109 ft., 4 in. – Maybe the pads are getting “bedded”?

•107 ft., 8 in. – Bang! Best ever!

•109 ft., 11 in. – Still working great!

•109 ft., 3 in. – Did it again!
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Old 03-15-2019, 03:59 PM
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Originally Posted by Richard454 View Post
Here's a good read- this was done by fellow member "427Hotrod"

Stock versus the Wilwood-

http://www.amosauto.com/corvette-braking-test/

Stock
151 ft., 2 in. – Nice quick stop to get an idea of how hard I could push it on that surface.

•123 ft., 7 in. – Worked it much harder. No brake lockup or drama.

•118 ft., 3 in. – Back to back. Now I knew I could work it harder.

•109 ft., 5 in. – Hit it hard and kept it right on the edge of lockup. Never could repeat it.

•135 ft., 1 in. – Real hard and locked up front wheels early and rears near the end.

•111 ft., 4 in. – Very similar to test four.

•113 ft., 2 in. – Another good one!



Wilwood
•130 ft., 9 in. – Good feel but sliding at the end.

•129 ft., 6 in. – Nearly identical.

•115 ft., 5 in. – Finding the “sweet spot”.

•109 ft., 4 in. – Maybe the pads are getting “bedded”?

•107 ft., 8 in. – Bang! Best ever!

•109 ft., 11 in. – Still working great!

•109 ft., 3 in. – Did it again!
Yes....that is a good comparison. With the exception of the 135ft for the stock calipers on test brake 5, the 2 caliper designs are very equal. Especially the final brake test on both calipers with the willwood 2-4 ft advantage which is insignificant. My recollection was that the tests were not done with the same brake pads for both calipers, however..

The only way the wilwoods can out brake the stock system on identical cars with the same brake pads and tires is with the 4 piston caliper on a 13/14 inch rotor in front or the 6 piston front caliper on a 12/13/14 inch rotor.....this physics and cannot be changed......

Last edited by jb78L-82; 03-15-2019 at 04:05 PM.
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Old 03-15-2019, 04:06 PM
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My experience with regard to the Willwood OE replacement

The six piston fronts offer no noticeable additional stopping power as they have the same piston area as stock. They will improve the wear on the pads as the pistons are unequal in diameter. This means that they have a preferred orientation, left to right and are marked accordingly

The rears have a mounting bolt length issue resolvable with a washer. They need to be checked for centering. In bleeding, to purge all the air, they need to be partially dismounted and held upright as the bleeders are not in the stock position. Front's are ok.

The rears also have the same piston area as stock and that preserves the original factory imbalance. No need for any kind of proportioning valve.

You really oughta get their master cylinder. Which one depends on whether or not you have power brakes.

You will want SS sleeved hoses and the Willwood kit provides everything you need.

Wilwood is spelled with one 'el'. I never can remember this, don't know why. Spellcheck is no help. Maybe writing this down this way will help me!

Last edited by ignatz; 03-15-2019 at 04:11 PM.
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Old 03-15-2019, 05:31 PM
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Originally Posted by jb78L-82 View Post
I personally would not go willwood for a street driven C3 unless you go 6 piston front calipers and bigger rotors. Willwood 4 pistons calipers will NOT stop your car any faster than the stock delcos BUT are lighter being aluminum. If you plan to keep it basically stock, I would rebuild your current calipers if they are already stainless steel sleeved OR buy rebuilt stainless steel calipers from one of the vendors. You can also buy NEW cast iron calipers in either regular lip seals or o ring. Some folks swear by o ring calipers BUT I have had SS Delco calipers with lip seals on my C3 since 1985 and the car is hardly driven so I don't buy the longevity theory with O ring seals. Change you brake fluid every 4-5 years is the best insurance for leaking calipers.
The six piston calipers won't stop you any faster than the four piston calipers.
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Old 03-15-2019, 06:35 PM
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Originally Posted by 69427 View Post
The six piston calipers won't stop you any faster than the four piston calipers.
I know that you and I have debated this question before so I don't want to rehash the same old BUT:

A 6 piston caliper (whether it has more area or not over the 4 piston caliper) coupled with a larger rotor (13/14 inches in this case)will absolutely stop a car faster coupled with a proper ultra high performance tires quicker than a 4 piston caliper with a 11.75 inch rotor.

Here is my post from last year on this issue and the math:

There are 4 ways to increase the brake torque of a C3, reduce the stopping distance, besides better tires:

1. Increased coefficient of friction of the brake pads
2. Increased rotor diameter-increased brake torque
3. Increased caliper piston area-increased clamping force
4. Brake line pressure in PSI

Clamping force: The clamping force of a caliper is the force exerted on the disc by the caliper pistons. Measured in pounds clamping force, it is the product of brake line pressure, in psi, multiplied by the total piston area of the caliper in square inches. This is true whether the caliper is of fixed or floating design. Increasing the pad area will not increase the clamping force.

Braking torque: When we are talking about results in the braking department we are actually talking about braking torque - not line pressure, not clamping force and certainly not fluid displacement or fluid displacement ratio. Braking torque in pounds-feet on a single wheel is the effective disc radius in inches times clamping force times the coefficient of friction of the pad against the disc all divided by 12. The maximum braking torque on a single front wheel normally exceeds the entire torque output of a typical engine.

Clamping force is brake line pressure X total piston area of caliper in square inches

Brake Torque (The Holy Grail)= DISC RADIUS (half the diameter of the rotor) x Clamping force X the coefficient of friction of the brake pad.


The brake torque number can be increased with a larger diameter rotor which is why high performance cars today have 14/15/16 inch rotors usually with a LARGER caliper of 4/6 pistons (more piston area with more clamping force) versus the standard size caliper for that car.


The brake torque formula is key and note that just increasing rotor diameter with no other changes increases brake torque, the holy grail for brakes.

I said in the prior post that a 6 piston caliper coupled with a larger rotor will stop the car faster than a 4 piston caliper (with a smaller rotor). The willwood 6 piston caliper is actually slightly less piston area than their 4 piston caliper, 5.51 versus 5.56. Most cars that have a larger caliper with multiple pistons will have more piston area than the smaller 4 piston caliper but not in the C3 willwood products which is bizarre......

There really is no debate here. The math does not lie or can be debated........

Last edited by jb78L-82; 03-15-2019 at 06:51 PM.
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Old 03-15-2019, 07:24 PM
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I don't see that a larger rotor with the Wilwood's being discussed here is a realistic option. The OP mentions $500 for the front kit. I think it is actually a bit more.

And anything else is a lot more money and this discussion may be confusing the situation. If he puts more aggressive fronts on his car the back brakes become even more irrelevant.

And .... he really ought change them all out!

Last edited by ignatz; 03-15-2019 at 07:26 PM.
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Old 03-15-2019, 08:35 PM
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Originally Posted by ignatz View Post
I don't see that a larger rotor with the Wilwood's being discussed here is a realistic option. The OP mentions $500 for the front kit. I think it is actually a bit more.

And anything else is a lot more money and this discussion may be confusing the situation. If he puts more aggressive fronts on his car the back brakes become even more irrelevant.

And .... he really ought change them all out!
I agree...I digressed...sorry
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Old 03-15-2019, 08:46 PM
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Originally Posted by jb78L-82 View Post
I agree...I digressed...sorry
No big deal, one of the hot topics that folks like to bat around.
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Old 03-15-2019, 10:11 PM
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Originally Posted by jb78L-82 View Post
Yes....that is a good comparison. With the exception of the 135ft for the stock calipers on test brake 5, the 2 caliper designs are very equal. Especially the final brake test on both calipers with the willwood 2-4 ft advantage which is insignificant. My recollection was that the tests were not done with the same brake pads for both calipers, however..

The only way the wilwoods can out brake the stock system on identical cars with the same brake pads and tires is with the 4 piston caliper on a 13/14 inch rotor in front or the 6 piston front caliper on a 12/13/14 inch rotor.....this physics and cannot be changed......
Nor same conditions-

All debates aside- I think they just look better!!!

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Old 03-15-2019, 11:42 PM
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Originally Posted by shurst View Post
I hope I'm not beating a dead horse, but here it goes;
I just noticed that my front calipers are beginning to leak in my 1974 convertible and I am contemplating the best repair path. I noticed that Wilwood has a very nice kit that is quite lightweight, assumed to be high quality, and comes with the pads and SS lines for about $500. My question is, has anyone else used the Wilwoods, and are they worth the extra money, or am I better off going with something else? Of course, I would value any other suggestions as well.

Thanks in advance!
Good pricing through these guys for Wilwood and easy to deal with. https://www.southwestspeed.com/
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Old 03-16-2019, 12:46 AM
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I purchased the D8-4 Wilwood brake kit with their 1 piece 11.75" rotors for the rear and the D8-6 Wilwood brake kit with the 11.75" 1 piece rotors for the front.
I'm very happy with the calipers and rotors which all fit with the 15" rally wheels.
If you plan to run 15" aftermarket wheels do a fit check before you purchase the wheels.
The D8-6 front calipers and rotors fit with my aftermarket wheels but the clearance between the wheels and calipers were at the minimum tolerances so I went to 17" wheels just to be on the safe side.
If I had the D8-4 calipers and 11.75 rotors on the front the 15" aftermarket wheels would have fit on all four corners with no issues.
I purchased the Wilwoods because I have been a satisfied repeat customer of Wilwoods for many years and have never had any issues with their products.

Last edited by OldCarBum; 03-16-2019 at 12:48 AM.
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Old 03-16-2019, 02:02 AM
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Looks like on sale from one of our vendors. https://www.ecklers.com/corvette/196...-246551-1.html
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