Custom Brakes
Race Director
Joined: May 2006
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Safety Car
Joined: May 2003
Posts: 3,814
Likes: 105
From: Dearborn Heights Michigan
I just installed Wilwood D8-6 & D8-4 calipers and new discs on my 70 in the same size as stock. The calipers have larger bore pistons in addition to the front being 6 piston vs 4 stock.
Supporting Vendor
Joined: Jun 2008
Posts: 2,199
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From: tempe Arizona
Pistons in the D8s are the same size as those of the stock caliper. This was to keep both bias and displacement the same. If they were larger the piston travel would be greater and the pedal softer. The D8-6 while having six pistons and a differential bore design has nearly the same identical area as the four- it simply spreads it by way of two small and one large piston vs two medium bores. This will help pad wear but is not going to have an significant change in braking performance. (exacting cross fit would require a piston size not produced it all)
Instructor
Joined: Jan 2013
Posts: 145
Likes: 1
From: Edwards CA
Good point Tod,
It seems like the D8-6 design was an idea that came to Wilwood "Later" (A better idea), increase the surface area of direct pressure...as opposed to a narrow surface area (D8)
I will go D8-6 isf its not too pricey.
My GOAL is to upgrade but not for CAN-AM OR GT-1 style racing...LOL
It seems like the D8-6 design was an idea that came to Wilwood "Later" (A better idea), increase the surface area of direct pressure...as opposed to a narrow surface area (D8)
I will go D8-6 isf its not too pricey.
My GOAL is to upgrade but not for CAN-AM OR GT-1 style racing...LOL
Melting Slicks
Joined: Jul 2000
Posts: 2,541
Likes: 0
From: Chicago
Good point Tod,
It seems like the D8-6 design was an idea that came to Wilwood "Later" (A better idea), increase the surface area of direct pressure...as opposed to a narrow surface area (D8)
I will go D8-6 isf its not too pricey.
My GOAL is to upgrade but not for CAN-AM OR GT-1 style racing...LOL
It seems like the D8-6 design was an idea that came to Wilwood "Later" (A better idea), increase the surface area of direct pressure...as opposed to a narrow surface area (D8)
I will go D8-6 isf its not too pricey.
My GOAL is to upgrade but not for CAN-AM OR GT-1 style racing...LOL
Instructor
Joined: Jan 2013
Posts: 145
Likes: 1
From: Edwards CA
Let me re-phrase this:
More equal pressure over same size surface?
Anyway, that is the set I am ordering
Thanks Nassy/Vette
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Safety Car
Joined: May 2003
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From: Dearborn Heights Michigan
According to an article in the Oct. 2012 "Vette" Magazine.
Stock 72 calipers have front piston bores of 1.41" , Wilwood D8-6 frts has 1.88,1.35& 1.25. Sock rear is .925, Wilwood is 1.125.
Total areas of both front and rear are cosiderably greater than stock.
Stock 72 calipers have front piston bores of 1.41" , Wilwood D8-6 frts has 1.88,1.35& 1.25. Sock rear is .925, Wilwood is 1.125.
Total areas of both front and rear are cosiderably greater than stock.
Supporting Vendor
Joined: Jun 2008
Posts: 2,199
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From: tempe Arizona
The specs of the Wilwood calipers match my notes but I'll confess I don't have the specs of the stock parts to compare. That being said the Wilwoods are noted as working with the stock mc and those are some odd bore sizes; leading me to believe they were selected for specific reasons. While I've never heard of any issues from ones I've sold, that doesn't mean there isn't one of course.
Area wise those specs provide some horrendous differences in area.
Wilwood at 5.167
Factory at 3.123
I'll go out on a limb here a bit and say those factory specs are somehow mixed up. I'd buy them being the height of the pistons perhaps, but that's a very, very small area for a car of this era. It's on par with a mc bore of no larger than 7/8".
** I believe I've found the fly in the ointment here. The pistons they measured are most likely the seal cut section and not the actual piston diameter. (I'm fairly confident they are 1.875 x 2, same as the four pot front Wilwood)
This should clear up the confusion:
You'd like to think a magazine would know how to measure this...but then their job is selling magazines! lol
Area wise those specs provide some horrendous differences in area.
Wilwood at 5.167
Factory at 3.123
I'll go out on a limb here a bit and say those factory specs are somehow mixed up. I'd buy them being the height of the pistons perhaps, but that's a very, very small area for a car of this era. It's on par with a mc bore of no larger than 7/8".
** I believe I've found the fly in the ointment here. The pistons they measured are most likely the seal cut section and not the actual piston diameter. (I'm fairly confident they are 1.875 x 2, same as the four pot front Wilwood)
This should clear up the confusion:
You'd like to think a magazine would know how to measure this...but then their job is selling magazines! lol
Last edited by Todd TCE; Jan 16, 2013 at 09:36 PM.