Brake rotors hats offset
Thread Starter
Racer
Joined: Apr 2007
Posts: 251
Likes: 0
From: Milan
Brake rotors hats offset
I'm going to buy 2 pieces wilwood rotors with aluminium hats.
I've got direct fit Wilwood D8 calipers and I will choose standard size rotors (11.75" x 1.25"). Which is the correct offset for the hats? I've seen 1.41", 1.59", 1.71", and 1.96"..
I've got direct fit Wilwood D8 calipers and I will choose standard size rotors (11.75" x 1.25"). Which is the correct offset for the hats? I've seen 1.41", 1.59", 1.71", and 1.96"..
Thread Starter
Racer
Joined: Apr 2007
Posts: 251
Likes: 0
From: Milan
I've found an old discussion where seems that stock rotors has 1.846" offset with a .390" wall thickness.
Could anyone confirm it? front and rear are the same, right?
Could anyone confirm it? front and rear are the same, right?
Last edited by Dream Bikes; Apr 5, 2011 at 11:00 PM.
Burning Brakes
Joined: Sep 2006
Posts: 1,242
Likes: 12
From: Kalispell MT
I'd say email Wilwood's tech department or call them. I've talked with them a couple of times recently as I purchased my big brake upgrade kit and they are very knowledegeable and eager to help. I went with the 13" kit front & rear while stepping up to 18" wheels.
You have a great looking car and it has to be a real eye catcher in Italy! I've stayed up in Bergamo many times and really love the Milan area.
You have a great looking car and it has to be a real eye catcher in Italy! I've stayed up in Bergamo many times and really love the Milan area.
Thread Starter
Racer
Joined: Apr 2007
Posts: 251
Likes: 0
From: Milan
Thanks Ray, I will send an email directly at Wilwood 
Yes, any vette is always an eye catcher
Here in Italy we have a national Corvette club (Corvette Italia) and other local clubs. Next week we have our national Corvette Day at Garda Lake near Sirmione an awesome location for beautiful cars
Now we have got the best weather, sunny and warm...almost hot (25-29 °C)
http://www.corvetteitalia.it/
Yes, any vette is always an eye catcher
Here in Italy we have a national Corvette club (Corvette Italia) and other local clubs. Next week we have our national Corvette Day at Garda Lake near Sirmione an awesome location for beautiful cars
Now we have got the best weather, sunny and warm...almost hot (25-29 °C)
http://www.corvetteitalia.it/
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
rotors have different hat offset dimenstions for front and rear.... i dont have the measurements with me but i have them at home....i found one i will have to take a picture of the other.
Last edited by bobs77vet; Apr 7, 2011 at 01:32 PM.
Thread Starter
Racer
Joined: Apr 2007
Posts: 251
Likes: 0
From: Milan
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Supporting Vendor
Joined: Jun 2008
Posts: 2,199
Likes: 119
From: tempe Arizona
I'm not certain everyone is interpreting this info correctly, but the result may be correct.
The offset of a hat is the depth of the hat. Only the hat.
To determine the offset required to substitute a stock rotor this is the 'formula'.
Total height (shown) less rotor thickness, (not shown), less face thickness (not shown)
Assuming the rotor shown is 2.687, the rotor 1.10" and the face .250 then the offset is 1.59. The result may be correct but it's making these assumptions of rotor width and face width.
The offset of a hat is the depth of the hat. Only the hat.
To determine the offset required to substitute a stock rotor this is the 'formula'.
Total height (shown) less rotor thickness, (not shown), less face thickness (not shown)
Assuming the rotor shown is 2.687, the rotor 1.10" and the face .250 then the offset is 1.59. The result may be correct but it's making these assumptions of rotor width and face width.
Instructor
Joined: Sep 2007
Posts: 138
Likes: 1
less face thickness (not shown) WTF is face thickness? If its the thickness of the outer surface, it's .280 and .380. It's right on the drawing, no math required
Supporting Vendor
Joined: Jun 2008
Posts: 2,199
Likes: 119
From: tempe Arizona
Beg pardon but the only drawing I see above shows "rotor depth": 2,11/16". Which to many doesn't mean much when trying to figure out hat offset. Maybe I'm missing something for an image but that's all that's shown. The formula however is correct for anyone wishing to determine true hat offset: Total height - rotor width - face thickness = net hat offset.
Where as;
Total is the entire assembly on a flat surface.
Rotor width is the actual disc thickness.
Face thickness is that passing over the studs.
Not trying to make a simple question more complicated but the OP asked about the required hat offset. Being a 19yr Wilwood dealer...and custom application builder for them...that's how it's calculated. Which one is right for him depends upon what the goal is.
To determine the correct hat needed take the total height of the oe rotor, less the rotor width (1.25) less the oe face thickness (.280 or .380 <a big difference there>) and he'll rightly have the required offset. If the choices available don't meat this within perhaps .020" then I'd urge you to consider either custom hats or modifying the hat to meet that spec. Given the nature of the fixed mount D8 caliper you won't have a lot of fudge factor for centering that you'd have on a floating caliper.
Where as;
Total is the entire assembly on a flat surface.
Rotor width is the actual disc thickness.
Face thickness is that passing over the studs.
Not trying to make a simple question more complicated but the OP asked about the required hat offset. Being a 19yr Wilwood dealer...and custom application builder for them...that's how it's calculated. Which one is right for him depends upon what the goal is.
To determine the correct hat needed take the total height of the oe rotor, less the rotor width (1.25) less the oe face thickness (.280 or .380 <a big difference there>) and he'll rightly have the required offset. If the choices available don't meat this within perhaps .020" then I'd urge you to consider either custom hats or modifying the hat to meet that spec. Given the nature of the fixed mount D8 caliper you won't have a lot of fudge factor for centering that you'd have on a floating caliper.
Pro
Joined: Aug 2000
Posts: 503
Likes: 17
From: Jacksonville FL
Dream Bikes, Did you get your problem solved back then? I was looking for answers for my '69 wanting to replace the rotors with two piece units while keeping the stock calipers and my experience is that the offset or depth of the rear rotors is much less than the .18 the drawing from Vet MOD would indicate.
I cannot get out in the garage and measure it now because the car is finally in the paint shop (after only nine years!).
What did you find?
Locke
I cannot get out in the garage and measure it now because the car is finally in the paint shop (after only nine years!).
What did you find?
Locke
