Brake rotor question

My car is apparently an early car. It appears that the car was assembled and ran very, very little. It has the Wilwood SL6 calipers on it and what appear to be the brake rotors that appear in the build photos. It also has the same tires that appear in the build photos and are date coded from that same time frame.

My question is this, what rotors did these Wilwood equipped cars use? They appear to be C4 Corvette rotors. In looking for the C4 rotors, they come in 12" and 13" sizes.

I haven't had a chance to pull a wheel and check the diameter. The car is kept in a facility that is some distance away so running over there to check is problematic.

I was wanting to get a new set of rotors and pads for a track day next month. Also, do these calipers both use the 7420 pad shape in the 20mm thickness?

Thanks in Advance

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Howard Jones

Supporter
That would be the new pad correct thickness (.8) for a 1.25" thick rotor. Those rotors are about 1.1 thick and are of a very low spec. Ok for street but watch them carefully if you run them hard. Also the thickness of a brand new pad will be ok but the wear will quickly add up with the thinner rotor to a marginal condition. You more or less start with about 60% effective pad thickness. I never run pads under 50% thickness. The Wilwood calipers don't like very high heat/race conditions with short pads. It exposes too much of the piston and they can and will differentially heat causing intermittent sticking in the clamped or "brakes on" mode. This may only effect one caliper at a time making releasing the brakes after a high speed stop interesting to say the least. Ask me how I know. Watch what you are doing carefully. Take an easy on the brakes.

You could try and shim the pads to make up the difference but IMHO you should change to a 1.25 thick two piece quality rotor for track use. See my build thread as it relates to brakes. Lots to consider there.

7420 is the correct pad pattern.
 
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That would be the correct thickness for a 1.25" thick rotor. Those rotors are about 1.1 thick and are of a very low spec. Ok for street but watch them carefully if you run them hard. Also the thickness of a brand new pad will be ok but the wear will quickly add up with the thinner rotor to a marginal. condition You more or less start with about 60% pad thickness. Watch what you are doing carefully. Take an easy on the brakes.

You could try and shim the pads to make up the difference but IMHO you should change to a 1.25 thick two piece rotor. See my build thread as it relates to brakes. Lots to consider there.

7420 is the correct pad pattern.

Thanks Howard. I am ditching the crapola rotors and pads that are on it. I'm trying to find out what they are so I can go from there and find something better for now.
 

Howard Jones

Supporter
I gave mine to a friend that has a firebird. Street driven, weekend drives, and car shows. They have been fine on it. I wouldn't throw them out they will fit a lot of Chevys. Give then to a buddy.

I could tell you what I have on my car. BUT it is not a direct bolt on. You will need to be prepared to do some caliper mounts to suit and match to proper master cylinder sizes.
 
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