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mnm99

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Discussion starter · #1 ·
Anyone know off hand what the front disk brake piston size was on a 68? It looks like a large single piston. I called wildwood about a manual master and he asked about the piston size. I'm not home right now. Anyone know?
 
hard to say- your 68 came stock with 2 (or was it 4?) piston calipers stock if it had disc brakes.
if you have single piston calipers, then it's probably a 69 setup, but could also be 78-88 G body "metric" parts if someone put drop spindles on it somewhere along the line.
pull a caliper out, take the pads out, and measure the piston with a tape measure to get a rough guesstimate of what you've got.
 
Discussion starter · #3 ·
Thanks I got it. 2 15/16". Wildwood recommended a 1" or 7/8" bore master for the manual brakes. Not sure what to go with....:confused:
 
Discussion starter · #5 ·
What brake pedal setup are you running? Hopefully the Wilwood tech asked about pedal ratio and disc size too.... without it, I don't know how they'd guess at the right master cyl.

Stock 67-69 brake pedal with the manual (upper) hole is about 6:1 for manual brakes (or so I've read). With stock front discs and calipers, I don't think I'd go any smaller than 1" bore master cyl. 7/8 would give lower pedal effort, but I think you'd run out of travel with the large 2+15/16" front calipers. 1" might be OK, but might be a little close. I think I'd start with a 1" at least...

-T
 
Discussion starter · #8 ·
What brake pedal setup are you running? Hopefully the Wilwood tech asked about pedal ratio and disc size too.... without it, I don't know how they'd guess at the right master cyl.

Stock 67-69 brake pedal with the manual (upper) hole is about 6:1 for manual brakes (or so I've read). With stock front discs and calipers, I don't think I'd go any smaller than 1" bore master cyl. 7/8 would give lower pedal effort, but I think you'd run out of travel with the large 2+15/16" front calipers. 1" might be OK, but might be a little close. I think I'd start with a 1" at least...

-T
Yea, I told him the size and ratio. Those are what he recommended. What year and car one should I look for? I've been reading corvette ones?

I'm concerned about how it stops though. Right now I have a 1 1/8 bore with a dual 8" booster. It didn't work good at all. I ended up moving it by using washers and lineing the brake rod with the upper hole. It stops good right now. I'm wondering how good it will be if I remove the booster and use a smaller bore. Would it stop the same?
 
Discussion starter · #11 ·
1 1/8" was never used on manual brakes. You will have to stand on the pedal in hopes of getting it to stop. 1" is correct.
I know 1" is correct for manual. I'm wondering the difference from 1 1/8" power to 1" manual. Not sure if I'm going to like it.
 
Discussion starter · #13 ·
Go with the 1 inch M/C . I tried the 1 1/8 M/C with factory disc and will stop but foot pressure is to high. Noticable difference with 1 inch. Stay away from 7/8 one. IMO Is there a reason going from power to manual?
Room for twin turbo headers and 3" downpipe.:D
 
I'd do the 1" bore MC.
1" bore was used on the 67 manual disc option with 4 piston calipers, but those calipers had a little less total piston area than the single piston type you have, so your pedal effort should be lower.
David
 
Discussion starter · #16 ·
I'd do the 1" bore MC.
1" bore was used on the 67 manual disc option with 4 piston calipers, but those calipers had a little less total piston area than the single piston type you have, so your pedal effort should be lower.
David
Thanks David. I hope I'm making the right choice. Like I posted I'm running a 1 1/8" bore master with a 8" dual booster connected to the top hole in the pedal. I just ordered a 67 Corvette Manual 1" bore master. Am I going to have to stand on the pedal to stop this way?

Is there a way to calculate the pressure of a Dual 8" booster with a 1 1/8" master compaired to the 1" with both 6-1 ratio?

How much would this booster put out working correctly?
 
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