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1LE Brakes and Master Cylinder Size. Dual bore (1.25" & 0.945") MC ?

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1LE Brakes and Master Cylinder Size. Dual bore (1.25" & 0.945") MC ?

Old 01-16-2019, 09:17 AM
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1LE Brakes and Master Cylinder Size. Dual bore (1.25" & 0.945") MC ?

The 1LE Calipers on Thirdgen used same piston size as the C4 Calipers which are twin 1.5 with 12 rotors. In order to keep my 15 wheels, I want to use the C4 brakes on an S10 which has a Master Cylinder of 1. My S10 rotors are only 10.5". From everything I read here, the Thirdgen with 1LE brakes used master cylinder with dual bore design (1.25" & 0.945"). However, the C4 Corvette used Master Cylinder of 15/16" bore (0.937"). Typically, the caliper piston area, master cylinder are and the brake pedal ratio are matched to provide optimum clamping power.

If I am not mistaken, the 1.25 bore on Thirdgen Master Cylinder is for the front brakes. If so then I would not have any problems using C4 calipers on my S10 if the brake pedal ratio are similar ratio. C4 may have used a smaller brake pedal which is why it may have used a Master Cylinder of 15/16" bore (0.937").

Is the 1.25 bore on Thirdgen Master Cylinder for the front brakes?

Anyone know the brake pedal ratio on the Thirdgen ?

Thanks



Waid

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Old 01-16-2019, 10:38 AM
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Re: 1LE Brakes and Master Cylinder Size. Dual bore (1.25" & 0.945") MC ?

Originally Posted by waid786 View Post
Is the 1.25 bore on Thirdgen Master Cylinder for the front brakes?

Thanks
Waid
No, it is the quick-take-up section of the MC. The stock calipers are a low drag design that retracts the pads further. The 1.25" MC bore section provides a lot of fluid early on to get the pads back up against the rotor. Then the smaller main bore takes over.

RBob.
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Old 01-16-2019, 10:43 AM
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Re: 1LE Brakes and Master Cylinder Size. Dual bore (1.25" & 0.945") MC ?

Originally Posted by RBob View Post
No, it is the quick-take-up section of the MC. The stock calipers are a low drag design that retracts the pads further. The 1.25" MC bore section provides a lot of fluid early on to get the pads back up against the rotor. Then the smaller main bore takes over.

RBob.
So I should be able to bolt on the Thirdgen M/C in the S10. Correct?

The S10 uses integrated proportioning valve that is bolted to the ABS module. Would I need to switch the the proportioning valve?

I have 8.5 rear end with disk brakes with 11.6" rotor and 1.9" caliper piston size.

Waid

Last edited by waid786; 01-16-2019 at 10:55 AM.
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Old 01-16-2019, 02:57 PM
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Re: 1LE Brakes and Master Cylinder Size. Dual bore (1.25" & 0.945") MC ?

Originally Posted by waid786 View Post
So I should be able to bolt on the Thirdgen M/C in the S10. Correct?
Recall that the 3rd gen MC has the lines exiting toward the engine. So need to be sure that there is enough room. Another item is that the 3rd gen master may not fit into the S10 vacuum booster.

Going with a C4 MC may be a better idea.

The S10 uses integrated proportioning valve that is bolted to the ABS module. Would I need to switch the the proportioning valve?
I don't know.

I have 8.5 rear end with disk brakes with 11.6" rotor and 1.9" caliper piston size.

Waid
BobR.
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