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Old 07-21-2009, 10:52 PM
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How Much Pedal Travel

Here is what I have (so far)

Disc / Drum
8" dual diaphragm booster
Corvette MC
5.5:1 pedal ratio

I measured the full stroke of the MC and came up with 1-1/8".

My problem is that if I set the pedal so that it pushes the MC through full stroke before the pedal hits the floor, the pedal at rest is too high. With the slop in the linkage and booster, the pedal needs to travel almost 7" for full travel. The toe board and firewall on my 41 are just not conducive to that distance.

Should I

A. Set the pedal where it is comfortable and live with the MC only having about 75% of its available travel.

B. Set the pedal high and live with it.

C. Set the pedal high and move the seat, gas pedal and steering wheel back and just live with reaching for any switch or control mounted to the dash.

D. Something I haven't thought of yet.

Looking forward to your input. This has been driving me nuts.

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Old 07-22-2009, 02:13 PM
Will I ever get it done?
 

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OK While I was waiting on one of you, I thought about maybe changing the pedal ratio to 4.5:1. Is that numerically too low for the 8" dual diaphragm? That would give me about an 1-1/8 over the 5.5:1.
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Old 07-23-2009, 08:50 AM
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Many brake systems utilizing "power" brakes have a pedal ratio of 4:1. You should be fine.
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Old 07-23-2009, 06:29 PM
Will I ever get it done?
 

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Thanks Frisco. I made the modifications last night so it is now approx. 4.5:1. I had actually calculated wrong to begin with. The ratio as purchased was approx. 6.5:1. The pedal is now at a reasonable height and the MC bottoms before the pedal hits the firewall. With a firewall pad in place, it will be a toss up which would happen first. Hopefully, it will only get close during brake bleeding.
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Old 08-29-2011, 04:27 PM
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Quote:
Originally Posted by redsdad
Here is what I have (so far)

Disc / Drum
8" dual diaphragm booster
Corvette MC
5.5:1 pedal ratio

I measured the full stroke of the MC and came up with 1-1/8".

My problem is that if I set the pedal so that it pushes the MC through full stroke before the pedal hits the floor, the pedal at rest is too high. With the slop in the linkage and booster, the pedal needs to travel almost 7" for full travel. The toe board and firewall on my 41 are just not conducive to that distance.

Should I

A. Set the pedal where it is comfortable and live with the MC only having about 75% of its available travel.

B. Set the pedal high and live with it.

C. Set the pedal high and move the seat, gas pedal and steering wheel back and just live with reaching for any switch or control mounted to the dash.

D. Something I haven't thought of yet.

Looking forward to your input. This has been driving me nuts.
I've got a 41 Chevy and I'm having a problem with way to much brake pedal travel before the brakes are applied. Is the rod connected to the brake pedal something I can just buy a longer one?

Russ
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Old 08-29-2011, 05:24 PM
Will I ever get it done?
 

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Quote:
Originally Posted by Russgolfs
I've got a 41 Chevy and I'm having a problem with way to much brake pedal travel before the brakes are applied. Is the rod connected to the brake pedal something I can just buy a longer one?

Russ
Russ,

Low brake pedal before application is usually due to other reasons. Usually drum brakes which are out of adjustment.

Using a longer rod may cause the MC piston seal to cover the compensating port. If that happens, the brakes will apply when the brake fluid temperature increases.

If you have disc brakes and you still have the MC below the floor, you will need a residual pressure valve (2 psi for discs) to keep the fluid from draining back into the MC. This can cause more pedal travel prior to application of brakes.
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