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 Post subject: Re: Tundra 7 442
PostPosted: January 5, 2020, 10:26 am 
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GonzoRacer wrote:
Oooooh!!! Bubba like shiny thing!

:cheers:
JDK

8) :lol:

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 Post subject: Re: Tundra 7 442
PostPosted: January 5, 2020, 10:47 am 
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Pretty! If you fit spacers between the flanges so you can use bolts and nuts through the flanges, the flanges are much less likely to eventually crack and tear out.

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 Post subject: Re: Tundra 7 442
PostPosted: January 5, 2020, 5:16 pm 
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Miatav8,MstrASE,A&P,F wrote:
Pretty! If you fit spacers between the flanges so you can use bolts and nuts through the flanges, the flanges are much less likely to eventually crack and tear out.

I do have thin nylon washers that go in there.

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 Post subject: Re: Tundra 7 442
PostPosted: January 5, 2020, 6:40 pm 
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I'm not talking about a bushing. The spacer provides a positive stop for you to clamp the bolt against to keep the bolt from rotating back and forth with the pedal. If it rotates, it will slowly slot the aluminum flanges. On the tracker shifter, I built similar to your pedal hinge but in steel. I used nylon bush on the bolt shank and no spacer, but I added shoulders to the flange that lock the bolt head so it cant' turn and used jamb nuts to set the end play. This meant the bolt shank always rotated with the flanges (i.e. no relative motion/wear between the flanges and the bolt shank. Also, it is a just a shifter so very low, not critical loads.

A spacer also greatly strengthens the flanges so the load is spread across a much larger area to prevent tear out and cracking. A brake pedal failure could be very dramatic. Just imho.

A thin steel spacer will work if you make room for steel washers inside the flanges to spread the load so the thin steel tube dose not dig into the aluminum flanges.Open up the pedal id enough to clear the spacer and use grease on the inside edges of the washers and the tube/spacer od. If there is enough cross section left in the pedal end, you can fit a bronze or plastic bushing.

If you can prevent the bolt from rotating with the pedal, that would work. Even with a bush, the friction will cause the bolt to turn unless it is held in some way.

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 Post subject: Re: Tundra 7 442
PostPosted: January 5, 2020, 8:18 pm 
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Miatav8,MstrASE,A&P,F wrote:
I'm not talking about a bushing. The spacer provides a positive stop for you to clamp the bolt against to keep the bolt from rotating back and forth with the pedal. If it rotates, it will slowly slot the aluminum flanges. On the tracker shifter, I built similar to your pedal hinge but in steel. I used nylon bush on the bolt shank and no spacer, but I added shoulders to the flange that lock the bolt head so it cant' turn and used jamb nuts to set the end play. This meant the bolt shank always rotated with the flanges (i.e. no relative motion/wear between the flanges and the bolt shank. Also, it is a just a shifter so very low, not critical loads.

A spacer also greatly strengthens the flanges so the load is spread across a much larger area to prevent tear out and cracking. A brake pedal failure could be very dramatic. Just imho.

A thin steel spacer will work if you make room for steel washers inside the flanges to spread the load so the thin steel tube dose not dig into the aluminum flanges.Open up the pedal id enough to clear the spacer and use grease on the inside edges of the washers and the tube/spacer od. If there is enough cross section left in the pedal end, you can fit a bronze or plastic bushing.

If you can prevent the bolt from rotating with the pedal, that would work. Even with a bush, the friction will cause the bolt to turn unless it is held in some way.

Oh man I didn’t think all that out. I do have bronze bushings in the pedal where the bolts go through. Not the rest of it.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 12:27 pm 
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I uncovered a problem with my mechanical advantage or pushrod throw. My rod is only moving 1/2-3/4” forward so I am only using a fraction of the cylinder throw which is 1.5”. Would one of these versions build in some extra throw? Am I missing something here? It’s no wonder I can’t get the air out, my compression sucks. As did my braking. I may not have had to pull this master. For the hell of it I measured the throw and was very surprised.


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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 12:58 pm 
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Steve, are you concerned about the M/C throw when driving? Or only trying to bleed the brakes better?

When in use, the amount of M/C travel is determined by things other than pedal geometry. Personally, I like to see the pushrod centered on the M/C axis when the brakes are engaged. This puts minimum bias on the piston in the M/C at full braking. Moving the pushrod pivot location like you have shown will change that relationship.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 1:08 pm 
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rx7locost wrote:
Steve, are you concerned about the M/C throw when driving? Or only trying to bleed the brakes better?

When in use, the amount of M/C travel is determined by things other than pedal geometry. Personally, I like to see the pushrod centered on the M/C axis when the brakes are engaged. This puts minimum bias on the piston in the M/C at full braking. Moving the pushrod pivot location like you have shown will change that relationship.


Both I guess. In my head this thing should collapse the full stroke, no? As you add pressure in the stroke the stopping power increases, right? Also I am pretty much certain the lack of stroke is causing me to not be able to bleed properly.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 1:50 pm 
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No, ~95% of the stroke is used to take up all the space between the brake pad/shoes to the rotor/drum. After that the pressure is the pressure. Any "pressure" you feel during that 95%, is simply to overcome the brake shoe springs, pedal return springs etc. and seals. Once that is done, in an ideal system there would be no more motion, only pressure. The remaining ~5% of motion is from flex in the mechanical bits such as pedal, brake lines etc. based on the amount of pressure applied.

If the M/C used all its travel to fill that 95%, then there is no way to apply pressure to the fluid since the M/C piston is now against the back of the cylinder.

Pedal pressure and the resulting brake action is not to be confused with pedal stroke. They are 2 separate things.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 2:01 pm 
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If you feel the lack of stroke is causing you the bleeding issue, you can disconnect the pedal from the pushrod and apply pressure directly to the pushrod during the bleeding process. But that should not be necessary if the output of the M/C is at the highest point of the M/C. If you are close to highest, but not quite, perhaps you could park the car on an incline and bleed it there?

I had an issue with my brakes due to a bias on one caliper's slide pins that caused, what felt to be trapped air. The pad wore more on one edge due to misalignment between the piston/pad/caliper and the rotor. The one pad would initiate contact on an edge while the other 3 met flat. Further pressure would cause more pedal movement as the one pad later made full contact.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 2:09 pm 
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rx7locost wrote:
If you feel the lack of stroke is causing you the bleeding issue, you can disconnect the pedal from the pushrod and apply pressure directly to the pushrod during the bleeding process. But that should not be necessary if the output of the M/C is at the highest point of the M/C. If you are close to highest, but not quite, perhaps you could park the car on an incline and bleed it there?

I had an issue with my brakes due to a bias on one caliper's slide pins that caused, what felt to be trapped air. The pad wore more on one edge due to misalignment between the piston/pad/caliper and the rotor. The one pad would initiate contact on an edge while the other 3 met flat. Further pressure would cause more pedal movement as the one pad later made full contact.

The masters are on the floor of the engine bay. Everything is higher. The calipers, everything.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 2:50 pm 
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I would raise the masters one inch and drill the push rod hole in the pedal one inch higher. This will result in a firmer pedal but higher effort.

Only the reservoirs need to be as high or higher than the calipers.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 2:55 pm 
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Had to go back to page 15 to see your setup. There has to be a way for air to get to the top of the reservoirs and I don't see a hole. Oems have vented caps with a rubber seal that deforms to allow the fluid out. Make sure you have a hole in the caps.

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 3:05 pm 
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Miatav8,MstrASE,A&P,F wrote:
Had to go back to page 15 to see your setup. There has to be a way for air to get to the top of the reservoirs and I don't see a hole. Oems have vented caps with a rubber seal that deforms to allow the fluid out. Make sure you have a hole in the caps.

I don’t have a hole. Shoot. But when bleeding I have them open. If I preload the master by 1/2”? Bad idea? Also how could a guy make a progressive ratio on the pedal?

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 Post subject: Re: Tundra 7 442
PostPosted: January 12, 2020, 3:21 pm 
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The hole can be extremely small. Check out a wilwood cap.

It looks like you have 2 psi valves already that essentially preload the brakes to drag. The 2 psi is line pressure so the clamping force is more like 8 lbs of pressure on each rotor depending on caliper bore size. No need for the residual pressure valves.

Never preload the pedal. The hole that connects the reservoir passage to the master bore is covered and blocked as soon as the piston moves. This is called the compensation port.

It looks like the threaded pin on the bottom of the reservoirs is designed to protrude through a grommet in the panel to support the res. They are held down with a large washer underneath secured by a screw/bolt threaded into the pin. Just fyi.

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