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Hey Rob: Looking forward to more information on the brakes. I just took a look on the internet for your truck "Hellboy" and found some pics. WOW, that thing makes my heart race. Where can I find more and more pictures? Hey, where is the radiator? In back? Tell us more about that as well. How well does it cool? I imagine that you dont drive this anywhere except for autocross. |
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I'm in the same boat and got some feedback a page or two back. I'm going with the Monroe shocks. Rob is in the process of developing some that are specific to our trucks but I'm not sure when he'll ha e those available or what the price point will be. He has the Monroe's on his site but ok not sure how to pick the right shock. There has to be a formula that he uses to determine the proper dimensions (extended length and collapsed length). Posted via Mobile Device |
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Found this thread half way down page 2 and I started feeling sad, so I am bumping it back to where it belongs!
Mr. Rob, do we have any more great info on brake systems? |
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Rob,
I have a question about Sway Bars. I am certain it has been covered but sifting through 56 pages to find it is proving to be more difficult than I had imagined. The truck is a '71 C-10 Stepper and I have your Fatbar 4-link w/ 6.9" single adjustable Shockwaves attached to a F@$d 9" and a 4x2 custom back half. I am looking at buying the Speedway Engineering swar bar but I'm not sure what bar I should get. Should I get a solid/hollow bar and what thickness should I get? The front end is the Porterbuilt mild dropmember with their sway bar and RS-7 bags Thanks in advance, Adam |
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I'd go with a 1" splined bar and arms. I tried a 1 1/4", and even at .065" wall, it's a little stiff. Once you're set up with the 1" bar, you can change bars easy. I'd start with a 1" solid.
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On to Master Cylinders It's all about line pressure. And that means numbers. The first thing we all have to agree on is how hard to push on the pedal. The DOT standard is 30 to 40 lbs foot pressure. But we need a standard that everyone can agree on. I like to use 30 lbs on street drivers, and 40 lbs on race/performance builds. If thats OK with everybody, we'll start there. So, for the street, lets say 30 lbs of pressure comes from your foot. This would be multiplied by the pedal ratio. ?? What? I'll work on a picture for this. But for now, lets say you truck has a pedal ratio of 7-to-1. So, 30 lbs from your foot, times 7 from the pedal, = 210 lbs of force pushing into the master cylinder. Now to covert that into P.S.I. (line pressure) we need to know the size of the master cylinder. The area of the piston in the master can be calculated using the formula for the area of a circle. or, Area = 3.14 x R x R ( thats the best way I can type it in.) R being the Radius, or, 1/2 of the diameter. So, a 1" bore master has a 1/2", or .5" radius. 3.14 x .5 x .5 = .785 sq.in. of surface area. To get line pressure, we take the input force (lbs) and divide by the piston area (sq.in.) For our example, 210lbs / .785sq.in. = 267 lbs of line pressure. Not much. This will not stop your truck very well. So, what to do.
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Adam |
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I had asked earlier but I think it got blown buy. In regards to the front swaybar, If I were to bone-yard one, which is the best one? I found a 3/4t burban with the optional heavy-duty unit. Keeper? I've got your panhard rod kit and shock relocate. I'll be getting your rear swaybar next week (still in stock?). I'd also like to get the Monroe shocks from you, but I'm not sure what I need with the drop I've got. Still offer 10% to board members? Thanks! |
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my square is only 3.5:1.. dunno if the 67-72 is the same.
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Boosters This is the most common way to gain pressure. A power brake booster is like a stereo amp. It takes the the signal coming in and amplifies it on the output side. Bigger Boosters are like bigger amps, - more power.
The other key item is vacuum. Gotta have some. We use 18" as a test standard. Over the years we have tested a lot of boosters, and of coarse, we gathered all of the info. So, it's kinda like this: For a givin size of a booster, you can have an approximate multiplier, based on 18" vacuum. This multiplier can be factered into the line pressure calculation. A 7" single diaphram booster has a 1.7 to 1 multiplier 7" dual diaphram = 1.95 to 1 8" single = 1.9 to 1 8" dual = 2.25 to 1 9" single = 2.15 to 1 11" single = 2.45 to 1 Now these are averages from years of collecting data. **your results may vary**:lol: If we go back to our example, at 267 psi. and add an 8" dual diaphram booster (267 x 2.25) we can expect to get 600 lbs of line pressure, givin 30 lbs of foot pressure on the pedal, and 18" af vacuum. With this information, you can figure out the results of changing ratio's, boosters, and bore size. |
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Great information on the vacuum brake boosters Rob, but do you happen to know the approximate multiplier for a hydroboost? Some of us like to run big cams that don't make much vacuum ;)
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Oh yes, I was gettin to that. Hydro-boost units use the pressure from the power steering, (hydrolic pump) And have a great amplifier advantage. There are many factors here too, such as p/s pump output, hydroboost bore size, and the pressure loading of the acumulator. As a general rule, I would use a multiple of 3.5 to 1 for most hydro units. The downside is a loss in pedal feel, some of this can be gained back by lowering the pedal ratio.
Next up, the good, the bad, and the ugly of all these items. |
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Rob, I was looking at a manual pedal setup with a 5.75:1 ratio that is floor mount. Do you think this would be safe on the street with some getting used to?
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Well now, if we all wanted safety we wouldn't be hanging out here. :) But, yes, I think this is do-able. If you run a 7/8" master, you will end up with appx 391 lbs of line pressure at 40 lbs from your foot. Then look for an aggressive brake bad. You'll have some brake dust, but she'll stop. If it is a tandem master cyl set up, try a 3/4" bore (front)and a 13/16" bore (rear)
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Two big events today. GoodGuys @ indy, watch out for Brad Coomer and the Summers and Sons C10 on the Auto-X. It's Brads Birthday, and he wants a Pro class trophy in a bad way. In Ohio, @ the Lingenfelter Performance Nationals, Chris from Smitty's has his fresh C10 build out on track. As of last night Chris was only 2 sec. off the overall leader, and this is his first full day of Auto-X in the new truck. BTW, Chris recieved an invite to the Optima OUSCI, Great job Chris, watch for a feature on this truck soon.
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Any tricks of the trade for stabilizing a solid axle over mid-corner bumps?
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http://youtu.be/OWnW2VkgfVY Hellboy in action.
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OK, some yes, some no. First off, I'll say that I'm not a big fan of urathane in the trailing arm bushings. It's one of the only spots I'd say no to. If I was going to change the front pivit, I would fab in a uni-ball (steel) or a Monster-ball (delron lined) This would allow full articulation without any axle shift. If you don't want to do that, stay with the rubber here. Second, almost every spring and shock I've seen is too stiff, WAY too stiff for a goood handling vehicle, of any kind. Lets face it, we're not going to the high banks at Daytona. Food for thought, a stock rear spring has appx 600 lb/in, where as my Hellboy truck currently has 150 lb/in springs. I am looking into 'A' body springs to check out compression hieghts vs. spring rates, to see if we can make use of them. The longer panhard rod, especially if it is a low mount unit, will help eliminate the side-skip. And, if the springs and shocks were correct, then the swaybar could do it's job, and you'd never feel the bump. A mercedes 550 can do it, why not us?
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Thanks for the info Rob, let us know about the 'A' body springs. |
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