Anyone ever designed a cheap braking system?

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Hey people, after having some free time in this vacations, I encouraged some friends of mine to build a soap box racer each so we can race them in a mountain here where I live (of course it´s paved). To keep it cheap we decided to use no suspension and hand truck wheels.(I think that´s the correct name I looked for it on northerntool).However, to be sure it was fun I went to the "track" and tested it with my Jetta, and even with its sucky aerodinamic coeficient I did get to 120 kmph in some straights, and I timed about 8 mins of continuos racing. I think that with the low drag of the soap box racer, I can easily get up to 140-150 kmph so I need some DECENT brakes....I was thinking of using the V brakes of the bicycles, with a kind of disk that is attached to the hub, however, after the track testing I started thinking that the pads would wear very easily and fail, or get sticked to the disks. ( I don´t  have a drawing of it yet, but tomorrow I´ll take a pic of the dummy I made)So I was wondering... has anyone of you guys designed a good braking system that´s cheap to make and RELIABLE? Of course this is only primary braking and I will have an emergency, but I wanna win this race. . BTW it´s a mountain descent so it has lots of curves where brakes are needed, and lots of gravity power I´ve already designed the structure in CAD, pic attached (btw, the seat ain´t really the seat, I will go almost lying down and just a little of my head sticking out. Chassis is almost finished with 1.25" square tubing (main structure) and triangulation done with 1" square tubing, each having .075" wall thickness.Any suggestions? Thanks!  Attached ImagesLast edited by elvergon; 04-06-2007 at 04:50 AM.My Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Nice idea but I would add a roll bar to protect your head if you loose control at those speeds. Also your drawing is off. You have your tire centers equal to your frame floor. This will allow for way to much ground clearance and will causes you to loose far to much control. I designed and frame that looked like a A frame suspension but instead of using shocks, I used threaded rode so I could manually set the ride height. This is great for getting maximum aerodynamics and control while allowing for the surface condition on the track. As to your brakes, I used a band and drum brake from a go cart. I used a 6 inch drum setup. With the band brake setup you can make sure their is no drag on the drum until the brakes are applied by having a spring holding the band away from the drum. This will allow no drag for starts and running until you need it.Another safety factor to remember is with no suspension and sold tires. traction for steering and braking will be very limited. Most soap box car use very narrow tires and will not stop very fast so you might want to do some tests before trying to top out on max speed.Have fun but keep it safe. Miller DVI2Lincoln Precision Tig 225Thermodynamics Cutmaster 38Everything else needed.
Reply:You can use a scrub brake which is pretty inexspensive to make. I have an old manco minibike which uses one and it stops the bike pretty wellWill   Supports Autism Awareness                            My ToysBobCat 225 PLusMillermatic 130Miller Spectrum 300 CutmateEverlast Power Tig 185 Micro April is Autism Month .
Reply:ok so lets see some pic's of the real thing here. i still can not picture the wheels you are going to use. 140MPH with no suspention... that sounds a lil nuts to me but hay we all gotta go some time right.the role cage idea sounds like a good one.soap box racer??? you talking about a gravity powerd only cart right?? its going to take some good design to pull off 140 along with a good hill and a lot of insanity. be shore to take lots of pictures.have you gotten a look at the compitition's designs?? summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:what cad design software did you use ?? i been looking for a decent one thats not going to break the bank??any help here would be great. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:At those sort of speeds you will want more than a crub brake. It will cost a little bit more, but look at mt. bike disk brakes, they will have plenty of stoping power and let you brake late in the corners.
Reply:For future posts, its kilometers per hour not miles per hour. 1.6 KMP = 1 MPHwhere do you live elvergonMiller DVI2Lincoln Precision Tig 225Thermodynamics Cutmaster 38Everything else needed.
Reply:Wow - 87 to 93 MPH in a soapbox? I would probably do a good set of used motorcycle calipers!John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:If you ran the rear axle straight through you could, with a little time and thought, mount a rotor and caliper set up from a street bike. There are bike salvage yards all over the place. You could incorporate the lever and master cylinder into the cockpit. Keep in mind that a rear only braking system will leave you vulnerable to spin outs._________________Chris
Reply:Originally Posted by jamlitNice idea but I would add a roll bar to protect your head if you loose control at those speeds. Also your drawing is off. You have your tire centers equal to your frame floor. This will allow for way to much ground clearance and will causes you to loose far to much control. I designed and frame that looked like a A frame suspension but instead of using shocks, I used threaded rode so I could manually set the ride height. This is great for getting maximum aerodynamics and control while allowing for the surface condition on the track. As to your brakes, I used a band and drum brake from a go cart. I used a 6 inch drum setup. With the band brake setup you can make sure their is no drag on the drum until the brakes are applied by having a spring holding the band away from the drum. This will allow no drag for starts and running until you need it.Another safety factor to remember is with no suspension and sold tires. traction for steering and braking will be very limited. Most soap box car use very narrow tires and will not stop very fast so you might want to do some tests before trying to top out on max speed.Have fun but keep it safe.
Reply:Originally Posted by lorenzoIf you ran the rear axle straight through you could, with a little time and thought, mount a rotor and caliper set up from a street bike. There are bike salvage yards all over the place. You could incorporate the lever and master cylinder into the cockpit. Keep in mind that a rear only braking system will leave you vulnerable to spin outs.
Reply:Originally Posted by fun4now.ok so lets see some pic's of the real thing here. i still can not picture the wheels you are going to use. 140MPH with no suspention... that sounds a lil nuts to me but hay we all gotta go some time right.the role cage idea sounds like a good one.soap box racer??? you talking about a gravity powerd only cart right?? its going to take some good design to pull off 140 along with a good hill and a lot of insanity. be shore to take lots of pictures.have you gotten a look at the compitition's designs??
Reply:Originally Posted by elvergonThe problem is that if I use a solid axle It will act like if it has no differential, making very hard to turn in corners, since this mountain has LOTS of them, I discarded the solid axle idea, But I will take a look of it again... Thanks!
Reply:Me in there... Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:chassis and mock up wheels Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Wheels...yeah, the priority in this project is to keep it CHEAP Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:V brake system designed....this would act like a caliper...and a steel disk would go attached to each single wheel Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:another Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:another of the "caliper" Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:How it looks with 2 wheels lol Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:my original V brake Idea...Still disk attached to the wheel is missing but you can imagine it for sure... Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Welds  Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:More welding Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Last welding... Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:BTW rust won´t let take a good look at the welds...I know they will hold but I´ll take some close ups later for you guys to look at...Here´s more less what the race and the geography looks like...We will race at 3 am cause its a street too and we will be very low on the ground for someone to notice us... Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!Originally Posted by fun4now.what cad design software did you use ?? i been looking for a decent one thats not going to break the bank??any help here would be great.
Reply:Originally Posted by lorenzoHow about having two half axles extend into the area behind the seat mounting a set-up on each independent axle. This could done with your v brake idea or the disc brake set-up off of a mountain bike. The reason I suggested the motorcycle brakes is because I don't know how well the other brake systems would handle the heat and glazing you will get from the speeds you are anticipating.
Reply:I did a lot of this gravity insanity when I was a kid before I got my license and became really dangerous. I think your wheels will seriously impact your ability to reach the 150 kph (90 mph) speeds you mentioned. When we got serious about going fast we used official soapbox derby wheels that had really good bearings and a very narrow contact patch and the difference in speed was dramatic although the cornering ability was pretty marginal. Google "gravity racing" and see what the serious racers are running and the speeds they are achieving. Here are a couple examples:http://www.carbodydesign.com/concept...ravity-car.phphttp://www.3dyn.com/gravity.htmlI think a more realistic speed target for your setup would be 45 mph which is plenty fast when you are only inches off the ground. Going 90 mph would require a death wish.Keep us posted on how the race goes.Cut an MGB and widened 11" C4 Corvette suspension and LT1 Chevrolet power & 6 spd. Pictures here:Part 1http://forum.britishv8.org/read.php?13,7581Part 2http://forum.britishv8.org/read.php?13,22422
Reply:I agree, if anything you should build a bodyboard and put a set of high end skateboard wheels on it. You're asking for a death wish, you might as well give yourself a shortcut.  John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:i think if ya manage to get that thing up to the speeds you are looking for some one is likely not to make it.jim has a good point about those wheels limiting your speed wich is a good thing. looks like the hill could make for a great run and lots of fun if you keep the speeds in controlable #'s2AM so have you looked into lighting options, holding a flashlight out the side is not likely to work out too good. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:Originally Posted by Jim StabeI did a lot of this gravity insanity when I was a kid before I got my license and became really dangerous. I think your wheels will seriously impact your ability to reach the 150 kph (90 mph) speeds you mentioned. When we got serious about going fast we used official soapbox derby wheels that had really good bearings and a very narrow contact patch and the difference in speed was dramatic although the cornering ability was pretty marginal. Google "gravity racing" and see what the serious racers are running and the speeds they are achieving. Here are a couple examples:http://www.carbodydesign.com/concept...ravity-car.phphttp://www.3dyn.com/gravity.htmlI think a more realistic speed target for your setup would be 45 mph which is plenty fast when you are only inches off the ground. Going 90 mph would require a death wish.Keep us posted on how the race goes.
Reply:Originally Posted by MicroZoneI agree, if anything you should build a bodyboard and put a set of high end skateboard wheels on it. You're asking for a death wish, you might as well give yourself a shortcut.
Reply:Originally Posted by fun4now.i think if ya manage to get that thing up to the speeds you are looking for some one is likely not to make it.jim has a good point about those wheels limiting your speed wich is a good thing. looks like the hill could make for a great run and lots of fun if you keep the speeds in controlable #'s2AM so have you looked into lighting options, holding a flashlight out the side is not likely to work out too good.
Reply:Why waste your time on anything more than the brakes that rub on the tire ?? Your tire/ wheel selection is already your weakest link !!! Didn't see the mortuary on your diagram. NOt to be so negative, but those type of wheels are a bad idea at best. Seen them pop the bearing directly out of the box...Just an idea.Then again I seen a man try to reach the moon in a rocket powered 76 lincoln - of course he made face of death video!!!Good luck.....
Reply:Originally Posted by 8angusWhy waste your time on anything more than the brakes that rub on the tire ?? Your tire/ wheel selection is already your weakest link !!! Didn't see the mortuary on your diagram. NOt to be so negative, but those type of wheels are a bad idea at best. Seen them pop the bearing directly out of the box...Just an idea.Then again I seen a man try to reach the moon in a rocket powered 76 lincoln - of course he made face of death video!!!Good luck.....
Reply:Outside the safety arena, brakes are going to be a very critical element in speed control and the win/loss factor here too. Poor brakes aren't going to let you run at optimum speeds once a guy over shoots a corner or two and gets reduced gonad syndrome. You are going to want to exit each corner at the maximum controllable speed, build up as much speed as possible then slam it down quick at the last possible moment. I don't see a hot set of rubber pads off a bicycle doing that for the entire course. I'll bet you're going to have to agree on something that is more than you'd like to spend but yet functional and hopefully doesn't bust the budget. Maybe set a top limit on the bucks spent on brakes so it's more of a level field. Think performance.
Reply:reduced gonad syndrome. LOL is that coverd under medicare. i gotta remember that phrase. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:I like where this project is headed, but V-brakes at 80-90mph makes me think of this http://saferacer.com/foonem2he.html
Reply:yep cheap break systems and 80+ Mph just dont belong in the same sentance.a helmit ??? come on were talking about home made buggys on $5 wheels with little to no brakes and speeds over 80 Mph, you dont need no stinking helmit for that. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:Originally Posted by elvergonThanks a lot man, actually the idea of the A arm setup with the threaded rod is pretty nice, and I tought of that, but speaking with the competitors, we agreed that it will  make it more sofisticated and thus more expensive, and ge want to get this stuff rolling fast...As for the drum brake,  I really don´t like drum brakes that I´ve used in go karts, and finding one here in Mexico would be really difficult and expensive too...As for the tires, yeah, they won´t have much traction, actually the ones that  I have and using for mock up are 3.2 in wide...Here´s the pic of the disk brake system that I designed using the V brakes of the bike...
Reply:I admire constructive insanity. I will add to the warnings of the others about the wheels.  They arn't made for the lateral loads of the turns, and they arn't made for the speeds, and they can't take much heat.The bearings are likely to go from side load and speed, if the wheel halves don't seperate first or the tire walk off the bead, and this will adversely affect handling.Heat will damage the tires and may weaken the structure of the wheel halves, and you will get heat from the bearings, road friction, and the brakes. At a minmum, the brakes need to be far enough from the wheels to avoid overheating them. Any brake that acts direcly on the wheel itself, or has a short heat path to the wheel, is asking for a failure. Overheating can lead to loss of the tire or loss of strength of the wheel material.Cost aside, I second (forth? fifth?) the recommendation to upgrade the wheels.
Reply:The bearings are likely to go from side load and speed, if the wheel halves don't seperate first or the tire walk off the bead, and this will adversely affect handling.Heat will damage the tires and may weaken the structure of the wheel halves, and you will get heat from the bearings, road friction, and the brakes. At a minmum, the brakes need to be far enough from the wheels to avoid overheating them. Any brake that acts direcly on the wheel itself, or has a short heat path to the wheel, is asking for a failure. Overheating can lead to loss of the tire or loss of strength of the wheel material.
Reply:Originally Posted by SandyOutside the safety arena, brakes are going to be a very critical element in speed control and the win/loss factor here too. Poor brakes aren't going to let you run at optimum speeds once a guy over shoots a corner or two and gets reduced gonad syndrome. You are going to want to exit each corner at the maximum controllable speed, build up as much speed as possible then slam it down quick at the last possible moment. I don't see a hot set of rubber pads off a bicycle doing that for the entire course. I'll bet you're going to have to agree on something that is more than you'd like to spend but yet functional and hopefully doesn't bust the budget. Maybe set a top limit on the bucks spent on brakes so it's more of a level field. Think performance.
Reply:Originally Posted by jamlitWell after seeing your pics I have a few issues to mention. I could be wrong here but the tires you are showing will not handle the speeds and turning at thoughs speeds. I would think a proper go cart wheels would be much better suited. Also I can't see the brakes being good enough and at the least you will need to have your setup on all four tires. I didn't realize the weight you are going to have in your cart as the frame you are showing weighs as much as a completed cart that I have worked on. The size of the tires you have will allow for good enough ground clearance but have you tired turning something like that at though speeds. I got into racing tractor lawn mowers awhile back and with the small tires and even with tight steering, it was some crazy handling experiences. The rear axle I designed was two axles for each side. each having low friction bearing and a drum brake for each side. their were two brake pedals, one for each side that were close enough together to be used as one but separate so that they could be used independently to add in steering. this worked great for the racing we did but sucked for traditional soap box racing. I wish I had pictures of the last cart I built as I didn't have a digital camera then. My completed car with the adjustably suspension most likely weighed allot less than what you are going to end up with. Have you decided on the steering setup yet. Keep us up to date on your decisions and build as I am interested to here you findings after trying this contraption.
Reply:Originally Posted by enlpckI admire constructive insanity. I will add to the warnings of the others about the wheels.  They arn't made for the lateral loads of the turns, and they arn't made for the speeds, and they can't take much heat.The bearings are likely to go from side load and speed, if the wheel halves don't seperate first or the tire walk off the bead, and this will adversely affect handling.Heat will damage the tires and may weaken the structure of the wheel halves, and you will get heat from the bearings, road friction, and the brakes. At a minmum, the brakes need to be far enough from the wheels to avoid overheating them. Any brake that acts direcly on the wheel itself, or has a short heat path to the wheel, is asking for a failure. Overheating can lead to loss of the tire or loss of strength of the wheel material.Cost aside, I second (forth? fifth?) the recommendation to upgrade the wheels.
Reply:Originally Posted by elvergonLol, nevermind about scaring me off...it´s cool to have bunch of opinions in here....Remember 120 kmph is just 2 straights in the race....most of the time I´ll be going at 60-70 I think....The tires are not tubeless too...however bead could fall off...but.... what tha....After all your comments I think that I might want to throw myself lots of times increasing the speed until...until it feel safe  At least those are my thoughts for now....Fkin rain =( won´t let me work..( no garage, just backyard welding and cutting)....gotta do some tests then
Reply:One speed control tool that works pretty well is eddy-current drag. Has the properties of a) no wear, b) braking increases with speed and drops off as seed decreases... Not a sole solution, due to factor (b), which requires a friction brake for low speed and stopping, but good for speed control.A half dozen rare earth magnets and an aluminum disk with good airflow around it will provide much drag.Make note that the rotating disk will get HOT. Slotting or venting it will reduce the braking action by interfering with the eddy currents. Attached ImagesLast edited by enlpck; 04-08-2007 at 03:19 PM.
Reply:dont they use that system on the high speed cars at the flats going for speed records?? seems like i saw it on a rocket car once. wonder how dificult or expensive it would be to set up??? and what the operational speeds for it would be?? summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:Originally Posted by fun4now.dont they use that system on the high speed cars at the flats going for speed records?? seems like i saw it on a rocket car once. wonder how dificult or expensive it would be to set up??? and what the operational speeds for it would be??
Reply:you could use 2 independent rear axles if you added additional tubing at the center point beneath your back/head and utilized to bearings and housings. Brakes to consider would be the disk and calipers used on micro sprint cars, they use motorcycle components and are similar to our american open wheel sprint cars. braking could be set up equal or through a proportioner valve."Si Vis Pacem Para Bellum"Lincoln Idealarc 250 AC/DCMillermatic 251   Syncrowave 300   30A spoolgunLincoln MP210Hypertherm 45(2) LN 25(2) Lincoln Weldanpower 225 CV(4) SA200   1 short hood    SA250    SAM 400