maximize YOUR BRAKES
By Mike Burrell
often overlooked until an topic arises, your kart ’ mho brakes are a key component that needs attention on a regular basis .
Most karters have left our karts in a cold garage over the winter, ran the same brake fluid for two seasons, or used double over the fabrication ’ south recommended bracken embroider shims to extend the life of the pads. But to what extent are we jeopardizing guard and losing performance by not paying attention to our brakes ? We ’ ll ask a pair of brake experts and go over rebuilding and maintaining the brake arrangement in the end of this article.
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Robert Sollenskog, former Toyota Atlantics driver and inventor of the full-contact Thor Brake ( see sidebar for this floor ), describes the fundamentals of what is occurring under brake : “ Braking is the childlike creation of friction between a brake pad and rotor. ”
“ For any given semi-metallic brake pad and steel brake rotor to “ work ” properly, the brake rotor must have clash material transferred to it from the adjacent contacting brake pad. clash between the two like materials during a brake event has the effect of decelerating the vehicle. ”
basically, kart brakes work the same as any car magnetic disk brake or racecar brake. however, there are some differences in pressure ratios, pedal change of location, and pad return key .
“ Brakes are brakes, ” declares Paul Martin of MCP Brakes, America ’ s leading kart brake manufacturer. “ Kart brakes are basically the same in blueprint as any other disc brake system, whether it be on your syndicate sedan or your race car. One deviation that many kart brake systems have versus car brakes is the spring come back brake pads. ”
All gearshift karts ( and some others ) run systems that require double master cylinders and diagonal adjusters. These items besides need to be inspected for functionality and safe operate on a regular footing .
“ Back in the 70 ’ s, the spring return brake pad arrangement became the most coarse brake because it offered a bracken system that didn ’ t have any brake drag like automotive systems or previous kart brake designs. Larger racecars and your family car can not use a organization that has mechanical brake retraction because the hydraulic ratios are identical different. ”
“ The master cylinder on your car is closely the same piston size as our kart brakes but it has to feed four calipers that have very big caliper pistons. This ratio is well in excess of our typical 5:1. If each brake pad pulled back from the rotors .030 ” of an inch, the brake pedal would have enormous travel before the brakes would come on. You can see this would never work in the average car and surely not a racecar. This does put a little clash in the system but is never noticed because the engines are thus mighty. In many karts with merely five horsepower engines, this scuff can be a big detriment to top end. I call it “ complimentary horsepower ” because if you don ’ t take it away with drag, you have it to use to go debauched ! ”
Sollenskog concurs with Martin and continues a step far, “ A proper racecar brake has three main characteristics :
1. A potent pedal that can be used to modulate the brake press and therefore the stopping force .
2. A short stroke pedal point. possibly a _ ” to _ ” of travel until the brake pads contact the rotor. Traveling at those speeds drivers do not have confidence in their brakes if the pedal needs to travel 2 ” to slow down. Without assurance they can not maximize their brake .
3. Brakes are set up to provide effective stopping power without losing drivability. By this I mean that the brakes can not be over medium and prone to locking up .
many kart brakes do not offer any of the characteristics of a formula racecar brake system. The full-contact brakes that we ( Elevation Engineering ) offer do perform like racecar brakes are meant to : giving the driver a short, stiff pedal allowing he or she to modulate their brake imperativeness giving them the performance to out brake other karts. ”
common Kart Brake Issues :
But many karters don ’ metric ton even know the signs a brake trouble is about to arise until the brake bicycle is pushed to the front man bumper with little or no stopping office. however, most brake problems can be prevented with a little hindrance maintenance and everyday inspections .
“ Routine inspection of the bracken organization should be share of every track day experience, whether racing or merely commit, ” says Martin. “ I start with the obvious mechanical connections starting with the brake pedal and bet on to the victor cylinder. All pivot points should be checked for excessive wear and be certain the safety restraint ( cotter pins, quick pins etc. ) are in locate. I then check the caliper and magnetic disk for all forcible connections to the frame and axle. Again, looking for loose caliper or magnetic disk bolts and being indisputable the cotter pins are in seat. ”
Martin continues to explain how this inspection time is besides a good time to check for excessive pad wear and leaks, two of any brake system ’ s most common problems. “ This is a effective time to look at the brake pads for unusual clothing or any bang-up or ‘ debonding ’ of the friction material from the backing plate. Examine all occupation connections for any signs of escape. Follow the brake line back to the master cylinder being indisputable that at no fourth dimension are the lines able to contact the track or top points on the frame. This could cause a catastrophic failure on traverse. once back to the master cylinder, again examine the condition of the fittings and be sure all is dry with no sign of escape. If all of this is in good condition, there is typically no reason to expect any brake problems. ”
In addition to routine inspections for leaks, most brake experts will recommend changing the seals in the master cylinder and caliper during the off-season. “ I have always recommended that if the kart is used for a full season of race, the brake system should be contribution of the winter maintenance schedule, ” states Martin. “ It would be appropriate to disassemble the system, blank and inspect all the components. I would recommend rebuild kits for both the master cylinder and caliper .
Sollenkog elaborates, “ Brake fluid tends to dry the seals out. As a seal begins to dry out it creates more friction in the behave in which it travels. The clash causes the fall locomotion to slow down. A slower brake revert can cause fleeting reduction in acceleration out of corners. A leak cachet happens at the end of the cycle not the begin. If you wait until you have a leak ( badly ) seal you have already suffered through weeks if not months of ill performance. ”
“ The moment chief cause is dirt and dust. Road dirt will cause seals to deteriorate much like brake fluid will. At minimum, alimony between race meetings should involve pulling off dust covers and flushing dirt and debris out with a quality brake clean solvent on both the masters and calipers. A WD-40 chaser is good to maintain lubrication on the piston wear. Replace all dust covers. ”
For a heavily glazed rotor, carefully sanding the shiny/glazed look off with a culture medium grit emery paper and a sanding wheel can save time .
occasionally, even with all the preventive care and inspections problems do arise in well prepare racing equipment. One problem that many karters encounter at some point in their rush careers is “ glaze brakes. ”
Brake “ Glazing ” and Proper Pad Bedding :
“ Glazing of the brake pad is a term used to describe the circumstance of the clash material when it looks identical glazed. This depends largely on the character of friction material. many years ago, the brake material of choice had asbestos in it, ” states Martin. “ That type of clash fabric was identical prone to glazing over. When this happened, the brake pads merely wouldn ’ thyroxine grip the rotor when the brakes were applied, literally giving the driver the impression he had no brakes at all. As asbestos was phased out and better friction material of carbon paper metallic compounds became the average, the glass trouble is not the like. ”
Sollenskog continues, “ Glazing happens when the clash material on the rotor and pad catch overheated. The glaze acts like a surface hardened condensed coating that has reduced coefficient of friction on the reach surfaces. Brake efficiency is reduced causing brake torsion to be reduced as well ( i. The brakes do not slow the fomite down like they are supposed to ). ”
“ You can see glazing with the eye and feel it with your bracken foot. A mild sheath of glaze can be fixed with emery paper. By hand sanding or with a small ability drum sander, sand the glaze off the rotor and pads. After re-installing the pad components bleed the brake and bed in the pads and rotor .
For bedding in we suggest :
1. 10 stops from at least 80 % full accelerate using 50 % brake .
2. Park and let cool for 5-10 minutes .
3. 10 stops from at least 80 % full speed using 75 % brake .
4. Repeat gradation 2
5.You should be quick to use brakes as normal .
If you are an aggressive driver on the brakes or on an aggressive brake track ; consider adding a cooling tube to feed air to the brake. ”
Paul Martin has never seen the MCP carbon metallic material ‘ glaze ’ in severe quiz, but has had customers over the years tell him they have experienced glass. “ I have constantly found that when this appears to occur, there were other reasons the brakes were not operating by rights. typically, this has been a poor brake pedal apparatus that good doesn ’ t allow the driver to apply the sum of physical coerce on the system to provide adequate hydraulic imperativeness to the brake pads. ”
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“ In other words, the driver may be pushing with a fantastic sum of campaign, but that doesn ’ t necessarily relate to system pressure. The integral brake arrangement is nothing more than a mean to convert and multiply the drivers pedal feat into the movement that squeezes the brake pads against the brake disk. The multiplication of feat starts with the mechanical advantage of the brake pedal, added to the mechanical advantage of the typical dominate cylinder, then added to the hydraulic advantage of the overcome cylinder over the caliper. As an exercise, the MCP brake system has a normal recommend pedal point leverage of 2:1 to 3:1. The overcome cylinder has a crop of 1.5:1 to 2.5:1 proportion. The standard brake system has a 5:1 hydraulic advantage. When multiplied, the system recommendation offers a range of 15:1 to 37.5:1. As you can see, this is a reasonably broad rate. This allows any driver to find the brake campaign and feel he likes the most. The allowance of these mechanical advantage points is crucial to setting up the brake system. ”
“ I ’ m a little off subject, so I ’ ll get second to the sugarcoat. How to prevent it is to be certain you have the systems setup to provide crisp and relatively easy brake action when the bicycle is applied. The previously mentioned adjustments are how to obtain that. Most people would “ de-glaze ” the brake pads and rotors if they think it has occurred. De-glazing is normally done by removing the pads and sanding them until the “ glaze ” is removed. Likewise, the rotor can be sanded until it appears dull in appearance. This should offer at least a short-run fixate to glazing. I am convinced if the driver would set the system up correctly, this will not happen with nowadays ’ s bracken pads. ”
Brake Fluid – There is a dispute :
credibly the etymon campaign of the majority of brake problems karters brush are a result of moisture in the brake fluid ( that is assuming the brakes are bled by rights and wholly of air ). Unless you can bleed your system in a moisture loose clean room, ampere soon as the bottle of brake fluid is opened moisture assimilation begins .
“ Like all fluids in a high operation vehicle, brake fluid should be changed at the start of a new season and every couple of races. Brake fluid begins to deteriorate vitamin a soon as the cachet is broken on the bottle exposing it to the moisture in the air. All those open bottles that you have in your garage that are older than 2 months or have been sitting without the top securely fastened : throw them out ! ” decrees Sollenskog .
“ Changing of fluid color is never an accurate indicator of fluid novelty. Brake fluid “ goes bad ” when it absorbs flush the smallest percentage of water. The huge majority of brake problems can be directly attributed to “ bad ” bracken fluid. Change your brake fluid in regular intervals and when in doubt. ”
Sollenskog continues, “ The minimum brake fluid that should be used is DOT 5. All the DOTs are glycol-ether based except for DOT 5.1, which is silicon based. Dot 5.1 is debatable in eminent performance applications. Silicon has a a lot higher rate of expansion than the glycol-ether based fluids. Unless you are bequeath to run a across-the-board brake pad air gap to compensate for the loss of gap ascribable to DOT 5.1 expansion, stay away. Remember the larger the air gap the longer the pedal travel !
Since our full-contact brakes are designed with minimal pedal travel we found out in testing DOT 3, 4, and 5.1 wouldn ’ triiodothyronine study for us. After initial fluid problems and an extensive fluid study we chose to use synthetic NEO 610 with our brakes. The good fluid is worth it and that is why we supply a bottle of NEO 610 with all our brakes. The 600 series is above DOT-5 and removes all doubt. ”
Paul Martin agrees, but offers a counterpoint concerning the advantages of using DOT-5 silicone based bracken fluid : “ Most american build karts using the MCP/Enginetics systems use DOT-5 silicone bracken fluid. This fluid is non-hygroscopic, meaning it does not collect moisture. In its master form, the fluid is clear but a purple dye is added to give it color. If using nylon bracken line, the sun ’ mho rays will bleach this color out and the fluent returns to near acquit. This has no effect at all on the properties of silicone brake fluid. ”
“ Standard DOT-3 and DOT-4 fluid are highly hygroscopic, ” continues Martin. “ They are very prone to absorbing moisture, specially in a humid environment. When subjected to moisture, these brake fluids absorb this moisture and the consequence is a lower of the boiling point of the fluid. This is why most race bracken systems suggest changing the brake fluid every slipstream day. DOT-5.1 fluent is a synthetic fluid with properties more in credit line with glycol based DOT-3 and DOT-4 fluids. It has a high boiling orient but not vitamin a high as silicone fluid. Every bracken fluid has it dear points and badly. Go with the brake fluid recommendation and you should be finely. ”
Maintaining the Pad and Rotor Air-gap :
Along with faulty, or the incorrectly brake fluent, the air out break between the embroider and rotor are another item of controversy for karters to concern themselves with. For obvious reasons, karters don ’ metric ton want the pads and rotor to make contact when they ’ rhenium not applying the brakes ( for example, while under load exiting a corner ). This will rob the kart of horsepower as easily as choking the drive. however, there is a deal off ; besides much air gap will give an extra hanker pedal throw which isn ’ metric ton optimum for performance .
“ Air gap for the pads to rotor clearance is another of the many adjustments available to the exploiter. If the driver likes a long brake pedal stroke, then he/she will use a fairly boastfully pad gap, ” explains Martin. “ obviously, the antonym is in effect if the driver likes a short pedal stroke. If you start out a race with a unretentive stroke and the stroke increases perceptibly during the race, your pad break will be much larger and need care. The entirely reason a “ besides big ” air gap might cause the brakes to lock more well will happen more because the pedal point ratio will change as the stroke gets longer. ”
Sollenskog elaborates on the changing pedal proportion : “ many karts have different linkage pick up points on the brake bicycle and chief cylinder to change the kinematics. In effect by changing the mechanical advantage in the linkages you can increase the bulk of fluid relative to the pedal travel. Keep in thinker however that when this is done, the effective line atmospheric pressure to the bracken slog is reduced. This creates less brake force. It is a sturdy balance act and most racers merely deal with a long bicycle. ”
“ Brake rub as many racers have experienced happens in corners as the chassis flexes allowing the inside raise wheel to lift off the earth. As a principle of ovolo the longer in overall distance the bracken launching pad is, the more air col is needed to compensate for brake hang-up. The increased air travel gap leads to an increase in pedal travel to achieve a brake consequence. ”
One rather new ( at least to karting ) concept to eliminate brake rub is the concept of the floating rotor. Used in formula cars for years, many of the top european manufacturers at least offer a rotor system with some degree of free-float. Some of the new full-contact systems, such as the Thor Brake, have over six degrees of free float, which according to the manufacturer allows for a rear wheel to be up to 3 ” off the grind under chassis load without any rub .
Karters do have a few options in reducing ( or managing ) air-gap. Most karting systems require a flimsy aluminum shim to reduce the air-gap. Some manufacturer ’ mho systems, such as CRG, are self-adjusting via a free-floating pad that knocks back the caliper piston when the rotor bend against it. MCP has a simple system that allows for adjusting the air-gap with an Allen wrench while in the pit/garage .
“ The shims are broadly thin sheets of aluminum that do not hold their flatness. These stacked together will act like a bounce giving the driver a spongy feel at the pedal, ” states Solleskog .
Martin explains the use of shims in a bit more detail, “ There are two ways to use shims. The american systems of the past used shims between the caliper halves to adjust pad gap. There was no reasonable limit to how many shims could be used in this manner. The european dash of using shims puts the shims immediately behind the pad between the brake pad and the caliper piston. There will be a limit to how many shims can be used in this manner because as shims are added, the amount of solidus is being limited. It would be potential to add so many shims that the return key springs reach a gyrate bind state. As shims are added, the feel of the brake is effected reasonably because the return springs are being compressed more every meter another shim is added. Although the springs don ’ t have a lot to do with pedal point feat, you can feel how much is required good to push the springs as this is the press required up to the distributor point the pads make rotor reach. This feat will increase as the springs are forced to start from a more compressed status. ”
Rebuilding the Master Cylinder & Caliper :
As Paul Martin suggested earlier in this history, it is a commodity idea to rebuild your caliper and dominate cylinder annually. Brake fluid is a identical harsh chemical and dries seals out, particularly when left baby-sit for a drawn-out menstruation of time causing escape and a loss of pressure. In the following paragraph and photos, we ’ ll examine the dismantling and surrogate of the bracken seals .
step one is to break the channel and drain the old brake fluid –trying to keep it off the kart ’ s paint. Remove the brake note from each mounting point on the master cylinder and caliper, and blow out an excess fluid with a compress air out beak. The following, and obvious step, is to remove both the master cylinder and caliper from the kart .
For this example, we ’ ll assume the caliper is of the traditional type ( this excludes the Birel “ banana ” caliper, which uses an external piston invention ). see that all the fluid is drained ahead ; this might require not only remove the lines but venting the organization by removing the hemophiliac screw. future, remove the brake pads. As mentioned earlier, most kart calipers use a organization of servant bolts and return springs to ; these will need to be removed for the pads to be removed and finally the caliper pistons .
With the pads and brake fluid removed, it ’ second prison term to remove the caliper pistons. Over the years, many karters have tried twist, pull, and prying the pistons out. This is 100 % the improper thing to do ! It is necessity not to scratch the piston or cylinder wall ; this could cause a escape of fluid or failure to build enough blackmail to stop the kart at all .
To by rights remove the caliper pistons, the first step is to seal off the hemophiliac screws and all but one of the brake credit line fittings. If the caliper has two brake line fittings, it is likely they operate independently and you will not need to seal off the opposite one. Using a very moo air blackmail and increasing it lento, place a condom tipped air-nozzle in one of the brake line fittings and “ boast ” ( slowly ! ) the piston out. You may even use a small piece of wood where the brake rotor would be to stop the piston if it shoots out quickly .
Behind the pistons or on them ( o-ring ) is the piston seal. typically, anytime the caliper pistons are removed, the seals are replaced. besides, take a look at the caliper cylinder walls for scratches to assure no debris got by the piston and seals .
At this point, the pistons need to be inspected for brake dust and other buildup that has not allowed them to return amply into the cylinder. Often there is some residue from brake pads, grease, and “ track crap ” that build up around the out edge of the piston. To remove any buildup, wipe off with a brake parts cleaner soaked shop rag .
Clean all pieces thoroughly with brake parts blank, and begin to reassemble with new seals. When installing the newfangled seals and pistons, lightly coat both with the manufacturer ’ second recommended brake fluid. This will help ease reassembly and assure a better seal .
At this point, it ’ second time to move to the master cylinder. Most kart master cylinders are very simple, and not that dissimilar to any other racecar ’ sulfur master cylinder –with the exception of the book of brake fluid. The lever that joins to the bracken rod, and finally the bicycle, pushes a piston –which is normally backed by leap .
The master cylinder piston is normally held in by a snap-ring. By removing this snap-ring, the piston, seal, and spring can be removed. Both the seal and leap should be replaced ( springs can become compressed and reduce bicycle atmospheric pressure ). Clean out the victor cylinder and guarantee no debris scratched the cylinder walls. reassemble as it came apart with exchangeable procedures used on the rear caliper. Most master cylinders have a debris shield at the pry to keep dust out of the piston area ; assure these shields are in set and release of tears .
In this exercise, the piston & dust ring ride in front of the seal. As atmospheric pressure forces fluent against the seal, it pushes the piston out. The piston is returned when the spring press from the pad retainer springs/bolts exceeds that of the hydraulic pressure coming from the reverse direction .
Reinstall the calipers, dominate cylinder, and brake lines. ultimately, you will need to bleed the brakes using the manufacturer ’ second recommended fluid. What ’ mho testify best to bleed kart brakes time and time again is a gravity fed hemophiliac that screws into the master cylinder. This expressive style hemophiliac basically pushes the publicize out the bleed screw, about doing the work for you. Be sure all air bubbles/pockets are forbidden and test the brakes before hitting the path full moon strangle !
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With the exception of full-contact brakes such as Sollenkog ’ s Thor Brake line, the future of karting brakes appears to have reached an evolutionary period. Carbon fiber pads and rotors made a brief appearance around the go of the millennium ; however, price issues legislated them out .
“ Carbon/carbon systems normally require a carnival come of heat to work by rights. This is hard to achieve in the short-change prison term karters go out for qualifying sessions or the first few corners of a race. Most carbon metallic systems work immediately regardless of temperature and consequently have prevailed. I don ’ thyroxine think exotic materials have a station in karting in my impression. This doesn ’ thyroxine base they won ’ metric ton appear, ” explains Martin. This being said, some karts are arriving from Italy with optional ceramic-based rotors .
Your kart ’ s brake arrangement is a important a separate of the overall performance as it is a base hit item. Today ’ s kart brakes come in a diverseness of shapes, sizes, and pad compounds giving drivers the opportunity to tune their brakes to their personal preference. But no count what combination is best for your personal driving style, it is well advised to follow the manufacturer ’ randomness recommended maintenance schedule and use entirely their recommended fluid to assure condom and reproducible performance.
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