Being a little hard on your brakes? In the off-season, we need to evaluate our brake needs
One of the hardest working parts on a race car is the brakes. Maintenance of this part of our car is often an ongoing affair. Regardless, when the season is over, we need to do an evaluation, removal and repair of the entire brake system. Here are some thoughts on how to organize your end-of-season brake system maintenance.
Over the course of the year, we've probably gone through several sets of brake pads because of wear or need for a different compound. We've tweaked our brake balance to suit changing track conditions, setups and driver styles. Now is the time to take all of that into account and prepare for next season.
Evaluation The first step in the process of year-end maintenance is to evaluate all that went on during the season. How did the brakes perform? What changes did we make to affect brake efficiency and balance? Do we still have work to do to make our system better?
Before you disassemble the front hubs/brakes, look closely at how well the calipers align
Once we have thought out the processes we went through during the season, we can then decide where we want to go for next year. If all was well, we would probably just want to go over the system and do regular maintenance. If we have the need to improve, then we need to consult a brake specialist and get some answers.
If we adjusted our balance bar to tune the braking balance, we need to take a look at where the balance bar is positioned in relation to the two master cylinders. It should be centered, but often is not. If the balance bar is off to one side, we need to think about making changes to the caliper piston and/or master cylinder bore size at the front or rear to help balance the system so we can center the bar.
Reducing the master cylinder bore size will generate more force on the pads. Increasing the size of the caliper bores will also generate more force on the pads. The opposite is true for both the master and the calipers. So, you can use different sized bores to balance the system.
Let's say you are having to use more and more rear brake to keep the front tires from locking up on entry and your balance bar position is biased toward the rear master plunger rod. You can either decrease the rear master bore size or increase the rear caliper bore size to generate more force on the rear brake pads and then center the balance bar.
You can also take force away from the front brakes by increasing the master bore size or decreasing the front caliper bore size. The decision on which end of the car to change might be decided upon inspection and finding one or the other damaged and needing replacement. If the front calipers are broken or worn out, now would be the time to change to a different size on that end of the car.
As you remove the hubs, inspect the bearing races. This is a good time to look for any lea
The same is true of the masters. If they are worn and need replacement, think about making changes to the force balance by ordering a different size than what you've been using. Your brake company technical department can help you decide what degree of change will help with your particular problem.
Inspection We will need to completely disassemble the brake system in order to do a thorough inspection. But first, we need to look over the complete installation and see if there are any visible conflicts.
A conflict is where the caliper rubs on the rim, or the pads are wearing at an angle from the alignment with the rotor being off due to an earlier crash or just hard use. The brake lines might be damaged from work done on the car to remove and replace the engine or suspension parts. We can now decide if the brake lines could be relocated to avoid future conflicts.
We can note the condition of the lines including the flexible lines. We need to take a close look at the rotors to see if any cracks or unusual wear is evident. We need to measure the width of the rotor and see if it's within tolerance for the amount of material the manufacturer recommends is safe.
The connection between the rotors and the hubs is a source of problems. A lot of heat and mechanical force is applied to the mounting tabs and connectors in these areas. See if you can spot problem areas that can be addressed later on.
If you run the same calipers and fluid the entire season, there will be dirt and dark, used up brake fluid present. This caliper is overdue for maintenance.
The routing of the brake lines is a concern. Make sure that where you run the lines doesn'
One problem we ran into with a recent inspection was that we observed a taper in the width of the rotors. The outer half inch was narrower than a reading farther in toward the center. This was most likely due to the caliper spreading out as the brake force was applied to the pads. Interestingly, the pads were not worn to a taper, but the rotor was.
As previously stated, we need to note the position of the brake balance bar at the pedals. The bar should be centered within 1/16 inch. If not, think about making changes to the bore sizes in either the calipers or masters or both. Also check the bushings in the brake pedal and make sure there's no excessive play.
Note the look of the brake fluid including color and texture. If the lines are rusting, the fluid will be a rusty brown. If moisture has invaded the fluid, the color might be a more milky white, usually more toward the calipers. Check for leaks around every connection and around the caliper piston bores.
Maintenance The maintenance of the brake system will consist of the following. If any questions arise during this process, consult with your brake manufacturer. It is as interested in your system working correctly as you. Your success is its success too. The primary functions of brake maintenanceare on the following page:
A comparison between an old rotor (top) and a new one reveals how worn the old one has bec
A. Brake Pad Replacement Make sure the compound you have been using is correct for the type of car and racetrack you will be racing on. If you're moving to a new track next year, or going on tour, you will need to re-evaluate your brake pad selection.
Taking rotor temperatures during the season will help you make an informed decision. When talking to the brake manufacturer, temperature information will be most helpful. You might have to experiment when in a new setting, so be prepared to buy more than one compound.
B. Rotors You will either keep and run your old rotors or select new ones. If the present rotors are scored, tapered or otherwise not smooth, you will need to turn them or replace them if there is not enough material to do so.
Take a close look at the rotors and make sure there are no cracks that represent structural problems. Many rotors have small heat cracks in the surface that do not reach the edge. But, if you detect a crack that starts at the edge, the rotor is not safe to use any more. Remember that a broken rotor almost always occurs at the most critical moment in the lap, on initial entry to the corner where speed is high and the need to slow down is the greatest. Don't take a chance with a cracked rotor.
If brake cooling has been a concern, see if you can find a rotor that will pump more air to improve cooling. Inspect the air hose location and device that directs air to the center of the rotor to see if you can improve the cooling of the rotors.
This rotor showed irregular wear. The outer portion of the rotor was thinner than it was 1
C. Calipers Remove and disassemble the calipers. Always rebuild your calipers at least once a season. This includes replacement of the seals and pistons, and honing the bores according to the manufacturer's specifications and recommendations.
You will want to clean and chase the fitting threads in the calipers. Check the bolts, cross tubing and O-rings and replace as necessary. Most brake companies will recommend replacing any part that is suspect. And don't forget what we mentioned earlier, take note of the alignment of the caliper and mounting plate to the rotor. This is critical to proper brake efficiency.
D. Master Cylinders Remove and disassemble the master cylinders. All rubber parts are to be replaced. The bore needs to be honed as per the manufacturer's specs. Note the condition of the clevises and where the tubing is connected. Clean and chase the threads where the brake lines attach.
Cracks such as this one in the middle of the photo running from the inside edge of the rotor can't be tolerated. This rotor can fail at any time and should be discarded. This could be caused by any number of conditions including racing accidents.
All O-rings, seals and dust covers must be replaced. Never use a seal twice. These items are relatively inexpensive and could cost you much more in repair fees if the brakes fail.
Master cylinders can look all right from the outside but hide worn plungers, corrosion and
If you decide to make a size change in master cylinders to affect the brake balance, keep your old cylinder just in case your balance situation changes. You may change the master size and then find that you have been using the wrong pad compound at either end of the car. Then you may have to go back to your old size masters.
E. Brake Lines Now would be a good time to replace all of your brake lines, especially the flexible lines. With steel lines, moisture accumulation in the fluids will promote rusting of the inner walls of the brake lines. There's no fix for this other than to replace the lines.
If you have stripped the car in the off-season, it will be easy to remove and replace the brake lines. As we said earlier, choose your routing carefully and note where there may have been conflicts or contact before and avoid those areas.
Inspect each end of each hose for leaks, damage from contact with wheels, wrenches, feet,
F. Brake Fluid Brake fluid absorbs moisture quickly. Do not leave the top of a brake fluid container open for more than a few seconds. Moisture causes expansion of the fluid and possible brake failure under high heat conditions.
Use containers designed specifically for bleeding brakes so you can pump the fluid through the system to remove all of the air completely. Use new, quality fluid designed for racing. Passenger car fluids are not designed to handle the high temperatures that are generated in a race car.
G. Timing The timing for when you will assemble and load your brake system is important. You might want to run that new line and mount the master cylinders once the chassis has been cleaned and painted, but completing the installation might be best left to the end of the car build.
This is a clean junction of brake lines. It's protected behind the crossmember and below t
One of the last things you should assemble on your race car is the brakes. Install the calipers, connect the brake lines and fill the system toward the end of your complete car maintenance. That way, when you're installing the rearend, motor, tranny, control arms, spindles, and so on, you will not damage the brake system. Just remember to cap the ends of the lines and the master cylinders to prevent dirt from getting in while the rest of the car is being put together.
Conclusion I can't stress enough how important it is to consult your favorite brake manufacturer's tech people when designing your system, replacing parts or having a problem that is brake related. These people are a wonderful resource and they talk with hundreds of racers a year. Their level of knowledge can't be matched by most racers, no matter how long they've been in the game. They can make you aware of new processes, new parts and better brake pad developments.
This flexible brake line is at the right rear of the car and it shows a kink where the rea
You can also go over other parts while you have the hub off the spindle. This is a really
This flexible brake line is at the right rear of the car and it shows a kink where the rearend was allowed to drop and pull on the brake line. It's this kind of hidden damage that can cause problems. When you're under the car or looking inside the wheel well with the wheel off, try to notice things like this. When I look over a team's car, these are the things I try to look for and alert the team about.
You can also go over other parts while you have the hub off the spindle. This is a really nice brake cooling hose bracket manufactured by Coleman. It bolts/clamps directly to the spindle and directs the cooling air into the center of the rotor where it does the most good.