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How To Scale Your Race Car (Part 6 of 7)
By Jon Roetman (c) - Author of “The Racers Edge Series” Race Car Setup Books Taken from the “How to Scale Your Race Car” Book
Important Points to Remember
1. Each time you make an adjustment, bounce the car and rock each corner to settle the springs. This will give you the most accurate readings. It is best to do this on the floor or on the spacers you have made to go behind each scale pad.
2. Several factors will effect cross weight percentage. It’s very important what the effect is so you can make accurate adjustments for changing track conditions. Three factors will affect weight percentages caster, stagger and fuel load.
· Caster
As the wheels are turned, caster will cause your ride heights to change, which also altars your cross weight. To check this you can turn the front wheels to the right or to the left while the car is on the scales. This will show you exactly how much the cross weight changes due to caster.
· Stagger
Stagger also affects your cars ride height. Right rear stagger raises the right rear ride height, which also reduces your cross weight percentage. The only way to avoid this change in cross weight is to readjust the ride height. Stagger and reduced cross weight will reduce a push condition (car will not turn in corners) Front stagger increases right front ride height, which does just the opposite as the rear, and increases your cross weight percentage. Remember these adjustments when adjusting your car.
· Fuel Load
Fuel is a transient weight. As the race goes on, fuel is being burned up, thus affecting your race cars handling. The rear weight percentage is effected the most and the left side and cross weight percentages may also be effected. It is very important to know how much effect there is so you can make good setup choices before you race. When do you want your race car to run the fastest? At the start, at the end or some type of compromise, knowing how fuel load affects your race cars percentages will help you find the best set up for your car. If you run at a track that has qualifying laps, fuel load will also help you find a fast qualifying set up.
By determining how these three factors affect weight percentages, you can gain valuable clues to find the best set up for your race car.
Read our – “How to Set Camber Caster Toe” book for more detailed information.
Next Post - Part 7 - All Done Finally!
You can get a FREE copy of How to Scale Your Race Car and other race car setup information by visiting our website at www.racersedgebooks.com or www.jonroetman.com
Source: racersedgebooks.com
How To Scale Your Race Car (Part 5 of 7)
By Jon Roetman (c) - Author of “The Racers Edge Series” Race Car Setup Books Taken from the “How to Scale Your Race Car” Book
Adjusting the Weights
Left Side and Rear Adjustments: There is only one way to change left side and rear weight percentages. To change these weights you must move or add weight in the car. Examples of this are – adding ballast or weight and/or moving the battery to a different location. Wheel offset (location of the wheel and tire in and out from the chassis) can be used to change the left side weight. More back spacing (moving tire in) on the right side and less
(moving tire out) on the left will move weight to the left side. Adding fuel will also change the left side and rear weights. Be careful when doing this: Remember to set your fuel level to the chassis manufactures recommended level. Varying from this a little to get the correct weights will work, but use it as a last resort.
Cross Weight Adjustments: The only way to change cross weight percentage is to change ride height. By changing cross weight you will not change left side or rear weight. The best way to change cross weight is to make small ride height adjustments at each wheel, rather than one large adjustment at one wheel.
When you raise the ride height at one corner (this is also referred to as “putting in a round of wedge” or “putting a turn in”) you are adding weight to that corner and the diagonally opposite corner, and also reducing the weight at the other two corners. Here is an example: If you want to increase the cross weight percentage, raise the right front and left rear ride heights and lower the left front and right rear ride heights. If you want to decrease cross weight just do the opposite.
Just make sure your ride height adjustments do not cause your cars ride heights to severely exceed your manufacturers ride height settings.
Once you have found the desired cross, left and rear weights, record the ride heights each wheel weight and all percentages for future reference. Do this after each change you make.
Next Post - Part 6- Important Points to Remember
You can get a FREE copy of How to Scale Your Race Car and other race car setup information by visiting our website at www.racersedgebooks.com or www.jonroetman.com
Source: racersedgebooks.com
How To Scale Your Race Car (Part 4 of 7)
By Jon Roetman (c) - Author of “The Racers Edge Series” Race Car Setup Books Taken from the “How to Scale Your Race Car” Book
Finally, Let’s Scale the Car!
Everything is checked and everything is set. Zero the scale pads and roll your car on to them.
Next - before taking your scale readings. The race car ride heights must be set. Set the ride heights to your chassis manufacturer’s recommended settings. Once again, if you built your own car or do not know who did manufacture your car, check with some of the other racers and see what they are setting their ride heights at. If you ask more than one driver, (I would suggest asking as many as you can) you are not going to get all the same answers. Just take an average of what you are told and set your cars ride heights accordingly. Then over the next few weeks try to make small adjustments to your ride heights to figure out exactly what works for you and your race car.
Since you are setting ride heights while the car is on the scales make sure you add in the height of the scale pad to the ride height of your car. Do this on top of the scale pads, as they will settle as the car rests on top of them.
In this picture, we have the scale pad on the bottom and your cars frame rail on the top. The red box represents the manufacturers ride height. The blue box is the height of your scale pad. When setting ride heights on the scale pads you must remember to add the scale height (blue box) to the recommended ride height (red box) This way when you are done scaling and take your car off the scales your ride heights will be exactly where you want them to be in relation to the ground.
Next Post - Part 5 - Adjusting The Weights
You can get a FREE copy of How to Scale Your Race Car and other race car setup information by visiting our website at www.racersedgebooks.com or www.jonroetman.com
Source: racersedgebooks.com
How To Scale Your Race Car (Part 3 of 7)
By Jon Roetman (c) - Author of “The Racers Edge Series” Race Car Setup Books Taken from the “How to Scale Your Race Car” Book
Pre-scaling your race car
Ok, your scale pads are level and you have your ramps or blocks in place.
Roll the car on the scale pads and start adjusting right? Not Quite Yet, there is a short list of things that need to be done before rolling your race car on to the scales.
1. Set each tire pressure and record it – set each tire to the same pressure that you do at the race track.
2. Measure tire stagger or roll-out – roll-out is the circumference around the tire. (Do this only after setting tire pressure) After you measure each tire the difference between the right and left side tires is called stagger. Tire pressures change tire circumference (stagger) and stagger changes ride height. Ride height (more on this in a little bit) in turn will change cross weight readings.
3. Fill the fuel cell to your chassis manufacturers recommended level for scaling – if your manufacturer has no recommended level or if you built you chassis yourself, put the same amount of fuel in the fuel cell as you normally would before you go out on the race track. Make note of this so you can always scale the car with this amount in the fuel cell.
4. Install everything on the car in the position it will be in under racing conditions – Examples: sheet metal, weights, etc…
5. Make sure all fluids are full – Oil, Anti-freeze/water, Brake and Clutch reservoir etc.
6. Un-hook one end on all four shocks so your race car chassis is free – Disconnecting the shocks from the chassis is important, because they can have enough resistance to prevent all the weight from “settling down” as it would under racing conditions and the effects of your chassis adjustments will be masked.
7. Check for binds in the suspension – While keeping the suspension lubricated is a great maintenance idea it doesn’t prevent bent, damaged or worn out parts from binding. A small bind at a single point in the suspension can have dramatic effects on the wheel weights displayed by the scales.
With or Without the Driver
Ever since the idea of using scales to set up a race car there has been an on going debate over scaling your race car with or with out the driver in the car. Both sides of this on going debate do have valid points, but one point always seems to win out on both sides. Scale your race car the same way each and every time, with or with out the driver. If you are scaling your car to the recommended chassis manufacturer’s specs, then the answer is simple. Scale your race car the way they tell you to. Your chassis manufacturer has a ton more experience than you do. They have the hours on the track and have done miles and miles research. So, do it the way they do.
Next Post - Part 4 - Finally, Let’s Scale the Car!
You can get a FREE copy of How to Scale Your Race Car by visiting our website at www.racersedgebooks.com or www.jonroetman.com
Source: racersedgebooks.com
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How to Scale Your Race Car (Part 2 of 7)
By Jon Roetman (c) - Author of “The Racers Edge Series” Race Car Setup Books
Taken from the “How to Scale Your Race Car” Book
Get Them Level
Ok, lets get your scale pads level and get to the exciting part, actually scaling your car.
The first thing you need to do is pick out an area in your garage or race shop to setup the scales. Make sure this area has enough room for making adjustments to your car, jacks, scales and other equipment you may need when scaling.
Next, mark the spot where all four scale pads will sit. By marking each spot, you will be able to return each pad to the exact same spot every time you scale your car. (Consistency, Remember) By doing this it will ensure that you will have consistent readings every time you scale your car. This will also prevent having to repeat the leveling process every time you scale your car. Being consistent is crucial! How can you be confident in your scale readings if you don’t know if the angle of the car is the same as the last time you scaled it?
The ONLY way to ensure consistency is to have all four scale pads level with each other every time you scale your race car. Only then can you be confident with consistent sales readings each and every time you scale your race car.
Ok, you have your spot to scale your car and you have marked the spot where each scale pad will sit with tape or paint.
It’s time to level the pads. (Remember you only have to do this one time) The pads should be leveled independently and in relation with the other scale pads. Setting the car one inch one way or the other may make as much difference as a round or two on the weight jack screw.
A laser level with the beam turned horizontal is a great way to level your scale pads. Just go around each of the four sides of the scale pads and shoot a beam across the pads. When the beam touches the pads evenly all the way across you know you have them level. This is a quick and easy way to level your pads.
If a laser level is not available try this next method. It’s a little more time consuming but will get the job done just as well.
Tape a string to the center front of the left or right side scale pads. Run it across the top of the pad to the center of the farthest edge on the adjacent scale pad. Pull it snug and tape the string to the edge. Do the same to the side of that scale pad to the side of the opposite scale pad. Repeat this process until you have a box of string connecting all four scale pads and forming an X dissecting the top of each scale pad from front to rear and side to side.
This is how your scale pad setup should look as you look at it from the top view. Note: the bold marks to the outside of each of the scale pads. This would be your tape or paint on the floor to mark where your scale pads should be placed every time you scale.
Now, look carefully along the string, it should rest lightly across each pad without any space. If you find a pad or pads with a gap between the string and the pad, leave it for now. These are the pads that need to be raised.
This is an incorrect view of how the string should lay across the top of the scale pad. Notice the gap between the string and scale pad on the right side. This scale pad needs to be raised in order be leveled with the scale pad to the right.
This is the correct view of how the string should lay across the top of the scale pad. Notice there is NO gap between the string and the scale pad. This scale pad is level with the scale pad to the right.
Take a look at the opposing scale pad where the string drops sharply off the edge. This is probably the high pad.
This is an incorrect view of how the string should lay across the top of the scale pad. Notice the sharp drop in the string on the right side of the scale pad. This scale pad is higher than the scale pad to the right.
Take a carpenters level and level the high pad from front to rear and side to side using shims. Be careful to support all four corners so the scale pad does not rock.
If the string still drops off the edge of the scale pad, it’s time to raise the other three scale pads and level them. Once they are leveled, with a carpenter’s level, from front to back and side to side, slide shims under the whole pad until the string lies evenly across the scale pad. Vinyl floor tiles work great as shims to raise your whole scale pad. Doing this should bring the string even on the top of the high scale pad as well.
Be sure to take notes or mark your shims for each corner so these steps can be quickly and easily duplicated every time you scale your race car in the future.
A Quick Tip:
Instead of jacking your race car up and setting it down on the scale pads, you may want to consider placing some sort of ramp or block behind each of the scale pads. They don’t have to be anything special, just something to set the car on or roll the car up on to the scale pads. Just make sure that whatever you use that when in place they are not touching the scale pad. If it is touching the scale pad it will throw off your readings. These ramps or blocks are also great when making adjustments to your race car. Roll the car back, make your adjustments, zero the scale pads and roll the car back on the scales.
You can construct your own ramps or blocks out of wood, steel, aluminum or what ever you want. You can also purchase these from any of the big name race parts suppliers or maybe even your local race parts supplier.
If you are looking for something cheap (racers are always on a budget, right?) and easy, cut a 2X10 or 2X12 piece of wood into 4 3-foot sections. The wood pieces are not quite as tall as your scale pads but still work great and two people can easily roll the car on and off the scale pads.
Next Post - Part 3 - Pre-Scaling Your Race Car
You can get a FREE copy of How to Scale Your Race Car by visiting our website at www.racersedgebooks.com or www.jonroetman.com
Source: racersedgebooks.com
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How to Scale Your Race Car (Part 1 of 7)
By Jon Roetman (c) - Author of “The Racers Edge Series” Race Car Setup Books
Taken from the “How to Scale Your Race Car” Book
Consistency!
Before scaling your car the one utmost important thing to remember is consistency! Yes, consistency……. meaning you absolutely must be consistent every time you scale your race car.
Lets get into a little more detail about this consistency thing. Using scales to set up your racecar is an excellent idea that allows you, the racer, to understand and see the effects of adjustments made to the car/chassis. Scales are able to sense exactly what is placed on them; they are not however able to sense what is below them. In other words scales are not able to tell if they are completely level or level with each other nor are they able to level themselves or level themselves with each other.
Not scaling your racecar on a level surface will alter the amount of weight each wheel carries and has proven time and time again to have a great effect on handling. The surface you are going to scale your car on may “look” level but in reality could be slanted a ½ inch or more. A ½ inch my not seem like much but span that over the length of your race car and who knows how much it could be off!
Next Post - Part 2 - Get them Level
If you want a FREE copy of “How to Scale Your Race Car” Go to our webiste at www.racersedgebooks.com and click on the newsletter & FREE eBook page.
Source: racersedgebooks.com
