"Many racers are running stacked springs (pictured), or dual-rate springs, or soft, long-travel . TVW CWP FWP or, 2,800 0.52 0.51 = 685B. 5 So, five rounds in the right-side springs (along with the corresponding Multiplier to the left-side springs) changes the crossweight percent by 5.6 percent, which is 1.12 percent per round, or 0.89 rounds per percent of crossweight. Conversely, if the car feels tight throughout the corner, raise both track bars. racers discovered they could insert an actual wedge into the left rear
This is my 2001 S2000 with 1/2 tank gas, 216
The overall effect is much like having no shock in the equation. LR coil overs 2 1/2 turns. Wedge
I used a laser level to project a horizontal
Disconnect the shocks, when possible, and the anti-roll bars. Grassroots Motorsports Understanding Corner Weights. Here's how we find the multipliers. I can see binding throwing off each corners weight but the sum should be the same. Typically, this adjustment will make the car tighter on corner entry or in the center, and a little looser on exit. Corner_Balance.zip Excel spreadsheet. the driver seat and reconnect them so there's no preload on them. I will say that if I'm starting on a fresh setup, or the car has been lowered, or I find myself making massive spring perch changes, then I will loosen all of the suspension bolts so that the bushings can relax and find their new happy place. 12. of the scale to take a reading. We don't ever move weight around to get crossweight, but we do move weight to change our front-to-rear percent or the side percent of total weight. You can use rubber tires on very specific tracks and seasons. Shock binding is not caused by the fluid (which is only a factor withfluid movement through orifices/valves), but from the seals, which possess both static and dynamic friction. Right handers vs left handers feel quite a bit different-I run out of suspension on right handers much more often, and on left handers the car loves having me hanging out over the inside of the contact patches working the corner. Left Rear tire is carrying more weight so it will get more traction and
If most of the important turns on your
(adsbygoogle = window.adsbygoogle || []).push({}); If you prefer Microsoft Excel a Corner Weight spreadsheet is available for download here
"weight jacking," or "scaling," involves adjusting the spring perches of a car
In this example, we will adjust the crossweight percentage on a sample car with different rate springs. calipers. You will never find a perfectly level spot at the track, so don't waste time looking, unless you can set up your scale pads and set up ramps level. On Dirt cars, adding Rebound to the Right Rear will make the car more stable when it slides into the cushion. < Enter your corner weights in pounds or kilos and click 'Calculate'. the scales. Always record the cross-weights and ride heights for reference at the race track in case changes are needed. May run 4 pole motors. difficult to position all 4 scales so you can just drive up on all of them at
13. Changing the amount of weight on each corner will change how the kart handles in a turn. Changing the ride height at any corner will change the cross-weight percentage. Intercomp SW500 EZ Weigh Scales. To favor right turns, put more weight on the
Typically, a road racing car should have 50%
Just to confirm the theory I checked the corner weights with
Timely refresher that leaves me with a question Ive had for the last couple years that I have not found an answer to in hours of searching. lb driver, no passenger, spare tire removed, soft top up, Magnaflow mufflers (-20lbs), Braille
If you shocks are working normally they are not worth worrying about. RC Oval racing is probably the easiest form of RC racing right, right? Also double check that the
It was a good car. Additionally, it is much more difficult to change rear percentage much, since rear weight is mostly a design function. LF and RR (extend coil over), remove preload to RF and LR (shorten the coil
Now that's pretty cool! I used a laser level to project a horizontal
Since oval
The roll center is an imaginary point around which the rear of the race car rolls. I
Then if it's for a particular road course, you will find several seconds optimizing for select turns and throwing any of the above methods out the window A friend's Chump Car found 2 sec at VIR making it turn right better than left. The other two corners will gain weight. 4 Establish the exact weight change in percent that a given spring height change will make and record that number. Make sure the floor is perfectly level; use shims under the scale pads if needed. The same thing happens with a race car. Compressing the spring of a left-rear wheel or adding wedge puts more of the car's weight on that corner. If you increase the amount of cross weight or left side, you will decrease the amount of bite in the kart. Wedge is a term used in the
At the rear, your rear control link angles are critical to maintaining rear alignment and determining rear steer angles and/or reducing rear steer altogether. Plan to win in a repeatable fashion. rod movement from the wheel to the coilovermovement. When you adjust your coil overs
that as a result the coil springs must bequite beefy and stout, 600 lb/in or more. Put the driver weight in the car, preferably the driver. When a NASCAR crewchief says he's "adding wedge",
My big stumbling block on this subject is how to get accurate readings by removing all the friction/bind from the tires, sway bars, bushings, etc.
them for the corner balance. Take the total weight of the car in the configuration you decide on, with driver or without, and to find the corners, do the following: TVW = Total Vehicle Weight = 2,800, LSP = left side. difficult to position all 4 scales so you can just drive up on all of them at
. the same time. Even 1/8 inch difference will make a difference, especially if you have
Afterward you need to adjust the settings to the correct maneuvers. racers only turn left we can balance the car for better grip in left
In the example at the beginning of the article, this was the problem: a cross-weight percentage that was less than 50 percent, and probably off by at least two percent. To find LR weight: Get it right and your car launches down the corner, hits that hard hairpin just right and holds the corner at full throttle. A place where you can add in your Photo Galleries. It is important that you complete the corner weighting process before doing an alignment. on each wheel to speed shock adjustment. If your car's diagonal corner weights are not equal then its handling will be unbalanced--it will turn better in one direction than in the other (all other things being equal). ride heights after every change. difference that made. I had to do this with my truck. Since each side at each end will usually have different rate springs, the amount we change the spring height adjusters will differ side to side. shocks set to same length left to right (front to rear will be different). you run on the track. Sprint kart classes are broken down into driver's age, engine package, and total vehicle/driver weight. Mudboss Setup #3 - Traxxas Slash transmission setup and diff oil for oval racing Oval RC 216K subscribers Subscribe 812 Share 51K views 2 years ago #diff #setup #mudboss Traxxas Slash. If you do have adjustable end links then disconnect
We were racing dirt oval about a month ago, and then I tried this scale system . At the front, we will move the LF and RF adjusters up by 0.0625-inch. Note the "Conditions and Changes Made"
It's
I highly recommend using a laser level to confirm the 4 scales are level to one
And if you hold the inside wheel so it can't spin, the outside wheel will turn 400rpm. To find RR weight: on my garage floor for future reference. If you want to lower the rear of the car then retract the LR
If we remember, or record this number, then we can easily make changes in the future to get to our intended crossweight percent fast and easy. Adjust the cross weight for more extreme conditions or different circumstances. on the right front and left rear tires. The total spring perch
Now with the steering straight ahead and both hands on the steering have your buddy record the . The angles are another way to set the suspension for the desired ride height and cross-weight percentage. The problem with this option is simply that hub stands aren't cheap - the lowest priced ones I've found are $849, kind of a lot of money for something most people wouldn'tdo all that often. Leebo's Corner. If the driver lifts early but still has a fairly good amount of roll speed into the corner, there probably isn't much brake being used. But this doesn't explain why the Vette's readings came in so well, while I had to jump up and down on my door sills quite a bit before my car's weight stabilized at its expected value. Custom iRacing Setups and Paints for dirt oval and asphalt oval cars. Or do you just mean an old, worn-out strut? Make sure all of the weights are in the car including fuel, oil, battery, cooling water, hood, and so on, or weights that will simulate those. Plus it sounds like street and autocross pressures are about the same stagger front to rear, so it really shouldn't have a noteworthy impact. Most chassis manufacturers will tell you what ride heights are best for their cars. I saved a copy of the spreadsheet for each
Those will tend to reduce friction and bind at the expense of NVH and added wear. One of the most important aspects of racing is having a good handling balance. Today's oval
the same time. Bite and Wedge Delta are
I put the car on the scales and input the four corner
cross weight. This obviously means that decreasing cross weight or left side weight Use a load of fuel for where you you want the car balanced, either at the start of the race, the end of the race or an average between the two. There is work involved in going fast for the full race and racing other racers clean. scales. Disconnect and adjust later. Keeping track of Bite and
However, most importantly you need to take care of the handling. I recommend you start with your car at your desired ride
3) Reverse stagger: The opposite of stagger when your left side tires are . On the other hand, it drives really, REALLY good for being setup by this idiot behind the keyboard, and I really don't wanna spoil a good setup by chasing after a perfect setup at least not yet. after this adjustment we still need to add 39lbs to the Left Front and
Do this by making equal changes to the adjusters on each side. Full of fuel, everything done, full of oil, lead bolted down. Basically so long as I don't completely overcook a corner entry, it does better than any car this heavy has any right to Good stuff. Grassroots Motorsports Understanding Corner Weights
Yeah, I'm a little puzzled by my result when I let me car down on my new scales as well. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. tires. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. The cosine of 18 degrees is 0.95106, and that into 1.0 is 1.05146. the front ramps then jack up the rear and lower it onto the rear scales. If you think about this process and become familiar with the intent of it, then your process for setting ride heights and weight distribution should become easier and faster to do, not to mention less frustrating. as Left Rear Bite + Right Front Bite. You need a nice, flat and level surface for the scales. bite, a negative value means the Right Rear is favored. My car is a 1987 Honda CRX, set up according toITC class rules. One of the most important aspects of car setup is the static weight distribution and the cross-weight percentage. The intent of the track scales is to determine a car's total weight to meet minimum weight rules and left side percent (or right side weight) to meet a side weight rule. These are your target weights which will yield a 50% Cross Weight: Left Front =
Bite tells us how much we
Kart racing chassis are designed in a manner to allow it to turn the only way it can, without having a read differential - with the inside rear tire lifting off the track on corner entry. We have 4.1875 front and 5.1875 rear. Moving weight to the front of the kart will provide more front-end grip. Motor: 550 or 540 motors only. If most of the important turns on your
Left front weight + right rear weight = right front weight + left rear weight.
The following are screen shots from the
spread when the car is lowered onto the scales. March 2017 - F1 suspension rules, independent rear suspension for dirt oval. Reduced stopping power with normal brake pedal: Pad fade - due either to unbedded new pads or to temperature beyond. are favoring the left rear tire for better acceleration out of left
Recheck the ride heights and adjust to fine tune, making changes to the front and rear at the same time. However, for dirt oval RC cars, foam tires are the norm. In oval racing you always run more weight on the LR. If you're setting up a FWD race car, and you can see this in historical VW Golf or original Minis, they often lift and inside rear-wheel. When Wedge is balanced at
Carry some in your tool kit and buy tarus wheel studs if you want a dirt cheap slightly longer wheel stud to have more safety. You could also raise the left front or right rear ride heights to do the same thing. So as long as you are draining the fluid from your shocks, also remove or cut away the seals. If you want to raise the front of the car then extend only the
that turns equally well in both directions. There are many ways to corner balance a car. Step 1 - Determine Sprung Weight. This approach is commonly used in oval track racing. Choose the cold temperatures because when the tires get hot, they will expand and your ride heights will be providing more adequate heights to pass tech after the race. Here's apoor mans way to reduce the effects of tire scrub/binding when the car is lowered onto the scale pads: Spray Pam into open bagto coat and lubethe inside, rub the bags between your hands to distribute. "If your car is really tight or really loose during hot laps, you have to take a look at the things that are going to make the biggest difference. These weights are in ready to race form (including driver on board). The first spreadsheet below is what I started with. Don't be in a hurry to set ride
The total weight will ALWAYS be correct unless you can find some way to suspend gravity, if you can let me know. turns to the Right Rear: I still needed more weight on the LF and RR so I added +4 to the LF: I still needed more so I added +2 to the RR and drove the
Check your tire pressure and bump it up to the hot pressure
Funny. We also take five rounds times the multiplier for the front of 1.25 5 = 6.25 rounds out of the LF. It turns out my car has a very close to 50/50 weight distribution so I never noticed that it was actually recommending corner weights that satisfyLF/LR = RF/RR! And since the necessary scales to complete this process cost in excess of $1,000, I suggest you have the corner weighting done by finding another club racer in your area who has (or knows someone with) access to scales and would be willing to help you. I needed 3 linoleum tiles (0.045" thick
First the tires. rear. 35 psi hot tire pressure target . . Do this at every wheel. I was surprised to find, contrary to my experience, that the Vette came is very close to itsexpected weight as soon as it was let down on the scales, without having to take bind out of the suspension. much Wedge Delta and make the handling worse. stiff springs on your coil overs. another. I would imagine that disconnecting the shocks is only applicable to setups where the shock and spring are separate, like a lot of solid axle cars, or Mk2 Supras in my experience. Then there is what I do for FWD stuff That is forget the rear weights entirely, and just balance the fronts to be equal. Bite = Left Rear - Right Rear and a positive value means the
If you are using scales as a base, level the scales with a long level, a long straight piece of tubing, square or round with a smaller level, or better yet, an instrument level such as a construction level. I use this technique and it
It's a lot of
few inches several times on the scales before each reading though just for good
Small angles can throw off your readings significantly. The suspension of the racecar uses the same general theory and needs to be adjusted so that the car is stable. If we subtract the existing ride heights from the desired, we have front low by 0.0625-inch and the rear high by 0.4375-inch. However, you can choose to use them. Free Download Chapter listings from. First off, you must maintain the legal ride height to pass tech. Don't just blindly cross weight it thinking it's the "right" way. suspension). But this is almost never the case. pounds of preload to the scale weights. You will need to weight your vehicle on each tire to use this tool. Bite and Wedge Delta are
Please post on the appropriate 4m forum. That makes every little detail that much more important. Static weight distribution is the weight resting on each tire contact patch with the car at rest, exactly the way it will be raced. is especially true if you don't have adjustable spring perches. Jacking weight will not alter the left side or the rear percentages. Adjust the rear down by using the same method as in No. Choose your ride heights before you measure and/or redesign your front geometry and then maintain those chosen ride heights. Ah, OK, thanks for the clarification. Wedge Delta can also be thought of
If the car understeers or oversteers in only one direction, check the cross-weight percentage. Using dead strut inserts could be an option for cars with strut suspension. All 4 scales must be within 1/8 of an inch. We will deal with preload on the bar later on. I primarily just making sure it meets class mininum weight, but I may mess with the balance if its off by much, but I dont think it is. %Right Weight =
This will not change the left-side or rear weight percentages. Delta which is simply the difference between the two diagonal tire weights. RC Dirt Oval Basic Setup & Tuning Guide (21.5, dirt oval, GFRP, Custom Works, Purpose Built) - YouTube 0:00 / 43:10 Dirt Oval Setup & Tuning Tutorials RC Dirt Oval Basic Setup &. LF coil over 5 turns. Iretighten them after I've made all my adjustments. I mainly run the 3/8. Wedge Delta can also be thought of
12. track are left turns then having more weight on the Right Front and Left Rear
9. I don't like the lower weight ratings and plastic scale pads of proform. It changed the wheel weights by 10 pounds at each wheel: I finally went too far when I took two turns off the Right Front (went
surface. used cheap linoleum tiles (49 cents each at Home Depot) to shim two of my scales
will help with those turns. Once you get the car up on the scales you'll
Bite tells us how much we
Find the difference from the desired average ride heights. There are legal issues too at the front. end-link into the anti-roll bar's hole. To properly corner weight the car, it is necessary to add weight to the driver's seat which is approximately equal to the weight of the driver (or have the driver sit in the car). can help us get our setup right with less testing. 1 Establish the corner weights you think you need for your car. Wheelbase: 9.5" min, 11.5" max Maximum width: 10.250" Minimum weight: 57.0 oz All cars must have 4-wheel independent suspension, single speed transmissions only. I plugged in a bunch of numbers into my calculator and it all checks out. The weight transfer process occurs regardless of the spring rates at each corner of the car. Delta is equal to (Right
2. Since the front and rear shocks are of different lengths you
The other two corners will lose weight. "This is called chassis pre-load.