9. We delve deeper into race suspension tuning basics here. Excessive front toe in will make a car turn into a corner quicker, & may create a loose condition. Brake pads badly taper worn - replace. Bearings, like sealed roller bearings,solid bushings, or spherical joints. The tiles & salt seemed to help because the weight never
Changing the ride height at any corner will change the cross-weight percentage. The driver is optional based on No. Took it to be corner weighted and it transformed the car in to a front runner that the drivers raved about. rod movement from the wheel to the coilovermovement. An analogy which is commonly used is to imagine that the car is a four-legged table. My car has solid/spherical bushings everywhere, so there should be very little bind from them. of the scale to take a reading. from +1 overall to -1): I put + 3/4 of a turn back on the Right Front and ended up
On a road course, the cross-weight percentage should be very close to 50 percent, within a half-degree either way, to keep the handling balance similar in a right-hand turn compared to a left-hand turn. Corner_Balance.zip Excel spreadsheet. These weights are in ready to race form (including driver on board). On oval track cars, cross-weight is usually used in conjunction with stagger (where the right rear tire is larger in circumference than the left rear tire) to balance handling. Once static weight percentages are set, work on cross-weight percentages. Unless you have some kind of stupid hyper-critically damped NASCAR type dampers this isn't really necessary. Corner weighting your car is
I run generally 34F/30R for the street and usually (again depending on the day) drop the fronts to around 30~ and the rears to 26 or 28. Most chassis manufacturers will tell you what ride heights are best for their cars. Left Front and Right Rear but you'll have to test to find out what works best. turns. Choose a level spot in your setup area. Cross-weight is also called wedge: If the percentage is over 50 percent, the car has wedge; if below 50 percent, the car has reverse wedge. To find RF weight: To help you, here is a method you can use to set the spring height on the shock using a spring rating fixture with coilover ends installed. the scales. Bottom line, you can strive for perfection, but ultimately youll just make yourself crazy. The front is usually the lowest point on the car and most sanctions maintain a minimum ride height rule. Conversely, if the car feels tight throughout the corner, raise both track bars. This also coveys other advantages, the short shock travel means that it can be shorter and lighter. I dont get this. Your ride heights determine your arm angles up front, as well as the cambers, and, to a lesser degree-excuse the pun-the caster angles. Forum Actions: Forum Statistics: Threads: 167; Posts: 1,367; Last Post: . Understanding corner weights. Today, dirt late model racers are using cutting-edge tools to pinpoint where gains can be made based on hard data. racers discovered they could insert an actual wedge into the left rear
and stock rear sway bars connected. Delta is equal to (Right
March 2017 - F1 suspension rules, independent rear suspension for dirt oval. The following weights are with the front Comptech adjustable
If most of the important turns on your
Besides the eventual move to an adjustable ride height set up, I feel like I need 100 lbs or so more spring in the left front. Then move components like the battery or fuel cell. It would just automatically settle. Granted, moment centers will stay fairly consistent with small movements of the chassis in dive and roll from the ride heights being off a little. corner weight calculations: Corner_Balance.zip
spread when the car is lowered onto the scales. coil over 5 turns. and without me in the driver seat and yup, the theory is right--the cross weight
4 Establish the exact weight change in percent that a given spring height change will make and record that number. As long as the tires have near "1 to 1 traction" with the ground, you should set up your race car like an asphalt car (see the Chassis Set-up At The Rear For Cornering page). the sway bars because they fail so often and the bars only added a couple of
the same time. Calculate the average front and rear desired ride heights. Adjustable end links are more
used linoleum tiles to shim two of my scales to get them all level. R. racing junky Member. difficult to position all 4 scales so you can just drive up on all of them at
But if you corner and the inside wheel slows to 150rpm, the outside wheel will spin at 250rpm. turns. In order to perform the set up routine the car needs to be completely ready to race. You can
Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK. 3. suspension changes to track your progress. Now with the steering straight ahead and both hands on the steering have your buddy record the . Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. The only way to change the static weight distribution percentages is to physically move weight around in the car. Of course you can add too
Today's oval
Adjust the cross weight for more extreme conditions or different circumstances. It will let you predict and understand the effects that various modifications have on handling, performance and lap times. So LF/LR = RF/RR is what you shoot for. Please post on the appropriate 4m forum. Left Front and Right Rear but you'll have to test to find out what works best. It varies with weight removal, added. racers only turn left we can balance the car for better grip in left
Even on a track with mostly right-hand turns, the problem in the left-hand turns costs a lot of time. 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. Right Front weight: Left Rear weight:
If you decide to have a tuning shop complete the corner weighting and assuming you are not driving the car to the shop, disconnect the rear sway bar yourself to save the shop time and you money. To keep it clear in my head, I think of the car as a four-legged table sitting on a mattress. It has to, it's just the laws of physics. weights: Corner Weight Calculator if
And if you hold the inside wheel so it can't spin, the outside wheel will turn 400rpm. A jumbo ziploc bag prevents lube from escaping when not in use. If you want more turn in one direction put extra weight into the inside rear or outside front. Adjusting the sway bar is time consuming and questionable unless it is really stiff. Front and Right Rear need 51 lbs of additional weight to balance the car. One of the most important aspects of racing is having a good handling balance. Just to confirm the theory I checked the corner weights with
surface. Youre always going to have some friction, especially depending on the type of suspension used. 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 weight percent = 0.54, FWP = front weight percent = 0.51, CWP = Crossweight percent = 0.52. Disconnect and adjust later. Bite should be positive for oval racing, Wedge =
then leave them connected. A good starting point would be tank of gas. tiles) on the left front and 1 on the left rear to level the scales. You can also use this technique when adjusting your alignment and
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). However, if you have to apply opposite lock steering (turning the steering wheel to the right) and you drive the car throughout the corner balancing it with the throttle . renting/borrowing/buying some scales and corner balancing your car. Other than that you need to watch the suspensions. more important corner balancing becomes. Corner Weight: (1/2 the front or rear weight) Use an accurate racecar scale that will weigh each corner of your car. The less fuel in the tank the tighter the chassis will become. I'm off by 0.1% (see numbers on left side of the spreadsheet). When Wedge is balanced at
height and the shocks set to the exact same spring perch height
Corner balancing, sometimes referred to as "corner weighting,"
Finding The BBSS Front Spring Pre-Loading 12. Any corner weight adjustments that you make will impact the alignment of your car. lowered onto the scales the tires will need to spread out to unbind the
I saved a copy of the spreadsheet for each
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. on my garage floor for future reference. the scales and zero them with no weight on them. When I drive down a strait road the I can clearly feel that the drivers side is heavier over bumps expansion joints and dips and the like. The process is so basic to the setup of the car. It puts power down better, and any decent FWD car will be carrying a wheel in the air around a turn anyway, so by default the outside rear gets 100% weight transfer when it's being asked to turn anyway. Since this article still gets a bunch of traffic, just bumping it up. June 2017 -Center spring steering, corner judder w/ swing axle or beam axle . Ideal weight percentages: Front - 43-45% Left - 53-56% Cross - 52-54% What do these numbers mean? If one leg is longer or shorter than the others, the table will rock and thus be unstable. You're better off not corner balancing the car than doing it on an unlevel
For our example we use: LF 200, RF 250 - 250 200 = 1.25 multiplier for the front. another. 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. Race Tires: Are You Ready to Spend Some Money? This was my first adjustment: Four turns of positive coil
Some of the most popular engine packages are the Yamaha KT100S, Parilla Leopard, Honda CR125, Briggs L0206, Honda Clone, TaG (Touch and Go) and many more. Then measure from the lower wheel rim edge up to a spot on the fender on a piece of masking tape. 12. Dirt track racing in Australia has a history dating back to the 1920s and 1930s. (corner weights) instead of moving shims above / below spindle? A trucking company scale meant to weigh 80,000lbs may not be accurate enough for a 3000lb car. Delta which is simply the difference between the two diagonal tire weights. How would you makesomething like that? Similarly, dirt oval cars often represent crossweight as "bite", or weight on the left-rear tire relative to the right-rear tire. That is what you need to read on the spring rate fixture at installed shock length. The car should be at minimum weight, using ballast as needed to make the proper weight. The shock length as it is installed in the car at ride height. Brake pedal is soft, spongy and/or long before the car is run: Air in the system - bleed brakes. dry)! stiff springs on your coil overs. (I suppose cooking oil, motor oil, KY, or Astro-Glide would also work). T-Bucket . Right Front tires. Rock or bounce the car helps. document your current ride heights and your coil over changes each time
For the teams that are running very soft front coilover springs, you will have a very difficult time moving the adjustment ring with your shocks in the car because of the high amount of pre-load on the spring. oval racing world and is simply another word for Cross Weight. Adjust the front up by 0.0625-inch and the rear down by 0.4375-inch. It is best to get 50 percent left-side weight when possible. It's a lot of
And don't ever believe the track scales. Record each spring rate. %, Bite =
The fact about this concept is when you put a softer right rear bar in, the car rolls more to the right rear but it is actually transferring less weight. The rear weight percentage is found in a similar manner: Add the LR and the RR weight together and divide the sum by the total weight. Bounce the car at each corner to free the suspension from any bind, then roll the car onto the scales. Take your shock, compute the spring preload, and compress the shock/spring combo to the installed spring height in your spring rate fixture. Right Rear weight: < Enter your corner weights in pounds or kilos and click 'Calculate'. This will not change the left-side or rear weight percentages. Motion Ratio of the lower control arm. It's just turning left 2 times per lap. Calculate the spring rate multiples. If you want to lower the ride height then retract both RF and
anti-roll bar with the end-link adjusted so it's easy to insert the
The situation isfrustrating. Scale Type: .
Also you will obviously want to have some way to ensure all your scale pads are level with each other. Corner-Weight Distribution Bickel points out that corner-weight distribution refers to the amount of weight carried by diagonally opposed pairs of wheels. 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. (TVW FWP) - RF = 743C. Oval Track. We will deal with preload on the bar later on. 5 diameter stainless ball bearing on top of a 1" shortwell socket on the center of a floor Jack and jack the car up in the center of the rearend housing.
Since I went to 800 front and 700lb rear springs over the winter I
The important thing to remember is that the laws of physics are the same whether you are racing on an oval or a not to push it off the scales, to unload the suspension (as the car is
Muscle Car. [Up] [HarnessInstall] [WingInstall] [RemoveA/C] [OilCooler] [FireSuppress] [CutoffSwitch] [RaceExhaust] [Differential] [CornerBalance] [CatchCan] [RollCenters] [FrontBumpSteer] [Alignment] [ShockTuning] [Aerodynamics] [CatRemove]. While several different setup parameters could have caused this situation, a likely cause is excessivecross-weight. One of the most important aspects of car setup is the static weight distribution and the cross-weight percentage. If you go to a tuning shop that provides this service, estimate that it will cost you $90 $150 to have them corner weight the car for you. TVW - (RF + LF + LR) = 603. To find LF weight: For example, if your initial setup is 52 percent cross-weight, and you want 50 percent cross-weight, lowering the right front or left rear corner will decrease cross-weight percentage. Today's oval
The "Corner Weight" (virtual scales) now determines the ride height and/or corner weigh . Currently, dirt car racing involves a left-hand weight measurement of 53.5-55, along with a wedge between 75-125 pounds. much Wedge Delta and make the handling worse. This makes the cornering force balanced from left to right and offers the best performance overall. pounds of preload to the scale weights. When dealing with advanced suspension tuning, some people may adjust the corner weights in a manner to impact the way the car handles based on the tracks layout. Adjust the rear down by using the same method as in No. track are left turns then having more weight on the Right Front and Left Rear
4. As with the table, the corresponding diagonal corner of the vehicle gets more of the car's weight. I use this technique and it
Avoids a mess on scale pads and tires,prevents dirt fromcontaminating lube. Here is what you do. cars through the corners and thats where there eating me up. For road racing and autocrossing, the ideal left weight percentage is 50 percent. used cheap linoleum tiles (49 cents each at Home Depot) to shim two of my scales
I lowered the left rear spring perch 1 1/4 turn and put it on
Yeah, I'm a little puzzled by my result when I let me car down on my new scales as well. is especially true if you don't have adjustable spring perches. For information on corner
This adds pressure to that end of the car just like putting the paper wedge underneath the table leg. Since the front and rear shocks are of different lengths you
After these items are completed, it is necessary to corner weight the car. you run on the track. center of gravity (CG) height by using this page:
I use 2x6 wood planks as ramps to drive the car onto