[LSC9901]

Do you have one of those questions that you just can't seem to find the answer to ?? This is the thread to ask it. This thread isn't to complain/honor any specific team/driver, it is more for question such as "could someone tell me what they mean in NASCAR by taking wedge out".



To avoid the deleting of posts please remember that this is just to ask questions and to give responses to questions. This is also not the place to add an opinion. If you know the answer, post it. If you don't please keep checking back to see if anyone does know the answer.



Credit Simple Simon for this idea.

[Souporscotty]

EXCELLENT idea! Oh, wait, that was an opinion. Sorry.

[Racer Duck]

OK, I'll bite.

What does it mean to "take the wedge out"?

Originally Posted by Racer Duck

OK, I'll bite.

What does it mean to "take the wedge out"?

Well once you have a "wedge" in your car....you can therefore take it out.

Now if I hadda wedge I would be careful about taking it out.

Chances are it will put you too low....but that's just me...

[hacksaw]

Wede is where the right side of the car is higher than the left so when they take wedge out it lowers the right side of the car. wedge makes the car turn left better......

[wardfan]

does each track have its own NASCAR officials or do the same ones travel with the circuit? This would be the ones on pit lane

[Racer Duck]

Originally Posted by wardfan

does each track have its own NASCAR officials or do the same ones travel with the circuit? This would be the ones on pit lane

NASCAR officials travel with the series .. they don't "belong" to any track. However, NASCAR will hire replacements at the track if needed (but your name has to be on their "officials" list.)

[indyNASCARgirl]

What is camber? I know it has something to do with the tires.

[Racer Duck]

Originally Posted by indyNASCARgirl

What is camber? I know it has something to do with the tires.

Good question.

Camber is the leaning in or out of the top of the tire. Positive camber is out at the top and negative camber is in at the top and is measured in degrees. Camber gain is how much the angle changes going thru a turn.

If you look closely at the front tires on a circle track race car you will see the right front is leaned in at the top and the left front is leaned out. The idea is when the car goes into a corner, the car will roll (lean over) towards the outside of the turn and the tire will straighten up giving the most traction. When there is too much camber the edge always in contact with the track usually blisters and wears faster than the rest of the tire (sometimes blowing out!!!)

[Racer Duck]

Originally Posted by Racer Duck

OK, I'll bite.

What does it mean to "take the wedge out"?

I really thought someone would answer this correctly, but.....

WARNING: this is a long post.


Wedge: what it is and why you have it.

Historically, wedge was used to describe the difference in height of two wheels on the same axle when that end of the car was jacked up from the center of the axle. For instance the car was considered to have 2" of wedge if, when the car was jacked up at the center of the rear end and the right rear tire ended up 2" higher off the ground than the left rear. While this condition was easy to see and measure, it didn't correctly describe the actual setup of the car. The more modern (and correct) term is "cross weight". But "wedge" is the popular nickname used in NASCAR and most short track racing for cross weight. Measuring "wedge" in the old fashioned sense is not reliable and can give false indications of the actual weight distribution on the car. So for the purpose of this definition, "wedge" is the nickname we'll use for "cross weight".

One of the primary characteristics of a race car is it's weight and how the weight is distributed. All racing series have weight rules that limit the total weight as well as static distributions (left vs right & front vs rear).

In order to increase the speed of the car in a turn it's important to understand the weight transfer dynamics in place as the car enters the turn, goes thru the middle of the turn and exits the turn. Properly positioning the car's weight will result in increased speed thru the turn. The only traction the car has is the contact patch between the tire and the pavement. While the car is in the turn, if you are able to have each tire carrying the same weight, then the car will be "neutral" and will have maximum traction, thus able to carry the most speed thru the turn. The weights on each tire contact patch are usually referred by their "corner" or position on the car, i.e., left front (LF), right front (RF), left rear (LR) and right rear (RR).

While weight distribution is a 2 dimensional term, i.e,, the location in an XY plane of the weights on "corners", weight transfer is a 3 dimensional term in which the height of the weight becomes important because of the pendalum effect. A "top heavy" car will roll severely in a turn and possibly roll over. Race cars are the opposite of "top heavy" to decrease the possiblity of a roll over.

Wedge is a term that describes an unequal weight distribution in a race car (a 2 dimensional term). This condition is also known as "cross weight". Cross weight is the amount of weight on the RF and LR tires while in a static condition on a level surface. Other static weight distributon characteristics that are important to know are "left" (LF+LR) and "rear" (LR+RR) wieghts. These static weight distribution characteristics are represented in percentages of the car's total weight.

Because of the pendalum effect, you want as much of the car's weight on the inside tires in a turn, i.e., the shorter radius. Thus the "left side" weight becomes an important characteristic. Most "circle track" racing series have left side weight rules that limit the amount of weight allowed on the left corners. And because of the momentum effect, you want more of the car's weight on the rear tires because of forward transfer when braking. That's where the "rear" weight gets to be important (not all racing series have rear weight rules.) Terms you may hear refer to "loaded tire" and "unloaded tire" - these refer to the "corner" having weight transfered to and from, respectively.

So, let's take a look at weight transfer. As you go into a turn the weight of the car will transfer forward and to the right (if you're turning left.) The faster you slow down, the more forward transfer you have. The tighter the turn and the flatter the track, the more right transfer you have. The most weight is transfered from the LR corner and the RF receives most of the weight transfer from the other corners. In the middle of the turn there's no acceleration or deceleration, so the weight transfered to the LF now moves to the RR (back to static "rear" percentages). As you exit the corner and apply power, the front weight transfers to the rear, most coming from the RF and going to the RR. After exiting the corner the weight that was transfered to the right now returns to the left.

With more than half of the weight of the car on the left side and more than half of the weight of the car to the rear, the LR carries the most weight (statically) of the four corners.

The optimum setup requires the LR+RF combination to carry the most weight in a static condtion. Cross weight (wedge) rules usually limit this total to about 58%. All cars are different, even ones from the same builder. And each driver has different wants to suit his/her driving style. Thus there is one cross weight that gives the driver the best "feel" and allows him/her to go the fastest. But condtions (weather, track temp, track "green-ness", fuel level, tire wear, etc.) change. Filling the car with fuel and putting on new tires returns the car to the original point, but if other conditions have changed, the team has to make adjustments to find a new setup that works with the current conditions. One of those adjustments is "taking wedge out" or decreasing the cross weight.

Because most race cars are built with adjustments that compress the suspension springs, the typical NASCAR car has adjustment "holes" in the rear window/bodies to allow a tool to be inserted into a bolt/shaft that raises or lowers the upper mount of the rear suspension spring, thus decreasing or increasing the spring compression or weight, respectively, on that corner of the car.

So to "take wedge out", the team member inserts the tool into the RR weight adjusting hole and lowers the upper spring mount (turns clockwise a number of turns) thereby increasing the weight on the RR (transfering weight from the LR to the RR which reduces the cross weight.) An alternate method of reducing the cross weight is doing the opposite on the LR. There are subtle differences between the two, so which side is adjusted depends on how those subtle differences will affect the car.

The effect of "taking wedge out" is decreasing the rear traction causing the car to be loose (oversteer). Of course, if the car is already loose, you will want to do the opposite: "put wedge in" which will make the car push (understeer) more. Most drivers like a small amount of loose, but some tracks, like Darlington, require more push, i.e., you don't want your rear end hanging out at Darlington!!!

[Racer X]

Great explanation, RD! I new what the effect of “wedge” was and why it was done, I just did not know how it physically affected the car. I have another question…

From time to time you hear drivers talking to their crew chiefs about how they are “tight in, loose off” or “tight in the middle and loose off”. What can be adjusted on the car to loosen it up in the middle and tighten it up as they exit the turn, or vice versa? How can any adjustment have one effect on the car at one point in the turn and another effect on the car at another point in the turn? It seems to me that any adjustment would make the car, on the whole, looser or tighter. The only thing that is variable is what the driver is doing in the car in terms of steering, gas, and brake. Along the same lines, how can a car be adjusted if they it is tight in Turn 2 but loose in Turn 4? Any adjustment, to me, would make the car looser or tighter on the whole…

I hope my question makes sense…. I have been struggling with this concept for years. Thanks for any insight you can give me.

[wingkey1]

Originally Posted by Racer X

Great explanation, RD! I new what the effect of “wedge” was and why it was done, I just did not know how it physically affected the car. I have another question…

From time to time you hear drivers talking to their crew chiefs about how they are “tight in, loose off” or “tight in the middle and loose off”. What can be adjusted on the car to loosen it up in the middle and tighten it up as they exit the turn, or vice versa? How can any adjustment have one effect on the car at one point in the turn and another effect on the car at another point in the turn? It seems to me that any adjustment would make the car, on the whole, looser or tighter. The only thing that is variable is what the driver is doing in the car in terms of steering, gas, and brake. Along the same lines, how can a car be adjusted if they it is tight in Turn 2 but loose in Turn 4? Any adjustment, to me, would make the car looser or tighter on the whole…

I hope my question makes sense…. I have been struggling with this concept for years. Thanks for any insight you can give me.

What can be adjusted on the car to loosen it up in the middle and tighten it up as they exit the turn, or vice versa? Many things. Don't ya just love that answer? Unfortunately it is however true. The "right" thing will vary / be dependent upon how the car has been set up initially. Things like spring weights, shock rates, roll center, caster, camber, static weights - the list goes on. Having said that - one potential "fix" could be to raise the rear track (panard) bar to slow/delay/stop the weight roll over on to the right rear tire. Too much weight on the right rear causes it to "tightly" grip the track, resulting in "pushing" of the front end/tires. How much the bar would be raised would be determined by at what point in the turn things were getting "tight". With a "perfect" adjustment, the weight roll over would not occur in the middle of the turn (not enough enertia, thus keeping you loose-er), then would occur exiting the turn (thus making the car tighter).

[Racer Duck]

Originally Posted by wingkey1

What can be adjusted on the car to loosen it up in the middle and tighten it up as they exit the turn, or vice versa? Many things. Don't ya just love that answer? Unfortunately it is however true. The "right" thing will vary / be dependent upon how the car has been set up initially. Things like spring weights, shock rates, roll center, caster, camber, static weights - the list goes on. Having said that - one potential "fix" could be to raise the rear track (panard) bar to slow/delay/stop the weight roll over on to the right rear tire. Too much weight on the right rear causes it to "tightly" grip the track, resulting in "pushing" of the front end/tires. How much the bar would be raised would be determined by at what point in the turn things were getting "tight". With a "perfect" adjustment, the weight roll over would not occur in the middle of the turn (not enough enertia, thus keeping you loose-er), then would occur exiting the turn (thus making the car tighter).

additionally there are things that could be masking the real problem. for instance the car may be tight everywhere, but too much rear brake bias will cause loose in then as the brakes are released the car would revert to it's tight condition. the brake balance is adjustable by the driver (in most series), so is an easy thing to check by the driver (thought the crew chief usually has to remind the poor soul to check it - he's so busy fighting dragons, you know...)

on a Cup car, the "bar" adjustment is on the right side of the car right next to the "wedge" adjustment. moving the right side of the bar up or down will raise or lower the rear roll center of the car, which in turn changes how/when the weight transfers from left to right and back at the rear of the car. an odd characteristic of the panhard bar is that because it is normally mounted to the frame on the right side and to the left side of the rear end (the dirt guys mount it the opposite way), it actually forces the left rear tire down when the car rolls to the right... depending on the split (the difference in height between the right side and the left side of the bar) the car may roll enough that the bar begins raising the left rear - which could result in the car rolling over... teams try to avoid that 'cause it upsets the drivers and they end up having to fix the car instead of going to the lake...

[Bob Tanner]

Steve, I don't know whose idea this particular thread was, but as Dr. Ruth would have said, "Bravo!" This is possibly one of the most potentially valuable threads I have seen in ANY forum I've been associated with.

Kudos to everyone involved!

[LSC9901]

Originally Posted by Bob Tanner

Steve, I don't know whose idea this particular thread was, but as Dr. Ruth would have said, "Bravo!" This is possibly one of the most potentially valuable threads I have seen in ANY forum I've been associated with.

Kudos to everyone involved!

For as much as I enjoy this forum and respect many, many of the posters and do my best at keeping it active I have to pass all the KUDOS to Simple Simon. He brought it up as an idea in our moderators forum and I thought I would put it to the test.

With all that said this is your area to shine Bob !!!