LR Bite vs Cross vs Drive

[DirtRacer9x]

Ok so I keep reading about or hearing about people raising lr bite to gain drive. This to me doesn't make sense at all. Reason I say this is Because the car is ending up when hiked the same final drop, bar angle, and if off spring well it's simply off the spring. So I do not understand how you would want more lr bite for the slick. Especially since if I'm thinking properly on this as well the more lr bite you have the looser you will be on the brakes since it would help load the front more. The only way I can see more bite working is if I raised cross. Say, one turn in RF and LR and out 1 turn RR and LF. So can anyone tell me if I am correct on this thinking. It makes sense to me just wanted thoughts from everyone else and am explanation.

[Bcollins82]

Raising your LR bite IS raising crossweight... Dirt racers just tend to compare LR weight vs RR instead of giving a crossweight percentage. You cant raise LR bite without raising crossweight unless you physically move weight around in the car.

[drtrkr244]

If you're off the spring, you are losing a lot of traction. Theres enough springs being made to stop that or you could run the stacked deal.

[Bcollins82]

If you simply turn say 3 turns into the lr and at full hike you're off the spring say 1/2" and the 3 turns reduced that gap to 1/8" nothing has changed on throttle... This is what I'm trying to clarify.

If you crank 3 rounds in the LR only, you are adding crossweight. If you add crossweight you add preload to the RF spring, and take weight away from the RR and LF. This added crossweight will still put more pressure on the LR on throttle because of this. The increased preload in the RF still pushes harder on the LR whether it pushes against a spring, or against the bars, and there is still less weight on the RR and LF... And changing birdcage rotation through rod angles and mounting points on the birdcage itself will change the amount of preload a LR spring has without you changing the spring rate to a softer one.

[Nobody]

I have to disagree sitting here thinking about it. As soon as I put turns into the others I'd see more of a change but of spring is unloaded the total remains the same as far as loading. Help me understand more please. I could have with the same hike say 5" and there is any distance or gap from the spring not loaded say 1/8"- 1" and the car would be the same once hiked and locked in on the limiter chain. Statically I see how it changes but I can't see it adding drive all the way down the straight. I could see more instant drive at first but that's it. I can only see the reaction until full hike that there be any change. Otherwise over all I see no change once up ok bars and chain tight.

Because your basically right. The amount of dynamic wedge the car has is basically limited by the chain length and the compression/rate of the other 3 springs on the car (I'm over simplifying cause the RR can also climb the bars similar to the LR and effect wedge on the car.

Anyone that thinks adding static LR bite to a car will add drive down the straights if fooling themselves.

[Bcollins82]

Because your basically right. The amount of dynamic wedge the car has is basically limited by the chain length and the compression/rate of the other 3 springs on the car (I'm over simplifying cause the RR can also climb the bars similar to the LR and effect wedge on the car.

Anyone that thinks adding static LR bite to a car will add drive down the straights if fooling themselves.

So you think that it doesn't matter how much crossweight you have, LR travel is the only factor determining your total dynamic wedge amount? Lol Go scale your car with 100lbs of RR and see how much drive you still have compared to normal. Yes, adding drop is a much bigger change, but it doesn't mean a small crossweight change does nothing to forward drive when you are up on the bars. Your cross/LR bite is still a factor in the amount the other 3 springs are loaded.

[7uptruckracer]

You MUST remember the rear ends of these cars DO NOT load the tires via the springs for the most part on exit they load the tires via THE BARS using thrust angle. even if your LR is off the spring when you add cross you take weight off the RR. You move to upper bars to effect roll steer somewhat but your upper bar angle gain is what loads your tires. Your upper and lower bars when angled if you draw and imaginary line that extends each bar until both bars intersect take that point and draw a line back to the center of your contact patch that is your thrust angle thats why when you raise the left upper bar you gain traction on the LR and are tighter on throttle when you raise the RRU it makes you looser because it loads the tire more. Bite of cross does the same thing. A spring that rebounds 3" (hike) is going to take X amount of weight off that tire because its in a state of rebound X is a constant given the same spring and same hike number. So if you add more weight to the LR which takes it off the RR your still going to rebound the same X of weight off the LR but the bite you added has left you with a higher remainder on the LR compared to before

[Nobody]

So you think that it doesn't matter how much crossweight you have, LR travel is the only factor determining your total dynamic wedge amount? Lol Go scale your car with 100lbs of RR and see how much drive you still have compared to normal. Yes, adding drop is a much bigger change, but it doesn't mean a small crossweight change does nothing to forward drive when you are up on the bars. Your cross/LR bite is still a factor in the amount the other 3 springs are loaded.

Once the car is against the chain the Dynamic bite is set and only effected by the other 3 corners of the car (for this discussion: I'm eliminating this slight variances from ride heights from changing the static wedge) so assuming that the slight static wedge change isn't going to effect the other 3 corners much dynamically.

So a car set with 100# of RR bite is going to end up with almost the exact same amount of dynamic bite as if it were set with 100# of LR bite. I'm saying that once the car is against the limiter and assuming that the dynamic ride heights of the other 3 corners didn't change, then the dynamic bite is the same.

Anyone that thinks adding static LR bite to a car will add drive down the straights if fooling themselves.

I said down the straights, which is referring to the car being on the limiter. There is no denying that wedge will effect the car, never said it wouldn't. However what I said is it has such a small minute effect on the car once against the limiter, that you aren't going to notice a difference for the most part.

Higher wedge generally doesn't add drive per say as in forward drive, which isn't the same as tight or loose off the corner. Higher wedge will allow the car to drive with more wheel spin before the back-end starts to drift out. If you have ever used telemetry to monitor wheel spin and various other things on a LM: 1. you will be amazed on the amount of wheel spin the cars are driven at. 2. You can see what effects the amount of wheel spin before the car gets too much yaw and loses time.

Again that last statement is dealing with the car against the chain, if the car isn't or not staying there then that changes things.

If you choose to disregard or disagree with my statements, I have no issue with that. But think about what I have said

[Bcollins82]

Once the car is against the chain the Dynamic bite is set and only effected by the other 3 corners of the car (for this discussion: I'm eliminating this slight variances from ride heights from changing the static wedge) so assuming that the slight static wedge change isn't going to effect the other 3 corners much dynamically

So a car set with 100# of RR bite is going to end up with almost the exact same amount of dynamic bite as if it were set with 100# of LR bite. I'm saying that once the car is against the limiter and assuming that the dynamic ride heights of the other 3 corners didn't change, then the dynamic bite is the same.



I said down the straights, which is referring to the car being on the limiter. There is no denying that wedge will effect the car, never said it wouldn't. However what I said is it has such a small minute effect on the car once against the limiter, that you aren't going to notice a difference for the most part.

Higher wedge generally doesn't add drive per say as in forward drive, which isn't the same as tight or loose off the corner. Higher wedge will allow the car to drive with more wheel spin before the back-end starts to drift out. If you have ever used telemetry to monitor wheel spin and various other things on a LM: 1. you will be amazed on the amount of wheel spin the cars are driven at. 2. You can see what effects the amount of wheel spin before the car gets too much yaw and loses time.

Again that last statement is dealing with the car against the chain, if the car isn't or not staying there then that changes things.

If you choose to disregard or disagree with my statements, I have no issue with that. But think about what I have said

I hear what you are saying, but you can't add static crossweight without changing the loading of all 4 corners dynamically. If you have wheel weights of 600lbs on every corner, then you add 100 lbs of LR bite and have wheel weights of 650 lr, 550rr, 550lf, and 650rf, then add wedge dynamically through thrust angle, even if the LR is against a positive stop, you will have less weight on the LF and RR, and more weight on the RF and LR than you would if all 4 had started equally at 600 resulting in higher total dynamic crossweight.

[7uptruckracer]

No that's totally wrong if you've added bite youve taken away RR load.

[FlatTire]

Thank you Nobody and DirtRacer9x. What you guys stated confirmed my thoughts and what I always felt in the car.

[7uptruckracer]

The LR spring is in a state of rebound it isn't adding any load to the LR tire. All the LR spring does is control how quick it can index and get onto the bar. When you change the static ride height your change the static bar angles and bird cage clocking and timing which will effect the LR load thats why the change helps add drive your changing the sweep and starting point your in a different part of the bars curve. Your arguments are irrelevant until you can explain how a spring in a state of rebound is also sending a force downward. THE BAR LOADS THE TIRE. thats why its coming off the spring the bar is applying the downward force to plant the tire. Its also why you chain the RR so the bar doesn't overload the RR and make the car loose. Its balancing upward thrust to forward thrust and the balance LR to RR. The only time a spring matters is when its in a state of compression. All your changing with the collar is your starting points and sweeps of loading until its off the spring from a bar standpoint which has effected its loadings compared to the RR

[Matt49]

So my RF spring doesn't affect my setup when it's NOT being compressed?!?!?
I beg to differ.
Unloading (rebound) of a spring is critical to handling because that load has to be going somewhere.

[7uptruckracer]

Thats not what I'm saying they are limiting hike at X and trying to say somehow they are keeping the same spring and making it rebound the same amount moving the collar and its not changing dynamic LR bite which isn't true.

[7uptruckracer]

The RF also doesn't load via a bar now does it? Rf tire load is effected by the springs energy absorption. To say the chain stops here so it can't effect bite. Is asinine, what did it do till it got there? Thats why the LR collar change works it changes everything it does until that point correct?

[Matt49]

The RF also doesn't load via a bar now does it? Rf tire load is effected by the springs energy absorption. To say the chain stops here so it can't effect bite. Is asinine, what did it do till it got there? Thats why the LR collar change works it changes everything it does until that point correct?

I think we're saying the same thing...but to be clear, I'm responding directly to your comment:
"The only time a spring matters is when its in a state of compression." That statement is not true.

With regards to the LR and adding bite I'll say this...It does (at a minimum) three things:
1) adds static cross weight
2) give dynamic cross weight a head start
3) increases static j-bar rake

Reason number 3 is why "adding bite" can tighten you on exit AND entry. Because you're doing more than just "adding bite". You're changing other rear end geometry at the same time.

I think a lot of racers (myself included) get in the habit of adding bite and subsequently over-tighten their cars on entry by doing so. I know more than a few really fact racers that say set your bite where it works and LEAVE it.

[7uptruckracer]

Agreed I was trying to say a spring in a state of rebound is transferring weight elsewhere BECAUSE its rebound being its doing that one action it can't also be loading the LR those loadings are coming from the bar which is causing the spring to be in the rebound state. They are trying to say your catching the car at 14" of hike no matter what so you bite at that point will be the same EVERY time and it will not.

I think we're saying the same thing...but to be clear, I'm responding directly to your comment:
"The only time a spring matters is when its in a state of compression." That statement is not true.

With regards to the LR and adding bite I'll say this...It does (at a minimum) three things:
1) adds static cross weight
2) give dynamic cross weight a head start
3) increases static j-bar rake

Reason number 3 is why "adding bite" can tighten you on exit AND entry. Because you're doing more than just "adding bite". You're changing other rear end geometry at the same time.

[7uptruckracer]

No because a change to the RF height will effect front end geometry like roll centers, caster, camber. Thats why when you rough your car in they give you all the heights but the LR.

I'm pretty lost on this one guys. But if there is nothing on the lr spring at full hike I believe nothing changes at all once full hike is achieved. From not hiked to hiked I believe would change though due to the added cross. Now wouldn't adding turns to the rf be better than lr since we know this would translate to the rear since it is always loaded?

[Matt49]

Cross weight is cross weight regardless of which spring you turn to achieve it.
But if you go cranking on the front you're going to change static ride height which will change static roll center subsequently dynamic roll center migration timing, camber gain timing, etc., etc.

Just remember, every time you make a change something on a car to achieve something (in this case, changing ride height to achieve cross weight) you are also "achieving" other things (in this case, increased static bar angles and birdcage indexing).
Once you learn to think like that about your setup changes, you'll have a much better understanding of what's going on. I call them byproducts. Some byproducts will compliment your setup and some won't.

[DirtRacer9x]

So would a turn in and out each corner be better than just adjusting LR?