LR Bite vs Cross vs Drive

[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?

[Bcollins82]

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

Yes, in my opinion that's absolutely the best way to do it. Always try to adjust wedge on the scales so you can keep your ride heights the same if you have the option. Obviously you can't do that at the track, so adjusting all 4 corners is the best option there. Some people play on the scales to find how far to turn each corner to achieve X amount of change, but I have always preferred to make other changes at the track if possible.

[drtrkr244]

I've been using Joe Garrisons method for years and it works on all cars.
1 round in RF, 1 out LF, 2 in LR, 2 out RR= 50lbs more bite.

I usually do 1/2 of these to get 25lbs more.

[Nobody]

Jesus, I just lost a 2 page post, trying to explain this better, LOL.

I'll try to retype it later, sorry

[gaz05]

Have been reading this with interest, is there a percentage of cross weight where its too high, eg 52% or should it be in the high 40s ?

[DirtRacer9x]

Well any input please help with. I'm still wanting to have it explained when the strap is right how I'd have more drive even though I'm not touching the spring. Also isn't there other ways to keep spring loaded and have drive. Example like not hike as much and have more cross, have less front rebound, or more lr bite etc? Or does having a gas charged shock act as a spring at say 30-45lbs of rod pressure?

[dfhotlm33c]

The scientist in me wants to see an empirical study....
Set your car up at ride height with the amount of LR bite you normally run with.
Put the car in full hike position...use a long rod instead of a shock perhaps and get the left rear where it would be at full hike...use a chain or other mechanism to compress the right front to its dynamic position on exit of a corner, including accounting for countersteer..as well as the right rear..(Use your travel indicators on your shocks as the guideline for where these points would be)..even compress your fifth coil to its position when you are at full hike...Now put it on scales. determine your weights...put back to ride height...crank a bunch of extra bite in it, or as some are saying, go the opposite direction and put 100 lbs RR in it...put it back to full hike position...measure again...see if there is a change..
this wouldn't be perfect...it would require a set of rollers like on a chassis dyno, and person in the drivers seat mashing the throttle to truly mimic wrap up and other factors and variables (hmmmm....there's an invention for someone to create..a set of "dynamic" scales that would allow you to truly measure the weight movement under given conditions...or better yet..some chassis data acquisition package that would use the basic principles of physics and sensors to provide you with that information on a test car at the track.)
We could all speculate all we want but this is one to "prove" one way the other...

[keeks]

Question......If I were to try and mimic the position of the car statically say using ratchet straps to achieve my shock and spring compressions, would I strap the car to itself, or to the ground?

I'm thinking I would have to have floor anchors and pull the car down to mimic the forces produced during racing.

[DirtRacer9x]

There is no way to mimicking what the car would be doing. Simply doing travel of spring would let you know how much weight is placed onto each spring but all the ballast weight is moving as well. That's my thinking on that at least.

[DirtRacer9x]

But as for lr spring should I always have it loaded? Because once it's unloaded any turns at all I don't believe affect total drive once hiked. I believe there will be a difference from spring loaded to unloaded but overall hike and added drive won't be different. I think Initial on throttle drive may go up because yes you have added cross but you're ending up off the spring still with the same hike. So should I always have the car on the spring even if its compressed just 1/8-1/4". Meaning take hike out of the car and change maybe some calving instead on shocks?

[c.mac.4]

Question......If I were to try and mimic the position of the car statically say using ratchet straps to achieve my shock and spring compressions, would I strap the car to itself, or to the ground? I'm thinking I would have to have floor anchors and pull the car down to mimic the forces produced during racing.

not with any kind of accurate results... you would have no way to simulate engine torque, 5th arm/pullbar effects, or even inertia pulling the car sideways. HUGELY critical variables.