"racing promotor" do I have this correct??
Higher or lower cross???
- Thread starter T-roy
- Start date
"racing promotor" do I have this correct??
racing promotor
Moderator
BINGO !!
never thought about it like this before.. if this is correct than let me set up a hypothetical.. Let's say you are at 58 left and 64 cross... if you keep adding cross it may loosen the kart on entry so your "closer to left the cross is makes the kart tighter" theory holds true. However, you will get to a point when you keep adding cross that you will start to overload the RF and shear it off the track causing the kart to get too tight on entry.
XXX#40
2A supporter
Depends on what kind of camber/caster and degree spindles you're running
Yes, this will change what your cross % is in the static state (and probably affects how weight is transferred dynamically too) but the theory i proposed should still hold true.... I think
paulkish
old fart
racing promotor replied: Correct and I don't disagree
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Butt I wan't to throw in some theory basics.
1. You cannot push unless the thing can't turn. The only things to turn you are the front tires working with the track or the back tires with a solid axle and stagger working with the track to turn you.
So if you want to fix a push going in you can only do it by slowing down, getting more turning ability from the fronts, the backs or both or do something to reduce your kart wanting to go straight.
High cross/low cross is about how much weight you have combined your RF and LR tires. To know why you may or may not have fixed a problem when you change cross because cross is a combined number, you need to understand where you actually added weight and how it effected the operation of your RF and LR tires.
I'm going to now make a blunt statement about loose. You can only become loose when your LR tire no longer has enough grip to work with the RR tire holding the backend in. Sure the RR tire with enough grip can by itself hold the backend in but in general dirt oval racing when your LR gives out you become loose. That's because in general the backend is not setup for the RR to hold the back end in on it's own. Why it's not is if your using the RR to exclusively hold in the backend in your not getting any rotational or turning benefit from stagger.
Because of what I wrote above when you change cross to solve either push in or loose in because the only number you have to look at is a combined number it makes a difference weather you raised cross by adding mainly to the RF or the LR.
... just tired of writing and I hope the above did not confuse but made you think about how adding weight to maybe the LR may cause the LR to gain grip or it might move it over it's grip limit. Same with adding your cross mainly to the RF may get you needed grip to make it turn or the additional weight may further push your front end over it's limit of grip. It all just depends.
sorry if this was confusing I think without already having additional knowledge to bring into the picture it is very easily confusing. But it may help if you have thoughts and other ideas in the back of your head about how your kart works and they all of a sudden sort of fit in. Understanding this stuff is a long process.
One last thing I just thought about. Maybe your kid and their weight are just sitting too darn low on the LR. Push in may be then be caused by you just can't get weight away from the LR area of the kart to do something for you, like help the fronts turn. And if it's setting down on the LR area of the kart too much it can also make you prone to easily adjust into a loose because weight at the LR is wanting to throw straight to the right off the LR tire. hope that was ok ???? ...
Phiddy
Member
I have been taught cross is related to left side. Cross is a fine tuning tool, not a problem fixer. Fix your problem then tune the cross to your liking. No two drivers like the same "feel" cross will give you the feel you like. Again this is only my opinion of millions. My advise is- Listen to one person, till you don't want to. Then listen to another one person. If you listen to everyone you will be so confused with their opinions and facts.
racing promotor
Moderator
BINGO !! The reason some get confused is trying to fix a major handling issue with ONLY cross adjustment you don't get consistent results, OR as mentioned above they add cross thinking it will tighten the kart ( which it will ) However they add to much over loading the RF and it gets loose on entry and they take that as there results it loosened it up, failing to realize WHY !! Base line set-up needs to be real close with what ever cross, then based on what you seeing and driver is feeling tweak it, If it looks lazy on entry add cross as long as you did not go to far it will carry through and look more sporty on exit as well.
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MikeleoneCT
Member
What!
Got that from one of the popular karting set up books, Todd Goodwin I think. Awesomely difficult book to read and understand. After reading and doubting I experimented and proved it out. Had several different types of karts at many different tracks(all asphalt). Some karts we ran low cross setups, like 40-45% and most karts we ran 56-58% sometimes higher (to loosen kart). The farther you get away from that magic number the looser you get, over or under. That holds true until you go too far (35% or 65%+) Having said all that you shouldn't tune with cross like you would on a big car. You should start with you ideal cross based on nose and left weight, ideally from the manufacturers recommendation. Then get the balance with: camber, caster, wheel location, stagger.
racing promotor
Moderator
Here is your original post I responded to because I read this as in general and the discussion is dirt racing, 54 to 56 % cross might have been the magic number for certain era chassis ( TRUE every kart has a magic number, and I'll add every kart has like a 2% dead spot on cross where you see NO change ) and for asphalt, or would be closer for champ karts, BUT it sure is NO where close now for 2012 and newer chassis on dirt, and a set-up that is right with the right tires regardless of the cross will run the entire race, Cross in relationship to left should of been mentioned in the parts of this post that does make some sense, Bottom line since I read it as in general most always figured a lot of the newer guy's did as well, I responded to put doubt into play so they would not just do this and get screwed up as some of it applies BUT some is misleading without 100% of the details you have now added, like older chassis and racing on asphalt.
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paulkish
old fart
How much cross you can use or need is related to how fast your going to be entering the corner and the amount of initial turning done on entry. Example: high grip indoors will need less cross.
Beyond entry the magical balance becomes available to you. The magic is a balance of turning between your front tires and your back tires to roll freely through to exit or the start of acceleration depending on track configuration and grip. That's where thoughts of fine tuning of cross comes into play. Too much or not enough use of either the front or the back tires during the time between turn in and exit/the start of acceleration depending on track configuration, will slow you down.
From turn in to the start of acceleration there is only one fastest line which is set by the driver to determine where you want to be positioned on exit. IMHO that fastest line will 99% of the time be an arc which leads to break, insert arc, turn, accelerate. Most horsepower jockeys are clueless about how what they need to be fast is no different then a stock predator.
Beyond entry the magical balance becomes available to you. The magic is a balance of turning between your front tires and your back tires to roll freely through to exit or the start of acceleration depending on track configuration and grip. That's where thoughts of fine tuning of cross comes into play. Too much or not enough use of either the front or the back tires during the time between turn in and exit/the start of acceleration depending on track configuration, will slow you down.
From turn in to the start of acceleration there is only one fastest line which is set by the driver to determine where you want to be positioned on exit. IMHO that fastest line will 99% of the time be an arc which leads to break, insert arc, turn, accelerate. Most horsepower jockeys are clueless about how what they need to be fast is no different then a stock predator.
racing promotor
Moderator
LIKE
and If tires are not right NONE of it matters !!
paulkish
old fart
LIKE
What I wrote applies to everything from a bone stock predator to a winged 410 1000hp sprint car, per my observation over many years.
Yes tires have to be right to be able to run at the limit of grip during the arc. Fast is also a matter of bringing tires to the track which will make up losses of available grip per track conditions. Have tires with not enough grip to carry the hp potential given to you by the engine and you will be slower. Put tires on with an excess of grip to handle your hp potential and you will be slower.
What can happen weather your running a bone stock predator or a 1000hp winged sprint is excessive grip during the 'arc' can and will force your engine to loose rpm's when your dumb horse jockey has their foot to the floor and grip is forcing the engine to slow.
I was challenged by a famous 410 engine builder to find a fix for dumb horse jockeys who abuse his engines as I stated. My solution and the only solution is too educate drivers. With a lower hp bone stock predator in the 'arc' the same problem can occur and is more likely to occur, with the complaint being the thing has nothing for me right off the corner. Fix the driver.
The engine builder who told me it was his number one engine problem and to see if I could come up with an "engine" fix. When I told my son of the issue he challenged me to find a solution for, my son's reply was the solution is easy, more motor is needed. ...
butt were talking mostly predators and clones now and you ain't going to solve poor driving with perfect setup and tires with hp
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MikeleoneCT
Member
I wasn't saying that 54-56% magic number is where you should run the cross, it's just the % where the effects of adding or removing cross change around. The questions was does adding wedge loosen or tighten, I'm saying that will depend on what cross% you're starting from before you adjust it. I totally agree with the 2% dead spot and will also add that you're never fast with wedge in that dead zone.
racing promotor
Moderator
Thanks for clearing that up.
alvin l nunley
Site Supporter
In Sprint racing, which I'm very familiar with, if the kart was pushing, it was caused by not getting the inside rear wheel off the ground.
In oval racing, you have stagger so, supposedly, if the "stagger is correct for the track your driving", you don't have to get that LR off the ground. Think of rolling a Styrofoam cup on the table, that gives you a picture of what stagger does. Hard to make it perfect, but get it as close as you can.
When I think about stagger, if it's set correctly, I see both tires are rolling around the corner, if it's not set correctly, I see one tire fighting the other, poor handling is often the result. When you are going straight, I see the big tire driving a smaller tire and that can cause drag, so, depending on the track and the length of the straight's, you sometimes have to make compromises between getting through the corners and/or, getting down the straight.
In oval racing, you have stagger so, supposedly, if the "stagger is correct for the track your driving", you don't have to get that LR off the ground. Think of rolling a Styrofoam cup on the table, that gives you a picture of what stagger does. Hard to make it perfect, but get it as close as you can.
When I think about stagger, if it's set correctly, I see both tires are rolling around the corner, if it's not set correctly, I see one tire fighting the other, poor handling is often the result. When you are going straight, I see the big tire driving a smaller tire and that can cause drag, so, depending on the track and the length of the straight's, you sometimes have to make compromises between getting through the corners and/or, getting down the straight.
paulkish
old fart
Very good Al. Let me add because your turning left and weight will always go right per loss of grip on the left, the LR in most cases will still unload. I think after reading what I quoted, you might now for oval racing start relating to a controlled loss of grip at the LR(inside rear). I think Al with specific setup even without stagger sprint racing retaining some grip at the inside rear, can be used to get some rotation out of the non staggered axle. You can get the rotation for the same reason controlled use of the LR can enable the RR to roll around the somewhat anchored or ruddered LR.
I've see it done sprint racing Al in a junior class. Writing this and thinking about it, the ability to use the inside rear as an anchor/rudder sprint racing is probably related to over all sprint course speed, especially entry speed. In a nutshell the faster your going the less likely sprint racing you will be able to get usable rotation from your non staggered axle. The other thing is do you 'need' to gain rotation from your axle?
Again Al very good, your reply to me shows your gaining new understanding.
paulkish
old fart
With your road course/sprint experience maybe you could relate to the inside rear sort of holding you in and helping you rotate in a sweeper or monza type turn where speeds are maintained longer and entry not so abrupt to get the inside rear unloaded?
Just speculation on my part Al and I did see and was amazed about the junior sprint setup I saw and how well it worked. But then again how well something works depends a lot on the competition it's put up against. ...
I'm trying to offer a concept which seem plausible to me as they say on TV. Yes I'm assuming I'm correct and looking for holes to be shot into it.
Just speculation on my part Al and I did see and was amazed about the junior sprint setup I saw and how well it worked. But then again how well something works depends a lot on the competition it's put up against. ...
I'm trying to offer a concept which seem plausible to me as they say on TV. Yes I'm assuming I'm correct and looking for holes to be shot into it.