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View Full Version : Any Thoughts of Less LR Hike But More Drive Off Corner from Video?



bumpdrafter
05-22-2010, 04:51 AM
Was watching some video from the Lucas race at Wythe on 5/15. There was a point early in the feature where Owens and EPJ ran several laps side by side. It appeared that EPJ had more LR hike but less drive off the corner than Owens. Any thoughts?

Here is the video I was watching.
http://ovdtr.com/2010/05/16/wythe-raceway-video-highlights/

lovinlatemodels
05-22-2010, 07:29 AM
That is more the the Bloomquist style. It's more of a balanced set up that works on his cars.

MasterSbilt_Racer
05-22-2010, 09:18 AM
I can't watch the video right now, but often the appearance of more drive off the corner is really being able to get back in the gas sooner or carrying more speed through the middle.

timmayb
05-22-2010, 09:48 AM
It has alot to do with the front end of Owens' car. His rf is pinned and stuck to the track so hard that it's picking up enough sidebite for the car to be able to go forward without the LR hiking up.

Also it's coming up more then it looks, those bloomquist bodies are very deceptive.

MasterSbilt_Racer
05-22-2010, 03:35 PM
After watching the video, I say Owens is beating him on entry and to the middle. Even though Owens is running a lower line, he is coming in as hot or hotter. Pearson pulls him off the corner until Owens takes the spot.

4bangerhotrod
05-23-2010, 11:52 AM
less hike hold more wedge in the car, if you can get side bite with out the hike you can get the side bite and more drive off the corner

jedclampit
05-23-2010, 01:30 PM
I'd say EPJ is too tight to run the top, looks like he is pinching the brakes to keep it turned , he usually runs better as a catfish anyway! :p

Egoracing
05-23-2010, 02:37 PM
less hike hold more wedge in the car, if you can get side bite with out the hike you can get the side bite and more drive off the corner

When the LR is really hiked up the LR is basically solid, the LF is about completely unloaded and the RR is using the spring for side bite. There is no more wedge in the car than when it is fully up on the bars on the LR. Put one on the scales like that and see where the weight is, the only thing you can not duplicate is the side bit but the LR and RF will be carrying about 80% or more of the cars weight.

4bangerhotrod
05-23-2010, 07:44 PM
ok ego i forgot your a genius, we dont know nothing call rocket chassis and ask us about it.

JTSjet
05-23-2010, 09:34 PM
i think someone is forgetting about a little thing called gravity that directs weight to the right side of the car when the left is raised. "sidebite" or lateral force will exaggerate gravity. increasing bar angle on the lr does NOT necessarily mean you will increase the drive on the lr tire.

Egoracing
05-23-2010, 10:15 PM
I said it did not include side loading, BUT a rigid LR is carrying a TON of weight. Put even springs on the across the fronts, lets say 500's and put 250's across the rear and 0 stagger and try to race it. You will learn REALLY quickly that the LR is carrying most of the chassis weight when the car will not turn on the gas. This is why you have to run 4-6 inches of sagger AND use rear steer to loosen the car up throught the corner or you are going to knock the wall down. Tilt, or chassis angle have nothing to do with the way gravity effects the chassis. As the chassis rises up on the LR the center of gravity also raises and THAT will add a lot to the side loading of the RR and RF.

MasterSbilt_Racer
05-24-2010, 08:18 AM
i think someone is forgetting about a little thing called gravity that directs weight to the right side of the car when the left is raised. "sidebite" or lateral force will exaggerate gravity. increasing bar angle on the lr does NOT necessarily mean you will increase the drive on the lr tire.

I'm a bit confused here. You can raise the left side ride height all you want and it will not effect static left percentage. On a modern 4 link, you would eventually notice a change, but that would be because the rear end's location would move because of the j bar.

Now it is true that the higher the left side is, the more weight that gets transferred laterally during cornering. This is because the CG has been raised. It is also true that more hike means more steer with everything else being equal.

In general, I agree that more hike equals more dynamic wedge. Now if you are hitting limiters and picking tires up off the surface, all bets are off.

fwdbite
05-24-2010, 11:04 AM
dynamic wedge

JTSjet
05-24-2010, 11:38 AM
MasterSbilt_Racer, you pretty much said the same thing in your 2nd paragraph.

i believe there is some truth in theory of 4bangerhotrod's statement. a car that has the lr jacked up and flopped over on the right side is not necessarily going to be producing the best drive off the corner, regardless of your limiter lifting the lr wheel. we've had this discussion before.

this "dynamic wedge" term seems to get thrown around a lot. maybe i'm confused but setting a car's attitude and suspension geometry to simulate a particular race situation and measuring it on a set of scales is nothing more than a static measurement. sure you're applying more crossweight into the car by doing that but it doesn't tell you much about how the car will handle. dynamic wedge cannot be measured but by the seat of your a$$ (or some pretty sophisticated telemetry equipment).

ego, how about you and me get a pair of cars, set them up with 500's/250's and 0 stagger and we'll see who knocks the wall down first? lol.

MasterSbilt_Racer
05-24-2010, 11:53 AM
i believe there is some truth in theory of 4bangerhotrod's statement. a car that has the lr jacked up and flopped over on the right side is not necessarily going to be producing the best drive off the corner, regardless of your limiter lifting the lr wheel. we've had this discussion before.

The best drive off the corner is not the setup with the most dynamic wedge. It is a setup where the 2 rear wheels are equally sharing the load. That does not disprove that fact that raising the lr adds wedge.

It ain't fancy telemetry, but when the dynamic wedge increases enough, it becomes pretty obvious in the sidewall of the lr tire. :D

JTSjet
05-24-2010, 12:04 PM
:) touché
.........................


The best drive off the corner is not the setup with the most dynamic wedge. It is a setup where the 2 rear wheels are equally sharing the load. That does not disprove that fact that raising the lr adds wedge.

It ain't fancy telemetry, but when the dynamic wedge increases enough, it becomes pretty obvious in the sidewall of the lr tire. :D

davis2902
05-25-2010, 10:19 AM
You can hike the drive right out of the car! Higher doesn't always mean more drive.

Ltemodel
05-25-2010, 02:03 PM
I think it is all in how you determine the term of wedge. If you consider wedge to be a static measurement of the weight balance of the car sitting on the springs, then if the LR spring is unloaded there is no wedge left in the car. If you consider wedge as being a static and dynamic difference in weight between the LR and RR, then dynamic bar angle wedges the car up a ton.

I think the key is how everyone relates to car tuning. For me, I separate static from dynamic and think about the force through the rear trailing arms differently than the wedge set statically on scales. I subscribe to the theory that when the car is rolled up, and the the LR spring is unloaded, there is no more wedge in the car. It makes it just easier for me to visualize what needs to be done.

Kevin

Jazz
05-25-2010, 05:26 PM
* I subscribe to the theory that when the car is rolled up, and the the LR spring is unloaded, there is no more wedge in the car.*

What if the LR spring is preloaded, say with either a stacked spring or a spring spacer so the LR is loaded all the time, up on the bars or not. Could some of these guy be running a step up like that with a short limiter chain so the car roll is to a minimum and side bite is controlled through the RF spring and shock, but still have lots of drive off the turn ?

Egoracing
05-25-2010, 06:09 PM
I think it is all in how you determine the term of wedge. If you consider wedge to be a static measurement of the weight balance of the car sitting on the springs, then if the LR spring is unloaded there is no wedge left in the car. If you consider wedge as being a static and dynamic difference in weight between the LR and RR, then dynamic bar angle wedges the car up a ton.

I think the key is how everyone relates to car tuning. For me, I separate static from dynamic and think about the force through the rear trailing arms differently than the wedge set statically on scales. I subscribe to the theory that when the car is rolled up, and the the LR spring is unloaded, there is no more wedge in the car. It makes it just easier for me to visualize what needs to be done.

Kevin
If you have a LR with a 250lb spring and it has 1000lbs on it while the car is static. During cornering on the track you are transferring 500lbs to the right your LR is still carrying 500lbs. It does not matter if it is on the spring or not the weight is still there.
Think of the 4 link and lift arm bars as a crow bar. IF you put the car on scales and put a crow bar from the chassis to the rear end tube and lifted the bar until the spring was unloaded how much weight is still on the tire? That is the same way the bars lift the chassis, they do not transfer weight and make the LR lighter, they lever the chassis weight up off of the spring. Different angles on the bars increase or decrease the leverage.

Ltemodel
05-25-2010, 09:53 PM
It's just the way I look at things. You're right, if you are on the gas and you will always have the LR loaded because of bar angle leverage and an anti-squat type of thrust, but if you lift off the gas and the spring is off the perch, the car won't have any spring wedge in the car until the car settles down back onto the spring. Now I know there will always be some weight there because of unsprung weight or sticktion in the j-bar or trail arm rod ends, but I try to separate what is going on there kinematicaly verses what is going on with the elastic weight transfer. There is so much going on there in the LR, with motion ratios and spring loads; it seems to be just a little easier determining what to make changes to if wedge is used to only describe spring load.

A stacked preloaded spring will hold wedge and on point and shoot style tracks it seems to work pretty well. These are the types of places that are short radius and you don't need to drive in too far on the right rear before you apex the corner. The wedge held in the spring will help it free it up to turn and aid in acceleration off if the car falls down off the bars too far in the middle of the corner.

I think we all think along the same lines, just have a little different terminology to describe it.

Kevin

Graff Spee
05-25-2010, 10:59 PM
Sometimes you use what you need, not all that you can get!:D

let-r-eat
05-26-2010, 12:17 AM
I think alot of people underestimate what trail braking techniques are doing as well. Most are using that to keep things from unloading unnecessarily. Most, like those in the video are using the brakes to steer and drive the car. Hammer pedal is down............

jedclampit
05-26-2010, 06:40 AM
I think alot of people underestimate what trail braking techniques are doing as well. Most are using that to keep things from unloading unnecessarily. Most, like those in the video are using the brakes to steer and drive the car. Hammer pedal is down............

If the car is right, this is whats up................. but not flat footed.

Egoracing
05-26-2010, 06:51 AM
When going onto the corner and off the gas the car is typically in yaw when you come off the gas and the mechanical leverage goes away you are loading the right side wheels as the LR goes limp. The LF being a heavier spring catches more weight which also loads the LR tire. All of this helps keep the car under you going in. If/when the lr comes down and hits the spring it spikes the amount of traction the LR has which subtracts from the traction of the other 3 tires (mostly the RF) which causes the car to get loose as the RF gains an advantage and pulls the car in that direction.
Trail braking and shock package can keep a lot of the load on the LR which keeps the weight center line higher creating more side bite and rear steer in the chassis. It will remove some of the side load but it is consistent and more drivable by keeping the LF pinned to the track.

jedclampit
05-26-2010, 09:12 PM
Never mind...........................................

Graff Spee
05-27-2010, 12:41 AM
Never mind...........................................

Ha Ha Ha, good answer!