traction on the bars or climbing?

[sidewinder69]

always wondered this, do you make the most traction climbing up the bars , or when your actually on the bars? i see alot of different theories but no real explanation in the direction they are going.

[MasterSbilt_Racer]

always wondered this, do you make the most traction climbing up the bars , or when your actually on the bars? i see alot of different theories but no real explanation in the direction they are going.

Once your car is topped out, there isn't much force on the bars. Not sure if that is what you are asking? You are gonna make the most traction when the car has the highest rate of acceleration.

[sidewinder69]

okay that makes sense, so if you have more drop and climb the bars through the corner. would that in theory be a positive?

[Matt49]

Also keep in mind that the higher you lift the LR the higher the center of gravity is. This promotes weight transfer under acceleration. There is also the added down force but plenty of people will tell you it doesn't matter that much. Those same people will tell you we have to do something to get the bodies under control. Late model car attitude is becoming a very important part of the setup. I can't help but notice that some late model guys are focused far more on maintaining a certain angle of attack than they are on mechanical grip. It's a stretch of a comparison but that is very much a Formula 1 approach and it works in that world.

[Kromulous]

I was reading what the OP posted and giving it some thought. Climbing the bars, or maxed out and let the weight transfer generate the traction. I believe the best is neither because you really want to car maxed out on entry and thru the middle, concerning the LR travel. Once you get to corner exit and really trying to gain speed you want the weight transfer to come back on the LR.

My thinking wrong here? wont be the 1st time LOL.

[grt74]

watch some videos of madden and scott, you'll get your answer

[sidewinder69]

Can you elaborate grt

[grt74]

while they only drop 1-2 inches on entry (when they let off the gas) it takes just about the whole straightaway to top out on the bars, if your topped out there isn't anymore traction to be gained
remember everything is a compromise, what works on some tracks may not work on others, some tracks you may want to top out quick

[MasterSbilt_Racer]

^^ that's what you would want. Can't say I have seen bloomers car do that. And I don't know how you could achieve that with today's rules and Newtons laws of physics.

[Austin34471]

Things to consider:

When the chain is taught:
--You have the stiffest effective LR spring meaning for longitudinal weight transfer your LR will receive more weight proportionally... which = traction (depending on track conditions)
--You have the highest CoG. Good for longitinal acceleration... maybe bad for lateral acceleration (depending on track conditions)
--Your deck will have the steepest angle of attack (assuming you aren't pulling the LF off the ground with it)
--You have the least amount of actual suspension forgiveness to absorb bumps and keep optimum contact patch
--and... You have the most steer (Front and Rear track misalignment)

2/5 hurt traction 3/5 help. Don't ask me to list them in order of importance.. lol

[billetbirdcage]

Things to consider:

When the chain is taught:
--You have the stiffest effective LR spring meaning for longitudinal weight transfer your LR will receive more weight proportionally... which = traction (depending on track conditions)
--You have the highest CoG. Good for longitinal acceleration... maybe bad for lateral acceleration (depending on track conditions)
--Your deck will have the steepest angle of attack (assuming you aren't pulling the LF off the ground with it)
--You have the least amount of actual suspension forgiveness to absorb bumps and keep optimum contact patch
--and... You have the most steer (Front and Rear track misalignment)

2/5 hurt traction 3/5 help. Don't ask me to list them in order of importance.. lol

That can't be right, more bar angle/thrust even against the chain pushes the tire down on the ground harder..... Don't you know that.... Billet rolls eyes and is obviously being sarcastic

[Austin34471]

That can't be right, more bar angle/thrust even against the chain pushes the tire down on the ground harder..... Don't you know that.... Billet rolls eyes and is obviously being sarcastic

^^
This is only if you are running Kevlar tire inserts. That’s what my friend who’s got this friend who’s got this friend who’s got this friend that does lawn work at bloomers shop told me.. take it to the bank

[CageFaraday]

always wondered this, do you make the most traction climbing up the bars , or when your actually on the bars? i see alot of different theories but no real explanation in the direction they are going.

I came to realize that the way they run these cars now, they don't have much LR drive. What gave it away for me was I was watching the Super Bowl of dirt on DOD last year and you know how cold it is during that time. Well I got to noticing when they focus in on the back of the cars in 1 & 2, when they gas up they had vapor only coming off the RR and then I further notice most of the mud kicked out under throttle was also mostly coming from RR, almost nothing with the LR. Todays setups/chassis seem to be mostly about carrying momentum, where as 10 years ago or more they were more about "drive". My guess is as they continued to soften the RF which helps keep the LF down that you lose your dynamic cross from the axle thrust(climbing the bars). I mean race cars still work in an "X", but if you give the LR nothing to push against(ie a stiffer RF spring) then you can't have much load on the LR for traction. Combine that with pinning the RF with "Tie-Down" shocks then you hinder the weight transfer as well. So all your left with is momentum, so in 20 years of "On The Hook" we've migrated from massive "drive" to massive "side-bite". At least that's what I observe, haven't been active in a few years and lost interest after 2015. I could be wrong but that's what I see.

[95shaw]

I came to realize that the way they run these cars now, they don't have much LR drive. What gave it away for me was I was watching the Super Bowl of dirt on DOD last year and you know how cold it is during that time. Well I got to noticing when they focus in on the back of the cars in 1 & 2, when they gas up they had vapor only coming off the RR and then I further notice most of the mud kicked out under throttle was also mostly coming from RR, almost nothing with the LR. Todays setups/chassis seem to be mostly about carrying momentum, where as 10 years ago or more they were more about "drive". My guess is as they continued to soften the RF which helps keep the LF down that you lose your dynamic cross from the axle thrust(climbing the bars). I mean race cars still work in an "X", but if you give the LR nothing to push against(ie a stiffer RF spring) then you can't have much load on the LR for traction. Combine that with pinning the RF with "Tie-Down" shocks then you hinder the weight transfer as well. So all your left with is momentum, so in 20 years of "On The Hook" we've migrated from massive "drive" to massive "side-bite". At least that's what I observe, haven't been active in a few years and lost interest after 2015. I could be wrong but that's what I see.

Consider, the tire which is slipping generates more heat.
Also, kicks more mud.

Just food for thought.

[Matt49]

Thrust angle is real and a chain stopping it from increasing doesn't change the anti-squat vehicle dynamics. Add the RF bump stop and we have cars with HUGE amounts of dynamic wedge. And now (due to aero) we are trying to keep the car at the same basic attitude all they way around the track. A lesson learned (on purpose or on accident) from Formula 1 racing. We do this a number of ways (high compression/PSI LR ahead shocks, trail braking, etc.). This holds the dynamic wedge in the car and holds in the rear steer. And this (in my opinion) is why we have to do some things to get side bite back. (NOT so much for the trail brakers because they aren't engine braking the rear tires as much.)
It's also worth mentioning that tethering the LF (increasingly popular to help seal the nose for aero) HURTS side bite. So we have to compensate somewhere to get the car to NOT step out the rear up to the center of the corner.

[CageFaraday]

Consider, the tire which is slipping generates more heat.
Also, kicks more mud.

Just food for thought.

^^^This is what I see.^^^ Reckon his LR or RR is doing more work?

We use to see the LR of a DLM wrinkle like a drag car leaving the line(mucho drive), but lately I'm hard pressed to see that anywhere. So in theory I understand 2 solid bars on the LR pushing up/over towards a nearly solid bump rubber on the RF sounds like the ultimate, but if you can't keep the RF pinned to the bump under accel you lose all that dynamic cross the instant it lifts and all you're left with is aero and whatever LR% remains. I'm not an engineer or an educated scientist, all I know is what I observe. JMO

[Matt49]

^^^This is what I see.^^^ Reckon his LR or RR is doing more work?

We use to see the LR of a DLM wrinkle like a drag car leaving the line(mucho drive), but lately I'm hard pressed to see that anywhere. So in theory I understand 2 solid bars on the LR pushing up/over towards a nearly solid bump rubber on the RF sounds like the ultimate, but if you can't keep the RF pinned to the bump under accel you lose all that dynamic cross the instant it lifts and all you're left with is aero and whatever LR% remains. I'm not an engineer or an educated scientist, all I know is what I observe. JMO

Aside from both having 4 tires and an engine, the similarities between a modern dirt late model and a sprint car are pretty much non-existent.
Short of getting on a shaker rig, I don't know of a way to prove to you that a dirt late model has considerable dynamic wedge.
The wrinkling of the tire thing is a different story. The reason that you don't see it as much has to do with the heavy LR components and needing more PSI to maintain contact patch compliance.

[Kromulous]

I seen Bloomquist and Richards going at it during Speed-weeks (East Bay), and they were in the lead for 20 or so laps. All of the sudden they both got so tight on the throttle the car would shove the RF across the track literally 5 or 6 feet. Obviously they went backwards from there, but i never seen a SLM that tight off the corner when they tried to pick up the gas.

So when Matt49 says these cars make unreal dynamic wedge, yep i agree.

Moyer SR is one to watch too, he keeps his car so wedged up he has to literally turn to the left all the way down the straight-a-ways.

[RaceEngineer]

Thrust angle is real and a chain stopping it from increasing doesn't change the anti-squat vehicle dynamics. Add the RF bump stop and we have cars with HUGE amounts of dynamic wedge. And now (due to aero) we are trying to keep the car at the same basic attitude all they way around the track. A lesson learned (on purpose or on accident) from Formula 1 racing. We do this a number of ways (high compression/PSI LR ahead shocks, trail braking, etc.). This holds the dynamic wedge in the car and holds in the rear steer. And this (in my opinion) is why we have to do some things to get side bite back. (NOT so much for the trail brakers because they aren't engine braking the rear tires as much.)It's also worth mentioning that tethering the LF (increasingly popular to help seal the nose for aero) HURTS side bite. So we have to compensate somewhere to get the car to NOT step out the rear up to the center of the corner.

Thrust doesn't exist when the vehicle isn't accelerating. Once the chain is tight, the load is strictly the static load, the load gained from jacking that corner up, and aero load.The more you load the bars, the more you load the chain. No relative motion means net force is zero.

[Matt49]

But thrust DOES exist when the vehicle IS accelerating. DLM cars are RARELY not accelerating when the driver is on the gas.
Stopping the motion with the chain doesn't void the anti-squat loads that were achieved up to that point. It just puts a cap on it. As long as acceleration is happening, weight transfer is happening. If it isn't going into a spring, it's going to the tire. That's the entire point of anti-squat.