8 second OEM 4 link drag race chassis setup

[KEVINS]

OK. One last try. Are you saying that you are trying to do the most work at the expense of some of your power?

Possibly, that depends on how you define it. We wont be losing power just getting different results by the application of it.
One way may use enough power to pull a good wheelie while another may move the car forward faster.

The power that we are trying to use will always be constant, it can't change, but it can be re-directed.

ks

 

[Alky V6]

Possibly, that depends on how you define it. We wont be losing power just getting different results by the application of it.
One way may use enough power to pull a good wheelie while another may move the car forward faster.

The power that we are trying to use will always be constant, it can't change, but it can be re-directed.

ks

Which link position are you saying would do one or the other?

Back to the baseball analogy. If a person were to hold the bat by the fat end and hit the ball at the far end of the bat (skinny end), I imagine the energy transferred to the baseball would be a whole lot different. Why would that be? Shouldn't it be the same as when holding the bat correctly? A lever is a lever.

 

[Alky V6]

I think I understand the redirection of energy through varying the length of the levers connecting the axle housing to the links, but I just can't seem to grasp how the energy is being transferred through the upper link in the way you're describing it. I can picture it in my head better if the CG inertia were attempting to push back to the axle housing through the upper link, since the CG is higher than the upper link.

 

[Alky V6]

I could see the upper link pulling during forward acceleration if both links were above the axle housing, but that isn't the case with our cars.

 

[Alky V6]

I should note now that the UCA axle mounting on my car is higher than the OEM arrangement. I don't want anyone assuming that I'm using the OEM location. The Moser 12 bolt housing is manufactured that way. Without looking at my 4link program, I believe it's about 1" higher than the OEM location.

 

[Alky V6]

The hunt is on for the G body IC sweet spot!

The "G spot"!

The adventure and specs to be recorded in this thread.

 

[KEVINS]

How about this:
Think about the rotational engery that is being stored in the torque converter especially if the car is equipped with a t-brake and then the button is released.

That stored engergy from the converter is transmitted through the driveshaft causing the pinion to "instantly" climb the ring gear causing the axle housing to "instantly" rotate upwards.

When the housing rotates upwards the UCA holes that are farthest from the axle centerline will be traveling faster (have a higher velocity) than the UCA holes are closer to the axle centerline.

It's that extra velocity from the farthest hole that has a higher "impact" that acts on the frame causing the suspension to react quicker when the car is launched.

ks

 

[Alky V6]

How about this:
Think about the rotational engery that is being stored in the torque converter especially if the car is equipped with a t-brake and then the button is released.

That stored engergy from the converter is transmitted through the driveshaft causing the pinion to "instantly" climb the ring gear causing the axle housing to "instantly" rotate upwards.

When the housing rotates upwards the UCA holes that are farthest from the axle centerline will be traveling faster (have a higher velocity) than the UCA holes are closer to the axle centerline.

It's that extra velocity from the farthest hole that has a higher "impact" that acts on the frame causing the suspension to react quicker when the car is launched.

ks

This spike, or impact is only occurring instantly and for a very, very short period of time. Correct? Kinda like the clank you can sometimes have when a transmission downshifts, when the circumstances are right. Usually, endplays and clearances play a big part in that scenario, allowing a momentum to build and then suddenly stopped, or being acted against. It is a common practice in the transmission world to locate any excessive clearances and endplays and tighten them up to lessen clanking.
After this initial and short impact, and the forces at work settle in, what do we have left?

 

[Alky V6]

I'm figuring my AS% is going to need to fall somewhere between 100% and 126%, ignoring the IC length for now. I already know 93% static doesn't work to my satisfaction.
I'm going to cut the above range in half and start at 114% and see what I have and work from there.
That will mean dropping the LCA axle mounting location .85".
There is a 1/4" difference in the mounting height at the LCA axle locations. Lower on the right side, increasing AS% on that side. In moving the mounting holes, I'm going to maintain that relationship. A little bit of dynamic anti-roll. This 1/4" difference was already built into the Moser housing.

 

[Alky V6]

Notes: Having the LCAs level with the ground minimizes roll steer.
Moving the LCA rear mount lower than the front mount increases roll oversteer. If roll steer is inevitable, it is preferred to have roll understeer, not oversteer. Roll understeer gives more control to the driver.
How much oversteer is manageable, I don't know.

Roll steer is when the car enters a corner and when the car begins to roll, the rearend will begin to steer the car.
Roll understeer happens when the rearend steers the rearend of the car into the turn, demanding the driver to enter more steering input to cause the turn.
Roll oversteer happens when the rearend steers the rearend away from the turn, causing the rearend to swing outwards and point the car deeper into the turn, demanding the driver to input less steering into the turn to keep the rearend from swinging out.

If the car got out of shape on a run, having the LCAs level with the ground will give the best stability.

 

[Alky V6]

I just got a new book to study. Dave Morgan's "Door Slammers: The Chassis Book". And, I discovered an absolutely amazing thread on another site that covers the suspension problems I'm addressing here. A treasure chest of information.
I'm in seventh heaven. Off to study.

 

[charlief1]

I just got a new book to study. Dave Morgan's "Door Slammers: The Chassis Book". And, I discovered an absolutely amazing thread on another site that covers the suspension problems I'm addressing here. A treasure chest of information.
I'm in seventh heaven. Off to study.

Well post a link Donnie.:biggrin: I'd like to see what's posted to see if it's the same as I'm thinking about.

 

[Alky V6]

Well post a link Donnie.:biggrin: I'd like to see what's posted to see if it's the same as I'm thinking about.

Is it against the rules to post a link to another forum?

 

[Alky V6]

Do you have any pics of the front suspension limiter setup? I'm getting ready to go that route.

Sorry I haven't gotten around to getting that photo for you.
The device is really very simple. It's just a rectangular block of aluminum bolted to the frame directly underneath the stock rubber bumper that's on the upper control arm.
The height of the block controls the travel of the control arm. It just takes up the clearance between the bumper and the frame.
The rubber bumper allows a gradual change in weight transfer, rather than having the control arm travel abruptly stopped by a strap, chain or bolt. Less chance of upsetting the rate of weight transfer and ultimately rearend traction.
The bumper actually compresses a lot with the block in there, since the coil spring is more compressed when the travel is halted. This puts a lot of load on that rubber bumper, but I think it's worth it with the bumper helping to gradually bring the travel to a stop. When the front end lifts, there are no bumps or bangs that I can feel when the travel tops out.
The down side of using the rubber bumper is, if the plan is to restrict front end travel to a really low number, you'll probably have to do it without the bumper. Surprisingly, from the point that the bumper first starts to compress to the point where the suspension stops is about an extra inch and a half to two inches of travel.
The stock rubber bumper that is used is considered a variable rate bumper.

 

[charlief1]

Is it against the rules to post a link to another forum?

For this example it should be ok Donnie. It's tech after all and if it makes TB's a little faster I'm sure we can allow it. If you don't feel good about it send it to me in an email.:biggrin:

 

[Alky V6]

For this example it should be ok Donnie. It's tech after all and if it makes TB's a little faster I'm sure we can allow it. If you don't feel good about it send it to me in an email.:biggrin:

If there's a problem, just delete it.
This is the most amazing source of chassis setup examples I've come across. A lot of fellas sharing detailed setup information and testing results of some high horsepowered stock suspension cars.

anti squat percentage, IC height & distance-radial FOX Mustang - Yellow Bullet Forums

 

[Alky V6]

Here's another link to some amazing information. I suggest reading it start to finish.

http://www.racetec.cc/shope/index.htm

 

[Dusty Bradford]

The rubber bumper allows a gradual change in weight transfer, rather than having the control arm travel abruptly stopped by a strap, chain or bolt. Less chance of upsetting the rate of weight transfer and ultimately rearend traction.

That's what the shock is for and is why you want a good shock rather than something like competition engineering junk. Even something like an AFCO or Santhuff can be valved wrong for your set-up. Shock sensors will tell you all you need to know about how a shock is supposed to work. If a shock tops out in just a couple tenths of a second.....it's too loose. I went down the worst track I've been on all year and the front travel didn't top out until 1.2 seconds.

 

[Alky V6]

That's what the shock is for and is why you want a good shock rather than something like competition engineering junk. Even something like an AFCO or Santhuff can be valved wrong for your set-up. Shock sensors will tell you all you need to know about how a shock is supposed to work. If a shock tops out in just a couple tenths of a second.....it's too loose. I went down the worst track I've been on all year and the front travel didn't top out until 1.2 seconds.

From what I understand, the amount of front suspension travel and the rate of travel has much to do with the available torque the particular setup has. I'm beginning to think that it can also be a way to fine tune an IC that may not be exactly perfectly placed.
I would think in your case, Dusty, tying down the front suspension alltogether might be an option, also. But, if I remember right, back in this thread, you did mention that you found that you needed a certain amount of travel. Have you changed your setup? Have you found that the car is now needing something different than what you were posting earlier in the thread?

 

[Alky V6]

OK. This is my final revision. I'm drilling the holes for this one.
Strangely enough this one is going to place the IC directly under my bottom. Is Charlie the one that made this IC suggestion? Let's see how it works!
This will require me to drop the LCA rear mounting point 7/8".