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8 second OEM 4 link drag race chassis setup

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Yea, for the initial measurements let's use the 1.81" for now since thats what the arms are made to work with on the 10bolt. That hole position should clear the existing torque box which is the biggest concern.
I can make longer or shorter ones if needed once you measure where that hole will actually be located on the chassis.

Just to clarify why I would need you to mark the hole position on a piece of cardboard then measure the desired length of the new control is b/c my c.arms are designed for the 10bolt which has the UCA bushings lower than the 12bolt. In order to mount these arms to the taller mounting ears of the 12bolt I may have to make longer arms in order to reach the higher mounting points.

Also, if you drill new holes to level the LCA's and the IC gets moved back round 43" then I would test that setup before installing these buckets.

ks
That won't work with the existing UCA geometry. That gives me 48.9 IC length and 108.7 AS%. That's going the wrong way.
 
Then I'll need you to plug in the proper hole height needed to achieve the desired IC values.
Or you can send me the control arm numbers and tire size, etc you're using so I can play with the hole height.

ks
 
Then I'll need you to plug in the proper hole height needed to achieve the desired IC values.
Or you can send me the control arm numbers and tire size, etc you're using so I can play with the hole height.

ks
I'm going to set this up so that I have about the same amount of asymmetrical link arrangement that I currently am running. That means the left IC length will be longer than the right. Should I set the IC lengths up so that the two sides average out at 36", or should I just set the right side for 36" with the left side being what it will be?

Right now, I have 36 for the right side and 39.1 for the left.
 
Since we're doing this let's set it up so the IC is the same for both sides. I'll drill different positions for each hole in the buckets.

Since you're plugging in numbers there is one hole already in the brackets the new hole will need to clear. It needs to clear it by at least .25".

It's located 1.81" back and 1.59" down from the factory hole. So the new hole can be pretty much anywhere above this hole in order to get us the 36"-38" IC length and as low a AS as possible.

KS
 
OK, Kevin. This is what I came up with. 'x' is -1.81" (projected length).
Choices are;
Left side IC length, AS%, amount down (y); Right side IC length, AS%, amount down (y)
36.1", 150.2, -0.30"; 36.0", 147.2, -0.10"
37.0", 146.7, -0.26"; 37.0", 143.1, -0.05"
37.9", 143.2, -0.22"; 37.9", 139.7, -0.01"

Notice that trying to get the IC lengths equal left to right, is giving me an asymmetrical AS% that is opposite that which is preferred. I'd rather have the higher AS% number on the right side, not the left. This is going to force me to have to add more spring or ARB preload to straighten out the launch.
For whatever reason the top and bottom frame mounts on the left side are both about 1/4" higher than the right side. That's what's throwing off the AS%.
 
Excellent!

I like this one:
Left side IC length, AS%, amount down (y); Right side IC length, AS%, amount down (y)
37.9", 143.2, -0.22"; 37.9", 139.7, -0.01"

But measuring the brackets puts the hole too close to the existing hole in the bracket. If the 1.81 is changed to 2.13 I think this will give me more material to work with.
Can you figure out a new 'Y' using X= 2.13" and still maintain the same AS/IC values or something real close?

Good Job!
KS
 
x = -2.130 projected length.

Left side IC length, IC Ht, AS%, amount down (y); Right side IC length, IC Ht, AS%, amount up (y)
37.9", 10.8", 143.3, -0.140"; 37.8", 10.6, 140.0, +0.070"
 
x = -2.130 projected length.

Left side IC length, IC Ht, AS%, amount down (y); Right side IC length, IC Ht, AS%, amount up (y)
37.9", 10.8", 143.3, -0.140"; 37.8", 10.6, 140.0, +0.070"

Hey! I think that will work!
Is there a way that you can now locate this point on your car then measure the length of the desired control arm? Within a 1/4" should be fine since the control arm lengths can be adjusted.

KS
 
Hey! I think that will work!
Is there a way that you can now locate this point on your car then measure the length of the desired control arm? Within a 1/4" should be fine since the control arm lengths can be adjusted.

KS
I'll figure out something.
 
The upper links have been installed. Thanks, Kevin. The installation was straight forward and was much, much easier than would have been the case if the torque box itself had to be modified. Very nice product.
Something must have been off with my measurements. I had to fab up new adjustment sleeves to lengthen the arms. They turned out to be too short the way they came, and the thread engagement was on the low side. I had to add about an inch of length.

I took some measurements, but there is one more that I want to double check before I list the new suspension specs (IC length, height, AS%).

I took the car out yesterday and she launched perfectly straight with the preliminary settings I made with the new links. Spring preload the same as last time, and one half turn preload on the RB. I had to make zero conscious decisions to correct steering. She was on a string through the launch. The front tires didn't feel like they lifted much. I still have some shock adjustment work to do. The front rebound is still almost full tight. I'll slowly loosen it until I'm happy with it. The 60 foots were in the 1.34-1.38 range. No records set today.

Still, traction is an issue through second and on the top end with relatively large boost numbers. I would have to say at this point that there hasn't been a change with this point either way.

When getting off the throttle and into the brakes the car reacted fine. No pulling left or right at all. Very uneventful. That's good.

I got some comments in the pits from people about how well it looked like the car was setup with the way it launched. Hmmm. That made me wish I had some video. I'm not sure what a good launch should feel like. The launches actually felt very boring. Maybe that's how it's supposed to feel?
 
Glad everything installed easily and thanks a bunch for the update, Good info!

The launches/run should feel very lazy and boring if the suspension is set up correctly so your comments fall in line with what others have said. Some people even commented that their car felt slower b/c it was so stable.

The required length of the stud did seem strange to me b/c I cut .75" off to meet your measurements but that's good that you were able to make something.

I have to admit I was hoping to match your existing 60's (1.2's) but hopefully you'll be able to tune them in. Keep us informed of the progress.

Congrats and Thanks for your efforts!
Kevin:cool:
 
Keep us informed of the progress.
Kevin
I will.
Tomorrow I'll get that last measurement and post up the coordinates so that anyone using a 4 link sim can check it out.
I had to stray from the plan of having both LCAs level to get the ICs as equal in length as I could.
 
All right. Here are the coordinates.
Left side of the car;
Top axle bracket: 0 x 20.5
Bottom axle bracket: .688 x 10.657
Top frame bracket: 6.625 x 19.06
Bottom frame bracket: 19.875 x 10.75
The LCA on this side is nearly horizontal with the ground.

Right side of car;
Top axle bracket: 0 x 20.25
Bottom axle bracket: .688 x 9.375
Top frame bracket: 6.875 x 19.06
Bottom frame bracket: 19.875 x 10.5
The LCA on this side is pointed upwards.
 
Let me add that I also raised the rear 1/4" due to some tire rubbing from tire growth that I discovered. I put the upper rubber spring seat back in on the left side, and added another 1/4" spacer below the right side spring in addition to the upper rubber spring seat and the 1/2" spacer below the spring that was already on that side.

Static ride height.
IC length; height; AS%
Left side: 44.3; 10.9; 123.1 Towards the rear of Dave Morgan's box.
Right side: 47.1; 12.1; 128.9 Just in front of Dave Morgans's box.
Notice there is still a little dynamic roll control at static ride height.

If we add just .040" of dynamic body roll. Lower the RR .040" and raise the LR .040" to simulate normal body roll due to launch torque.
IC length; height; AS%
Left side: 54.6; 11.8; 107.9
Right side: 40.1; 11.0; 138.9
The dynamic roll control increases at a very nice rate to help cancel out body roll due to engine torque during the launch. With the new shorter UCAs and the new positions that they are mounted in, it appears the rate that the dynamic roll control comes in is steeper than it was with the previous longer UCAs and the positions that they were mounted.

This setup is working extremely well. I have to say that I could probably black out during the launch and after the 60 foot come to with the car going straight as an arrow. I have no plans to play with the IC settings any further. I will be playing with the shocks settings, though, to try to get my 60 foot a little quicker.

I also plan to get some video the next time I go out, too.
 
Saweet! Glad you like how it feels.
I hope the rest of the tuning can better or equal your previous 60's, I think it should.
I'd still like to see what a shorter IC would do but obviously you're limited by the tire clearance. Don't pay attention to that Dave Morgan recommendation. The last time I spoke with him he had no clue what I was talking about with that program when I asked about that box.
From what I can conclude that "box" is better for a true 4link car that's really low with 14/32's, tube chassis, etc. It seems the higher the car (stock ride height) the farther back the IC works, but naturally you're doing the best thing: TESTING! :D

ks
 
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