I have some questions.....how does the suspension react to adding/removing preload on the springs? I have tried both upper and lower holes so far and can feel the difference in tire hit, but there must be more tuning in the preload other then getting the car to go straight right?

Well I've only had mine out twice so my experience is not that good. 1st time out with the bar in the lower hole and an 1/8" gap between the spring and the top bolt and the shocks set at 5. Car ran in the 10.6's with a best pass of 10.59. 60's were 1.48 to 1.54 with an average of 1.52. My sig pic is from the 1st outing. 2nd time out I put 2 flats of preload in left side and 4 in the right. 60's were almost identical. The weather was worse so the car slowed about .1. The car left like this. http://www.erikandersondesigns.com/images/2009/06-13-MokanAllOut/0008/imagepages/image13.html Jim

I set both sides so you can slike a nickel under them, then add a flat to the passenger side. It's been 1.36 60' on 10.5" tires.

are you guys running the calvert mono leafs also?

I run the calvert monoleafs and set the bars just like the instructions said. It has been a 1.419 60 foot and 1.42's consistently. Ranchos set on 7.

set bars just touching, if car goes right, add preload to right bar till it goes straight

I had bars on lower hole, left side bar just touching and right was 1/2 turn preload. Rancho shock was at 7 position

I do have their mono leaf springs. shocks are QA=1's.

My Challenger has CalTracs w/ mono-leaf springs. Here are the details on my suspension:
- 6-cylinder torsion bars
- QA1 R-series front shocks
- Upper control arm bumpers cut down
- CalTrac split monos w/ 20" A-body front segment & stock ride height
- CalTrac bars for 20" A-body front segment
- Rancho 5-way adjustable shocks (#9116)
- AR Engineering front spring hangers for SS springs
- Pinion angle 3.5 degrees
- Link bar in lower hole
- 1/4 turn preload on driver side; 1/3 additional turn preload on passenger side
- Rear shocks on 3 of 5 (middle extension setting)
- Front shocks on 1 of 12 (lightest extension setting; fixed firm compression damping)
- Rear tires 17.5 psi
- Front tires 45 psi
- Front suspension set up for approx. 5 1/4" extension from static ride height

This is a summary of last five passes in current state of tune running on M/T 275/60R15 ET Street Radials:
60 / 660 / 660 MPH / 1320 / 1320 MPH
1.459 / 6.682 / 101.66 / 10.566 / 126.01
1.468 / 6.677 / 101.87 / 10.561 / 126.00
1.463 / 6.698 / 101.45 / 10.582 / 126.18
1.464 / 6.682 / 101.71 / 10.563 / 126.12
1.459 / 6.681 / 101.47 / 10.570 / 125.97

FWIW, two things which turned out to be critical for the car to hook consistently were (a) getting enough front-end travel (5"+ as per Calvert's guidelines) to keep from unloading the rear tires on the launch and (b) running enough tire pressure to keep the sidewalls from folding up and loosing traction right after the "hit".

Thanks for some great info Brad....I guess I just need to continue tuning/testing. I see some settings I need to change based on your info but my question is "when is too much preload too much?"......and how does preload affect the hit on the tire...does more preload hit harder and less softer? Would you make adjustments to the preload for track condition or just play with tire pressures and just leave adjustabilty for "bite" to that alone?

I found this an a non-Mopar site:

CAL-TRAC SETTINGS
Top hole – Hardest Hit (start here)

Bottom hole – Softer Hit, moves IC forward

More Pre-load, Softer Hit

Less Pre-load, air gap, harder hit

If car pulls to the right add a quarter turn of pre-load to the right bar and visa versa.

Set front shocks soft

Set rear shocks on #5, if car wants to porpoise go to 6 or 7 (harder).

If car spins, needs harder hit

Too much wheel stand…. Softer hit, restrict front travel

Dont forget to set them with the driver in the car. Or something of equal weight in the drivers seat. That made a big difference for me.

That also brings up the question. Any difference between bias or radial setup.

FWIW, I run mine bottom hole. Just touching driver side, 2 flats preload passenger side. 7 on the Rancho's, with 275/60's. Goes straight, just not as quick as I'd like. Dead consistent tho even on an unprepped street night.

I'm changing to a 29x11.5 QTP for next year, not sure what direction I should go with mine.

I have mine in the bottom hole,,,,

Rear shocks on 7 ( works best for me )

(any higher,,,8,9, etc,,,and the car SPINS)

Front shocks (for me) are QA-1 set on 3 (soft),,,it doesnt like one as much

I set mine so both bars just touch,,,and then add a 1/2 turn of preload on the passenger side,,, ( ps,,i do this without someone being in the car,,driver seat,,etc),,actually this is what i was told by Calvert,,,that it was ok to set it this way without the driver weight...

I think your rear shock setting it too high,,,,i would go for 5-7 and see what it does...

I know everyone runs their front end real loose,,,mine doesnt seem to like it as much,,,

I have very little experience with them also, however without them my best 60' was ~ 1.80 and with them I made 2 passes, both were 1.64 60'

My car is as heavy as yours, runs a bit less mph and has gone 11.67.

Mine are set; bottom hole, both just touching, 1 extra flat in the pass side without weight in the seat (I can't find 3 people to sit on each other in my seat ) Rancho's set to 5 or 6 (don't remember), Calvert front shocks and MT 275-60 ET Street Radials. Car went straight on both passes (and nothing broke )

The big question in my mind is the 4k launch, heavy car & small tire, you might need to to leave softer....

Problem is if I leave below 3800-4k she tends to bog down as the clutch catches up with the motor.. She likes 4K but she spins out of the hole...Guess I still have to find that sweet spot. Maybe I need a bigger tire....