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Discussion Starter #1
I have a 1987 Buick Regal and I am looking for a good starting point for my rear suspension with a drag radial.
Weight 3840lbs with driver 55% front 45% rear 108" wheel base
1200whp
8.5 rear with UMI LCA brackets and adjustable spring perches
Trick Chassis adjustable uppers with IS brackets on the frame
Trick Chassis adjustable lowers
Trick Chassis anti rollbar
Viking DA stock location shocks
125lb 12' spring
Pinion angle -2
3.08 gears
4L80E trans with a lockup converter and trans brake

Front is tubular upper and lower with travel limiters
Viking DA coil over with a 450lb spring

I want to say my car is driven on the street as much as it is at the track. I have done several hours of reading and I know I need as much extension on the shocks as I can get. I can achieve 1" extended at ride height with the adjustable spring perches. Any help would be greatly appreciated to help get my 60' times in the 1.4s and stay planted down the track.
 

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Only 1" of extension? I would be remounting the shocks or changing something, that's going to give you problems. Sounds like some excellent parts though,
 

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Lower bars pointed up (towards the front) 8*, and uppers pointed down 15*. You'll need to do all the math, but this should put you somewhere around 150% antisquat. Rear extension very loose, and compression very tight. The bars will be fine on the street, the shock settings are too harsh for the street. I run my da's wide open soft on the street. I have 6" of travel in my rear shocks, and at the track I leave 1" of shaft showing, allowing for tons of extension. On the street I flip the mounts and run the shocks in the middle of the travel. I am literally just finishing a 9" in a Bu, and used all the same TC parts.
 

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Discussion Starter #4
Boosted Bullet I think I worded it wrong. It has 1" of the shaft showing so it will have 6" of separation.

Mufflerguy thanks for the input. A lot of the stuff I have read has been from your posts. I just never seen a starting point for bar angles. Where did you guys end up for a spring rate on the rear? I haven't checked it yet and I dont know what will happen if the spring does unload at full extension. I have a Holley Dominator on my car so I plan to add the sensors to datalog the shock separation.
 

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Boosted Bullet I think I worded it wrong. It has 1" of the shaft showing so it will have 6" of separation.

Mufflerguy thanks for the input. A lot of the stuff I have read has been from your posts. I just never seen a starting point for bar angles. Where did you guys end up for a spring rate on the rear? I haven't checked it yet and I dont know what will happen if the spring does unload at full extension. I have a Holley Dominator on my car so I plan to add the sensors to datalog the shock separation.
I thought of that after I posted, sounds like you're well on your way! I also run my shocks full soft on the street and when it's being trailered, if you do run on the street, may want to avoid loading the trunk full of cargo and avoid fat chicks with only 1" compression, ?
 

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Discussion Starter #6
I thought of that after I posted, sounds like you're well on your way! I also run my shocks full soft on the street and when it's being trailered, if you do run on the street, may want to avoid loading the trunk full of cargo and avoid fat chicks with only 1" compression, ?
That's why I decided to go with the adjustable spring perches. It will allow me to raise the rear ride height to get the travel on the shock.
 

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I have run a 150# spring in the rear since day 1. Works well. The rear height will vary (about 1") from a full tank of gas to 1/4 tank.
 

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Discussion Starter #8
I plan on making it back to the track this weekend. Is there any advice on what to look for with slow motion video and what changes with what I see. As in more or less anti squat for what the video shows. I can mount a GoPro under the car so I can see the shock and the tire.
 

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Take a video from the side of the car/semi rear corner. You want to see how the front is reacting, and see the rear wheel well start to lift. My car, the entire car just lifts up, but it doesn't pull the front wheels at all. Very close, but not off the track. That is controlled by the shocks only. I run no limiters on the front. My buddies Bu that I just finished up, wants to snap the front wheels off the ground (I removed his limiters yesterday) and as soon as they come up, the front end drops back down and unloads the rear at the same time, blowing the tires off. I run 18 psi in my 275 pros. DA's are important to making a radial work.
 

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Discussion Starter #10
Thanks to the help from you guys I think I am headed in the right direction. My best 60' was a 1.54 leaving on 4psi and the car is staying glued to the track. I ran a [email protected] with a little wheel spin up top. Now to start working on the 60' times with some more boost and shock settings.
 

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With that et and Mph you should be able to get low 1.30 to high 1.20 sixties pretty easily once you’re dialed in.
 

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Thanks to the help from you guys I think I am headed in the right direction. My best 60' was a 1.54 leaving on 4psi and the car is staying glued to the track. I ran a [email protected] with a little wheel spin up top. Now to start working on the 60' times with some more boost and shock settings.
What I have learned is leave on all the boost, and limit launch power with timing. Timing power is instantaneous, while building boost after the fact is not. FYI, I have multiple different tunes depending on starting line conditions. I can leave on anything from 9 1/2#, all the way up to 11 1/2#.
 

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Just for the records: you are running an 8.5" with 1200hp? That must be the new highest I heard of. Good job.
 

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Discussion Starter #16
A little update on the car. We have installed the new 9" and at the same time I swapped from the Rosller to a Jakes D3 trans brake. In the process of this there was multiple trans issues that we finally got worked out. The track was very greasy but we were finally able to get it down the track. Still needs a lot of tuning but we are getting there. The car wouldn’t hook on anything over 2700rpms and I was having trouble building any boost but here are a couple videos in the link. 2700rpms 5psi on the hit.
 
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