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 Post Posted: Thu Nov 11, 2010 9:41 pm 
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Your dragster doesn't know it doesn't have a front suspension. It's still reacts like it has a front suspension, even though it may not move as much, it still transfers weight. All the normal (door car) things still happen, there is still a reaction to the power you are applying, you just have to control it differently. You can stiffen the frame or loosen the frame (add or take away diagonals) which will act like changing the limiters on a door car. You can add or subtract weight from the middle of the car and it will act like tightening or loosening the extension on the front shocks of a door car. You can also add or subtract weight from the nose to adjust the flex in the chassis. You can raise or lower the rear suspension to raise or lower the COG. You can move the IC to adjust where you apply the power. I'm sure others on here have other ways of adjusting a dragster.

Good Luck and keep us posted on your results

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 Post Posted: Fri Nov 12, 2010 9:49 am 
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The length of the chassis is built in leverage , even though the front half of the dragster is considerably lighter on scales (static weight) it has multiplied leverage by wheel base length . More static weight on the rear requires less inertia weight (produced by power) and chassis action (anti squat % )to keep it hooked.

My self I have a hard time understanding why the anti squat line should correlate to the centerline of the front strut or suspension on a door car. I view a spring on the front as "help" the amount of help it adds depends on how much weight is physically on the spring , stored energy it is holding , how much travel the shock or strut has, and how much unsprung weight is not being held up or helped by the spring.

If the front tire leaves the ground or not the anti squat % is still changing , if the front tire leaves the ground there is a different amount of weight that leaves the ground and the anti squat % as well as the ic of the chassis is getting higher off the ground. That is just me though =;


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 Post Posted: Fri Nov 12, 2010 8:34 pm 
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People need to stop thinking about the position of the front wheels. they have nothing to do with the physics. The physics of the car comes from the location of the CG. Thats all there is too it. In a Dragster the front wheel weight is low but its a long way forward of the CG so it has a high torque value at the CG. When you think about your 4 link you should think about its reaction to the CG forget about the front wheel position or if its got front suspension etc. The 4 link just reacts to the inertia of the CG. Its what force upward and forward thats imparted at the CG that cause a reaction at the front wheels.


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 Post Posted: Thu Dec 09, 2010 8:51 am 
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rick360 wrote:
Since my SBC weighs quite a bit less than the BBC that was in it before and a significant change in TQ as well, what changes should I make to the bars or shocks to account for the differences?

Thoughts? Opinions? Ideas? Theories? Experiences?
Rick



IMO what I would do first. Find out what springs (length and weight) it has on the rear of the car. Typically you drop 20-30lb spring pressure when going to the sb from a bb. A few even drop to a shorter spring (ex 10 to a 8")

As far as the front, I think a poor setup dragster is setup to carry the left front out of the beam 6-8", some say this is proper to get the long chassis to work correct but when the bar location, shocks/springs, tire & converter are all correct this is not a issue.

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 Post Posted: Thu Dec 09, 2010 10:40 am 
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Hammertime wrote:
rick360 wrote:
Since my SBC weighs quite a bit less than the BBC that was in it before and a significant change in TQ as well, what changes should I make to the bars or shocks to account for the differences?

Thoughts? Opinions? Ideas? Theories? Experiences?
Rick



IMO what I would do first. Find out what springs (length and weight) it has on the rear of the car. Typically you drop 20-30lb spring pressure when going to the sb from a bb. A few even drop to a shorter spring (ex 10 to a 8")

As far as the front, I think a poor setup dragster is setup to carry the left front out of the beam 6-8", some say this is proper to get the long chassis to work correct but when the bar location, shocks/springs, tire & converter are all correct this is not a issue.


It had 14" 110# springs with the BBC and I put 11"or 12" 110# springs on it. I could barely get the 14" springs off of the shocks. Had to build a spring compressor just to do it. With the shorter 110# springs it feels pretty soft in the back.

The front coming up is not an issue at my current HP/TQ and gearing (4.30). Moving the batteries (pair of small Odyssey) to the rear is being considered and I doubt the front would come up even with the batteries in back. Moving weight UP is something I think a slower accelerating car needs. Raising the engine has been considered also, but harder to do.

Rick


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 Post Posted: Thu Dec 09, 2010 11:04 am 
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I would think a 12" 110lb spring is what it should have (I assume the shocks are behind the rear end and not in front)

What is the ride height at the mid plate ? from the bottom of the chassis to the ground. I was very lucky when buying cars all done from Diamnd to be setup in the past but as of late my current cars I've bought used and had to work on them a bit. Sometimes its a challenge but now its one of the best I've ever had and yours will do the same with few tweaks I am sure.

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 Post Posted: Fri Dec 10, 2010 1:41 pm 
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Hammertime wrote:
I would think a 12" 110lb spring is what it should have (I assume the shocks are behind the rear end and not in front)

What is the ride height at the mid plate ? from the bottom of the chassis to the ground. I was very lucky when buying cars all done from Diamnd to be setup in the past but as of late my current cars I've bought used and had to work on them a bit. Sometimes its a challenge but now its one of the best I've ever had and yours will do the same with few tweaks I am sure.


Yes, the shocks are behind the rear end.

The chassis is 3-3/4" at mid-plate w/o me in car. Probably 3-1/2" w/ me in car. Crank c/l is 12-1/2" off ground w/o driver.

What tweaks do you suggest?
If I move batteries to back how fast can I go with no weight on the nose?

Rick

Edit: Measured again AFTER setting tire pressure down to normal and it's 3-9/16" w/o driver.


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 Post Posted: Fri Dec 10, 2010 5:32 pm 
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Ride height is actually a touch low, typically you'd like to see min of 4" and normally 4.5" with the driver.
The back holes on the 4 link, how many is there above and below the rearend and which holes are the bars in ? or any pictures of the suspension with the tire off ? It can be rather simple to get it right as it sound it is just setup to hit the tire to hard.

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 Post Posted: Fri Dec 10, 2010 10:59 pm 
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Here are some pics with a tire removed. The shock mounts are on the highest setting (up some from where it was). I wanted it higher but will have to buy/fabricate different mounts. If my memory serves me correctly, I raised the lower bar 1 hole in front from where the previous owner ran it. I also installed all new heim joints before I ran it.

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 Post Posted: Fri Dec 10, 2010 11:31 pm 
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I have to agree with Dave. The center of gravity height is the key, since it would be hard to move you or the engine back or forward. Low and forward for more power and higher and to the rear for less. No matter what you do with the IC adjustment on the 4 link, The COG height is the money maker.

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 Post Posted: Sat Dec 11, 2010 8:50 pm 
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All this is just confirming to me that if I buy another one of these "skinny" cars, it will be another hard tail "slip" car. =; Only thing to worry about with them is tire pressure. =;

I AM STILL LOOKING THOUGH! \:D/

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