Suspension set up

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MR4V

MR4V

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Hi All
Wanting a little advice on improving my suspension set up for racing on the Duster, as I believe there is some improvement to be made.
Here's what I have so far: front is stock A Body fully rebuilt, running competition 3 way adjustable set at 90/10, still have the sway bar connected, S/6 torsion bars.
Rear has new Mopar leaf springs, competition 3 way adjustable both sides set at 50/50, 8 3/4 running Mopar snubber.

I'm currently not running chassis connectors and haven't tried unclamping the rear spring clamps.

When I race I run MT ET radials that are 255/60 15, tyre pressure varries upon the track but usually between 16-14psi.
60 feet times are consistent at low 1.7 to high 1.6, Duster seams to launch best at 2800rpm, again depending on the track some times I get wheel spin sometimes not.
You can see in the photos that the drivers side rear tyre is getting side wall wrinkle yet the passages side is fine, is this normal for these? Can you see any improvement that can be made to my current set up?
Cheers
Karl

This run is launch at 2800rpm with 16 psi

These runs have the same launch and have 14 psi.


Normal stance
 
I don't have any experience with a radial tire, but I was always under the impression that radials work best with 20-25psi.
 
I run the same tire and have found 20 psi warm tire works the best for me. I drive to the track and lowering my tire pressure is the first thing I do while the tires are still warm. I do a small burnout just to clean the tire off. My snubber is 1/4" from floor, 90/10 up front, 70/30 in rear, Mancini 981/982springs, foot brake at 2100. Hot day is 1.64 60', cooler is 1.62
 
Tyres pressure is checked before and after each run as heat soak has seen my pressures increase by up to 10psi.
Softer launch at 1800-2500 with 14-16psi see's 60 feet in the 2.0plus. 20psi and above see's massive wheel spin.
 
More air pressure, 20ish range and put frame connectors on the car if at all possible.

Make sure the rear shocks are long enough.
 
Also disconnect the sway bar on the driver's side when at the track, it will shift more weight to the right rear. I also use 70/30 on a slick track and 50/50 on a track that hooks.
 
The first thing you need to do is buy double adjustable shocks. You don't need to blow you was on Pro Stock shocks but Viking or QA-1's that are DOUBLE ADJUSTABLE is where you should start.

Next goes the pinion snubber. You'd be better off with slapped bars.

Learn to work with the shocks. Keeping bump and rebound separate and adjustable is a must.
 
I think you need to try more air also.. In my avatar I am running 16 lbs in my 315/60 drag radials.
 
MR4V said:
Hi All
Wanting a little advice on improving my suspension set up for racing on the Duster, as I believe there is some improvement to be made.
Here's what I have so far: front is stock A Body fully rebuilt, running competition 3 way adjustable set at 90/10, still have the sway bar connected, S/6 torsion bars.
Rear has new Mopar leaf springs, competition 3 way adjustable both sides set at 50/50, 8 3/4 running Mopar snubber.

I'm currently not running chassis connectors and haven't tried unclamping the rear spring clamps.

When I race I run MT ET radials that are 255/60 15, tyre pressure varries upon the track but usually between 16-14psi.
60 feet times are consistent at low 1.7 to high 1.6, Duster seams to launch best at 2800rpm, again depending on the track some times I get wheel spin sometimes not.
You can see in the photos that the drivers side rear tyre is getting side wall wrinkle yet the passages side is fine, is this normal for these? Can you see any improvement that can be made to my current set up?
Cheers
Karl

This run is launch at 2800rpm with 16 psi

These runs have the same launch and have 14 psi.


Normal stance
Click to expand...
When the tread trys to roll over itself,......It need more air.

If you're planting the left rear harder then the right, you my need to stagger shock setting to slow down the plant or smash of the tire.
I'm no chassis guy so take my opinions as just that. side wall wrinkle good! Tread wrinkle BAD!

By the way Grate Pic's to help up understand whats going on. ;)
 
mderoy340 said:
Also disconnect the sway bar on the driver's side
Click to expand...

Thinking of removing the sway bar altogether

yellow rose said:
The first thing you need to do is buy double adjustable shocks. You don't need to blow you was on Pro Stock shocks but Viking or QA-1's that are DOUBLE ADJUSTABLE is where you should start.

Next goes the pinion snubber. You'd be better off with slapped bars.

Learn to work with the shocks. Keeping bump and rebound separate and adjustable is a must.
Click to expand...

There are a few Q1 shocks they range from 15.5"-23.87 extended and 10.25"-14.87 collapsed. What's the best way to choose the right one? Extend the rear suspension to max and messure the extension distance and reverse the process for the collapsed messurements?

Cudafever said:
I'm no chassis guy so take my opinions as just that. side wall wrinkle good! Tread wrinkle BAD!
Click to expand...

In the photo you see tread wrinkle on the drivers side, so defiantly bad.
The photographer is a diehard Mopar fan so it wasn't hard to convince him to take the photos, all up he took 90 odd.
 
MR4V said:
Thinking of removing the sway bar altogether



There are a few Q1 shocks they range from 15.5"-23.87 extended and 10.25"-14.87 collapsed. What's the best way to choose the right one? Extend the rear suspension to max and messure the extension distance and reverse the process for the collapsed messurements?



In the photo you see tread wrinkle on the drivers side, so defiantly bad.
The photographer is a diehard Mopar fan so it wasn't hard to convince him to take the photos, all up he took 90 odd.
Click to expand...


Both Viking and QA-1 have the correct part number for bolt in double adjustable for both front and rear.

Shock length becomes LESS of an issue as you get control of th rear axle. I want the least separation I can get. And I want to control how hard and how fast the tire gets hits. You do that with shocks and your IC. In your case the IC is pretty much fixed, so deal with shock settings and launch RPM.
 
As I understand it, when your car launches, the car tries to twist clockwise. But your axle does the exact opposite. It tries to twist counterclockwise. This causes the driver's side tire to plant harder than the passenger side. Possibly, what could help you out is a rear anti-roll bar to keep the tires planted evenly. I use one from Competition Engineering and it seems to work well.



I'd also recommend disconnecting or removing the front sway bar. I don't see that it will help anything but add weight. I'm not a chassis guy either so take all that with a grain of salt.
 
clinteg said:
As I understand it, when your car launches, the car tries to twist clockwise. But your axle does the exact opposite. It tries to twist counterclockwise. This causes the driver's side tire to plant harder than the passenger side. Possibly, what could help you out is a rear anti-roll bar to keep the tires planted evenly. I use one from Competition Engineering and it seems to work well.



I'd also recommend disconnecting or removing the front sway bar. I don't see that it will help anything but add weight. I'm not a chassis guy either so take all that with a grain of salt.
Click to expand...

This is correct, which is why with a open diff the passenger side tire smokes. The drivers side is being smashed into the ground by what is known as axle roll rotation. A ladder bar effectively stops this, but, that is not always a good thing!
 
clinteg said:
As I understand it, when your car launches, the car tries to twist clockwise. But your axle does the exact opposite. It tries to twist counterclockwise. This causes the driver's side tire to plant harder than the passenger side. Possibly, what could help you out is a rear anti-roll bar to keep the tires planted evenly. I use one from Competition Engineering and it seems to work well.
Click to expand...

Thanks that explains why the passages side is not having the same issues.
Would increasing the driver side tyre pressurse reduce this?
Next TnT I'll try that along with adjusting the drivers side shock and removing the front sway bar altogether.
 
Lose the sway bar..put frame connectors in..my car runs quickest with 16 psi in my drag radials.. has been 1.62 with the 360 1.42 with my 416 in the 60'...
 
stroked340 said:
Lose the sway bar..put frame connectors in..my car runs quickest with 16 psi in my drag radials.. has been 1.62 with the 360 1.42 with my 416 in the 60'...
Click to expand...

That's a dang good 60' on radials. I've never bested better than 1.7's on 325's
 
1.33 is my best 60 ft. in my D50. Pump gas small block on motor ,stock leaf springs with home made Caltrac bars 315/60 M/T Drag Radials. 2950 lbs
 
D-50394 said:
1.33 is my best 60 ft. in my D50. Pump gas small block on motor ,stock leaf springs with home made Caltrac bars 315/60 M/T Drag Radials. 2950 lbs
Click to expand...

I assume you're using a trans brake which makes a big difference from the footbrake guys
 
I run my radials in the 17-18# range and have been 1.38 on a 325. For the rear springs I'd remove all the clamps on the rear section and clamp every front section to make it as stiff as possible.
 
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