DOES THE HDK SUSPENSION K-MEMBER HANDLE BETTER THAN A T-BAR SUSPENSION?

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Mopar_Taxi_Guy said:
This guy built his own chassis using all Speedway Motors G-Comp components.





I'm trying to determine if he used the regular G-Comp universal kit or the G-Comp X as a starting point. As he is using a much taller coilover that mounts to the down bar.
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Based on the earlier pictures he posted on FB, he started with the regular G-Comp setup. He mentioned moving the UCA mounts around in the video, plus he used a much long coil over than the regular kit uses. Not clear what he was shooting for when he made the changes other than an I think he said he wanted an even better camber curve. Either way, I would bet he closely approximated the G-Comp X setup when he was done.
 
DionR said:
Based on the earlier pictures he posted on FB, he started with the regular G-Comp setup. He mentioned moving the UCA mounts around in the video, plus he used a much long coil over than the regular kit uses. Not clear what he was shooting for when he made the changes other than an I think he said he wanted an even better camber curve. Either way, I would bet he closely approximated the G-Comp X setup when he was done.
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You are correct.
 

DionR said:
Based on the earlier pictures he posted on FB, he started with the regular G-Comp setup. He mentioned moving the UCA mounts around in the video, plus he used a much long coil over than the regular kit uses. Not clear what he was shooting for when he made the changes other than an I think he said he wanted an even better camber curve. Either way, I would bet he closely approximated the G-Comp X setup when he was done.
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You can clearly see in the picture below what he did to the upper control arm mounting points.

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Mopar_Taxi_Guy said:
You can clearly see in the picture below what he did to the upper control arm mounting points.

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I saw the slots in the plate, but didn't see that he had a plug like that.

Based on this picture of the original G-Comp UCA mount, almost looks like he moved the mount up??

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To me, that's counter intuitive. Moving the mount down would add more camber as the suspension compresses, but moving it up seems like it would reduce the camber gain. At least to start.

I did ask him about it on FB, but I am not going to hold my breath. Not so I can duplicate it, just curious what the intent was. Feels like he might hold this close to the chest in case he can market it to other people. Which is fine, no hard feelings if he doesn't answer.
 
Ok, so based on these pictures, the X setup looks to lower the UCA ever so slightly.

G-Comp:

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G-Comp X:

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This is based on the visibility of bolt.

Note that the X kit has significantly more caster built in, too.
 
DionR said:
Very cool!

Don’t miss that the frame sits 1/2” higher on the G-Comp than the G-Comp X. 13.25” versus 12.75” from ground to bottom of frame with a 28” wheel.
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I lined everything up so you could see the direct comparison.
 
DionR said:
Right, but from the ground they don’t line up. It’s part of the difference between the G-Comp and G-Comp X.
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Their own CAD drawings show otherwise:

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When you read through all of the installation documentation, the dimension you are talking about changes between the 54" to 56" to 58" to 60" to 64" kits. But the dimension doesn't change between the G-Comp or G-Comp X kits as long as you're comaring the same width kit.
 
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mopowers said:
Isn't this racerjoe's thread about his Duster? Talk about a thread highjack.
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While you're not wrong that the we've derailed from the title of this thread.

The thread is about whether the HDK suspension handle better than a torsion bar suspension. It's isn't specifically about the Duster.
 
Mopar_Taxi_Guy said:
Their own CAD drawings show otherwise:

View attachment 1716461337

When you read through all of the installation documentation, the dimension you are talking about changes between the 54" to 56" to 58" to 60" to 64" kits. But the dimension doesn't change between the G-Comp or G-Comp X kits as long as you're comaring the same width kit.
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Those are just the mounts and the frame.

The images in post #857 are also CAD images from their instructions, and the centerline of the wheel matches, but the frame is 1/2” lower to the ground. The LBJ is longer and thus the knuckle is taller and the frame lower. At least that is my interpretation of the dimensions they give.
 
mopowers said:
Isn't this racerjoe's thread about his Duster? Talk about a thread highjack.
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Mopar_Taxi_Guy said:
While you're not wrong that the we've derailed from the title of this thread.

The thread is about whether the HDK suspension handle better than a torsion bar suspension. It's isn't specifically about the Duster.
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And a recent derail. We beat that horse flat over the last 33 or so pages, frankly I am surprised it took this long to get derailed.

At the same time, it’s not like we are talking about the best way to record videos. :p But we are talking about handling and options/ideas on how. In some ways, it was a natural evolution when some of us concluded that a bolt in kit isn’t a direction we would go.
 
DionR said:
Those are just the mounts and the frame.

The images in post #857 are also CAD images from their instructions, and the centerline of the wheel matches, but the frame is 1/2” lower to the ground. The LBJ is longer and thus the knuckle is taller and the frame lower. At least that is my interpretation of the dimensions they give.
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In your #857 post the drawing you have labelled G-Comp is from the 60" kit instructions and the drawing you have labelled G-Comp X is from the 54" kit instructions.

If you look at both sets of instructions for the 56" kit show the dimensions the same whether is a G-Comp or G-Comp X kit. The 56" kit instructions are the only ones I can directly compare because they only have the 54" and 56" G-Comp X instructions shown and they have the 56", 58", 60" & 62" G-Comp instructions shown. But if you open up the G-Comp 56"-62" instructions, you can see that the dimension changes with the different track width kits. The 56" & 58" kits have the same dimension. And the 60" & 62" kits have the same dimension. So I can only assume that the 54" G-Comp has the same dimension as the 54" G-Comp X.

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Mopar_Taxi_Guy said:
In your #857 post the drawing you have labelled G-Comp is from the 60" kit instructions and the drawing you have labelled G-Comp X is from the 54" kit instructions.

If you look at both sets of instructions for the 56" kit show the dimensions the same whether is a G-Comp or G-Comp X kit. The 56" kit instructions are the only ones I can directly compare because they only have the 54" and 56" G-Comp X instructions shown and they have the 56", 58", 60" & 62" G-Comp instructions shown. But if you open up the G-Comp 56"-62" instructions, you can see that the dimension changes with the different track width kits. The 56" & 58" kits have the same dimension. And the 60" & 62" kits have the same dimension. So I can only assume that the 54" G-Comp has the same dimension as the 54" G-Comp X.

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Interesting. I see what you are saying.

I didn't look at each set of instructions, I figured they wouldn't change other than the width of the frame rails.
 
JBrian said:
It's pretty ballesy to say Tim redesigned the HDK suspension. I know Tim asked Denny if he could lower the point for the LCAs to get the front down. You can actually see in the first picture with the original HDK K-Member that Tim's car sits higher than my torsion bar car. I wasn't aware that Tim provided the design for it. It was an ask that Denny reworked and delivered. See, that's what R&D is about design and test. If a test pilot says the plane does roll fast enough, it may be an issue with the ailerons. The pilot doesn't all of a sudden become the designer, he's testing and verifying. That's what Tim was doing with Denny, and in a very short amount of time Time jumped from 4th, 5th place at MoParty Grand Champion to winner. And his tires are still too small!

The only problem I have with Denny is that he didn't pick me! But I wasn't ready two ago and didn't have the driver experience Tim did in autocross, and I still don't. Congrats to Tim's HDK equipped HemiDuster for winning at MoParty 2025, outstanding job guys! Pictures from SCCA CAM Challenge earlier this year in STL.

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Two absolutely awesome Mopars!

Great job guys!!
 
sometimes....you have to start from scratch. Butch's next build. Whippled 6.4 Gen III / HDK built 28", 2 to 2-1/8" primaries step headers / TCI 6-speed automatic / recessed firewall / raised floor / 9" Ford / 4--link.....all in a low to the ground 74 Duster with flat stock hood .....old school. Oh yeah, forgot....with windshield wipers and A/C.

TRIGGER warning......NOT built for handling but to haul ***. Ought to go 200MPH easily (not with me behind the wheel), Butch has made plans to wind tunnel test to make sure it doesn't "fly"

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DionR said:
...................... In some ways, it was a natural evolution when some of us concluded that a bolt in kit isn’t a direction we would go.
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wait till ya' get the bill for your one-off, custom, super handling full chassis for your grocery getter. After all, you can put a helicopter engine in a submarine...if you have enough money.
 
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HemiDenny said:
sometimes....you have to start from scratch. Butch's next build. Whippled 6.4 Gen III / HDK built 28", 2 to 2-1/8" primaries step headers / TCI 6-speed automatic / recessed firewall / raised floor / 9" Ford / 4--link.....all in a low to the ground 74 Duster with flat stock hood .....old school. Oh yeah, forgot....with windshield wipers and A/C.

TRIGGER warning......NOT built for handling but to haul ***. Ought to go 200MPH easily (not with me behind the wheel), Butch has made plans to wind tunnel test to make sure it doesn't "fly"

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Wow!

Another wild build!

Coupla questions..

1. Am I seeing tone rings on the front spindle/hub assembly? Corvette??

2. Also, GM lower control arms?

3. Did you enlarge the firewall or section it and move the trans opening up closer to the cowel?

4. What Upper control arm is being used?

5. How does the front track compare to stock?

6. Fuel cell or stock gas tank?

Thanks Denny.
 
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