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

[DionR]

Why can't yall just agree to disagree and leave it there? I'm just glad someone offers something aftermarket that actually works and is available for MOPARS. Why not just look at it like that, regardless of whether you're going to use it or not?

In a nut shell, I think the discussion comes up over and over because often times someone makes it sound like the only way to get an old Mopar to handle is an aftermarket kit. This usually devolves into a "length contest" which goes no where. At that point someone gets their feelings hurt and starts calling people idiots and such.

 

[HemiDenny]

Ah, that's the crux of it this time.

Let me explain why I have the opinion that suspension geometry isn't "your thing".

1. Deflections when discussing your suspension geometry and if it was "improved' over the stock A-Body suspension. You state (and correctly so) that you never made claims that the geometry was better. Leaves the impression you really don't know what the geometry looked like at all.

2. Comments about roll center and such are never responded to. Only attacks or ignored. Zero discussion on geometry from you.

3. Suggests to build a handling car are (generally) responded with "I just like hanging with my buddies" suggesting that how a car handles isn't on your radar.

I could go back and quote you but too much time wasted to do that. And there might even be other reasons beyond the above that I might remember if I went back, but that's pointless.

Based on those things, I came to the conclusion that I did. If I am wrong, I am open to be schooled.

The comment that you co-opted Tim was maybe overly pointed. But you have to admit that it's not completely untrue. You already admitted you have enough on your plate so developing the kit for handling wasn't going to work for you to do it yourself. So you went looking for someone that would work it over and improve the design, which Tim did. You even said you hand picked him for that reason. Effectively, what Tim has under his car now isn't any of your design beyond the general layout, only the rack is in the same location as far as I know. It was a savvy move, you get a better handling kit to offer and exposure in a market you didn't really have much in before.




I don't ever remember saying I thought it wasn't durable. Plenty have, but all I have pointed out is the loading on the frame rails and some concerns for the rigidity of the system. I don't remember once saying durability was an issue.

But now that you mention it, I wonder if your k-frame would fold in and not allow a body to be dropped over the motor like a guy on here recently had with a Hellcat and an RMS kit. He had to jack the k-frame apart to get it past the frame rails. I haven't posted a comment about that here just to leave things alone, but feels pertinent to this comment now.

But saying I think the thing is going to fall out of the car and kill someone...that was someone else.

But I get it, I pissed you off. You reacted.

And if I didn't have anything to back it up with, why does what I say matter anyways?

you are correct, you only said I didn't know what I was doing. That was KernDog (God knows , I hate to rattle his chain) that questioned the durablity. I still think you are an asshole for making such a comment and BTW, in case you are wondering, I would have no problem saying it to your face.

 

[JBrian]

You already admitted you have enough on your plate so developing the kit for handling wasn't going to work for you to do it yourself. So you went looking for someone that would work it over and improve the design, which Tim did. You even said you hand picked him for that reason. Effectively, what Tim has under his car now isn't any of your design beyond the general layout, only the rack is in the same location as far as I know.

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.

 

[HemiDenny]

In a nut shell, I think the discussion comes up over and over because often times someone makes it sound like the only way to get an old Mopar to handle is an aftermarket kit. This usually devolves into a "length contest" which goes no where. At that point someone gets their feelings hurt and starts calling people idiots and such.

once again ....you are full of it.

WHEN have I EVER said ANYTHING even close to that.
back it up.

 

[DionR]

you are correct, you only said I didn't know what I was doing.

Yeah, I don't think I said that either. But whatever.

I still think you are an asshole for making such a comment and BTW, in case you are wondering, I would have no problem saying it to your face.

Fair enough.

 

[DionR]

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!

I would agree with you, if Tim didn't move the LCA's around and then that was incorporated into the new k-frame.

 

[DionR]

once again ....you are full of it.

WHEN have I EVER said ANYTHING even close to that.
back it up.

Is your name "someone"? I intentionally left it vague and wasn't pointing it at anyone specifically. And that included you.

I get the impression I could talk about a C5 corvette and you would take it as a personal insult from me to you.

 

[HemiDenny]

Dont try to sugarcoat....Your "someone" is pointed directly at me.

 

[DionR]

Dont try to sugarcoat....Your "someone" is pointed directly at me.

No, it actually wasn't. But read into things all you want, don't really care.

If I was pointing it at you, I would have called you out. Much like you calling me an asshole to my face, I'm not going to not name you if I mean you.

 

[HemiDenny]

Frankly, I think it was more to get someone to do some development work for him. He doesn't seem to understand suspension geometry based on the past comments so he needed the help. Add that since he makes no claims for better handling, it was a low risk deal if it didn't turn out well.

maybe this will rattle your memory from long ago.....like TODAY.

Tim got the out-of-the box standard A-body K package compliments of HDK. Same as anyone except he wanted to keep his trick UCAs and use his own spindle / brake combo.

After his first outing, Tim wanted to experiment / try additional (and what I would consider for a normal street car), somewhat aggressive caster (8 degrees) so I recommended he do an in house modification simulating the forward movement built into my K from 15 years earlier. I sent him new LCA spacers and new pivot shafts with lengthened stop pads to accommodate. He liked that idea because it would also help keep the tire centered in the opening.

He put a bug in my ear about changing the roll center with different lower ball joints and I told him I was not fond of that idea.

Then my tie rod supplier went out of business and I was forced to go look for a replacement. What I found was a tie rod end that allowed me to raise the LCA pivot. I called Tim to tell him about the new LCA pivot as an alternative and he loved the idea.....so I made him a new K.

All new HDK's are now built that way BECAUSE with the replacement tie rod end, I have no other choice. I also think it helps with the roll center..... a win / win

 

[NC Engine Builder]

Hell, I ain't going anywhere, I do this for fun and to get out of the house. Not surprisingly, I been around the woulda / coulda railbirds all my life. Hasn't bothered me yet, I sure ain't gonna loose sleep over the "also rans"

I'm not sure who your referring to as "also rans" but I can ASSURE you, I have more sanctioned event wins than you do sir. I ran with actual rules, weight, cubic inch, carburetor and a spec tire. I dont have any experience riding around in a parking lot around traffic cones, but I have a boat load of racing experience. Hell look at my profile picture. Those trophies are just ONE season. There is zero chance you could out handle that car with your system on equal tires.

 

[DionR]

maybe this will rattle your memory from long ago.....like TODAY.

Tim got the out-of-the box standard A-body K package compliments of HDK. Same as anyone except he wanted to keep his trick UCAs and use his own spindle / brake combo.

After his first outing, Tim wanted to experiment / try additional (and what I would consider for a normal street car), somewhat aggressive caster (8 degrees) so I recommended he do an in house modification simulating the forward movement built into my K from 15 years earlier. I sent him new LCA spacers and new pivot shafts with lengthened stop pads to accommodate. He liked that idea because it would also help keep the tire centered in the opening.

He put a bug in my ear about changing the roll center with different lower ball joints and I told him I was not fond of that idea.

Then my tie rod supplier went out of business and I was forced to go look for a replacement. What I found was a tie rod end that allowed me to raise the LCA pivot. I called Tim to tell him about the new LCA pivot as an alternative and he loved the idea.....so I made him a new K.

All new HDK's are now built that way BECAUSE with the replacement tie rod end, I have no other choice. I also think it helps with the roll center..... a win / win

Here's how Tim posted it.

On the original K, I trimmed the tube where the LCA mounts so I could move it forward. This gave me the ability to have 8.5+ degrees of caster and the tire is no where near contacting the back side of the wheel opening. This new K incorporates that adjustment and also moves the LCA mounting point up slightly. This will move the roll center along with allowing me to drop the car that same amount effectively lowering the CG also. So in layman's terms, I ran the LCAs perfectly parallel with the ground. If I would have lowered the car anymore, that would have angled them down toward the center of the car, along with the UCAs having a steeper angle down. This would put the roll center close to the ground and further away from the CG making the moment arm for roll much greater. Now I can lower the car while only making minor changes to the roll center all while lowering the CG. Thus putting the CG and roll center lower overall. This is my theory at least, which is as useful as a spare tire with no air in it.

 

[RustyRatRod]

Let me throw this out. Maybe Denny doesn't know geometry. Maybe he's a good guesser. Or maybe he considers the answers to some of these questions proprietary. Maybe. Do all yall really think he just sat back and made a "guess" as to how to build a suspension? I kinda doubt it. Like I said, I don't have a dog in the hunt. I like the stock Mopar stuff, because naturally, it's cheap, but it's also very effective. If all yall think Denny just rolled the dice and "made up" a suspension, I think yall are sadly mistaken.

 

[RustyRatRod]

I'm not sure who your referring to as "also rans" but I can ASSURE you, I have more sanctioned event wins than you do sir. I ran with actual rules, weight, cubic inch, carburetor and a spec tire. I dont have any experience riding around in a parking lot around traffic cones, but I have a boat load of racing experience. Hell look at my profile picture. Those trophies are just ONE season. There is zero chance you could out handle that car with your system on equal tires.

....and I bet those wins were probably all with Mopar style suspension. It's hard to improve upon.

 

[NC Engine Builder]

....and I bet those wins were probably all with Mopar style suspension. It's hard to improve upon.

Torsion bars, leaf springs, small block mopar, 904 and a 8 3/4

 

[HemiDenny]

nice hardware and no argument, you would not be considered an "also ran" in your series, I am just curious, asphalt? (car looks way to clean to be anything else). what size track?

All seriousness, how does circle track racing or the set up for it equate to auto-x????

 

[NC Engine Builder]

nice hardware and no argument, you would not be considered an "also ran" in your series, I am just curious, asphalt? (car looks way to clean to be anything else). what size track?

All seriousness, how does circle track racing or the set up for it equate to auto-x????

Asphalt, 1/2 mile tri-oval. High 18 second lap times, with a 7" spec tire, a holley 2 barrel carburetor, .420 lift rule cam at 3400 lbs. And how does it relate? It goes around corners at high speed. I could adjust the front end to a more "road course" setup, that would be what I'd do if racing around a short course. To me, handling is having the ability to control the car going into a 23° banked turn at 100+ mph with cars 2 inches away, and knowing it will stick, and go where I point it.

 

[TT5.9mag]

Asphalt, 1/2 mile tri-oval. High 18 second lap times, with a 7" spec tire, a holley 2 barrel carburetor, .420 lift rule cam at 3400 lbs. And how does it relate? It goes around corners at high speed. I could adjust the front end to a more "road course" setup, that would be what I'd do if racing around a short course. To me, handling is having the ability to control the car going into a 23° banked turn at 100+ mph with cars 2 inches away, and knowing it will stick, and go where I point it.

Can I drive pllleeeeeeaaaaassee!

 

[DionR]

Let me throw this out. Maybe Denny doesn't know geometry. Maybe he's a good guesser. Or maybe he considers the answers to some of these questions proprietary. Maybe. Do all yall really think he just sat back and made a "guess" as to how to build a suspension? I kinda doubt it. Like I said, I don't have a dog in the hunt. I like the stock Mopar stuff, because naturally, it's cheap, but it's also very effective. If all yall think Denny just rolled the dice and "made up" a suspension, I think yall are sadly mistaken.

Frankly, I don't believe any of these aftermarket suspension spent any time looking at geometry beyond making sure it will align. I think they were all built with the idea of maximizing space and using a rack and pinion. Denny even said earlier in this thread that the only reason he went to coil overs in his design was because the LCA pivots had to move to fit the rack and that meant no more torsion bars.

So yes, I think he built the suspension with the intent of making sure it could be aligned, but other than that it was to fit stuff in a small space. Not to make it handle better. He even says that.

Here's is Denny's post:

A often overlooked fact regarding the development of the HDK rack & pinion / coil over conversions is it was originally designed as only a rack and pinion conversion ....for room. However, it quickly became apparent to make a front steer rack and pinion work properly in our original rear steer Mopars, the lower control arm pivot point needed changed negating the torsion bars. I had no choice but to come up an economical and stealthy way to install coil shocks and springs. So....truth be told, coil overs were added not because (at least for me) we were seeking better handling / performance, we needed something other than the torsion bars to hold up the front of the car. The fact that they added even more room almost eliminating exhaust clearance issues was just another benefit.

I think even the later one's that now say "better handling" or "improved geometry" (which Denny does not on his website) added that as a sales pitch, not because they designed it for better handling. So many people buy into a coil over is better mindset, and for a GM and probably a Ford, it probably is. But for a Mopar there isn't (in my opinion) a good benefit to a coil over in the handling department. Not to say there can't be benefits, but for other issues like headers.

There are new COC kit's out there now and one of them has posted "geometry" info which I shared here. But the info was kind of pointless and didn't tell us anything, so I think it is kind of a "give them info and hope it confuses them" rather than actual info. I read into that info that the geometry really isn't better. Or they compared it to a stock bias ply alignment car and not what someone who is into handling would actually drive. Either way, the posted info isn't useful info and thus, so far, not one of the manufacturers has posted any real info.

If one of them actually had better geometry compared to a properly setup TB suspension, I doubt they would hesitate to plaster it all over the internet. And the argument that there are too many variable is bogus. Set some standards and compare them and remove the variables. Same 17" (or 18") wheels/tires, same ride height, match caster and camber and post the geometry for each.

 

[HemiDenny]

Let me throw this out. Maybe Denny doesn't know geometry. Maybe he's a good guesser. Or maybe he considers the answers to some of these questions proprietary. Maybe. Do all yall really think he just sat back and made a "guess" as to how to build a suspension? I kinda doubt it. Like I said, I don't have a dog in the hunt. I like the stock Mopar stuff, because naturally, it's cheap, but it's also very effective. If all yall think Denny just rolled the dice and "made up" a suspension, I think yall are sadly mistaken.

I learned about front end / rear end geometry in my Direct Connection Suspension manual in the 70's (we called it front end blueprinting) , got a refresher in the early 90's way before you could google it and actually had find it for yourself. Thank you Heidts Suspension for the tutorial (first three pages) in their your catalogs. Remember catalogs?

For the average hot rod / street car, nothing tricky about it, it is NOT rocket science......the fundamental basics NEVER change. If you can draw a straight line....go to the head of the class.

The reason I and HDK do not get too excited about what works best for auto-cross is because there are not only too many variables car to car, but in reality it is a very very small amount of the market. Would I run anything more than 6 degrees of caster on my street car....no thanks. Or cruise my streets with excessive camber....no chance and neither would 99% of the street and strip rides I build for. All about bump steer and tire (non) wear.

I bet I was working on eliminating bump steer before a lot of you were born.

1975...me and my friends drag car, we learned part of going fast is keeping the front tires straight regardless of suspension travel.

even back then, instead of just guessing hoping for the best, we read, experimented, tested and learned. BTW, it was a freakin' blast!

 

[TT5.9mag]

Frankly, I don't believe any of these aftermarket suspension spent any time looking at geometry beyond making sure it will align. I think they were all built with the idea of maximizing space and using a rack and pinion. Denny even said earlier in this thread that the only reason he went to coil overs in his design was because the LCA pivots had to move to fit the rack and that meant no more torsion bars.

So yes, I think he built the suspension with the intent of making sure it could be aligned, but other than that it was to fit stuff in a small space. Not to make it handle better. He even says that.

Here's is Denny's post:



I think even the later one's that now say "better handling" or "improved geometry" (which Denny does not on his website) added that as a sales pitch, not because they designed it for better handling. So many people buy into a coil over is better mindset, and for a GM and probably a Ford, it probably is. But for a Mopar there isn't (in my opinion) a good benefit to a coil over in the handling department. Not to say there can't be benefits, but for other issues like headers.

There are new COC kit's out there now and one of them has posted "geometry" info which I shared here. But the info was kind of pointless and didn't tell us anything, so I think it is kind of a "give them info and hope it confuses them" rather than actual info. I read into that info that the geometry really isn't better. Or they compared it to a stock bias ply alignment car and not what someone who is into handling would actually drive. Either way, the posted info isn't useful info and thus, so far, not one of the manufacturers has posted any real info.

If one of them actually had better geometry compared to a properly setup TB suspension, I doubt they would hesitate to plaster it all over the internet. And the argument that there are too many variable is bogus. Set some standards and compare them and remove the variables. Same 17" (or 18") wheels/tires, same ride height, match caster and camber and post the geometry for each.

I believe I read (somewhere on fabo not this thread) that the information regarding geometry was not posted and never will be because it is proprietary. As if all of the sudden when the numbers came out, everyone would be able to rush out and fabricate their own COC package with said numbers.

 

[DionR]

I believe I read (somewhere on fabo not this thread) that the information regarding geometry was not posted and never will be because it is proprietary. As if all of the sudden when the numbers came out, everyone would be able to rush out and fabricate their own COC package with said numbers.

Denny said that in this thread. No idea if anyone else has said it, but I know he did.

 

[DionR]

Would I run anything more than 6 degrees of caster on my street car....no thanks cruise my streets with excessive camber....no chance and neither would 99% of the street and strip rides I build for. All about bump steer and tire (non) wear.

Not saying you need it for your builds, but all the modern cars are running more than 6 degrees of caster. Not an argument, just an FYI.

Here are the specs for newer GT350.

Pretty sure the SRT8 Challengers are like 8 or more.

 

[HemiDenny]

Frankly, I don't believe any of these aftermarket suspension spent any time looking at geometry beyond making sure it will align. I think they were all built with the idea of maximizing space and using a rack and pinion. Denny even said earlier in this thread that the only reason he went to coil overs in his design was because the LCA pivots had to move to fit the rack and that meant no more torsion bars.

So yes, I think he built the suspension with the intent of making sure it could be aligned, but other than that it was to fit stuff in a small space. Not to make it handle better. He even says that.

Here's is Denny's post:



I think even the later one's that now say "better handling" or "improved geometry" (which Denny does not on his website) added that as a sales pitch, not because they designed it for better handling. So many people buy into a coil over is better mindset, and for a GM and probably a Ford, it probably is. But for a Mopar there isn't (in my opinion) a good benefit to a coil over in the handling department. Not to say there can't be benefits, but for other issues like headers.

There are new COC kit's out there now and one of them has posted "geometry" info which I shared here. But the info was kind of pointless and didn't tell us anything, so I think it is kind of a "give them info and hope it confuses them" rather than actual info. I read into that info that the geometry really isn't better. Or they compared it to a stock bias ply alignment car and not what someone who is into handling would actually drive. Either way, the posted info isn't useful info and thus, so far, not one of the manufacturers has posted any real info.

If one of them actually had better geometry compared to a properly setup TB suspension, I doubt they would hesitate to plaster it all over the internet. And the argument that there are too many variable is bogus. Set some standards and compare them and remove the variables. Same 17" (or 18") wheels/tires, same ride height, match caster and camber and post the geometry for each.

we think we may be getting on the same page, but your post is very misleading or maybe just hard to follow.

I think only one sentence in that is mine..... I think even the later one's that now say "better handling" or "improved geometry" (which Denny does not on his website) added that as a sales pitch, not because they designed it for better handling.

the rest are your thoughts/ remarks....correct?

 

[HemiDenny]

Denny said that in this thread. No idea if anyone else has said it, but I know he did.

can you show me where because I do not think I did.?

I would even wager if you are up for it....... looser apologizes