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

[72bluNblu]

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The design as far as how its welded/supported is identical. So even if improvements were made, unless they are just that much better welds, this can happen again, easily. The design of this particular one is just weak.

The factory suspension loads exactly nothing in the way that it's loaded in the Gerst/QA1 k-member as well as any of the other ones.
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Other than the steering box, the stock part pushes all the load directly into the main member, basically on the same axis with small moments at worst. If you fully welded one of these out, and braced the steering box mount, I honestly don't think you can really break one of these. Everything is a 3D shape and also naturally arched or triangulated. It's naturally quite stiff. The steering box mount honestly isn't though.

Of course my 55 year old one has been taking P275 tires for 10 years (it may only have been 12-14k miles in that time) and it had a lot of miles and questionable weld quality to begin with. For something designed to be mass produced and to a price it's a solid piece. The engineering of it is fundamentally solid, especially for when it was made.

I agree that the factory K is more likely to go the distance. This is especially if it's been seam welded, the steering box mount boxed and some of the factory welds corrected. But the stock K's had failures too, the K member that's on my '74 now came from a '74 Dart with less than 100k miles on it and the steering box mount was almost entirely broken free from the K, to the point that the mount itself had cracked in the middle. The factory welding wasn't exactly the best and the quality control was lacking too. Who knows how many were replaced back in the day because of weld failures.

QA1 increased the thickness of the tubes and some of the base metal, and the welding quality is far better. The design itself may not be the best, but QA1 is a major company that produces a lot of tubular suspension parts for a lot of different applications. I'm not saying they know everything, but I would bet that they know more than enough not to be putting a product on the market that they know will fail in short order.

They've also been going out of their way to replace people's Gerst made K-members, so I know they've seen the failures. I won't go as far as to say they're looking out for people and have everyone's best interests in mind, but from a legal standpoint I'm sure they don't want to be paying for more failures.

Looking at this pic, it looks like it was never welded properly in the first place.

Look at the rust around the circumference of the tubing.

Looks like water got in there.

Junk.

Run, don't walk away from this ****.



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Yeah you can see how thin the actual joint was, that's just piss poor construction. The weld and overall joint was wrong from the beginning.

As I've been telling everyone for over 13 years now with CAP, if you have Gerst made products on your car you should either contact QA1 about your concerns, or just straight up toss them. Some of the stuff they sent out the door should never have been run on the street.

 

[goldduster318]

Think about how much the factory does everything the quickest/cheapest way possible and then compare that to something you'd spend several thousand on. A failure on a stick welded, potentially by someone who was hungover, drunk, or high, while given mere seconds to do the task after 40-50 years, not going to say that surprises me. The QC on really any old car is pretty bad. The design itself is solid because more K-frames made it than broke even after 50 years. I have seen ones with the LCA tubes broken out also.

Frankly, I am unimpressed even if they increased the tubing thickness because the joining of a bent piece of round tube to a flat tube like that without anything to spread the load out isn't a great design. The area where there is actually a weld is the smallest possible. The HDK and AlterKtion have this done MUCH better, though all can be improved by gussets and triangulation to spread the load out. I wouldn't say any one of these is even remotely optimized for stiffness or has a super fantastic overall design. To me it's a bit of a shock in a world where we have all these incredible modern cars to look at at everyone is still doing Mustang II (read Pinto) front ends?

There are a lot of frankly horrible designs out there for k-members for a lot of different cars. For Mopars the Magnumforce, CAP, and Gerst ones are all garbage, and the QA1 has bascially the same design again. I certainly don't like the Ford Fox Body BMR, QA1, Team Z, or AJE ones. Frankly a lot of these have such a flimsy design I can't believe they would even hold up on the street, even without big tires.

It seems QA1 at least uses certified welders to do the welding which I'm sure helps but I question really their engineering if they did wall thickness and whatnot and didn't just go all out on actually improving the design. I'm glad they are trying to help the people out, but I still wonder if we won't see failures of their parts 5-10 years down the road too because the design is subpar. Guess we will find out.

 

[Kern Dog]

I bet that not one of these aftermarket replacement systems have ever been run 100k plus miles in actual real life road conditions, and that thin tubing and design that lacks any real engineering, I doubt has the oem durability.

I take a look at the lower control arm.....

....with the narrow 5 or 6 inches of width between mounting points and I compare that to the triangulated stock setup. I don't see how the aftermarket stuff would last and hold together. Think of how a man can easily be pushed over if his feet were 10 inches apart compared to his feet being 24 inches apart. A wider spacing equals greater stability. I'd be embarrassed to tell someone that I designed this. The upper control arm mounts are 1 1/2 times as far apart and the UCA carries only a fraction of the impact loads of the lower control arms.

 

[goldduster318]

I take a look at the lower control arm.....


....with the narrow 5 or 6 inches of width between mounting points and I compare that to the triangulated stock setup. I don't see how the aftermarket stuff would last and hold together. Think of how a man can easily be pushed over if his feet were 10 inches apart compared to his feet being 24 inches apart. A wider spacing equals greater stability. I'd be embarrassed to tell someone that I designed this. The upper control arm mounts are 1 1/2 times as far apart and the UCA carries only a fraction of the impact loads of the lower control arms.

Yeah, I was trying to make that point earlier in the thread (and many moons ago). You just don't see stuff like this on anything OEM. Even a stock Mustang II doesn't have this. Even worse is ALL of the aftermarket K-frames are essentially the same as this.

The upper control arm carries very, very little load. About 20 years ago one of my OEM control arms I no longer have had the ball joint back out and it wasn't even connected to any of the threads and it didn't even really drive that strangely. It certainly felt like there was something wrong but it wasn't even bad enough that I didn't drive it home. They're mostly following. The LCA takes all the load from the springs/torsion bars and the road load. If you've ever seen the sorry excuse for an upper control arm and ball joint on a 97-04 Dakota it would be obvious.

 

[NC Engine Builder]

That's because these front suspension systems are designed for people who know NOTHING about design and engineering. You know, people who read crap in magazines and fall for the shiny paint and bling.

 

[Kern Dog]

If I knew less about these cars, the coil over conversion kits (C.O.C.K.s) might seem like a good idea.

You get all new parts, new hardware and instructions.
There is no cleaning, pressing in bushings, painting or consulting a service manual.
I'm just teasing here....
WE can joke about this stuff, right?
Maybe if the welds are great and if the cars are driven on smooth roads, they would be fine. If a car is a 300 mile a year cruiser, you'd never endanger yourself. The guys that do autocross are competing solo so any failure won't hurt the driver or another participant.

 

[HemiDenny]

That's because these front suspension systems are designed for people who know NOTHING about design and engineering. You know, people who read crap in magazines and fall for the shiny paint and bling.

this statement by you.....makes me smile, mostly because I have read your rants.

 

[NC Engine Builder]

this statement by you.....makes me smile, mostly because I have read your rants.

Well, to my knowledge NOBODY that builds these things has the ability to test them even to the level the factory engineers did back when. I have never called you out personally, but you also have done no r&d on par with a OEM manufacturer. I WILL say, and HAVE stated before, your system is more robust than your competition, but nothing I have ever posted is untrue. Dont take it personally, your product has its merits, but its limitations also. And I have raced these cars with the factory suspension design in the real world, so I know how capable the oem design is.

 

[NC Engine Builder]

And @HemiDenny . In case you might have missed a important part of what I was saying let me do this third grade level screenshot for ya

 

[fishmens67]

If I wanted a coil spring frontend I would have bought a Camaro or Mustang. lol
Torsion bar suspension is what made Mopar, all my brand X buddies back in the day raged about the rise of my fastback, much better than their squatty *** launching brand X

 

[mopowers]

And @HemiDenny . In case you might have missed a important part of what I was saying let me do this third grade level screenshot for ya

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In all honesty, that may be just a little disingenuous. I'd say they're designed for anyone who wants to buy one - regardless of how much or how little they know. Just look at who started this thread. He seems to know what he's doing.

 

[Sublime one]

Well the only thing I got to say is that I have been trying to tear up @HemiDenny stuff for years at the track. If I was a better driver I would not land so hard on front suspension! I have multiple cracks in fiberglass front end from landing to hard, but I have yet to crack and or break @HemiDenny front end! Hah! And yes I have more than one car so equipped! I am not an engineer or even remotely intelligent, I am simply a red neck farmer who could tear up a pry bar in a sandbox.

 

[NC Engine Builder]

Well the only thing I got to say is that I have been trying to tear up @HemiDenny stuff for years at the track. If I was a better driver I would not land so hard on front suspension! I have multiple cracks in fiberglass front end from landing to hard, but I have yet to crack and or break @HemiDenny front end! Hah! And yes I have more than one car so equipped! I am not an engineer or even remotely intelligent, I am simply a red neck farmer who could tear up a pry bar in a sandbox.

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And what exactly does that have to do with "handling" which is what the OP asked about. People been going in a straight line, hell still do, with a model A ford straight axle, at speeds faster than what your doing, so what exactly is your point? Unless it's his welding is better, which it definitely is.

 

[NC Engine Builder]

Well the only thing I got to say is that I have been trying to tear up @HemiDenny stuff for years at the track. If I was a better driver I would not land so hard on front suspension! I have multiple cracks in fiberglass front end from landing to hard, but I have yet to crack and or break @HemiDenny front end! Hah! And yes I have more than one car so equipped! I am not an engineer or even remotely intelligent, I am simply a red neck farmer who could tear up a pry bar in a sandbox.

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Cool car by the way

 

[HemiDenny]

Well, to my knowledge NOBODY that builds these things has the ability to test them even to the level the factory engineers did back when. I have never called you out personally, but you also have done no r&d on par with a OEM manufacturer. I WILL say, and HAVE stated before, your system is more robust than your competition, but nothing I have ever posted is untrue. Dont take it personally, your product has its merits, but its limitations also. And I have raced these cars with the factory suspension design in the real world, so I know how capable the oem design is.

the fact of the matter is, it is what the OEM design is NOT capable of is why we build "these things".

 

[NC Engine Builder]

the fact of the matter is, it is what the OEM design is NOT capable of is why we build "these things".

Yes sir I know that. FITMENT is a huge plus for what you do. Having worked on Hemi A bodys I'm fully aware of that

 

[72bluNblu]

That's because these front suspension systems are designed for people who know NOTHING about design and engineering. You know, people who read crap in magazines and fall for the shiny paint and bling.

this statement by you.....makes me smile, mostly because I have read your rants.

I mean, yeah, that was a bit dramatic by @NC Engine Builder

But, is he wrong?

Because I don’t think he is. Honestly, I don’t think there’s any engineering in any of the coil over conversions. Not strictly speaking anyway, because I don’t believe any of the coil over conversions have actually been designed or analyzed by engineer.

I mean, did you have a structural or mechanical analysis done by an engineer @HemiDenny ?

And look, I know there are plenty of race car builders both current and historical that have built amazing machines without an engineer and some pretty problematic ones that were engineered. Not trying to discount that at all.

But there’s a difference between building a race car, or even your own car, and selling aftermarket components for a profit when you know they’ll be spending time on the street.

the fact of the matter is, it is what the OEM design is NOT capable of is why we build "these things".

And that right there is the problem.

Because other than a rack and header clearance there’s NOTHING that an HDK does that you can’t do with the torsion bar suspension.

And in the world of handling, road racing and AutoX it’s the coil over conversions that haven’t proved they’re better at all.

 

[NC Engine Builder]

But the original poster asked about a "handling" advantage... and that's where my focus was

 

[72bluNblu]

But the original poster asked about a "handling" advantage... and that's where my focus was

Exactly. There isn’t one.

If anything, the geometry analysis that has been done has shown that the coil over conversions require geometry correction to even get to where a mildly lowered, mostly factory torsion bar suspension starts at for geometry.

And a rack might “feel” better, but it doesn’t make you faster.

 

[NC Engine Builder]

How about if HDK, or any other manufacturer of a coilover conversion wants to REALLY show a handling advantage we do a shoot out? Let's say, each competitor puts in 10k cash into the pot, everyone weigh the same, scaled percentage the same on all 4 corners, and everyone run the same wheel/tire combo, (some spec tire) and we can run a professional road course or asphalt oval? Fastest lap time takes the pot? What yall think?

 

[HemiDenny]

I mean, yeah, that was a bit dramatic by @NC Engine Builder

But, is he wrong?

Because I don’t think he is. Honestly, I don’t think there’s any engineering in any of the coil over conversions. Not strictly speaking anyway, because I don’t believe any of the coil over conversions have actually been designed or analyzed by engineer.

I mean, did you have a structural or mechanical analysis done by an engineer @HemiDenny ?

And look, I know there are plenty of race car builders both current and historical that have built amazing machines without an engineer and some pretty problematic ones that were engineered. Not trying to discount that at all.

But there’s a difference between building a race car, or even your own car, and selling aftermarket components for a profit when you know they’ll be spending time on the street.



And that right there is the problem.

Because other than a rack and header clearance there’s NOTHING that an HDK does that you can’t do with the torsion bar suspension.

And in the world of handling, road racing and AutoX it’s the coil over conversions that haven’t proved they’re better at all.

I understand, some will obviously never get it.....and I'm A-Ok with that.

 

[NC Engine Builder]

I understand, some will obviously never get it.....and I'm A-Ok with that.

You wanna put up 10k and see if your stuff can out handle a 45 year old obsolete torsion bar mopar?

 

[HemiDenny]

How about if HDK, or any other manufacturer of a coilover conversion wants to REALLY show a handling advantage we do a shoot out? Let's say, each competitor puts in 10k cash into the pot, everyone weigh the same, scaled percentage the same on all 4 corners, and everyone run the same wheel/tire combo, (some spec tire) and we can run a professional road course or asphalt oval? Fastest lap time takes the pot? What yall think?

I already put up. I picked a guy who had no big luv for the coil over / rack conversion but had what I needed.....an open mind. He found that it made his Gen III conversion much easier all while increasing room, dropping nose weight and gaining adjustability.

Sorry if that isn't good enough for ya......BTW, maybe I missed it, but ya' got any pictures of your contributions to our hobby?

 

[NC Engine Builder]

I already put up. I picked a guy who had no big luv for the coil over / rack conversion but had what I needed.....an open mind. He found that it made his Gen III conversion much easier all while increasing room, dropping nose weight and gaining adjustability.

Sorry if that isn't good enough for ya......BTW, maybe I missed it, but ya' got any pictures of your contributions to our hobby?

I allready mentioned your system has more room, so not sure your point. I gave you credit for what your system does, which is provide more room, give a guy a rack and pinion, and supply all new parts. And I have mentioned your welding is superior to the other systems. What my hangup is, simply, like THIS thread started with, is does your system out handle a torsion bar suspension? And my answer is no, I can go faster on the same tire and weight with my torsion bar suspension than you can with your coilover kit. I'm willing to prove it, in public. But you gotta pony up 10k cash, and agree to my simple terms. OR we can just agree to disagree, I dont care. I have no ill feelings against you personally, I'll still consider you a mopar freind regardless.

 

[junkyardhero]

BTW, maybe I missed it, but ya' got any pictures of your contributions to our hobby?