pretty aggressive.....guys that buy these hot rods do not care much about tire wear which is what you get with that amount of caster / camber.
DOES THE HDK SUSPENSION K-MEMBER HANDLE BETTER THAN A T-BAR SUSPENSION?
- Thread starter racerjoe
- Start date
-
pretty aggressive.....guys that buy these hot rods do not care much about tire wear which is what you get with that amount of caster / camber.
come on....if you are going to say I said it, then post my quote and where / when.....don't quote someone else and pin it to me. the BS bus is back in gear.
DionR
Well-Known Member
Yes, my thoughts. There is the quote from something you said though.
DionR
Well-Known Member
There might be other places. The specifics of the conversation was I asked you to post your geometry data and you said:
BTW, I was wrong that it was in this thread. My memory failed me.
where do you think Tim got the idea to trim the K to move the LCA slightly forward for greater caster?....any good guesses?
which BTW, did NOT effect roll center what-so-ever.
Tim did tell me he wanted to work on changing the roll center by changing out the lower ball joints which I advised him against (elaborated in an earlier post).
I know what I am talking about, I was the one who made the initial call to Tim once I examined and tested the replacement tie rod end.....ask him.
???????????? so where do I EVER claim better geometry or handling ? actually it is the opposite
I have always and will continue to stand by the claim HDK has the ability along with other benefits (like room) for more aggressive alignment over OEM and to do things my competitors cannot. Longer shocks, narrower track width, better feel with the tie rod end vs heim joint.
All facts....your posts are nothing but your versions of he said / she said
I think your HDKDS has gotten the better of you.
JBrian
Well-Known Member
So let me get this straight. HDK has zero advantages over torsionbars, the geometry is terrible, Tim Talbot, completely redesigned the kit because Denny didn't know what he was doing. Even with that, there is no advantage to this system even thought Tim street drives it 50 miles to and from his local autocross venue, races, comes home and then wins Grand Champion Vintage beating a Speedtech equipped car with 315s square, runs 12.29 @ 115MPH in the 1/4. But it's all juke, got it. I could watch CNN for this crap, but I don't
DionR
Well-Known Member
I quoted you. Those are your words.
You can see where you posted that by clicking the little arrow next to your name.
See the above text where I made them bold and italics? That's called emphasizing.
If you click on the "click to expand" text at the bottom of the quote, guess what you will see.
Oh look, emphasized text. That you wrote.
No idea what tangent your rant started on. I quoted you and didn't even say anything about you claiming anything.
Last edited:
DionR
Well-Known Member
That's a pretty twisted straight line.
Never said an HDK didn't have it's advantages. I'm not going to rehash the pluses nor minus of both systems again, read the whole thread, not just a couple of posts that you don't like. They all have minuses and if you can't acknowledge that then you are working from emotion and are not rational.
Geometry is an unknown. So far we have some info from Tim that to start with, the geometry was terrible as the RC was underground. Tim improved it, no argument. Frankly, my idea of what good geometry is in flux, and he might have good geometry now. But he didn't start there.
I could quote Denny again where he said he didn't build the suspension for handling, but I won't. And yeah, whether it was Tim redesigning it, or Tim working with Denny to redesign it, in the end it isn't the same kit as before. Sure, some of that was do to a supplier, but without Tim it would have still been a kit with a RC in the ground. Not saying Denny did nothing, but until Tim was working with one it was pretty static.
The thing to acknowledge in the above statement is, it was a savvy move by Denny to get Tim involved. Per Denny's own words, he doesn't have the time, so why not involve someone who has shown the motivation to make stuff better. But Denny has also said that handling isn't his deal, so yeah, I think Tim was a big player in making it better.
Tim must have only beaten David in the drag race since he lost to him in the AutoX and the 3S. And no, I didn't ask Tim who beat him in the 3S to see if it was David, I figured he was 4th overall and the 3 ahead of him were late model cars with ABS.
Honestly working to keep this civil, not perfectly but trying. That's why I didn't respond when Denny called me an f'ing idiot, nor a railbird (other than pointing our it is a two way street). But this topic often is about defending our choices and that generally doesn't end with civil conversations regardless.
DionR
Well-Known Member
Here are the specs for a 2015 Challenger. People don't look at the base models really as hot rods and the people that buy them do care about tire wear.
DionR
Well-Known Member
So I should assume that Tim did nothing on his own? It was all you then?
Why caint we all just get along? LOL
Good grief this thread has been busy!
I wholeheartedly agree. What Tim did with his HDK was optimization, not redesigning. Some of the changes to the LCA mount and position may strike someone with a torsion bar set up as design, but, the HDK allows for easier movement there. It may be one of the only things that really differs in adjustability from the torsion bar set up. Of course, the fact that all of the HDK's are now that way because of a supplier change I mean, that's just luck then yeah? If the tie rod end change had a negative effect on roll center, then what?
And honestly, I think you're getting very close with your torsion bar set up. I know you're at the limit for lowering with your current set up, but I think that a set of QA1 tubular LCA's and slightly larger torsion bars would put you in a better spot than you are now. At some point the header flanges and inner fenders are limiting, that's pretty close to where I'm at. And that would be the same regardless of the type of suspension, that's just wheel height and available suspension travel.
This is not accurate. The reason behind that is changes in tire construction and design. You can run -1°+ of camber and 6.5°+ of caster and see absolutely zero tire wear issues because of those settings. I know because I do. I've run as much at -1.5° camber in the past, although that was about where I started to see camber wear. I'm at -1.2° now, and quite frankly now that my drive includes more mountain roads than freeways I'd be willing to bet I could probably get closer to -1.5° without seeing camber wear just because I spend more time with lateral loading than I used to.
I've also run as much as +8° of caster, I dialed that back because of the increased steering effort, but I probably ran that much for at least a year. Been a bit. Anyway, the two sets of tires I've been through in about 40k miles both ended up getting replaced because of rear tire wear anyway. I could give up some camber wear on the front and still have to change them out before the fronts were out of spec.
C'mon man.
The HDK (and other systems) get you a rack and pinion, header clearance, save some weight. We all know those are advantages. I mean the rack thing is really just feel, but if Denny's customers are willing to pay for it and they like it, well, here we are.
The out of the box geometry, or at least what has been shown, is not as good as a nearly stock torsion bar set up. Granted, we haven't even seen all of the geometry numbers still. It's not terrible, but, it's not better either. Tim used 2" extended ball joints to get to the point where the geometry he's shared was slightly better than a stock torsion bar suspension lowered only 1". And that's with the raised LCA pivot too. The static suspension alignment numbers are pretty much entirely down to the SPC UCA's, I've got similar static numbers.
Regardless, the geometry differences are still pretty minor. And as Tim showed, you can do a lot to tune suspension. But, that goes for torsion bars too, you can use extended ball joints, the same SPC UCA's as Tim, and play with the ride height to make the geometry what you want. Some of the geometry changes are arguable too as far as better/worse, some of that comes down to driver preference and car set up too. Look at Bill Reilly's article that has all the suspension data in it with the 73+ and FMJ spindles. The FMJ spindle swap slightly increases bump steer, which everyone knows is bad right?But it also improves camber gain. The argument being that with wide front tires camber gain is more important than a slight change increase in bump steer (which remains within tolerable levels). Is it? I mean I run FMJ spindles and 275's and I don't have any perceptible bump steer issues, but maybe you just run more static camber and call it a day. Head to head you'd need professional drivers to even begin to cut margins fine enough to know that, and hell, it would be track dependent. A bumpy vs smooth track might change the results on that.
And that's what it really comes down to, all suspension design involves a trade off. Better at one thing usually means worse at another.
I wholeheartedly agree. What Tim did with his HDK was optimization, not redesigning. Some of the changes to the LCA mount and position may strike someone with a torsion bar set up as design, but, the HDK allows for easier movement there. It may be one of the only things that really differs in adjustability from the torsion bar set up. Of course, the fact that all of the HDK's are now that way because of a supplier change I mean, that's just luck then yeah? If the tie rod end change had a negative effect on roll center, then what?
And honestly, I think you're getting very close with your torsion bar set up. I know you're at the limit for lowering with your current set up, but I think that a set of QA1 tubular LCA's and slightly larger torsion bars would put you in a better spot than you are now. At some point the header flanges and inner fenders are limiting, that's pretty close to where I'm at. And that would be the same regardless of the type of suspension, that's just wheel height and available suspension travel.
This is not accurate. The reason behind that is changes in tire construction and design. You can run -1°+ of camber and 6.5°+ of caster and see absolutely zero tire wear issues because of those settings. I know because I do. I've run as much at -1.5° camber in the past, although that was about where I started to see camber wear. I'm at -1.2° now, and quite frankly now that my drive includes more mountain roads than freeways I'd be willing to bet I could probably get closer to -1.5° without seeing camber wear just because I spend more time with lateral loading than I used to.
I've also run as much as +8° of caster, I dialed that back because of the increased steering effort, but I probably ran that much for at least a year. Been a bit. Anyway, the two sets of tires I've been through in about 40k miles both ended up getting replaced because of rear tire wear anyway. I could give up some camber wear on the front and still have to change them out before the fronts were out of spec.
C'mon man.
The HDK (and other systems) get you a rack and pinion, header clearance, save some weight. We all know those are advantages. I mean the rack thing is really just feel, but if Denny's customers are willing to pay for it and they like it, well, here we are.
The out of the box geometry, or at least what has been shown, is not as good as a nearly stock torsion bar set up. Granted, we haven't even seen all of the geometry numbers still. It's not terrible, but, it's not better either. Tim used 2" extended ball joints to get to the point where the geometry he's shared was slightly better than a stock torsion bar suspension lowered only 1". And that's with the raised LCA pivot too. The static suspension alignment numbers are pretty much entirely down to the SPC UCA's, I've got similar static numbers.
Regardless, the geometry differences are still pretty minor. And as Tim showed, you can do a lot to tune suspension. But, that goes for torsion bars too, you can use extended ball joints, the same SPC UCA's as Tim, and play with the ride height to make the geometry what you want. Some of the geometry changes are arguable too as far as better/worse, some of that comes down to driver preference and car set up too. Look at Bill Reilly's article that has all the suspension data in it with the 73+ and FMJ spindles. The FMJ spindle swap slightly increases bump steer, which everyone knows is bad right?But it also improves camber gain. The argument being that with wide front tires camber gain is more important than a slight change increase in bump steer (which remains within tolerable levels). Is it? I mean I run FMJ spindles and 275's and I don't have any perceptible bump steer issues, but maybe you just run more static camber and call it a day. Head to head you'd need professional drivers to even begin to cut margins fine enough to know that, and hell, it would be track dependent. A bumpy vs smooth track might change the results on that.
And that's what it really comes down to, all suspension design involves a trade off. Better at one thing usually means worse at another.
Last edited:
on the tie rod end, you could call it luck. Amazing how persistence can turn into ....luck.
I'll leave you guys alone for a while and give you a break....I got a lot of stuff to build.
Denny
JBrian
Well-Known Member
First, I love your Duster Demon, it was an inspiration for my build. I think I said before Tim's car and my car are as close to a match for HDK coil over and torsion bar you will find. I also run the taller UBJ and the SPC fully adjustable UCA with a stock boxed LCA, Bilstein shocks the big Helwig sway bar made for 18" wheels. I'm sure Tim runs more spring in the front than my 1.08" bars. Our rear suspensions are also virtually the same. My car weighs more than Tim's because of the insulation and sound system. We also ran 114.95MPH, Tim to my 114.49MPH in the 1/4. The biggest difference is tires, I run 245/40-18x9 and 275/35-18x9.5 Falkin RT660s. This year Tim stepped up to 265/40-18x9.5 and 295/35-18x10.5 Bridgestone RE71s which has been the standard go to autocross tire for several years.
I remember when Tim called me and told me about essentially extending the wheelbase to get more caster by simply changing the spacers per a conversation with Denny. I called him a cheating bastard if I remember! He presented Denny with a question, and Denny had a very simple fix. We all run power steering, and the more caster we can tune in allows for quicker steering inputs thru a slalom. So Tim wanted big numbers. I'm currently at 5.5/5.6 caster. Pretty much the most I can run without hitting the back of the fender. So Tim runs a more aggressive alignment than I do, but I like driving my car during the summer, so I backed off the numbers a bit.
Anyway, the other big difference between our cars is the driver. I just started autocrossing in August of 2023 when my car was a handling mess until this year. So I'm getting better now so I hope to close the gap. But nothing in racing or life for that matter is static, but we'll see. I believe with a good driver, our cars would be very close on the autocross and 3S. Which is better? Flip a coin. I kind of like old school stuff, so torsion bars and external shift linkage with my 855 5-speed. It's not the smoothest, but if I want that, I can shift my Mazda6 manual with my fingers. We both autocross a lot. Of course the STL-SCCA has the most competitive CAM-T cars in the country, including the SCCA National Champion, so I always have a great yardstick to measure against. We also both drive our cars to the track and enjoy driving them. I wished this post hadn't turned into a **** show. HDK has it's place, and it proven. If you decide to go that way, know that the winner of MoParty 2025 has that system under his car and will be back next year to run again.
Last edited:
racerjoe
Well-Known Member
One thing I think a bunch of ya'll talking about my initial roll center being terrible is I chose to use the spindle I have due to the ability to run the beefy corvette hub. It's a standard height M2 spindle. At the time, my knowledge of suspension dynamics was lack luster. I didn't know a short spindle would be such a detriment. However, I stand by my choice because I like the hub vs. the old school bearing setup I would have gotten with the TALL Wilwood spindle. I do think that TALL spindle would have prevented some of my issues early on, but I was ignorant at that point in time. So what have I gained, besides a giant trophy? I've given myself an education on suspension dynamics because I was determined to find the right ADJUSTMENTS to make it the best performing suspension the car has ever had. Knowledge is king and you should never stop learning. I enjoy helping people when they come to me for advice. I wouldn't be able to help if I didn't have real world experiences and the knowledge gained over the last year.
I can't express how badly I want the naysayers to get their car on an autocross, wherever you live. See how you compare to the fast guys out there. It isn't easy in a new car let alone something that's 50 years old. And I would love it even more for them to come jump in the car at any of the events I do. You will be holding on to something and pressing a brake pedal that doesn't exist. I don't care how many hills or curvy roads you have near your home. You aren't driving your car like you will on an autocross. At best I'd say 5/10 on the street and you would only know this if you actually did it.
Oh I love the "I don't drive around traffic cones in a parking lot, I'm an oval track racer". Again, come on out. I bet you get lost on course. Many road racers and oval track racers have said autocross is more complex than big tracks. Sure you don't get the door to door adrenaline, but who cares. Things are happening so fast you wouldn't want a car next to you. It's also a known fact that autocrossers make better road course racers. But this is a whole different argument that I'm sure will go off the rails.
I can't express how badly I want the naysayers to get their car on an autocross, wherever you live. See how you compare to the fast guys out there. It isn't easy in a new car let alone something that's 50 years old. And I would love it even more for them to come jump in the car at any of the events I do. You will be holding on to something and pressing a brake pedal that doesn't exist. I don't care how many hills or curvy roads you have near your home. You aren't driving your car like you will on an autocross. At best I'd say 5/10 on the street and you would only know this if you actually did it.
Oh I love the "I don't drive around traffic cones in a parking lot, I'm an oval track racer". Again, come on out. I bet you get lost on course. Many road racers and oval track racers have said autocross is more complex than big tracks. Sure you don't get the door to door adrenaline, but who cares. Things are happening so fast you wouldn't want a car next to you. It's also a known fact that autocrossers make better road course racers. But this is a whole different argument that I'm sure will go off the rails.
DionR
Well-Known Member
FWIW, I would love to get on a AutoX course. I've looked, and if memory serves I couldn't even find one in Seattle.
I think Randy Pobst wrote an article saying that, too. And he is one of the top road course guys, so I won't argue with that assessment.
I was curious and going to text you but I'll just ask here
what is the height of the your spindle / distance at the ball joints
the Wilwood or Helix Touring measures 8-3 /16", the basic street rod version measures 7-11/16"
normally sent with 1" extended stud upper ball joints
Mattax
Just the facts, ma'am
Yes most most people don't and maybe can't appreciate the difference between spirited street driving and autocross, nor between highway driving and being on a road course or other closed track.
Fortunately at least a fair number of participants in this thread actually do have that experience and so do know. I'd say more than typical in these sort of threads.
As to your first point snipped above, I'll say my limited experience with autocrossing newer sports cars has been that in the last decade or two they have really made it easier to do well. It is harder to compete in the national classes available with an older car without some modification and body trimming. ESP, CP, and CAM-T are the choices in SCCA.
Looks like they are right across the narrows from Seattle.
Solo Event Schedule | nwr-scca
nwr-scca.org
Yes he did, although maybe not as an absolute, but rather as a general observation. It had to do with the need for precision, and perhaps the discipline to control the speed rather than seek the high speed.
DionR
Well-Known Member
Looks like they are right across the narrows from Seattle.
Solo Event Schedule | nwr-scca
Cool! I bow to your superior Google-fu.
NC Engine Builder
Grumpy Old Man
- Joined
- Oct 10, 2008
- Messages
- 7,244
- Reaction score
- 12,239
I wasn't even gonna respond to this, as its absolutely ridiculous, but, I AM a glutton for punishment. Are you REALLY trying to say that zipping around in a flat parking lot with no walls, and no other cars, is somehow comparable to door to door oval track racing? Tell me you have never driven a FAST car in competition without telling me. How fast do you guys go? 50? 60 mph? What's the worst that can happen with "things happening so fast" at that speed, you gonna run over a rubber cone? Sheesh man.
JBrian
Well-Known Member
You ought to ride in the current/last GEN Camaro 1LE with just stock sized RE71s! They will put every CAM-T Mopar on the trailer. We have two that are always top ten raw time cars. The engineering GM put into those cars is on a level we simply can't replicate with our old Mopars. And don't even dream of a modern Challenger getting close, ImpossibleYes most most people don't and maybe can't appreciate the difference between spirited street driving and autocross, nor between highway driving and being on a road course or other closed track.
Fortunately at least a fair number of participants in this thread actually do have that experience and so do know. I'd say more than typical in these sort of threads.
As to your first point snipped above, I'll say my limited experience with autocrossing newer sports cars has been that in the last decade or two they have really made it easier to do well. It is harder to compete in the national classes available with an older car without some modification and body trimming. ESP, CP, and CAM-T are the choices in SCCA.
Looks like they are right across the narrows from Seattle.
[/URL]
Yes he did, although maybe not as an absolute, but rather as a general observation. It had to do with the need for precision, and perhaps the discipline to control the speed rather than seek the high speed.
Mattax
Just the facts, ma'am
Actually never played in CAM. Wasn't interested for a number of reasons which are not of importance here. HS, CP, then Street Mod. Next will be ESP if /when I decide to go back. The cars I shared were not in those classes which off the top of my head were Porsche, early gen Miata, and older BMW. I rarely ride as a passenger other than for instructing or helping. There its mostly about the game and the course. If they are already using their car well there's not a lot for me to help. That's for Pat Salernos and Mike Johnsons.
The most fun I had with my car was on Street TDs, but they are not easy to maximize their potential or the quickest, at least for mortals.
Dartsun
Mopar Dude
They set up AutoX all over here In Oregon have a traveling club, even go up to Washington. Oregon SCCA
-
Similar threads
