I'm confused on your comments here. Are you saying the QA1 arms don't add caster? It clearly says on their web site that they add about 3 degrees of caster.
DOES THE HDK SUSPENSION K-MEMBER HANDLE BETTER THAN A T-BAR SUSPENSION?
- Thread starter racerjoe
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I know YOU would not, I was giving a complete hypothetical.
The pic
it appears I am not up to date and if they do now, good on them.
They've always had +3° built in. Their UCA design has not changed since they went on the market. QA1 bought out CAP, and while QA1 substantially changed the UCA design from CAP's before returning it to the market, even CAP was building in +3° of caster. Had a set on my Challenger, was running +5.5° of caster on it.
In fact, I'm not aware of any tubular UCA for the A-body (or B/E for that matter) that doesn't have some amount of additional caster built in. That's always been one of the marketing points for tubular UCA's.
I have a set I took off a build and never noticed the receiver difference, just assumed that because the customer told me he (or whoever was doing his work) was unable to get any more than 3 degrees they were to OEM specs.
HDK takes a different approach with 1/4" and 1/2" spacers on the ends to maximize the ability to relocate the ball joint receiver. picture is with 1/4" spacers on each side of the poly end which when installed produces 4.5 degrees, Using the (provided) 1/2" spacers on the rear of the poly end produces 3 degrees, on the front side, 6 degrees, keeping the eccentric adjuster in the middle range.
Feel free to put me down for a correction.
No worries, I've seen at least one member here have issues getting past +3° of caster with the QA1's as well. But I suspect that's a factory tolerance/individual suspension/car set up issue. As in, with the factory arms they'd never get positive caster and need the +3° just to get out of jail.
Having run a couple different tubular UCA designs between my Challenger and Duster, I have to say I'm putting double adjustable UCA's on everything I plan on keeping from here on out. It's just so much easier to dial in the alignments.
Mopar_Taxi_Guy
Well-Known Member
Can someone please show me where it has ever been proven that any of the coil over kits offer "better" handling over an optimized torsion bar setup?
I've looked over a bunch of lap times from various events of Mopar people that have converted to coil over setups from torsion bars and from the coil over setups to the fairly new Mopar Speedtech parts and the lap times don't show any improvement in lap times.
I've looked over a bunch of lap times from various events of Mopar people that have converted to coil over setups from torsion bars and from the coil over setups to the fairly new Mopar Speedtech parts and the lap times don't show any improvement in lap times.
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that my friend.....could be a tuffy. If desired alignment specs can be achieved with either set up, how could one prove one is better than the other?
however....
apples to apples, manual steer to manual steer, the HDK coil over package is 30lbs lighter than the OEM equivalent. a power rack and pinion vs power steering box offers even more weight reduction. Less front end weight could be considered a "handling advantage"
with a rack and pinion (even power) the engine / driveline is often lowered in the cradle. Lowering the center of gravity could be considered a "handling advantage"
HDK offers the ability to move the track width inward / outward. Not even considering that adjustment may allow wider tires, a wider track width could be considered a "handling
advantage.
if you work on the your car, or are attempting to stuff a physically much larger power plant in, the absence of a steering box, drag link, steering arm , idler /pitman arm and torsion bars, especially the larger ones, while it likely would not be considered a handling advantage.......sure makes it a lot easier to work on.
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Lol!
Says the guy whose car is literally the one that's repeatedly bested coil over converted Mopars. And 3-series Beemers on the same track with the same driver.
Them:
"Better handling! Superior geometry!"
Hotchkis Tax: *exists*
Them:
Looses mightily to a 4 door B body with torsion bars, a big block and power steering
Uh, well the faster lap times he asked about would be a step in the right direction. Some event wins over proven torsion bar competitors?
Geometry maps can show improved geometry, but unless the geometry is dramatically better even that doesn't necessarily mean the car handles better overall.
Calling a ~30 lb weight loss a "handling advantage" is a bit of a stretch. I mean, sure it might help but so can a relocated battery. Or aluminum heads. Or putting the driver on a diet. Have we scaled all the torsion bar cars that were faster than coil over converted cars? Were they lighter or heavier? I mean, if a fully RMS equipped Duster loses to a 4 door B-body I don't think the 30 lbs off the front helped much. Especially since that B-body had factory power steering, just on steering it was a lot more than 30lbs heavier.
Have you calculated and compared the CG to a torsion bar car with the same engine? The engine goes lower, the spring go higher, and a lot of that would depend on the engine choice and components.
How much wider can the HDK go from a factory 73+ disk brake track? I mean, the hub to hub on my Duster is about 61 1/4" by the math. My track is about 58.5", that being the c-c of my 275/35/18's. Going narrower can absolutely hurt suspension geometry. Going wider can improve it, but, you have to fit the wheels in the fenders still. My 18x9's are at a +35 offset already, and I rolled my fenders to clear those. So you're gonna run +45 offsets up front? More?
As for fitting more tire, well, not really. With the torsion bar set up if you commit to 18" diameter wheels and run a "V" shaped UCA none of the suspension clearance is an issue anymore. It's frame rails and fenders. At that point, changing the hub to hub on the suspension only changes the offset you need to fit the wheel in the well. I've been told with the coil over conversions 17's will fit with a large backspace where on a torsion bar set up 17" and smaller diameters are tie rod clearance limited, but honestly for any of these road or autoX competitions the 18" wheels have better tire options anyway.
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DionR
Well-Known Member
There is so much more to handling than alignment. I would have thought you would have picked up on some of this over the last year plus of talking about handling. Two cars that have the exact same alignment can have radically different characteristics on a road course or autocross. One could plow in the corner with the outside tire rolled under and be a real handful to try and keep on line. The other could go right where you want it to go with little no drama or body roll and be an absolute joy to drive. Geometry is what influences that, which is why we keep talking about it.
This is like saying "my 318 has the same ignition timing as your G2 Hemi, so they make the same power and it would be hard to prove otherwise".
And lap times are a great way to get an idea of how a setup handles much like a drag strip proves power.
Maybe this will help.
DionR
Well-Known Member
Which is why putting the same guy in both cars is the better test. Like Tire Rack did with the Mopar Taxi and a 3 series BMW.
But it's a straw man answer, in my book.
so....you don't think lowering the center of gravity and 30lbs off the nose helps "handling" ? Ok, but I believe you just confirmed to me a severe case of CODS (coil over derangement syndrome)
TT5.9mag
Two atmospheres are better than one
I would say it “can” help handling but it’s not a given.
TT5.9mag
Two atmospheres are better than one
On our Miata we move weight all over the place depending on track conditions, what tire we’re using and what combination of sway bars we’re currently using.
Edited to add; also which driver is in the car makes a difference there’s two fat and one thin driver. Lol
Edited to add; also which driver is in the car makes a difference there’s two fat and one thin driver. Lol
NC Engine Builder
Grumpy Old Man
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I think anyone with the ability to think rationally from the data provided, can conclude, NO the hdk does not handle better than a torsion bar suspension. There are ACTUAL REAL WORLD TRACK TESTS to prove this!
A driver can't make the car faster than it is. Only slower.
So if coil over converted Mopars are faster, well, all of their drivers are a lot slower.
My favorite part of that video is when Woody says he's never driven a pro-touring muscle car before. So, dude that's never driven a pro-touring muscle car uses a big block, 4 door B-body to go faster than he does in the 3 series Beemers he drives for a living.
First, you haven't shown that your HDK actually lowers the CG. You claimed that and provided no evidence. If it lowers the CG let's see your evidence.
Second, sure, losing 30lbs off the nose can help handling. But that's a small change and easily replicated by doing other things (like the battery relocation I mentioned, plus many others).
And yeah, what's the weight difference from the Hotchkis taxi, a big block B-body 4 door with factory power steering to the coil over converted A-bodies it's put down faster laps than? Bet it's more than 30lbs heavier on the nose, still faster.
A well set up car does help but can you explain to me how one (professional race car driver ) loves a set-up and while another of the same caliper gets in the car only to remark...."I don't how you drive that thing?
and how about two cars built side by side to be identical and one is a rocket and the other a turd?.....it happens more than you think.
Still, it's hard to claim you've got the fastest car if you've never won a race.
DionR
Well-Known Member
Hmm...either BMW or maybe Denny complained about the Mopar beating the BMW because the video that actually shows it is now private and the one I posted only shows results for the tires they tested on the Taxi.
DionR
Well-Known Member
No argument, driving style has a big impact. But I would argue that there is a third car that neither driver could be fast in.
hm. a schrodinger's taxi then?
TT5.9mag
Two atmospheres are better than one
Stop being all rational and logical all the time.
If nothing else, the new tubular stuff looks cool.
If that is all you care about, feel free to make the change.
If that is all you care about, feel free to make the change.
I have several mount variables that drop the engine anywhere from 1/2" to 3/4" Fact is, almost impossible to accomplish with the OEM steering components to contend with. Maybe in your world that does not count as lowering the COG, but in mine it not only lowers the COG, but affords needed tunnel clearance for larger transmissions.
weight reduction calculations were apples to apples......HDK manual steer / no sway bar / no brakes w/ coil over package vs OEM manual steer/ no sway / no brakes w/ torsion bar. As fair a comparison I could make.....29.8 lbs if memory serves. All the other BS you threw out there could be done on either set up.
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