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

[NC Engine Builder]

And one distinct advantage of the torsion bar suspension over a coilover, or even a GM coil spring chassis for that matter, that I never see mentioned is unsprung weight. I found when I was competitively racing these cars, that the rougher the racetrack, the bigger advantage I had over the GM cars, and I think that's ties to unsprung weight, and to some degree, the way the suspension load is transferred to the chassis, low, and at the transmission crossmember. I had other competitors complain that there Camaro would get upset through a certain rough section of the track, and they couldn't understand why my dodge was "smooth" through the same section

 

[fishmens67]

Let's not forget b-bodies were no slouch in the handling department as came from the factory.
My old man drove his 68 Fury VIP with recaps like it was on rails on the twisty Idaho mountain roads, scared the **** out of me more than once. lol

 

[Mattax]

And one distinct advantage of the torsion bar suspension over a coilover, or even a GM coil spring chassis for that matter, that I never see mentioned is unsprung weight.

Might be mentioned in one or more of the classic books discussing the various systems (Puhn, Adams, Smith) as well as Mike Martin's book. Closely related and definately mentioned is the lower spring rate needed to get the same wheel rate as a coil spring.

 

[fishmens67]

The old spiral highway in Lewiston, Idaho is our test, down the grade and up the grade. lol

 

[junkyardhero]

Ok, here's what I'm getting at.

I think the "taxi" is much more than a "slapped together' build that anyone could do and get the same level of performance that Hoschkis got out of that Satellite.

The guys on here who constantly change and modify stock Mopar suspensions are certainly included in the group of experts I'm referring to , the OP, Denny, 72' , to name a few that can pull off this kind of performance.

This is not an "average joe' build by any means.

By any chance is there any video/information/pics of the build of the "Taxi" ?

That would be great to see.

as i recall there's nothing "trick" on that car. you could literally order up everything and then some online and recreate that magic on an a-body with basic hobbyist tools in a two car garage over a long weekend.

as mention above by @Mattax if you had even a skim thru the Mike Martin book, read a little here and have a passing knowledge of how it all works you could come up with something fairly formidable on the first try. it's not like there's some black magic secret voodoo to it. although i do keep a Santeria priestess on staff... but that's mostly for other reasons.

 

[HemiDenny]

From HPP.....

Do any of us need a coil over system?


Does anyone know why the aftermarket rack and pinion conversions almost exclusively utilize coil-overs?

 

[Kern Dog]

Uhhh…. Because it is the easiest to fabricate?
Boinking my slutty cousin is easy too but certainly not the best way to go.
Easiest does not guarantee the best end results.

 

[NC Engine Builder]

From HPP.....

Do any of us need a coil over system?


Does anyone know why the aftermarket rack and pinion conversions almost exclusively utilize coil-overs?

I dunno, the mustang 2 suspension your spindles are based on were not coilover in original configuration.

 

[Super-Cuda]

as i recall there's nothing "trick" on that car. you could literally order up everything and then some online and recreate that magic on an a-body with basic hobbyist tools in a two car garage over a long weekend.

as mention above by @Mattax if you had even a skim thru the Mike Martin book, read a little here and have a passing knowledge of how it all works you could come up with something fairly formidable on the first try. it's not like there's some black magic secret voodoo to it. although i do keep a Santeria priestess on staff... but that's mostly for other reasons.

I get that you can order parts and put them on a car , even vastly improve it.

Getting back to the "Taxi" though, I think its at another level.

Example.

Lets take NC Engine builder whom I guess by his handle, builds engines for a living.


Give him all the parts to assemble a Magnum 408 stroker engine.

Now, give all the same parts to a Hobbyist.

NC will build the better engine with more power at least 90% of the time because he's more experienced, knows all the power and tuning tricks and, has done this so many times , he knows the weak and power losing areas of the build.

I think the Taxi is at the level it is because of this type of experience and knowledge supplied by Hoschkiss and the other suppliers who helped build this exceptional car.

 

[Super-Cuda]

From HPP.....

Do any of us need a coil over system?


Does anyone know why the aftermarket rack and pinion conversions almost exclusively utilize coil-overs?

No.

But as I asked before, who do you know that switched their car back to a torsion bar based suspension after installing a RMS or HDK system?

 

[junkyardhero]

I get that you can order parts and put them on a car , even vastly improve it.

Getting back to the "Taxi" though, I think its at another level.

Example.

Lets take NC Engine builder whom I guess by his handle, builds engines for a living.


Give him all the parts to assemble a Magnum 408 stroker engine.

Now, give all the same parts to a Hobbyist.

NC will build the better engine with more power at least 90% of the time because he's more experienced, knows all the power and tuning tricks and, has done this so many times , he knows the weak and power losing areas of the build.

I think the Taxi is at the level it is because of this type of experience and knowledge supplied by Hoschkiss and the other suppliers who helped build this exceptional car.

while massaging the finer points will certainly make for a better end result, there's nothing there that can't be replicated with a little attention to detail and the faintest knowledge of suspension.

unless they moved mounts, altered pick up points or modified the components in some way there's no proprietary information lurking in there that isn't already common knowledge and implemented on other cars out in the field.

so i fail to see that comparison in this instance.

 

[HemiDenny]

From HPP.....

Do any of us need a coil over system?


Does anyone know why the aftermarket rack and pinion conversions almost exclusively utilize coil-overs?

the simple answer is because the rack location will not allow the OEM LCA pivot points, and since the torsion bars seat into the lower control arms at those pivot points, we need another way to hold up the car....like a coil spring.

I do not think a coil spring is any better than a torsion bar at all, two of my three hot rods still have them. Actually I find them much easier to adjust ride height.....their downside is for rack and pinion conversions, next to impossible to economically utilize. My first rack conversion (around 1995?) in a Hemi / A body used torsion bars. To make the geometry work, I fashioned a drag link for the rack to move and to pivot the inner tie rods from. It worked..... somewhat. The solution was to re-enforced the OEM upper shock mount (like the race cars from the 70's) and use a coil spring to hold the car up. The HDK chromoly hoop and upper shock mount has done the job for over 20 years now.....ZERO defects or failures. I don't think the OEMs can boast a better record?

I cannot speak for the other manufactures because they use a different method and usually a shorter spring / shock combo, but I bet you could not tell the difference in a street ride or Auto -X ride if you were on HDK coils or torsion bars. Please note, in this segment, I am discussing what is holding up the car.....not steering / spindle geometry.

in short, we don't run coils thinking there is ANY performance advantage, we just need a way to hold the car up. The FACT (I suppose some will want proof) that they increase exhaust / header room is an added bonus.

 

[Super-Cuda]

while massaging the finer points will certainly make for a better end result, there's nothing there that can't be replicated with a little attention to detail and the faintest knowledge of suspension.

unless they moved mounts, altered pick up points or modified the components in some way there's no proprietary information lurking in there that isn't already common knowledge and implemented on other cars out in the field.

so i fail to see that comparison in this instance.

I agree with most of this.

As I stated earlier, I would love to see some documentation of the build of that Satellite.

I have been around and involved with car builds since the late 70's and I have found that exceptional performance like that comes from a lot of experience in assembly and tuning.

 

[RustyRatRod]

Uhhh…. Because it is the easiest to fabricate?
Boinking my slutty cousin is easy too but certainly not the best way to go.
Easiest does not guarantee the best end results.

Is she hot? We need pictures.

 

[Kern Dog]

 

[RustyRatRod]

View attachment 1716447611

Hay Paco, you brought it up. lol

 

[fishmens67]

Is she hot? We need pictures.

He won't tell you, but she's over in the blue room.

 

[racerjoe]

Somehow I drug myself back into this thread but only skimmed through it. Ya'll have been busy. I wish I got paid for thread interaction so I could afford to buy another HDK. LOL just kidding, calm down. I have a few new comments.
I know the taxi has been used for reference many times about how it beat BMWs. I never actually paid attention or watched the video. Now that I have some autocross laps under my belt, I've learned that some courses cater to high HP cars while others cater to the more nimble small cars. So as this topic was brought up again, I immediately wonder what engine it had so I watched the video. Then the "pro" driver even commented on the power. What would make him make such a statement if HP and Torque don't matter? So where's the proof that HP and torque make a difference on an autocross? Here's my proof. There's nearly 5 years of results from my local SCCA where I would be say within the top 10-15 on a HP course, then on the more technical without long straights or quick acceleration sections where I'm usually around 20th position. Clearly those saying HP and Torque doesn't matter on an autocross either doesn't autocross at all, or regularly to learn this. Another piece of proof, and likely more relevant. Justin Peachy is an incredible driver winning or at least on the podium of nearly every autocross he does. He's been running a corvette with a 700HPish LS all year. He hurt the motor so he threw in a 5.3 to run the King of the Mountain race this past weekend. He finished 16th in his class and didn't qualify for the shootout. He was mentioning not enough HP all weekend on his social media. HP and Torque 100% matters on the autocross.

As far as pointing out where a coil over car beat a T-bar car... David Kruk with a QA1 setup on a 70 Superbee had the fastest autocross time at Moparty last year. Followed by two torsion bar cars, then me in 4th. There were 16 cars in the vintage class. I was .7 seconds from the second place car who was running 295s square A052s (top tier 200TW tires for those that don't know). I had a 235 Falken tire (likely about #4 200TW tire out there) on the front at that time. Moparty is in 2 weeks. Lots of people have made changes to their cars, including myself, so it's going to be fun to see how the chips fall this year. I'm not going there with the attitude that I'm going to win, but I am going with the attitude to have a ton of fun and hang out with my friends regardless of what suspension they run. I'll be driving the car hard and pushing it as far as my driving capability allows. Whoever is coming, bring a helmet and jump in for a ride. I don't care if you based me or my car, you will be impressed.

I know now that I've provided some real world data, ya'll will say the driver makes a difference now. Carry on...

 

[DionR]

1976 Dodge Dart Lite

I wish that Dart had gotten some use. Sounds like it had a clutch issue and got parked and who knows where it is now.

Cool build all the way around.

 

[DionR]

As far as pointing out where a coil over car beat a T-bar car... David Kruk with a QA1 setup on a 70 Superbee had the fastest autocross time at Moparty last year. Followed by two torsion bar cars, then me in 4th. There were 16 cars in the vintage class.

Did they ever post results from last year? I have looked and can't find them beyond the top winners. I figured because of the rain, they just gave up on finishing well and never went back and posted results.

And David stepped up his car a bunch with a full SpeedTech setup with 315/30R18's.

I'm not going there with the attitude that I'm going to win, but I am going with the attitude to have a ton of fun and hang out with my friends regardless of what suspension they run. I'll be driving the car hard and pushing it as far as my driving capability allows.

Best attitude to have.

It's a shame if you feel anyone has bashed your car. I don't remember anyone doing so, but I understand the feeling.

 

[TT5.9mag]

Santeria priestess on staff

Phone number please. And rate.

 

[DionR]

I know the taxi has been used for reference many times about how it beat BMWs. I never actually paid attention or watched the video. Now that I have some autocross laps under my belt, I've learned that some courses cater to high HP cars while others cater to the more nimble small cars. So as this topic was brought up again, I immediately wonder what engine it had so I watched the video. Then the "pro" driver even commented on the power. What would make him make such a statement if HP and Torque don't matter? So where's the proof that HP and torque make a difference on an autocross? Here's my proof. There's nearly 5 years of results from my local SCCA where I would be say within the top 10-15 on a HP course, then on the more technical without long straights or quick acceleration sections where I'm usually around 20th position. Clearly those saying HP and Torque doesn't matter on an autocross either doesn't autocross at all, or regularly to learn this. Another piece of proof, and likely more relevant. Justin Peachy is an incredible driver winning or at least on the podium of nearly every autocross he does. He's been running a corvette with a 700HPish LS all year. He hurt the motor so he threw in a 5.3 to run the King of the Mountain race this past weekend. He finished 16th in his class and didn't qualify for the shootout. He was mentioning not enough HP all weekend on his social media. HP and Torque 100% matters on the autocross.

To be clear, I wasn't saying I though HP didn't matter. My question was, on a tight course like that would it make up a second in time?

Running in a group where tenths and hundredths matter, absolutely it will have a huge effect. On a smaller course, certainly more HP is still better unless you can't put the power down. But is HP alone enough to shave a second off the lap time on a ~30 second lap?

And you have to admit, even if the comment about the BMW is hard to quantify, the comment in the article that the Taxi put down similar lap times to Woody's race prepped S2000 is pretty impressive.

The best thing about the Taxi vs. BMW test is that it was the same driver. Completely removes the question of driver skill. And yes he was impressed with ~500 HP after driving a ~240 HP BMW. But he was also impressed with the handling. He even commented on that before he said anything about the power.

 

[TT5.9mag]

Somehow I drug myself back into this thread but only skimmed through it. Ya'll have been busy. I wish I got paid for thread interaction so I could afford to buy another HDK. LOL just kidding, calm down. I have a few new comments.
I know the taxi has been used for reference many times about how it beat BMWs. I never actually paid attention or watched the video. Now that I have some autocross laps under my belt, I've learned that some courses cater to high HP cars while others cater to the more nimble small cars. So as this topic was brought up again, I immediately wonder what engine it had so I watched the video. Then the "pro" driver even commented on the power. What would make him make such a statement if HP and Torque don't matter? So where's the proof that HP and torque make a difference on an autocross? Here's my proof. There's nearly 5 years of results from my local SCCA where I would be say within the top 10-15 on a HP course, then on the more technical without long straights or quick acceleration sections where I'm usually around 20th position. Clearly those saying HP and Torque doesn't matter on an autocross either doesn't autocross at all, or regularly to learn this. Another piece of proof, and likely more relevant. Justin Peachy is an incredible driver winning or at least on the podium of nearly every autocross he does. He's been running a corvette with a 700HPish LS all year. He hurt the motor so he threw in a 5.3 to run the King of the Mountain race this past weekend. He finished 16th in his class and didn't qualify for the shootout. He was mentioning not enough HP all weekend on his social media. HP and Torque 100% matters on the autocross.

As far as pointing out where a coil over car beat a T-bar car... David Kruk with a QA1 setup on a 70 Superbee had the fastest autocross time at Moparty last year. Followed by two torsion bar cars, then me in 4th. There were 16 cars in the vintage class. I was .7 seconds from the second place car who was running 295s square A052s (top tier 200TW tires for those that don't know). I had a 235 Falken tire (likely about #4 200TW tire out there) on the front at that time. Moparty is in 2 weeks. Lots of people have made changes to their cars, including myself, so it's going to be fun to see how the chips fall this year. I'm not going there with the attitude that I'm going to win, but I am going with the attitude to have a ton of fun and hang out with my friends regardless of what suspension they run. I'll be driving the car hard and pushing it as far as my driving capability allows. Whoever is coming, bring a helmet and jump in for a ride. I don't care if you based me or my car, you will be impressed.

I know now that I've provided some real world data, ya'll will say the driver makes a difference now. Carry on...

You are literally the ONLY one doing a back to back comparison with a sorted tb car and a COC car. We’re counting on your data and results. Be safe have fun and keep the rubber side down. Oh one point, no one said power doesn’t matter. We said it’s not the only thing that matters. In fact I think my quote was “it isn’t all about power”. Your car doesn’t make 700hp right? And you took 4th?

 

[JBrian]

My HemiDuster and Tim's HemiDuster are as close a comparison of a torsion bar vs Coil over suspension as you can get. Time does have wider Bridgestone RE71s, the standard measure of all autocross tires. The BIGGEST difference between our cars is NOT the car, but the driver. Tim has more autocross experience than me, though in the past year I have gotten much more comfortable as I've finally dialed in my car.

So yeah, bring a helmet, ride with us and have some fun!

 

[JBrian]

Even with the same driver, if he's not used to a CAM-T car, he's likely not going to be able to take full advantage of it's capability. Last month, I let a very capable driver of a SRT 392 8-speed co-drive my car. My God, he had his hands full! These old cars are a true handful to drive without anti-lock brakes and slow steering. I figured he would be at least 1.5 seconds quicker than me. Instead, he was -.3. That was a surprise, but the reality of someone getting into a 50+ year old car.
Earlier this year, I had an instructor that was 6th overall in the country at SCCA Nationals in a Miata. He made one pass driving and it was enough! Too much power, slow steering, difficult brake modulation. These old car are difficult to drive quick on an autocross course. The quickest modern muscle car to autocross is a Camaro 1LE. They have tens or hundreds of millions of dollars of engineering and testing invested into them. Stock ones, with RE71s take down 95% of the CAM-T cars out there. We have a few in STL-SCCA driven by experienced drivers. Fortunity, one of those drivers is our main course designer, and he makes a fast, mean, safe course for us every month. For this alone, I am very lucky.