hi looking for advice on parts or kits to put coil springs on my 67 barracuda to replace the torsion bars is QA1 the only answer? thanks
coil spring front
- Thread starter squidbob
- Start date
-
@HemiDenny produces the HDK coil over conversion, that's a good choice. He's a member here as well. HDK Front Suspension Parts For Mopars
There's also RMS with their AlterKation conversion, probably been going the longest and run by a lot of folks. Front Suspension
The QA1 suspension was based on Gerst's offering, which was really just a cheaper copy of the AlterKation. QA1 has no doubt fixed some of the issues that came up with the Gerst suspension, mostly broken welds on their uprights due to a less than great initial design.
Of course, there stands as always the question of what you're planning on doing with the car, because the torsion bar suspension with the proper upgrades can handle just as well, or better, than any of the coil over conversions. And for less money.
There's also RMS with their AlterKation conversion, probably been going the longest and run by a lot of folks. Front Suspension
The QA1 suspension was based on Gerst's offering, which was really just a cheaper copy of the AlterKation. QA1 has no doubt fixed some of the issues that came up with the Gerst suspension, mostly broken welds on their uprights due to a less than great initial design.
Of course, there stands as always the question of what you're planning on doing with the car, because the torsion bar suspension with the proper upgrades can handle just as well, or better, than any of the coil over conversions. And for less money.
No, that's not bullshit. There are multiple instances where coil-over converted Mopars have gone head to head with torsion bar equipped Mopars and lost on the AutoX track. Torsion bar Mopars have bested new 3 series BMW's on the same track, with the same driver, with the same tires.
The coilover conversions on the market are all modified MII suspensions. There's really nothing magic about a coil-over, it's just a spring and a shock. I've posted lists of parts MANY times showing that you can replace everything in the torsion bar system with brand new parts and have just as much or more adjustability than the coil over conversions for less money. If the OP would like I can do it here as well, but I know you've seen it before.
The bottom line is that all suspension designs have their pros and cons. Coil over systems are no different. They have some advantages compared to a torsion bar based system and they have some disadvantages. But with any coil over conversion you have the challenge of placing the suspension loads on the chassis in a place where the chassis was not designed to handle those suspension loads. Torsion bar cars were designed to carry all the suspension loads in the K member and the torsion bar crossmember. Not on the front rails where coil over conversions place them. And that's not just an issue at the mounting points, that's an issue with how the frame rails are attached to the rest of the chassis.
It really depends on how the OP plans on using his car, for some applications (engine swaps, for example) a coil over conversion will have some nice features. But they're not some magic fix all, and like any aftermarket parts you have to consider what other modifications are necessary to make them work their best (like reinforcing the chassis to brace the frame rails to the cowl/body). And just like any suspension system they need to be tuned to fit the application, and better tuning is more important than the kind of spring you have.
But if you would like to provide the suspension geometry plots to show why a modified MII suspension is so much better than a modified torsion bar suspension I'd love to see them.
No sir, all true and I have the evidence. You're the one swearing and stomping your feet, perhaps you'd like to back up your claims? Here's the evidence for everything I said-
Look at the Hotchkis Taxi. They did a tire comparison on the TireRack track, using the TireRack test driver. He put down faster lap times with that 4-door B body than he puts down with a 3-series BMW that he drives for a living testing tires. Same track, same driver, same tires, 4 door B-body vs modern 3 series BMW, with a driver that has way more hours in that BMW and has by his own admission not driven older pro-touring style cars. I think that says a lot about what these cars can do with their torsion bars.
Here's the video, it's little long. You can pretty much just start at the 3minute mark. At 4:30 you can watch the Hotchkis Taxi kicking butt. And at 6:00 min TireRack's professional driver goes into how the Hotckis Taxi is a full second a lap faster than the BMW 3 series, even though Woody (tirerack's driver) had never driven a "protouring set up car" before the test and has probably turned thousands of laps with that 3 series.
Here's a fully RMS suspended Duster losing in every category to the same Hotchkis Taxi. That's right, a fully RMS suspended Duster getting beat around the track by a torsion bar suspended, 4 door B-body. Physics alone should give it to the Duster just on weight and size, but that's not what happened.
2013 Muscle Car of the Year - Popular Hot Rodding Magazine
The head to head for those that don't like to do all the reading
Hotchkis Challenger vs a 2010 SRT8 Challenger. The SRT8 lost on the skid pad to the Hotchkis Challenger, yup, torsion bar E-body.
2010 Dodge Challenger SRT-8 vs. 1970 Dodge Challenger
Another torsion bar E-body Challenger, winning SCCA and Moparty and other AutoX events.
’70 Challenger On Factory-Style Suspension is an Autocross Warrior
Won the vintage class at Moparty 2022
2022 Holley MoParty Presented By eBay Motors: Results And Awards
Again, for the OP, please do whatever you like. The HDK, RMS, and even QA1 systems are good ones. I don't know your build plans or how you plan on using the car, so really I can't say one way or another what's "best" for you. Coil over replacement systems have their advantages, but they also have their disadvantages compared to a modified torsion bar set up. You can usually save some money with a completely modified torsion bar suspension compared to any of the full coil over conversions, but it does depend on your plans. My point is just that if you want a great handling Mopar, you don't NEED a coil over conversion. If you just need to have a rack and pinion, well, that's the way to do it. All I'm trying to do is put all the information out there.
I don't have a stake in the dick measuring contest but do your own research. You have the same internet we do. The stock Mopar suspension has done everything from winning NASCAR to winning NHRA and everything in between. Be careful what you call an "upgrade" because it might not be. Just do your research.
Dartsun
Mopar Dude
Coil over suspension will give you more room for some headers. I haven’t seen any posts about the Gerst suspension welds failing.
They're out there. This is supposedly from a B-body page. Not my post, haven't personally verified it but it seems legit. Also seems like a bad place to put a weld, so it makes sense too. QA1 has in fact redesigned that area too, so it shouldn't be an issue with the QA1 version of that suspension, just the Gerst.
And yes, the header thing is true, but what headers are you going to run? Unless you plan to go significantly larger than the TTI or Doug's headers that are available that do fit with torsion bars there really isn't much of a point, and those headers will support some serious horsepower. For an engine swap application the header thing makes more sense, although there are also GIII headers out there to clear torsion bars. Yes, the Doug's and TTI's are expensive, but so is everything else worth having.
The only thing you really can't get any other way is a rack and pinion, and if that's a "must have" for you then a coilover conversion is really the only way to get there with streetable steering geometry. Personally I don't get it, especially with new steering boxes and the Borgeson power steering units out there. But that's just my opinion, and others are free to disagree. A rack and pinion is not a "must have" for me.
Pick your parts, spend your money. I'm just trying to put the information out there so people can make an informed decision about what it is that they're actually after when they write that big check to convert their suspension over. Just because it all came out of one box and bolts on does not mean that it's the best choice for every application.
the car will be used for street and strip im looking at getting rid of the bars for hedder clearance
Ok, well in that case I would look into the HDK or RMS. Denny should know what headers will work with his system depending on what you’re running for an engine. RMS should as well.
Nothing against the QA1 system either, they’re just the least proven at this point. QA1 in general makes nice stuff.
Rat Bastid
Dunamis Metron
What headers are you planning on running that clearance is an issue?
I ask because I use 1 7/8 tubes. Once they are on they fit better than almost every other header.
Unless you are building custom headers the extra room you are looking for may not matter.
" will be used for street and strip im looking at getting rid of the bars for hedder clearance" and THIS makes all the difference in the world when it comes to the best answer. So many times I see these threads and somebody has to ask "what is the intended usage and expectations" and/or "how much do you want to change your car from stock" whether for looks or historic or monetary value.
I have to admit though, as soon as I saw this thread title I thought somebody might be intentionally trying to elicit an answer from 72 in order to get OldMan going again.
I was all but ready to order the complete RMS system, & I still really like what Bill is doing, but I'm glad I saw that video back then
This is the part that sold me on the validity - the TireRack track, using the TireRack test driver, - faster lap times with that 4-door B body than with a 3-series BMW that he drives for a living (on that very track no less)
It would be a different story if it was a guy that had been putting (a lot) of laps strictly in a mopar up against somebody in a BMW, but those facts above are huge. Not that a 3 series is the end all be all, but it is a pretty high bar compared to a 50+ year old domestic car that was never intended to be a sports car.
I have to admit though, as soon as I saw this thread title I thought somebody might be intentionally trying to elicit an answer from 72 in order to get OldMan going again.
I was all but ready to order the complete RMS system, & I still really like what Bill is doing, but I'm glad I saw that video back then
This is the part that sold me on the validity - the TireRack track, using the TireRack test driver, - faster lap times with that 4-door B body than with a 3-series BMW that he drives for a living (on that very track no less)
It would be a different story if it was a guy that had been putting (a lot) of laps strictly in a mopar up against somebody in a BMW, but those facts above are huge. Not that a 3 series is the end all be all, but it is a pretty high bar compared to a 50+ year old domestic car that was never intended to be a sports car.
Last edited:
mopowers
Well-Known Member
If all you're trying to do is eliminate the torsion bars for header clearance, you don't need to convert to a full rack and pinion front end. I believe Hemi Denny sells the parts to swap over to coilovers using your stock steering box and linkage. Alternatively, you can simply buy a set of tubular upper control arms and modify your stock lower control arms to run coil overs. Lastly, you'd have to tie the shock tower into a snout bar, or the front frame rail somehow as the shock towers were not engineered to support the full weight of the front end of the car.
Also, be careful with some of the upper coilover mounts being sold. They require the use of a very short shock/spring package and could severely limit front end travel.
HDK Single Lower Control Arm Torsion Bar Eliminator kit
Sorry, late to the party.
advantages of the HDK single chromoly tube LCA assembly are.....
a) eliminates the sloppy OEM torsion bar mechanism
b) utilizes a new (supplied) HDK thru lower pivot shaft to allow for a 100% bolt on double sheer rear support of the LCA
c) re-positions the coil over shock / spring mount slightly outward for spring to frame clearance.
the HDK upper shock mount / chromoly support hoop which has been used for over 20 years (with zero failures) also re-position the coil over shock / spring slightly further outward for coil spring clearance
combine the HDK chromoly tubular UCA assemblies (supplied but not pictured in the above link) and easily achieve up to 6 degrees positive caster without putting the UCA in any kind of a bind.
UCAs are available for all three widely used A body spindles....both drum and disc small upper ball joint found on most pre 72 A body's and the later larger upper ball joint model.
Thanks for looking,
Denny
HDK
304-939-0097
hemidenny@rocketmail.com
Sorry, late to the party.
advantages of the HDK single chromoly tube LCA assembly are.....
a) eliminates the sloppy OEM torsion bar mechanism
b) utilizes a new (supplied) HDK thru lower pivot shaft to allow for a 100% bolt on double sheer rear support of the LCA
c) re-positions the coil over shock / spring mount slightly outward for spring to frame clearance.
the HDK upper shock mount / chromoly support hoop which has been used for over 20 years (with zero failures) also re-position the coil over shock / spring slightly further outward for coil spring clearance
combine the HDK chromoly tubular UCA assemblies (supplied but not pictured in the above link) and easily achieve up to 6 degrees positive caster without putting the UCA in any kind of a bind.
UCAs are available for all three widely used A body spindles....both drum and disc small upper ball joint found on most pre 72 A body's and the later larger upper ball joint model.
Thanks for looking,
Denny
HDK
304-939-0097
hemidenny@rocketmail.com
You can tighten up the “sloppy” torsion bar mechanism pretty easily if you box the factory LCA’s. @Jim Lusk ’s video shows how he removes the slop when he rebuilds the LCA’s using readily available boxing plates. Tubular QA1 LCA’s also solve that issue.
I’ve run as much as +8° caster with tubular UCA’s without any binding, and currently run +6.5° with my SPC adjustable UCA’s from @BergmanAutoCraft with plenty of adjustment to spare. So significant amounts of positive caster can also be achieved with a torsion bar system with the right parts.
No argument from me on the rest of it, like I said before, pros and cons to both systems and your HDK is a fine system that is well proven. Not much you can do about header clearance with the torsion bar set up!
That’s not entirely accurate. We all know that there have been LCA pivot tube failures, as well as cracked welds and mounts with the factory K’s. Heck the steering box mount on the V8 K I swapped into my Duster was cracked in two different places, allowing the steering box to move around when the steering wheel was turned back and forth.
Of course, those are issues you can fix by seam welding and reinforcing the stock K frame, which you can do for a lot less than a coil over conversion if you’ve got even amateur welding skills. I fully seam welded and reinforced mine with an old Millermatic 15, some 1/8” plate stock and some cardboard patterns.
And of course there are tubular replacement K frames for the torsion bar system too.
I should have been more clear.
You remember all those catastrophic weld failures in factory K members that resulted in wrecked cars?
Me neither.
You remember all those catastrophic weld failures in factory K members that resulted in wrecked cars?
Me neither.
I should have been more clear. I was not attempting to knock the OEM or a modified / aftermarket version of it. My response was meant mainly to point out the advantages of the HDK chromoly single down tube LCA assembly along with their components for anyone thinking about converting or modifying the OEM lower control arms for a coil over application.
mopowers
Well-Known Member
Can you post a photo of the double shear mount? The photo link from the link you posted is broken. Maybe it's just my computer??
True, but I haven’t heard of any catastrophic failures of HDK’s or RMS K’s or their suspension components either.
I have heard of failures of CAP K frames (now long out of business), as well as Magnumforce (redesigned since then) and most recently Gerst. Not saying I’ve heard of all the failures out there or even all the manufacturers.
And I’m sure we’ve all seen upper ball joints pop out of the factory UCA’s when they strip their threads. Factory parts fail too.
My point is just that I wouldn’t (and don’t!) always side with factory components, just like I wouldn’t blindly support any given aftermarket component without looking into the history and application. I wouldn’t worry about an HDK or RMS suspension any more than my torsion bar suspension with almost entirely aftermarket parts.
It just comes down to knowing what you want to do, how you’re going to use the car, and doing some research on the parts you want to use. Not every part or suspension system is right for every car.
Nah you’re not wrong, there’s a bunch of places in the OE suspension where there can be slop. My point was only that there are ways to fix it without a complete coil over conversion.
But, if someone really wants a coil over conversion that’s ok too. As I’ve said a bunch of times, I think you make a great product. I think a lot of people buy it for the wrong reasons and with the wrong expectations, but that’s a lack of knowledge on their part, not yours.
I will say you do a great job of education. If I ever have a question on the OEM stuff, you are the west coast professor..... along with Peter who handles the east coast.
it is broken and the web people want $1500 to fix it (click, click) along with a greater yearly fee to maintain it.
view from the bottom up. In typical HDK fashion, please notice how the brackets are tabbed and slotted for ease of install (and almost dummy proof)
HDK By far would be my choice. My first choice was HDK. Then I bought a race car to save some dollars with a AJE race only light weight suspension for the Demon. It is very light duty and I would not recommend it for the street at all. If I had to chose again I would not have bought the car with the AJE suspension in it.
mopowers
Well-Known Member
That looks beefy. Very similar to what I did on mine with the stock arms. Do you have any photos of the pivot side of the LCA?
Very slick design, I like it.
mopowers
Well-Known Member
Yes, thank you.
-
