A-body Torsion Bars, How Big is Too Big?

My experience with fatty torsion bars is only on a B-Body. I put 1.12 Firmfeel bars on that car and had to completely backoff the adjusters to get a reasonably low ride height. The fact that there was no adjuster preload didn't seem to be too big of an issue. Wish I would have gone for the 1.18s to start though.

For my 318 Dart, I'd like to go with either 1.18s or 1.24s, either Magnumforce or Firmfeel. I'm aware that the a-body length TBs are higher spring rate than the same diameter B or E body bars.

Anyone here run 1.24s on an a-body for a roadrace application? Is it too stiff with good shocks (RCD Bilstein, etc)? Planning on using 275ish tires on some 17x9 or so wheels.

I'm worried that with 1.24s the high spring rate will prevent me from getting the front end low enough even if I uncrank the adjusters all the way. I want the front of the car to be longtube-scraping low. Does anyone do huge TBs indexed for a low ride height with some adjuster preload? Kind of want to avoid 2" drop spindles based on what I've read about increased roll-center height.

Not at all all worried about on-road comfort, just trying to be as competitive as possible handling-wise with a torsion bar sprung mopar. This will in the not too distant future be a fully caged car and I'm going to be running a 1.25 tubular front bar (swaybar is on the way along with geometry corrected non-adjustable tubular UCAs), rear sway bar is TBD. I'll probably also be buying adjustable strut rods at the same time as I order the TBs, which strut rods would y'all recommend?

Any input by those with roadrace a-bodies with mega-fat TBs is appreciated. Thanks.

Funny you should bring this up I have a set of Firm Feel 1.24 Bars but haven't used them yet. I don't know what will happen or how it will sit. The Bars I'm running know have the adjusters completely backed out. and it sits low. I'm running 18 inch wheels its set up for autox now but I will also be running some track days. By the way I have a pair of 17x10 Bullet wheels for sale. I'm in Redwood city.

Tim Werner's red 68 Valiant has 1.24" and special selected/spec'd billstein shocks.

It's one of the most formidable stock bodied, torsion bar, leaf spring, stock suspension points street car.

Looks like a good ride height and with a smallblock. I wonder whether its just uncranked adjusters or indexed TBs to get there.

Joes, what size TBs are you running for autox? What wheel and tire specs with the 18s? I'm kinda trying to keep front and rear wheel & tire dimensions the same, I'm thinkng 10" wide wheels might be too much for the front of a dart even with backspace/offset nailed. Although I'm not opposed to massive flaring or reworking of fender openings, heh

Now I'm running 1.06 yes 17x10 up front might not work yet. I'm running 18x10s square 295s. I'm looking for 315 for rear. I have Tomswheels Purple Valiant. Its dialed in pretty good and ran very well with Tom driving. I'm a rookie driver my background is Drag racing but Ive given that up to drive more and not have to trailer anymore. I have a few different strokers to play with so I'm going to add more power to the car.

Bring it on down to Spring Fling Speed Fest and see what it's like. Get some seat time and work into the setup you want and are ready for.

There is no pre load to a torsion bar. The adjuster just sets the ride height. You can even remove the adjuster screw and run the lever arm sitting on the nut if it puts you at the right place height and weight balance wise.

With big t-bars you should step up beyond the RCD's. Like the bilstein adjustable level. 72 Swinger did that jump with a noticeable difference IIRC. And maybe some others.

Its going to half to be next year as I'm running up here in local Autox in Cam as Tom did. To much stress in this house with 2 Daughters trying to get into college.

One of my cars has 1.14s in it and you can lower the car down to the bump stops or all the way up to stock ride height, it really depends on the bar clocking. I was going to put 1.20s in it but they hit the headers on both sides and I didn't feel it was worth denting and bending them to fit the bigger bars.

The nice thing about getting Firm Feel bars is those guys are not idiots, and the hexes are in the right spot for the appropriate bar size.

I'm the current owner of "Tim's Valiant". It's pretty low, but not so low that you can't drive it around town. I believe that it has no bump stops on the lower control arms. I would have to double-check next time I'm out in the garage.

The one thing about the 1.24" bars is that header clearance is almost nonexistent. I think the headers are touching the bars. Could be an issue if the paint rubs off and they rust?

Lawndart, I know that you mentioned that you don't care about the ride, but just FYI, it's not that bad. The thing about the car that makes it a little unbearable for the street is the noise echoing through the car because of no sound-deadening material.

I see you're in the SF Bay Area. I am as well. If you want to check out the car sometime, that could be arranged.

Joe,

Just saw that you bought the purple Valiant. Congrats!

Lee

17x10 will never clear the outer tierods.

Thanks Lee, I'm running 18x10s Theres room to step up to an 11. I plan to stuff 315s in the rear 295s fit the front now. the 17x10s I thought he could use for his rear.

I took a peek at the car you traded for with Tom! It's nice. I wish it was mine. Hope you finally shove a stroker in that thing when you get more experience.

Ive got a few motors so that's not a problem. The trade was good for me to as I didn't want to start modifying my AAR Cuda.

Yeah, he was telling me about it. I'm glad you're both happy.

Autoxcuda, have any more info or p/n's on the Bilstein adjustables you mentioned?

Think I'm gonna go with Firmfeel 1.24s, talked to Dick there today and he says I should be able to get the car to ride on LCA bumpstops by uncranking TB adjusters. We'll see what happens when I get em.

Also think I'll order up the Hotchkis adjustable strut rods and the p-s-t greasable LCA pivot shafts and bushings on Monday.



lilcuda, which brand headers are you referring to when you say theres no clearance with 1.24 TBs? I'm about to swap in a less-crushed set of no-name longtubes for the very-crushed set of hedman longtubes on the car currently and I may just dent 'em a lil to clear the TB although I'll probably be going with a set of hedman shorties eventually.

Never done a set of longtubes on an a-body, looks freakin tight, does that job require lifting the motor or disconnecting brake booster/master cylinder?

IIRC he has the Fox non-adjusatbles shocks from Hotchkis. The adjustable one's are better.

As for headers, TTI or Dougs generally fit the best.

Wonder why the Doug's longtubes only go up to '72 for Darts per their site, mine's a '73? Do the TTIs or DOugs tuck up into the subframe rails better? I'm thinking about ditching longtubes because all of the (admittedly cheaper) ones I've seen on low a-bodies and b-bodies hang low enough below the subframe to where they scrape pavement pretty easily

One thing that has me troubled is once you through in the 1.24 bars the front is going to be pretty stiff but the rear spring rates are going to be really soft. Even the Hotchkis springs at 130 are not going to cut it. That's what is holding me back from the change over.

Get some custom ones made. I believe prrc got some composite springs made for his '65 Dart. Mopar Mitch has done the same for his ride. I believe ESPO or other companies will make whatever you want. Heck, a shop that works on trucks should be able to do it.

TTI and Doug don't hang as low as the Hooker and other brands as far as I know. TTI also offers a short tube header and I believe that is the best fitting header on the market. The only person I know who had scraping problems with TTI's was autoxcuda, but that was because his Barracuda had 24" tires on them and the T-bars cranked down a tad.

A few thoughts:
The Magnum Force dropped spindles give a 2" drop.
Headers with dents in them don't necessarily cost much in power. Hot Rod TV did a dyno test proving this very thing.
The 73-76 A body header fitment differs from the 67-72 because of the intrusive motor mount design of the 73-76 models.
The bigger the Torsion bar, the more critical chassis stiffness is. If the unibody flexes with .83 torsion bars, it will be worse with 1.24s. You also will never get the full advantage/stiffness since the flimsy chassis won't allow it. Subframe connectors, torque boxes, a welded K member, reinforced lower radiator support. etc are highly suggested.

I'd think custom leafs are the probably the only route to work well with a 1.24TB 1.25Ø sway bar front, especially if I'm going to minitub and move the perches in for more tire.

Still have to figure out tires and wheels, I'm leaning towards 275/35r18 or 275/40r17 to start. Seems like there's quite a few more options on the former size in the 200 and above treadwear range. Don't think a 25.6" tire is too big for a low Dart.

I think I'm gonna see how things go without drop spindles to start, just uncrank the adjusters and see where I'm at. Have all of those chassis reinforcement upgrades planned, but I think I'm going to do them after the cage. Thanks for the info on the 73+ motor mount header clearance difference

I'm not a fan of the 2 inch drop spindle its a shame no one makes a 1 inch drop.

I would go with the shorty headers, my full length TTI's are about 4 inches off the floor to the flange at the back of the collector, and they also touch the torsion bars.

at least affordable.

IMO, you cannot overspring the front end of a t-bar mopar for competition purposes. This is a shortcoming of mopars that leaves us with increasing sway bar sizes to raise front roll couple percentages to level others makes can achieve with just springs. The best we can get for wheel rates is the 1.24 bars for any body style. You could perhaps go bigger if you adapted C body hexes to A,B, or E bodies and had Mr Ross and company make a custom set, but that's about it. However, this is certainly class and venue specific and your mileage may vary.

As a result of the limited choice of t-bar selections, I've always been an advocate of set up the front, then backing into the required rear rates. You can always create your own leaf packs with a little effort. Its not terribly difficult, it explains how in the Mopar Chassis manual, but drilling centering holes in spring steel does suck. If you go with a set of true custom leafs, they will get spendy. There is a lot more tech in a set of leaf springs than many give them credit for and you'll have to come up with answers to questions you never thought of.

It goes without saying that uber high spring rates require chassis stiffening. You want to reduce the body as an active participant in teh suspension equation as much as possible.

There is a 1" drop spindle out there, but it requires extensive mods to work and they are hard to find. '73 C body spindles accomplish this, but they are far from a straight bolt on. They also are taller and modify roll centers too. Wouldn't recommend it unless you have machining capability or are good friends with one.

I believe the Valiant has TTI headers. They do hang pretty low, but I have yet to scrape them on anything. I don't know how hard they are to install, because they were on the car when I bought it.

BTW, I just checked out the bumpstops. I was right. There are none on the lower control arms. I measured from the frame to the top of the LCA and it is 1 1/4".

Helpful tip for TB purchase. Some terms used for indexing are: Flat to Flat, Point to Flat.

When you are approaching 1.08 and above TB installation you will quickly realize that the car doesn't settle as much in the front when lowering the car off the jack stands and on to the ground because of the newly increased wheel rate. Luckily it becomes more predictable as to what indexing you need for your car.

I have seen different cars, IE, A-body VS B-body have a different LCA to Trans cross member anchor relationship requiring different indexing.

So before ordering the bigger bars check your cars indexing. Remove your TB's. With a floor jack under your k-frame place your car at the desired ride height. Note where your trans cross member anchor is indexed and where your LCA anchor is indexed with the adjuster in the middle of its range and the tab seated. Most likely it will be flat to flat, or point to flat. If not, make notes of the degree rotation needed to rotate the LCA anchor to make it one of the above index configurations and order accordingly.

When all else fails and you already have big bars and your car wont set down where you want it, send them to Dick at Firm Feel and tell him what indexing you need and he will heat, twist, and re Rockwell them for your enjoyment. That's why I always buy from in the first place because his products are mostly made on site and knows mopar building and handling himself.

Then get on down to Willow Springs and let me drive you car. Providing you don't have any chineese spindles or brake parts on it...LOL


Are the Bullet Rims OEM and how much?

Thanks, Alltime.
When I swapped the 440 in my Charger in 2002, I also went from the stock .88 torsion bars to Mopar Performance 1.0 bars. Where the old stock set had the LCA adjuster bolt flush with the bottom, they now hung down over 1 1/4" with the 1.0 bars. I still had 5/8 to 3/4" from the LCA bumpstop to the frame rail so it wasn't as if I was riding that low.
When I installed the Bergman Auto Craft 1.15 bars about a year ago, I followed Peters suggestion on how to adjust them. Sorta funny, I've installed plenty over the years and thought I knew enough to get by but by following his guidance, the car sits the same height as before but the adjuster bolt sits flush against the bottom like stock.
I love the feel of the car with the bigger bars. It feels solid and responsive. Less brake dive, faster transitional response too.

LAWNDART -- I've tried multiple sizes of TBS... as well as making progressive changes to the rear leafs, etc.

I settled with the 1.24 TBs (then readily avlbl from a previous Mopar suspension company called California MoParts/Suspension--- they were way ahead of the market in the 1980s... unfortunately closed). The 1.24 is the largest physical size that fits into the 1.25: hex opening.

I've said many times to offer my suggestive help to those concerned with ride "stiffness"... using larger TBs... don't be afraid... even at ~1.12.. 1.15... 1.18... then... ~1.20-1.22-1.24... these are NOT that much stiffer than you mat think for street driving. IF you ride on bumpy pot-hole roads, and routinely cross RR tracks, etc, then consider small TB like 1.12 or less.

The larger TBs will, especially, help prevent lift and dive, as well; as lean... during extreme driving conditions (competition AX/HSAX/HPDE)... and.. if you have a heavy front end, such a with a BB engine, etc.

Contact FF and they'll make TBs larger than their advertised limit of 1.18... up to 1.24.

You'll say and only wonder why you didn't install larger TBs earlier on... such a the 1.18 or larger.

BUT... also remember to progressively stiffen the rear leafs... and get good quality shocks.

THEN... use the sway bar to "tune" your handling of the car.

Just got in my set of FFI 1.24s, huuuuge >:)

The bars I took of I haven't measured but I'm fairly sure they're in the .9ish range, after removal they sit flat to point on the ground in terms of hex clocking.

The FFIs are flat to flat, will let you know how the car settles after everything is back together.

Most A body bars measure between .83 to .87.

Maybe there is hope after all, I remember maybe a decade ago here being routinely dismissed for suggesting the timid to just step up to .96" bars, and the multitudes who were scared of a harsh ride. Oh well.

What are your plans for rear springs?

thats the same question I have I have had a pair of FF 1.24 bars sitting in my garage need to figure what rear springs that sit flat and have a higher wr.

which spring pack are you currently running?

If you had a heavy duty OEM set on there and the arch is what you want, you could take aonther main leaf and cut off the eye from each end and add it to your pack. That would get you pretty close.

Yeah, you may have to re-clock the bars. With zero offset bars your adjuster screw may not be in the center of its travel.
I haven't had any problems on my Challenger, but it doesn't look right with the screw in so far. On the race kit cars the hex on the crossmember was a bolt-in piece with a hex you'd weld after ride height was set and with the screw in the center of travel.

The bars that worked well for me had 15 degree clocking, somebody should make a rear anchor mount that kit that is splined to allow you to change the alinement (clocking) without buying different bars.

I added one extra leaf on my 69 Valiant when that was not enough I just bought some shocks with adjustable compression damping...now i can just turn the dial to make the rear stiffer.

The bars that worked well for me had 15 degree clocking, somebody should make a rear anchor mount that kit that is splined to allow you to change the alinement (clocking) without buying different bars. [/quote]

Something like that would be great, wonder how hard it would be to remove the stock mount cleanly?

Need to convert over to 48 spline Speedway splined swaybar size. Then you could use the infinite availability of 35" long gundrilled swaybars as torsion bars. The control arm would also need converted as well.

Need to get 4 of these and a TIG. http://www.racereadyproducts.com/splined-collars/sway-bar-arm-splined-collar/

Custom, hahaha. Going to aim for a high spring rate to match the stiff front and a 3" inward relocation of the leafs. Haven't decided on whether to go with steel springs or composite yet. I'd imagine a custom set of composites are more pricey than steel leafs, but I'd need to confirm that. Need to figure out how to translate wheel rates and leaf locations to spring rates. Also need to try and figure out the proper amount of free arch for a car that will end up with a heavy 1.75x.12 cage.

wheel rate - distance between spring mounts divided by distance between track width gives you the motion ratio. Multiply spring rate by motion ratio to get wheel rate.

On Leaf springs, you are talking roll rate rather them motion rate?

How big of a tire are you planning on running? If it was me I would try and use the 3/4inch offset shackle kit and flair out the 1/4s before I would move the springs in the full 3inches

Hyperco makes 225lb composites for $250to320 each.

Was planning to start with 275s (probably 275/35r18->25.6" dia, 10.8" wide). Figured since I'm going to have to weld on new perches with an explorer 8.8 anyways, might as well go for mega tire clearance with minitub and 3" relocation. Not really sure what flaring the rear arch an a .75" relocation would get me in terms of tire width if the car is sitting roadrace low.

I had a 275 on the back of my Valiant with the 3/4 off set shackle kit, that would be getting close to as big as you could go, although you might even fit a 285 if you could find tires you liked in that size.

You are correct, that is the roll rate on each rear wheel.

so..

roll rate - distance between spring mounts divided by distance between track width gives you the motion ratio. Multiply the static spring rate by motion ratio to get roll rate.

The wheel rate is the motion ratio squared then multiplied by the static spring rate.


Thanks for catching that.

I plan to add another full leaf to my Hotchkis springs, will see what they test out at after. Hoping to be in the 200 lb/in range. I added 2 half leafs last year as well.

Run into a bit of a problem. It seems the round on the FFI 1.24 TBs I got are bigger than the hex on the ends of the bars. The hex portions of the bar slide in easily but after a little bit of knocking the bar into the crossmember hex it is f*cking firmly stuck (drivers side), I think because the round is interfering with the hex socket. Was not able to knock it back through from the front side of the crossmember hex today, will try a slide hammer type approach from the back next time I work on it. I tried the passenger side without any tapping and the hex goes easily but it seems to stop up as soon as I get the round of the bar into the hex socket. On the non-stuck bar, I'm measuring 1.25 up to 1.275 in certain high spots, even without paint thickness.

I guess you are the one who has finally found out "how big is too big"

Can you exchange them for another set that measures closer to 1.24"?

I'm sure FF will fix this promptly, they have a good and long reputation.

OR you could oval the hexes just enough to get them in, we're talking .010", you could probably use a half moon file and get it done. Then you will KNOW FOR A FACT you have the biggest A-body torsion bars ever. Wouldn't hurt a thing.

Not a bad suggestion, although it'd be a bit of PITA. May try that as soon as I can get the bar un-stuck. Need to call FF and see what they say.

So what happened?
I would be interested in them , if all it took was a little relieving on the rear socket, if for nothing else, for bragging rights.

FWI you can get Leaf springs from the oval track venders like Speedway Motors. They have different rates and Arch heights. also have specific for dirt or asphalt so I would guess you would want asphalt ones. you can get correct ride height with lowering blocks.

Managed to get em in. Took a fair bit of filing in the middle of the hex flats which was a pretty big PITA from under the car, and had to strip almost all the powdercoat off one bar.

Hoping to get the QR steering together and get the steering wheel centered to the potman this Sat.

Old thread but i thought id add my experience with torsion bars, particularly zero clocking. Everywhere i looked including here said they would be a drama especially in a big block car, concerning getting enough ride height. I have a Valiant with 383, AND, 2 inch dropped spindles. This had me pretty worried, i bought them off a friend before i did research 🤦🏽‍♂️
Anyway, theyre 1.07” and went in great. I wound it up a fair way initially, still have about 1/2” adjustment, and i need to drop it back down an inch and a half.without the drop stubs it would be way up in the air.