Torsion Bar Upgrade for '65 Barracuda Formula S

[Bob Jasinski]

I'm considering upgrading the stock .87" torsion bars in my '65 FS to a bit thicker bar, possibly the .89" if I can find some. This is a restoration, it has the original 273 4bbl, but I am including some upgrades. These include KH disc brakes, 15" radial tires with rallye wheels, and Moog offset upper control arm bushings for more caster. I'm thinking of going with the next size up, .89" if I can find them. Does this make sense or should I just stick with the factory bars? I'm not going to be racing this car, I just want good handling. I know the .89" bars are for 383 applications so I assume the thicker bars compensate for the heavier engine, but would there be advantages with the stock 273 as well, or is it overkill?

 

[65 Dartman]

On my 65 Dart wagon with a 66 273/235 and 42RH transmission, i am going with PST 1.03 torsion bars with numerous upgrades: 73-76 disc brakes, with LBJ upper control arms, offset UCA bushings, Helwig 1.25 sway bar, and good adjustable shocks. I am following the formula posted by others for a good handling car

 

[junkyardhero]

the bigger bars would be a great addition. these cars were undersprung from the factory so upping the spring rate is an excellent idea.

keep in mind that if you go above .920 you'll need good (read: expensive) shocks to control them.

unfortunately, nobody makes/repops .890's or really anything smaller than 1.03 these days. so you'll be looking for used or some NOS ones kicking around on a dusty shelf. firm feel makes custom sizes if you're will to drop that kind of coin.

 

[72bluNblu]

I'd go 1.03" and never look back. With radial tires you still wouldn't be oversprung. A 1.03" torsion bar on an A-body works out to about a 215 lb/in wheel rate. Which is in the ballpark for most modern econo-boxes, and lower than most performance oriented cars.

A good set of shocks would be great addition, but as long as you don't use KYB's you'd probably be fine. I ran 1" bars on my Duster with those regular old replacement blue monroe's and it was still quite a soft ride.

 

[RustyRatRod]

I'd go 1.03" and never look back. With radial tires you still wouldn't be oversprung. A 1.03" torsion bar on an A-body works out to about a 215 lb/in wheel rate. Which is in the ballpark for most modern econo-boxes, and lower than most performance oriented cars.

A good set of shocks would be great addition, but as long as you don't use KYB's you'd probably be fine. I ran 1" bars on my Duster with those regular old replacement blue monroe's and it was still quite a soft ride.

That's about the smallest available new that I know of.

 

[mvh]

I put in .890s as an upgrade to the .870s in my 67. This incremental change is probably only worth doing if you already have the front end apart for a refresh. However, it is a good upgrade that helps control dive and does not result in an overly stiff ride.

It is really the sway bar that contributes to cornering performance — you don't need super-stiff springs for handling. On real-world curvy roads, which are generally secondary roads in rural areas that are not always well-maintained, extremely stiff springs will rattle your teeth out and reduce the amount of contact patch as the tires leave the road surface.

I just finished (well, almost finished — DNF'ed with a blown head gasket) a 850-mile vintage car tour on secondary and tertiary roads in Northern California. I have done this rally in one or the other of my Barracudas several times (not this occasion). The slant six convertible with the softest factory springs plus sway bar was just as capable as my tweaked Commando fastback for this kind of activity, although I wouldn't take it to track day at Willow Springs. Meanwhile, the replica Ford GT40 was crawling in low gear half the time (although as soon as the road surface smoothed out he was out of sight).

I did just install Bilstein shocks on the fastback and that seems to be an improvement over the KYBs, but I haven't had it on a rally yet.

 

[GY3 WEDGE]

I did get a set of 894-895 through Brads nos last month it was under p5249150 don t know if they had more than 1 set

 

[mvh]

I should add, you can pretty much find any size of t-bar you want at a large swap meet.

 

[junkyardhero]

I put in .890s a

I just finished (well, almost finished — DNF'ed with a blown head gasket) a 850-mile vintage car tour on secondary and tertiary roads in Northern California. I have done this rally in one or the other of my Barracudas several times (not this occasion). The slant six convertible with the softest factory springs plus sway bar was just as capable as my tweaked Commando fastback for this kind of activity, although I wouldn't take it to track day at Willow Springs. Meanwhile, the replica Ford GT40 was crawling in low gear half the time (although as soon as the road surface smoothed out he was out of sight).

I did just install Bilstein shocks on the fastback and that seems to be an improvement over the KYBs, but I haven't had it on a rally yet.

name of the rally?

(asking for a friend)

 

[Bob Jasinski]

I really appreciate the torsion bar feedback. To add perspective, (I'm in a reflective mood so skip to the bottom if easily bored) allow me to share a little bit of history of this car and how I came to own it. In April 2002, I found it sitting in an industrial park in Newark California, with "For Sale $2000" written across the windshield. I saw the tach in the dash and the FS badges. I took pictures of it and the fender tag, went home and did some research. I determined it was a real Formula S, and called the phone # on the windshield. He bought the car from the original San Jose owner, cut one side of the inner fender for a planned header installation and a built 340. His wife got pregnant and the car had to go. He included a full Legendary interior kit, front/back seats and full carpet, and extra parts. I offered him $1500 and he had to deliver it to my house, he agreed.

I enjoy rare cars, I own a 300G convert as an example, this FS was rare. Up to this point, I had owned 17 Plymouths, from a '48 to a '75. Deluxes, Furys, Sport Furys, Belvederes, Satellites, sedans, convertibles, wagons, 2 dr hardtops, never an A body, never even driven an A body, to this day. So, my goal for the car was a restoration, not a "build project". Didn't care to drop in a 340, hey, its already a factory performance car right? Well, I sent for a copy of Tom Condran's (then) recent book "Performance Handling for Classic Mopars". It really inspired me to give thought to minor upgrades that would "enhance" the handing experience of an already well handling car, albeit one that came new with skinny bias ply tires, but hey, they had blue streaks, so there's that right?

Well, that was 20 years ago, and the body and paint is now finished, only waiting for the headliner to be installed at the shop (my avatar will change soon I promise) . The original engine is rebuilt, .040" over, domed pistons, etc. It's mounted on the K frame and will be installed from below (I have a lift). The factory sway bar is going back in, and I'm ordering a new set of rear springs from Espo. I've followed Condran's advice and installed Moog offset bushings in the UCAs, and have a KH disc brake setup ready to go in. I'm going to 15" radials with new rallyes. This car will be driven to shows and weekend getaways in the wine country and coastal hiways, twisty roads, that sort of thing. I actually have a set of new KYBs, but if they don't work out they're easy to change. Does it make sense to put the original torsion bars back in? I think not.

72nuNblu says "I'd go 1.03", MVH says he likes his .89". So far, no one is telling me to stay with the original .87" bars. I'm going to call PST and discuss it with them. I'm leaning toward the 1.03" at this point. The KYBs can change but the factory sway bar stays.

 

[junkyardhero]

you won't be disappointed no matter the direction you take. the KYB's will ride rough, know that going in, the big 1.03's will exacerbate this. but you might find the ride acceptable, different people have different thresholds for things of that nature.

100% the stock bar back in.

another option, is to keep the stock .870's and up the front bar to something more substantial. this is what i'm doing on my 65 dart.

 

[72bluNblu]

I put in .890s as an upgrade to the .870s in my 67. This incremental change is probably only worth doing if you already have the front end apart for a refresh. However, it is a good upgrade that helps control dive and does not result in an overly stiff ride.

It is really the sway bar that contributes to cornering performance — you don't need super-stiff springs for handling. On real-world curvy roads, which are generally secondary roads in rural areas that are not always well-maintained, extremely stiff springs will rattle your teeth out and reduce the amount of contact patch as the tires leave the road surface.

I just finished (well, almost finished — DNF'ed with a blown head gasket) a 850-mile vintage car tour on secondary and tertiary roads in Northern California. I have done this rally in one or the other of my Barracudas several times (not this occasion). The slant six convertible with the softest factory springs plus sway bar was just as capable as my tweaked Commando fastback for this kind of activity, although I wouldn't take it to track day at Willow Springs. Meanwhile, the replica Ford GT40 was crawling in low gear half the time (although as soon as the road surface smoothed out he was out of sight).

I did just install Bilstein shocks on the fastback and that seems to be an improvement over the KYBs, but I haven't had it on a rally yet.

Respectfully, I disagree with pretty much all of this.

Sway bars are only a single, and secondary, component for improving handling. Yes, there are very experienced drivers/racers that have some differing opinions on wheel rate tuning with springs vs sway bars. But ultimately, with a good set of tires there is not a commercially available sway bar big enough to increase your wheel rate enough to compensate for .87” or .89” bars. You’d have to make your own NASCAR style splined sway bars to get large enough in diameter to get where you need to be.

As for rattling your teeth out on tertiary roads in Northern California, no sir. That’s what good shocks are for. Between my ‘72 Challenger with 1.12” torsion bars (270 lb/in wheel rate) and my Duster with 1.12” torsion bars (300 lb/in wheel rate) I’ve logged well over 100k street miles, the vast majority of which are on secondary and tertiary roads in Northern California. The Duster has 1.12” torsion bars AND Hellwig sway bars.

Maintaining suspension travel is one of the biggest considerations for going to larger torsion bars. Go too high in wheel rate and your wheels no longer track the ground. Go to low in wheel rate and you bottom out your suspension all the time, which ALSO results in your wheels not maintaining traction because you have 0 suspension at that point.

With 1.12” bars on my Duster, and maintaining the factory ~5.5” of total suspension travel, I still bottom out my suspension on occasion (mostly on little back roads!). Which means, smaller bars would bottom even more, resulting in worse handling.

I really appreciate the torsion bar feedback. To add perspective, (I'm in a reflective mood so skip to the bottom if easily bored) allow me to share a little bit of history of this car and how I came to own it. In April 2002, I found it sitting in an industrial park in Newark California, with "For Sale $2000" written across the windshield. I saw the tach in the dash and the FS badges. I took pictures of it and the fender tag, went home and did some research. I determined it was a real Formula S, and called the phone # on the windshield. He bought the car from the original San Jose owner, cut one side of the inner fender for a planned header installation and a built 340. His wife got pregnant and the car had to go. He included a full Legendary interior kit, front/back seats and full carpet, and extra parts. I offered him $1500 and he had to deliver it to my house, he agreed.

I enjoy rare cars, I own a 300G convert as an example, this FS was rare. Up to this point, I had owned 17 Plymouths, from a '48 to a '75. Deluxes, Furys, Sport Furys, Belvederes, Satellites, sedans, convertibles, wagons, 2 dr hardtops, never an A body, never even driven an A body, to this day. So, my goal for the car was a restoration, not a "build project". Didn't care to drop in a 340, hey, its already a factory performance car right? Well, I sent for a copy of Tom Condran's (then) recent book "Performance Handling for Classic Mopars". It really inspired me to give thought to minor upgrades that would "enhance" the handing experience of an already well handling car, albeit one that came new with skinny bias ply tires, but hey, they had blue streaks, so there's that right?

Well, that was 20 years ago, and the body and paint is now finished, only waiting for the headliner to be installed at the shop (my avatar will change soon I promise) . The original engine is rebuilt, .040" over, domed pistons, etc. It's mounted on the K frame and will be installed from below (I have a lift). The factory sway bar is going back in, and I'm ordering a new set of rear springs from Espo. I've followed Condran's advice and installed Moog offset bushings in the UCAs, and have a KH disc brake setup ready to go in. I'm going to 15" radials with new rallyes. This car will be driven to shows and weekend getaways in the wine country and coastal hiways, twisty roads, that sort of thing. I actually have a set of new KYBs, but if they don't work out they're easy to change. Does it make sense to put the original torsion bars back in? I think not.

72nuNblu says "I'd go 1.03", MVH says he likes his .89". So far, no one is telling me to stay with the original .87" bars. I'm going to call PST and discuss it with them. I'm leaning toward the 1.03" at this point. The KYBs can change but the factory sway bar stays.

You can look at my response above, but again, I’ve been running 1.12” bars in my Duster for years driving mountain and coastal roads in Northern California. I run Hotchkis shocks and Hellwig sway bars. If I do anything, I’d go UP to 1.18 torsion bars.

Now, my Duster has 275/35/18’s on the front and 295/40/18’s on the back with 200 tread wear tires, so with less traction and loading you’d want less wheel rate. But when I was running 225/60/15’s and 1” torsion bars on my Duster the ride was still quite soft and the body roll was still quite substantial- more than my current Hellwig bars could tame.

I do set my cars up pretty aggressively, but I also drive some pretty sketchy back roads. And I’ve never been bounced off the road because the suspension in my Duster or Challenger was too stiff. I have gotten out of shape because I bottomed out my suspension though.

All that said, I think 1.03” bars would do you just fine, and would significantly improve the handling on your car especially paired with a decent set of shocks (RCD Bilstein, Hotchkis Fox’s, RideTech, etc).

Another great resource for you is @BergmanAutoCraft , he will have much better knowledge and advice than PST.

 

[Bob Jasinski]

you won't be disappointed no matter the direction you take. the KYB's will ride rough, know that going in, the big 1.03's will exacerbate this. but you might find the ride acceptable, different people have different thresholds for things of that nature.

100% the stock bar back in.

another option, is to keep the stock .870's and up the front bar to something more substantial. this is what i'm doing on my 65 dart.

"The KYBs will ride rough" Others have said that too. The KYBs are said to be adjustable, right on the box, if they ride rough, won't the adjustability help with that?

 

[72bluNblu]

"The KYBs will ride rough" Others have said that too. The KYBs are said to be adjustable, right on the box, if they ride rough, won't the adjustability help with that?

KYB’s are not adjustable. And no. KYB’s are hot garbage.

I say that after running them for 10’s of thousands of miles on my Challenger before upgrading to RCD Bilstein shocks. It was like driving a different car, a night and day kind of improvement with the only change being the KYB’s going in the trash where they belong.

KYB’s are a kind of band aid for guys that want to keep the original torsion bars. The combination of a really soft torsion bar, with a really stiff shock, results in a ride that feels somewhat “normal” in fairly basic driving conditions. Handling performance remains trash, because neither component is doing the job it should be doing.

But paired with a torsion bar of an appropriate size for a modern radial tire, KYB’s will rattle your teeth out. And give lousy handling too.