Torsion bars the bigger the better???

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Brooks James

Brooks James

VET, CPT, Huey Medevac Pilot
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I don’t care about stiffness and hard ride I want concise handling if I race
Street manners unimportant
 
To a point.Too stiff may make it ill handling if the road surface is ruff/bumpy.
 
Seems the trend is to get >1.00 at a minimum nowadays.....with a good shock. Not sure why Mopar didn't do this from the start with the B/RB A's if it was such an improvement.... I mean they had million dollar suspension dynos and could probably replicate any torsion bar rate but they stayed with the .8xx for even the big blocks?
 
pishta said:
Seems the trend is to get >1.00 at a minimum nowadays.....with a good shock. Not sure why Mopar didn't do this from the start with the B/RB A's if it was such an improvement.... I mean they had million dollar suspension dynos and could probably replicate any torsion bar rate but they stayed with the .8xx for even the big blocks?
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It's because the tire technology sucked 50 years ago. Too stiff and it overpowers the tire sidewall tech that was available to them from way back when. Nowadays modern tire technology and wider tires can keep up with heavier torsion bars or a heavier sway bar. Also the designers had to strike a balance between too harsh a ride and too compliant. Most people bought this stuff for daily A to B transportation and needed to live with it every day. Radials didnt really hit the scene until mid 1970s. Until then it was bias ply or fiberglass belted tires.
 
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Also if you were to use stock big block bars on a small block car, then lighten up the small block by putting it on an aluminum diet, mini starter, aluminum radiator, how much more can you offset that? A stock big block weighs about what 250lbs more than a stock small block. How much more can you realistically shave off the small block with aluminum parts? 75 more lbs maybe? If you use aluminum heads, intake, mini starter, mini alternator, aluminum radiator. This makes those big block torsion bars a bit stiffer.
 
Thankfully the designers designed this stuff 50 years ago with big gaping wheel openings made for more modern rubber especially B body cars. It was as if they had a crystal ball.
 
My ride has the 1.03 bars, plus HD shocks, plus a 1.125 bar on the front, and it was a DD for 6 years like that, never too stiff.
Yes alloy heads and intake, plus battery relocated to the rear.
But to be fair;
the front runs 235/60-14s on aluminum 7.5s at 29psi, and the rear runs 295/50-15s on aluminum 10s at 24psi. These pressures are what it takes to run the treads flat to the road, for long tread life.

On my unit, I would not be afraid to run a bigger T-bar, but I would want better shocks,lol. And I certainly would not run less; been there done that.
 
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Consumers in those days loved the soft floaty ride too. They much preferred the boat like cruise over handling. My Dad had a 62 Chevy that was pretty floaty but when he got a new 65 Chevy it was almost a scary experience to drive and keep it in the correct lane, but everyone thought the ride was wonderful!
 
I currently run 1.14" bars. Chassis connectors and torque boxes. Sway bars front and rear. New Borgeson steering box. Hotchkis TVS.

Car has been used on road course and street. Handling is firm and enjoyable. Not horrible. Like a new car. NOTE: Car still has 15" wheels.
 
The roads were a lot worse back then, nothing like the new asphalt we have now. Some of the back roads were just patches over patches, so that floaty ride made it a lot more tolerable.
 
Brooks James said:
I don’t care about stiffness and hard ride I want concise handling if I race
Street manners unimportant
Click to expand...

Race only? What kind of tracks are we talking? And what kind of tires?

I’ve been running 1.12” torsion bars on my Duster on the street for close to 30k miles. With the 275/35/18’s, Hotchkis Fox shocks and Hellwig sway they’re still not too stiff for the street. After going to a set of Falken Azeni 615’s I can totally see how on a smooth track in warm weather I could run larger and still not be oversprung. On the street the 300 lb/in wheel rate is stiff but not harsh. I put 70k miles on a set of 1.12” bars on my Challenger, they were 270 lb/in and they weren’t stiff at all. I’ll probably go larger on that car just for the street.

For an aggressive handling street car I’d say 1.08”-1.14” wouldn’t be an issue at all as long as you’re running good tires, like 200-340 on the tread wear as just a general range. And a good set of shocks. I wouldn’t go bigger than that just because of the road conditions and suspension travel for the street.

On a track you could go stiffer even with the same tires depending on the track conditions. And if you’re running track only tires even more so.

It’s all based on the tires and how smooth the track is. If you have the grip you can go stiffer, as long as the track is smooth enough that you don’t need the travel to keep the tires on the ground.

pishta said:
Seems the trend is to get >1.00 at a minimum nowadays.....with a good shock. Not sure why Mopar didn't do this from the start with the B/RB A's if it was such an improvement.... I mean they had million dollar suspension dynos and could probably replicate any torsion bar rate but they stayed with the .8xx for even the big blocks?
Click to expand...

Pretty much already covered. The tires were trash, if the tires won’t grip the forces transferred to the suspension won’t be as high. As the tires get better they transfer more force the the suspension and you need higher wheel rates to manage the higher forces. Radials didn’t come out on production mopars until ‘77 I think? Part of why some of the suspension stuff changed for the F bodies.

And part of it was the market at the time, a smooth, floaty ride was the style of the day. What the consumer wanted, even ahead of handling.

If the factory was putting radials on these cars the bars would have been stiffer. If performance handling had been more in vogue instead of straight line speed they would have been stiffer again.
 
Brooks James said:
I don’t care about stiffness and hard ride I want concise handling if I race
Street manners unimportant
Click to expand...

As in drag racing? The MP suspension book shows you how to set up the front suspension using slant six bars. That's what everybody used way back when. Yes, there's modern tech and "all that" but the old way still WORKS and is usually much cheaper.
 
The correct answer: it depends.

How about some more info on your car, and the application?
 
Assuming the length, metallurgy, and shape are the same, larger diameter only increases the spring rate, (as in stiffer) the ride height will be determined by the adjustment.
 
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1.14s are no problem...my wife’s 2019 GT Mustang is firmer on the front

2F5D2B1F-85C0-4D3F-B8AE-8A694E88FAF2.jpeg
 
You can over spring a car.

depends on weight and setup.

I run 1.14”. You need shocks to control stiff springs.

there’s autocross nationally competitive old Mopars running 1.25” T-bars (largest possible). It’s a ~3200 lbs E-body with lightweight components.
 
Better make sure that crossmember is up to task at the torsion bar lugs when sticking them "baby leg" diameter bars under it. These things are 50 years old. A lot of em are fairly rusty inside. My sons car and mine werent at the lug mounts but were pitted on the bottom where water probably layed in them. I sandblasted them clean inside, touched up the lug welds and epoxy coated in there.

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moparmat2000 said:
Better make sure that crossmember is up to task at the torsion bar lugs when sticking them "baby leg" diameter bars under it. These things are 50 years old. A lot of em are fairly rusty inside. My sons car and mine werent at the lug mounts but were pitted on the bottom where water probably layed in them. I sandblasted them clean inside, touched up the lug welds and epoxy coated in there.

View attachment 1715681486

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basically rust free car here ! ...thank god.
 
moparmat2000 said:
Better make sure that crossmember is up to task at the torsion bar lugs when sticking them "baby leg" diameter bars under it. These things are 50 years old. A lot of em are fairly rusty inside. My sons car and mine werent at the lug mounts but were pitted on the bottom where water probably layed in them. I sandblasted them clean inside, touched up the lug welds and epoxy coated in there.

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I welded the sub frame connectors to the torsion bar sockets.
 
The subframe connectors that are in the car now, are getting replaced with 2x3 14 gage box steel.
 
moparmat2000 said:
Better make sure that crossmember is up to task at the torsion bar lugs when sticking them "baby leg" diameter bars under it. These things are 50 years old. A lot of em are fairly rusty inside. My sons car and mine werent at the lug mounts but were pitted on the bottom where water probably layed in them. I sandblasted them clean inside, touched up the lug welds and epoxy coated in there.

View attachment 1715681486

View attachment 1715681487
Click to expand...

All excellent suggestions and great work, as usual!
 
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