What diameter torsion bars?

-
buck351

buck351

Well-Known Member
Joined
Apr 22, 2010
Messages
427
Reaction score
37
Location
Campton Hills, IL
The 45 year old torsion bars need replacing. So what diameter? From what I have read the stock on the 1967 Dart GTS were .870. I see a number of options. .890 seems to be the restoration size but they go up from there. Any advise?
 
Depends of engine weight. What engine are you running.
 
http://www.bigblockdart.com/techpages/torsion.shtml pick your poison.

FYI, these cars were wayyy under sprung from the factory. This was back when the cushy ride was dominant.

The usual fix with a v8 car is to go with a .890-1.03 bar for street, good handling and modern feel, and a slant .810-.870 for drag racing for quick weight transfer. Adjust accordingly.

I just picked up a 1" bar from Just Suspension, $188 including shipping after discount code 'shopalizer'.

If this helps, hit the 'thanks' button and enjoy your weekend!
 
PoisonDart74 said:
http://www.bigblockdart.com/techpages/torsion.shtml pick your poison.

FYI, these cars were wayyy under sprung from the factory. This was back when the cushy ride was dominant.

The usual fix with a v8 car is to go with a .890-1.03 bar for street, good handling and modern feel, and a slant .810-.870 for drag racing for quick weight transfer. Adjust accordingly.

I just picked up a 1" bar from Just Suspension, $188 including shipping after discount code 'shopalizer'.

If this helps, hit the 'thanks' button and enjoy your weekend!
Click to expand...

Suprisingly I always thought it was rather stiff already. I didn't want to make it too stiff but I was finding the .890 recommended for restoration and more modern suspension. Is the .890'' a good compromise? I gathered the .870" was the standard on the GTS. So .02" makes a noticeable difference?

How fast does the stiffness go up as you increase the diameter?

Summit carries Mopar Performance. They have a set of the .890" for $315 and a set of the .920 for $319.
 
Look here for a spring rate comparison between different diameter torsion bars:
http://www.firmfeel.com/torsionb_a.htm

I have a slant six in my rag top running 0.940 bars. Slants and small blocks are close in weight, a big block comes in about 300 more pounds.

Chances are that your suspension has been bottoming out if your bars are weak giving the feel of a stiff ride. My Dart is softer riding than my 300 C AWD, so as things go, compared to a modern car, the Dart is on the soft side. I have a firm feel rebuilt steering gear from Steer N Gear, sway bar, and the car now feels and drives & corners flat like a modern car. With stock 0.810” bars it was a flopping, wallowing mess.

Where you have a big block I wouldn’t hesitate using a 1.00”or thicker bar, in conjunction with a good anti sway bar, and a Firm Feel steering gear; you’ll be happy. Also this would be a good time to install new front end bushings if yours are getting on the worn side.
 
buck351 said:
Suprisingly I always thought it was rather stiff already.
Click to expand...

Also keep in mind the fact these old bars have work hardened after 45 years. I'd like to think the newer bars have better metallurgy..


Now as far as quickening of spring rates, I'm gonna agree with wjajr, and add that it depends on the relationship between the weight of your front end, and the spring rate, so it's very elusive and depends on on a lot of variables so you can't say "it feels like this.". It's trial and error.

The opinion is: 1" seems to be a good compromise, and a safe bet between hard and soft.

I'd rock the 1" without a thought about getting scientific or wanting to be politically correct with it. Seems to be a pretty popular size, and the prices reflect that, which I see as a bonus.

Everyone has the same hesitation with "1 bars: 'Oh, that sounds too stiff!' then they install them and say they are 'Firm, embracing, modern (add positive adjective here) but not harsh, I love them!' ...and that's with small blocks. As you can imagine, big blocks would be even more cushy.

"Where you have a big block I wouldn’t hesitate using a 1.00” or thicker bar, in conjunction with a good anti sway bar, and a Firm Feel steering gear; you’ll be happy. Also this would be a good time to install new front end bushings if yours are getting on the worn side." -- wjajr

That's good advice.



Here is the link to the bar's I have:


http://www.justsuspension.com/pro-touring-torsion-bars.html


Also, it might be a good idea to hop up on energy suspension and grab some polyurethane dust boots, if you don't already have replacements. If you have fitment issues, stick the poly boots in the microwave, or boiling water for a few seconds, should loosen then right up.

Heres a link:


http://www.energysuspensionparts.com/proddetail.asp?prod=41701&PARTNER=gbase


Good luck!
 
67 383 cars used the same bars (.870) as the small block handling package cars. 68-69 big block A-bodies used the .890" bars. What you need does NOT depend on the engine, but your intended purpose for the car.
 
I have 1.06 FF bars in my iron head B engine car and im shocked at how good it rides. I have Bilsteins and Hotchkis rear springs and my Mother in Law even said "Woow this rides nice". She drives an older Lexus....
 
IMO, spring/torsion bar selection is affected by several things.
  • Intended use of the car.
  • Weight supported by the spring
  • Changes in spring rate at the other end of the car.
That said, I personnally would not go beyond a .890 TB unless you are also going to increase the spring rate in the rear or are not satisfied with the current handling balance.

Consider that stiffening the front suspension moves the handling balance more towards oversteer, while stiffening the rear suspension moves the balance more towards understeer. On the other hand increasing roll stiffness at the front increases understeer, increasing roll stiffness at the rear increases oversteer.

FWIW, what I did with the Demon was to install 1" TBs and six-leaf springs in the rear. I also added front and rear sway bars. For the rear bar, I fabricated brackets to replicate the body mount of the A37 police package of 1976. Bushings were replaced by polygraphite and the shocks are Monroe Gasmatics. Tires are 235/60-15 T/As. The car has a well-controlled ride, handling balance shows less understeer, and turn-in is much sharper.
Since I'm using radial tires, I went with a front end alignment that is better suited to take advantage of them. The most significant change was bumping up the caster setting to + 2º. I would have gone higher but that's all the body would give us.
 
Great input everyone.

What I didn't post was everything in the front end was replaced except the bushings on the swaybar and the torsion bars. But I did buy all the front end bushings which were polyurethane for the restoration. All the rear spring bushings were replaced with poly too.

A mechanic said you don't want to take apart the torsion bars unless you really have to do it. The shop doing the car wasn't sure how to change the swaybar bushing and the old ones still looked pretty good so I thought I'll figure it out later.

The shocks are still the Konis I put on years ago. They look old on the outside but amazingly are not leaking and still work. Someone talked me into them at the time. I had never heard of them and at the time they were about 3 to 4 times what the regularly brands were costing. I have to say I'm amazed how long they lasted. I thought about replacing them with new Konis and was surprised how much they cost now.
 
wjajr said:
Look here for a spring rate comparison between different diameter torsion bars:
http://www.firmfeel.com/torsionb_a.htm

I have a slant six in my rag top running 0.940 bars. Slants and small blocks are close in weight, a big block comes in about 300 more pounds.

Chances are that your suspension has been bottoming out if your bars are weak giving the feel of a stiff ride. My Dart is softer riding than my 300 C AWD, so as things go, compared to a modern car, the Dart is on the soft side. I have a firm feel rebuilt steering gear from Steer N Gear, sway bar, and the car now feels and drives & corners flat like a modern car. With stock 0.810” bars it was a flopping, wallowing mess.

Where you have a big block I wouldn’t hesitate using a 1.00”or thicker bar, in conjunction with a good anti sway bar, and a Firm Feel steering gear; you’ll be happy. Also this would be a good time to install new front end bushings if yours are getting on the worn side.
Click to expand...

Thanks for the Firm Feel link. I didn't think about checking them. I purchased my ferris granite disc pads from them.
 
I must add that when the new 0.940” bars were installed, I also installed six leaf rear springs at factory ride height, and sub frame connectors. My car does not have air conditioning or iron manifolds, but is equipped with KH disks & power steering, so the slant loaded front end is on the light side of all things Mopar. I do not run a rear anti-sway bar. Car is well balanced, dose not under steer, or want to let the rear hang out on dry pavement.

As a few have said previously, it depends what spring rates one needs on what you use the car for. My set up is for touring-daily driving and no serious drag racing. When I got the car it was a former drag queen that completed four winning seasons at Englishtown, NJ. in the nineties, built for the strip with mismatched torsion bars, and super stock springs. I could hardly keep it on the road, it was a death trap over 30 MPH, and handled as if the was a big hinge between the front & rear seats.
 
I have 1.03" bars in a small block '70 Dart. Rides a lot better than the .870" bars I took out. I prefer a firmer ride for handling.
 
PoisonDart74 said:
Also keep in mind the fact these old bars have work hardened after 45 years. I'd like to think the newer bars have better metallurgy..


Now as far as quickening of spring rates, I'm gonna agree with wjajr, and add that it depends on the relationship between the weight of your front end, and the spring rate, so it's very elusive and depends on on a lot of variables so you can't say "it feels like this.". It's trial and error.

The opinion is: 1" seems to be a good compromise, and a safe bet between hard and soft.

I'd rock the 1" without a thought about getting scientific or wanting to be politically correct with it. Seems to be a pretty popular size, and the prices reflect that, which I see as a bonus.

Everyone has the same hesitation with "1 bars: 'Oh, that sounds too stiff!' then they install them and say they are 'Firm, embracing, modern (add positive adjective here) but not harsh, I love them!' ...and that's with small blocks. As you can imagine, big blocks would be even more cushy.

"Where you have a big block I wouldn’t hesitate using a 1.00” or thicker bar, in conjunction with a good anti sway bar, and a Firm Feel steering gear; you’ll be happy. Also this would be a good time to install new front end bushings if yours are getting on the worn side." -- wjajr

That's good advice.



Here is the link to the bar's I have:


http://www.justsuspension.com/pro-touring-torsion-bars.html


Also, it might be a good idea to hop up on energy suspension and grab some polyurethane dust boots, if you don't already have replacements. If you have fitment issues, stick the poly boots in the microwave, or boiling water for a few seconds, should loosen then right up.

Heres a link:


http://www.energysuspensionparts.com/proddetail.asp?prod=41701&PARTNER=gbase


Good luck!
Click to expand...

Thinking about it does have some front end body roll that makes it feel a little unstable in turns.
 
I wouldn't hesitate to run 1" bars on your car. From the factory these cars were horribly under sprung in the front. They understeer like crazy. With a 383 in the front a 1" bar will be more than compliant. I have a couple pairs of Just Suspensions 1" bars, and all of my cars are small blocks.

My challenger, while a heavier car, has 1.12" torsion bars. It's quite a bit stiffer than the 1" a body bars, but its still not a harsh ride. Probably stiffer than most folks like, but still not bad as a daily driver. Should ride pretty close to a 1.06" a body bar.

As far as balance goes, I don't think you necessarily need to change the rear springs to run 1" bars. If you look at the handling recommendations from Mopar for the circle track cars, you'll see that they recommend a 120lb rear spring, which is SOFTER than stock. From the factory these cars were undersprung in the front and arguably oversprung in the back. 1" bars, stock leafs, and front and rear sway bars can balance the car pretty well. Not saying you can't do better than stock springs in the rear, but they're not as far off as you might think.
 
Thanks for all the input.

I talked to Firmfeel and they recommended the 1" like others who posted here. I ordered the 1" bars and the new boot/lock ring set. I have the polyurathane bushing somewhere since they were not installed on the torsion bars when the frontend was redone.

The place that will be replacing them suggested new adjusters for the torsion bars. They are concerned about the age and getting them off undamaged. Is this really an issue? They don't look badly rusted. I did find a source for them.
 
buck351 said:
Thanks for all the input.

I talked to Firmfeel and they recommended the 1" like others who posted here. I ordered the 1" bars and the new boot/lock ring set. I have the polyurathane bushing somewhere since they were not installed on the torsion bars when the frontend was redone.

The place that will be replacing them suggested new adjusters for the torsion bars. They are concerned about the age and getting them off undamaged. Is this really an issue? They don't look badly rusted. I did find a source for them.
Click to expand...


Smells like an up sell to me, hope you got a good deal on those bars, and you don't need the rubber boot if you've got the poly the lock rings should still be fine... Remember JS 1" we're $188 for me, can't beat that! Just trying to help you save some coin...
 
buck351 said:
The place that will be replacing them suggested new adjusters for the torsion bars. They are concerned about the age and getting them off undamaged. Is this really an issue? They don't look badly rusted. I did find a source for them.
Click to expand...

If the adjusters are in good condition you shouldn't have any problems. The threads can be damaged like any other bolt, and they tend to get exposed to a lot of crud. I usually spray some WD-40 or Kroil on them before I loosen them up, haven't had any issues yet. Biggest thing is not to adjust them while the car is sitting on its wheels, they can strip out if they're adjusted while under load.
 
72bluNblu said:
If the adjusters are in good condition you shouldn't have any problems. The threads can be damaged like any other bolt, and they tend to get exposed to a lot of crud. I usually spray some WD-40 or Kroil on them before I loosen them up, haven't had any issues yet. Biggest thing is not to adjust them while the car is sitting on its wheels, they can strip out if they're adjusted while under load.
Click to expand...

Thanks for the info. I hit them last night with some Blaster. Figured I'd start soaking everything before it's taken apart/adjusted. They are just rust colored and look in good shape.

I was going to let the shop change them but considering recent bills I may have to do these myself. Doesn't look to bad from what I have read and I also have the shop manual.
 
I was under the car today and noticed very little space between the torsion bar an the driver's side exhaust pipe. I measured it with a feeler gauge and it's only .116" which works with the current bar. It doesn't look like 1" bars will work. Doing the math I will only have .051" of space left unless I put a dent in the pipe that lines up with the torsion bar. A small dent to get some clearance would do it.
 
I was curious how much the car weighed. I drove it to work today and remember to weigh it. The whole car is 3460 and the front is 1920. That web site on torsion bars was talking about the spring rate on the torsion bars being 10% of the front weigh as I recall. The 1" bars I got are 195.
 
I got the 1" bars installed and had the alingment done. I had them get the alingment as close as possible the the suggest settings for radial tires on the older mopars. Noticable improvement in the driving and handling even thought it is a manual steering car. 1" bars didn't make the ride harsh. Rides better now with front end up leveling out the car and as 72bluNblu said the 1" bars with the stock rear leafs do a pretty good job of balancing out the suspension. Feels to me like he's right. I tried to get it close to the stock ride height spec after I installed the torsion bars. Guess I did good they said the height was right on.

Geez they have fancy alignment equipment now. They attached to the front and back wheels. First time I have seen this setup. I went to NTB and they were very cooperative in trying to get it set to the custom specs. They wasted a fair amount of time because the first laser/computer alignment device was malfunctioning. After he switched to another one it only took him 45 minutes.
 
You must log in or register to reply here.
-

Back
Top