Firm Feel vs PST Torsion Bars

[Monc440]

I went with PST 1.03s.. very very happy with the ride.. not too stiff. Just curious, why 112--118? honestly curious

My fury is a boat and I added about 150 pounds to the front when I installed a V10 Magnum engine and OD transmission.

 

[ckessel]

A tip I read awhile back in a Mopar suspension upgrade book was to go by the weight of the front end of the car, calculate 10% of that and it would give you your starting point for rates. Pretty much what Dick from FF set me up with on the front bars for my 65 after I gave him the scale figures once I had it weighed in the Ridetech tent many years ago at a Goodguys event. Have any access to a set of scales?

 

[Monc440]

A tip I read awhile back in a Mopar suspension upgrade book was to go by the weight of the front end of the car, calculate 10% of that and it would give you your starting point for rates. Pretty much what Dick from FF set me up with on the front bars for my 65 after I gave him the scale figures once I had it weighed in the Ridetech tent many years ago at a Goodguys event. Have any access to a set of scales?

I read an article that said the same thing, front end weight / 0.10 = WR. I live out in the sticks but we have a grain mill that they would probably let me use their scale. I estimated 220 to 230, I should probably get it on the scale.

 

[Charlie Brown]

I've got PST 1.03 bars in my 64 Dodge. Very happy with the results.

 

[TorRed]

So I've got a new set of MP .96 bars to go on the Bird, am I going to notice that big a difference than the 1.03 bars many here are happy about? Also have new FF XHD rear leafs and FF .75 rear sway bar to go on as well. Thx

 

[j-c-c-62]

It seems EVERYBODY is happy with ANY upgrade over OEM sized TB.
The issue then seems to be, how much happiness are you willing to settle for?
On your Bird, I believe you are wasting your money/time with only a .96" upgrade.
I am also not a big fan of formulas, they have been seat of the pants wrong for over 20 years

 

[Runcharger]

I have run 96's, I didn't notice much difference over 92's. I will go directly to 1.03's on my next build.

 

[ckessel]

It seems EVERYBODY is happy with ANY upgrade over OEM sized TB.
The issue then seems to be, how much happiness are you willing to settle for?
On your Bird, I believe you are wasting your money/time with only a .96" upgrade.
I am also not a big fan of formulas, they have been seat of the pants wrong for over 20 years

And part of that equates to what your daily driver is and what you're used to on ride stiffness/quality. For me, I've had 20 years of daily driving an 04 Dodge Cummins 2X Quad Cab Dually. Has a rack and pinion for steering. So I'm used to a very firm ride and stiff feel on the steering. Its what I prefer anyway.

 

[Moparfever65]

This may be splitting hairs, but I believe that a longer torsion bar of the same material and diameter would have a lower spring rate. The charts show the same spring rate for different lengths.

 

[j-c-c-62]

This may be splitting hairs, but I believe that a longer torsion bar of the same material and diameter would have a lower spring rate. The charts show the same spring rate for different lengths.

What maybe the answer here is they have the same wheel rate. Regardless your premise is correct, longer bars everything else being equal have a lower spring rate.

 

[Kern Dog]

Uhhh....The wheel rate will also be affected by the length of the lower control arms.
Most of you will be surprised to know that the A body cars has lower control arms that were 1/2" longer than the B and E body LCAs. That can make a difference even with the A cars having a 37" bar and the B/E having a 41" bar.
I don't know the specifics with the 73-up B or any C body.

 

[j-c-c-62]

Uhhh....The wheel rate will also be affected by the length of the lower control arms.
Most of you will be surprised to know that the A body cars has lower control arms that were 1/2" longer than the B and E body LCAs. That can make a difference even with the A cars having a 37" bar and the B/E having a 41" bar.
I don't know the specifics with the 73-up B or any C body.

And the same can be said for when one changes the rim offset.

 

[69_Coronet]

I just wanted to add a quick clarification here regarding the difference between "Spring Rate" and "Wheel Rate". In general, the value of interest is the wheel rate, as this is how much force is generated by the spring (regardless of type) for each inch the wheel is raised. The spring rate is the amount of force generated by the spring for each inch the spring is compressed. In a coil spring suspension, the wheel rate and the spring rate can be very different because of the geometry of where the spring attaches to the control arm. For our longitudinal torsion bars, the "Spring Rate" is not meaningful since the movement of the control arm causes a twist of the torsion bar rather then a compression. Because of this, manufacturers seem to use "Spring Rate" and "Wheel Rate" interchangeably while meaning Wheel Rate in both cases. Hopefully this helps with clarification. Cheers!

 

[69_Coronet]

Forgot to mention that I am using FF 1.00" torsion bars with a 200 lb/inch wheel rate. I am happy with these, but I think they are definitely stiff enough for my taste. Part of that is that I am running P245/40R-18 tires on the from of my Coronet, so they are a lot stiffer than the stock tires as well. The combination is plenty stiff for me. Cheers!

 

[j-c-c-62]

The problem, with all this terminology mostly IMO exists when trying to compare two different cars or say wheel set-ups, etc. If one is comparing two different bars on the exact same car, it doesn't matter much which rating one uses, as the comparison's basis stays pretty much the same. The unknown here is the wheel rate ratio, which few any way, but can be determined/measured for each cars individual set-up.

Meaning for example, a TB rate in lbs needed to move a 12" lever arm 1" might be 200lbs, A bar 10% stiffer would measure 220Lbs measured same way.

A car with a measured distance of 18" (arbitrary number) from the LCA pivot point to the center of the tire contact patch would need a TB rated at 300 lbs/inch to get a wheel rate of 200lbs
To get a 10% higher wheel rating of 220 one would need a TB rated at 330lbs/inch.