Update on new PST 1.03 Torsion bars.

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TrailBeast

TrailBeast

AKA Mopars4us on Youtube
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73 Swinger 318 with aluminum intake and 1 5/8 headers.

Well, I finally got around to replacing my stock T bars with PST's factory clocked bars. It seems I got real lucky with the swap because all I had to do was back the tension off the adjusters, pull the retainer clips and lower the rear section of my exhaust to get the mufflers out of the way and the stock bars almost slid right out. The passenger side didn't want to move by hand and I didn't have a removal tool, so I wrapped a small 1/8 x 1'' peice of aluminum flat around it and clamped a pair of vise grips on that and with a light couple of taps it came right out. (I don't intend to ever use them again, but someone else might.)

I slid the new bars in, reinstalled the retainers and adjusted the tension to about where they used to be (about flush with the bottom of the control arm) and set her down on the ground again. HOLY CRAP! it was a good three inches higher that it was before after pulling it back about 30 feet and then back in the driveway, as well as bouncing it hard by hand. I adjusted them down to about where I wanted the ride height, bounced it good and hard a few times, readjusted the toe and took her out for a test run. It was really nice to not have to watch for every dip in the road or ridges in driveways any more.

I drove it for one full day (yesterday) and it had settled about 1 inch by the afternoon. A quick readjustment on the height, and another toe check and it was good to go. I LOVE THE NEW PST BARS! Used to be if I had more than two people in the car it would bottom out the front on some of the dips in the messed up streets around here, but not any more. On the same dips the front end only dips about 1 inch and returns to normal very quickly. The car also corners much flatter than it did before, and I have a ton more height adjustment if I wanted it.

I would estimate that the new bars could easily give me 4 inches over stock ride height, but still adjust down to stock. I run BBP 15's and 215 70 series tires on the front and have it set where I have about 2 inches between the top of the tire and the wheel opening. At this adjustment I have about half of the adjuster bolt head below the control arm. This is one of the best results I have gotten since the subframe connectors.

VERY NICE PST, I Love em. Thank you.

P.S. The member discount and free shipping was pretty cool also.
 
This is nice to hear, I have a set waiting to go on my Val. Can't wait.
 
DNasty777 said:
This is nice to hear, I have a set waiting to go on my Val. Can't wait.
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I had mine for a couple of weeks before I had the time to do it, and it was driving me crazy to have them just sitting here in the office. What a difference.
They did somehow lower my fuel economy though.
Maybe due to the fact that the gas pedal can go down farther with them on there. :D
 
If your lower control arm bushings are rubber, wouldn't it be a good idea to unscrew the nut on the pivot bolt and let it turn a little then retighten so as to keep from tearing the rubber? I've been thinking of getting some bigger bars but worry about stiffening the suspension too much. I take it you're saying its not too harsh...?
 
Logan said:
If your lower control arm bushings are rubber, wouldn't it be a good idea to unscrew the nut on the pivot bolt and let it turn a little then retighten so as to keep from tearing the rubber? I've been thinking of getting some bigger bars but worry about stiffening the suspension too much. I take it you're saying its not too harsh...?
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I traded all the bushings for polygraphite some time ago, but you would be correct if I had rubber bushings. The stiffer suspension is WAY worth the trade off for me. I had heard there was a concern from others about that, but then I have also always heard they liked it after they decided to try the bigger bars. The car corners a lot flatter also, which is nice.
 
I just want to know what the wheel rate is on them. Been trying to get it from PST since they did the re-clock on them. Maybe before then?

I run Firm Feel's 1.12" bars on my Duster, but its set up fairly aggressive. Still, with the Hotchkis shocks on it I wouldn't even go as far as to say its "harsh", it feels very much similar in ride quality to my g/f's 2013 mustang with premium suspension. I had a set of 1" bars on it before, and those were too soft. Trying to figure out if I want to go with the 1.03" bars from PST for my slightly more mild Dart. Its either that or 1.06" bars from Firm Feel, which I'm starting to lean toward simply because I know exactly what I'll get, including wheel rate. And since the Dart is on a longer wheelbase I may just go with the bigger 1.06" bars anyway.

As long as you go with a good set of shocks, you'll have a hard time making the suspension "too stiff". It'll just handle better. I still run Helwig sway bars on my Duster, so my effective wheel rate is frequently even higher than the advertised 300 lb/in on the 1.12" bars. I'm sure the PST bars are somewhere between 200 and 250 lb/in, but that's a pretty big range still. Realistically they're probably 220-230 lb/in. The Just Suspension 1" bars were probably in the 185-200 range, but there's no published wheel rate on those either.
 
^^^ Any reason why you would just not back-compute the rate on the smaller bar from the larger ot get in the ballpark? I think it is safe to assume the spring steel properties are the same, bar to bar, as well as the shape at the ends. A simple re-clock should not effect it either.

Works out to 191 lbs/in for 1.00", 213 lbs/in for 1.03", and 240 lb/in for the 1.06" (starting from 300 lb/in for the 1.12"). If all other things are equal, the change in spring rate should be the 4th power of the ratio of the diameters.
 
Sounds about right I put the 1" just suspension bars (on sale) in my '70 duster when I put in the 360 and it made a world of difference. It seems to be a trait of t-bar suspension raising the spring rate really doesn't affect the ride much at all.

Now I just need the rest of the suspension parts to complement the springs

Question since t-bars rotate instead of compress how is the rate measured in pounds/inch?
 
72blunblu states 'wheel rate' in lbs per inch; an actual t-bar rate by itself has to be lbs per degree (of rotation) with a given leverage arm ( ft-lbs per degree really). Any spring will have it's actual rate by itself, and then there is the 'wheel rate', which is how many pounds to make the wheel move 1 inch when the spring is installed in the suspension.

The relation between the 2 is a mechanical calculation; for a typcial coil spring set up, it is based on the the wheel leverage on the spring based on the ratio of arm length to spring position on the arm. You can find the calculations plenty of places on the internet and in suspnsion and mechnical engineering books.
 
72bluNblu said:
I just want to know what the wheel rate is on them. Been trying to get it from PST since they did the re-clock on them. Maybe before then? I run Firm Feel's 1.12" bars on my Duster, but its set up fairly aggressive. Still, with the Hotchkis shocks on it I wouldn't even go as far as to say its "harsh", it feels very much similar in ride quality to my g/f's 2013 mustang with premium suspension. I had a set of 1" bars on it before, and those were too soft. Trying to figure out if I want to go with the 1.03" bars from PST for my slightly more mild Dart. Its either that or 1.06" bars from Firm Feel, which I'm starting to lean toward simply because I know exactly what I'll get, including wheel rate. And since the Dart is on a longer wheelbase I may just go with the bigger 1.06" bars anyway. As long as you go with a good set of shocks, you'll have a hard time making the suspension "too stiff". It'll just handle better. I still run Helwig sway bars on my Duster, so my effective wheel rate is frequently even higher than the advertised 300 lb/in on the 1.12" bars. I'm sure the PST bars are somewhere between 200 and 250 lb/in, but that's a pretty big range still. Realistically they're probably 220-230 lb/in. The Just Suspension 1" bars were probably in the 185-200 range, but there's no published wheel rate on those either.
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I wish I could help you on that but I don't know either.
All I know for sure is the car used to have about a 3" dip when crossing a local bump I went through all the time, and now it has about one inch of dip at the same speed.





nm9stheham said:
BTW, T-beast, what size t-bar did you start with?
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I had 890's on before and changed to 1.03's.





MOPEkidD-3 said:
Sounds about right I put the 1" just suspension bars (on sale) in my '70 duster when I put in the 360 and it made a world of difference. It seems to be a trait of t-bar suspension raising the spring rate really doesn't affect the ride much at all. Now I just need the rest of the suspension parts to complement the springs Question since t-bars rotate instead of compress how is the rate measured in pounds/inch?
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Thats kind of how it feels to me also.
The ride didn't seem to change a lot, but the travel of the suspension shortened.
When I put poly bushings all around (including the stabilizers) I heard and felt a little more road noise and feel, but I don't care about that either as it is totally worth the benefits to me.
 
TB I've found the easiest way to dislodge T bars is to pull the nuts off the LCA pivots, then you can get a bar "up in there" and force the LCA to the rear. This came about from reading here, and the fact, LOL, that the headers got in the way of my home made T bar removal tool
 
nm9stheham said:
^^^ Any reason why you would just not back-compute the rate on the smaller bar from the larger ot get in the ballpark? I think it is safe to assume the spring steel properties are the same, bar to bar, as well as the shape at the ends. A simple re-clock should not effect it either.

Works out to 191 lbs/in for 1.00", 213 lbs/in for 1.03", and 240 lb/in for the 1.06" (starting from 300 lb/in for the 1.12"). If all other things are equal, the change in spring rate should be the 4th power of the ratio of the diameters.
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The properties of the spring steel can in fact be different enough to create some variation if you're going from one manufacturer to another. Yes, its fairly small, usually within about 10 lb/in or so, but since PST is the manufacturer they should be able to get the spring constant for the actual steel they used, and not just a generic number.

For example, the rates you calculated don't match Firm Feel's advertised rates of 195 lb/in for 1" and 252 lb/in for their 1.06" bars, and that's starting from their advertised wheel rate for the 1.12" bars.

It's a small difference, but if the 1.03" bars are 215 lb/in I'd definitely use FFI's 1.06's. If they're 230 lb/in I would seriously consider the 1.03" bars because they're so much less expensive. It's enough of a difference to make it an issue. The 1" Just Suspension bars I bought are on the "light" side for 1" bars, I doubt they're above 190 lb/in, which is why I'm not running them on my Duster, and won't even be running them on my Dart. I'm pretty sure I can count on the PST bars to be between 215 and 230 lb/in, but that's enough of a difference (7% of the wheel rate) for me to change my mind on using them.

Also, if you look at the Mopar Performance chart below, you can see even bigger differences, especially for the larger bars. The MP 1.09" A body torsion bar is listed at 300 lb/in, which is the same as the FFI 1.12" bars I run. That's a pretty big difference given the change in diameter.

nm9stheham said:
72blunblu states 'wheel rate' in lbs per inch; an actual t-bar rate by itself has to be lbs per degree (of rotation) with a given leverage arm ( ft-lbs per degree really). Any spring will have it's actual rate by itself, and then there is the 'wheel rate', which is how many pounds to make the wheel move 1 inch when the spring is installed in the suspension.

The relation between the 2 is a mechanical calculation; for a typcial coil spring set up, it is based on the the wheel leverage on the spring based on the ratio of arm length to spring position on the arm. You can find the calculations plenty of places on the internet and in suspnsion and mechnical engineering books.
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Typically the torsional spring constant for the bars is given as in-lb/degree, which is why the wheel rate is typically given in lb/in. Torsion bars specs are usually listed by wheel rate, even if that's not made clear. Mopar Performance for example just lists their torsion bar specs by "rate", but it's in lb/in, so whether it says it or not it is in fact the wheel rate, and that's what most of us are used to seeing. You can find the equations on the 'net or in books like "Engineer to Win" or "Tune to Win" by Carrol Smith.
 

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OK, I was figuring PST would likley use the same source and steel and you would get reasoanble consistency in back-computing.

Interesting chart in the context of this discussion. Just as an FYI for the A body T-bars, starting with the 1.09" at 300 lbs/in rate as the reference and back-computing other rates from that, here are the Diameter/Advertised rate/Computed rates:
1.14/350/358
1.09/300/300
1.04/250/248
0.99/200/204
0.92/150/152
0.89/130/133

So they are back-computing within 2% or so of the advertised rates and I suspect the advertised rates were rounded to the nearest 50 or 10 lbs. And most cars can't be tuned that fine anyway with other things like bushing stiffness involved. Now you got me wondering why PST is not giving the data, 'specailly since you are looking for such a fine difference. And who measures their T-bar diameters with the paint on and who measures them with the paint off! lol

BTW, edit to add: the same type of back-computed comparisan for FirmFeel bars with 300 lb/in as the reference, is:
1.18/370/370
1.12/300/300
1.06/252/240
1.00/195/191
0.94/155/149
0.88/115/114

Just keep in mind that the published data is measured data (we presume!) and is subject to the errors of their measurements. The 'wire diameter to the fourth power' relationship is a laws of physics thing that simply IS, and when springs deviate from that it is due to manufacturing variances, spring end effects, and measurement accuracy, etc. Getting springs of the SAME rate that are within a few % of each other is doing pretty good.
 
67Dart273 said:
TB I've found the easiest way to dislodge T bars is to pull the nuts off the LCA pivots, then you can get a bar "up in there" and force the LCA to the rear. This came about from reading here, and the fact, LOL, that the headers got in the way of my home made T bar removal tool
Click to expand...

That is how I did it when I took it all apart to put the poly lower bushings in it, but I didn't expect the T bar to slide right out of the control arm so easy.
I just slid it all back to do the bushings but never took the T bars out of the control arm doing it.
The original lower bushings were coming out in small peices when I got the car, so there wasn't much concern about loosening the pin.:D
 
Trail, I tried looking at PST's website and I could not find the standard clock bars in the 1.03" Do you have a part number for them and how much were they? I need to upgrade from my current bars.
 
Good topic with some nice info here guys.
I've got 1" JS bars in my daily Dart but I'm already homing in on a larger set. I'm thinking 1.06 or 1.12".
Currently still running KYB's up front but have a pair of Hotchkis Adjustable Shocks coming my way.
 
I run the 1.06's and they are not too stiff for the street. Much softer than my kid's highly modified tuner car (Caliber SRT4). I think anyone would be happy with 1.03 or 1.06 for the street.
 
Thanks! all I found earlier must have been old B/C the ad said it would lower the car.
Glad I asked, so now I can get a set.
 
ir3333 said:
from that chart 440 b body .920 restoration bars @ 115?
is that a mis-print?
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No, it's not. B/E body torsion bars have a lower wheel rate for a given size bar. The bars are longer, and the LCA's are slightly shorter, hence the lower wheel rate. The 1.12" FFI bars on my Challenger have a wheel rate of 270 lb/in, the 1.12" FFI bars on my Duster have a wheel rate of 300 lb/in.

The B/E bodies also had more "anti-dive" built into their suspension geometry, so although all the parts look pretty much the same, there are some significant differences.

gliderider06 said:
Thanks! all I found earlier must have been old B/C the ad said it would lower the car.
Glad I asked, so now I can get a set.
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They still have the disclaimer on the website that the bars will lower the car. As far as I know PST only sells the re-clocked bars now.
 
The disclaimer should read the following on our site about the bars:

Note: PST’s High Performance torsion bars are intended for both stock and lowered vehicles. With our new indexing, you can achieve either a sleek, lowered pro-touring stance or stock ride height.
 
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