I bought a pair of AAR/T/A leaf springs quite a long time ago. I bought them from PST.
Then plans changed when I went with a 426 Hemi. I plan on buying a Dana 60 now.
Should I sell these or keep them?
What's the spring rate difference/ride height on each one?
If they are from PST, I'd question whether they are significantly different than their Hemi versions. At best, I'd guess the Hemi versions to be similar but with 2 extra half leafs on the right side. PST sells a lot of parts for a lot of makes and I've noticed a number of their items are not absolutely factory correct, so their accuracy to the factory specs is pretty general.
If they are true to factory spec springs, then I'd say it is like CP said, the TA set will have slightly more arc, but fewer leaves. Unless you are doing drag launches at the strip, these may be more than adequate for a cruiser and you may like teh rake they provide, especially if you use similar profile tires front and rear. If your going to be getting after it somewhat aggressively, I'd look for a spring with more bias control as the Hemi will produce a lot of torque roll in the chassis compared to a 340.
As far as actual rate, Chrysler was always kind of vague about their rates. Even the chassis books will only say they averaged from 80-120 pounds. I'd venture a guess to say the Hemi and AAR springs are probably very similar in rate. While the TA springs have slightly more arc and fewer leaves, those leaves they have were (originally) thicker. The Hemi packs used thinner leaves, but more of them. Additionally, the Hemi packs used additional half leaves over regular spring packs so their rate was only nominally increased while their control load capability was significantly increased. Mopar did rate the load control aspect of their springs as a ratio since they used asymetrical springs, unlike other makes that used symetrical springs. This rating was the amount of load the front section could control over the rear section. The best production spring for load, Hemi springs, had a 1.4 rating, which means the front can control 1.4 times as much load as the rear section. Super stock springs tend to be 1.7 to 1.8 in this aspect and I've never seen any rating for the AAR/TA springs, but I'd imagine them to 1.2 to 1.3, just taking a swag at it.
I would have thought springs for a T/A would end up with a car that was lower in the rear since they were supposed to be "handlers" for the trans am series. Glad you said something.
In the actual race cars, yes. But the street cars had that side exit exhaust that required a bit more rake to minimize the effect of having the muffler ripped off by curbs and driveways.
I bought the heavy duties from summit Racing are they the same as the Mopar performance XHD's?
They appear to be, but I've never looked at them first hand to see. Unlike the B body sets, factory E body XHDs actually had a similar leaf count on both sides but a different arrangement of half leafs. B body sets physically had more leaves in the right side than the left.
Here's a question for those who know... If springs are made to some specific spec, then there should be a way to find out the base curve and the spring rate etc. Don't the manufacturers publish specs for them?
Yes, the factory designed the springs to specific base curve and rate. However, I've never seen any OEM style replacement vendors ever publish this data. I'd even question if most of them even have it as I bet a bunch of them simply reversed engineered the packs. Some can provide it if you ask to bug their engineers, but their phone reps won't know it. The biggest exception to this is the companies that supply racing springs, such as Landrum, Afco, and Speedway. However, all of their spring designs are based off the mopar oval track spring, not the original heavy duty, hemi or super stock springs. The oval track spring was somewhat of a hybrid as the front segment is shorter than an original B/E body spring, but longer than a SS spring. They also use 9/16 thick leaves instead of 7/16 thick leaves that are in the regular packs and they only came in zero or 1" arch. A zero arch leaf, when installed, actually appears to curve backwards as the spring pad mounting point is in flat alignment with the center of the spring eyes.
