There's a company called QA-1 that make a pre-fabricated front suspension for A, B & E-bodies that are tubular and use coil overs. Maybe give them a call?
I think I might have discovered the reason for the pre-fab front suspension for the A,B,E-body cars, which includes coil-overs on the front. NOTHING about the common issues of "torsion bars getting the way of headers" or anything like that.
The smaller platforms for which the front structure is designed for gets rid of the torsion bars, NOT because they are different or because Ford or others use coil springs instead, but so the super-tourers can have more accurate steering. It seems that in order to reduce/eliminate "bump steer", the steering linkage needs to be higher in the chassis than torsion bars will allow. Any oil pan issues can be easily addressed with alterations to the oil pan, even a welded-in tube, if needed.
I happened across a YouTuibe video where a guy was seeking to modify his '68-'69 Charger front end to reduce bump steer. He talked about how horrible it was on the B-body torsion bar front end (which is very similar to the C-body set-up). He then did an illustration of what it would take to get rid of or diminish it on a Chrysler front suspension.
When a front wheel rolls over a bump, the tire rolls up and over it, but at the same time, the toe-in can change a bit when this happens due to the change of location of the front wheel. As in a slight bit of toe-in or toe-out, from specs sitting still. Which can also affect the direction the car might desire to travel in. Hence, a slight change of direction. The YT person than goes on to bad-mouth the "bad design" Chrysler torsion bar front end, at least for the purposes he desires to use his Charger for.
In the super-touring cars I've seen in magazines and in person at car shows, they typically sit lower, with very wide tires, and larger rim diameters to use the latest tires on. AND, they all have a different front crossmember with coil over shocks. Probably even rack-and-pinion steering, too.
He also talks about "rear steer" (steering linkage behind the front wheels, with "front steer" being like Gen II Camaros/Firebirds which have everything in front of the front wheels) being "bad". THAT part I would disagree with due to the accuracy of the Ackerman angles between the two different systems. Which a friend in the alignment business, 2nd generation, who was also a great dirt track driver, related in a discussion of the differences of the two designs.
In the later 1960s, when we'd take the Chrysler to the dealer, the floor in the shop was sealed, but not slick. When the cars turned into the stalls, little tire squeal was heard. By contrast, at the local Chevy dealer, in a similar situation, the tires squalled much more. I figured it was due to the GM's tendency toward understeer, which Chrysler did much less of. That was then, before I knew what was going on. When the main vehicles which were rear steer were Chrysler Products and Corvettes. An interesting combination
As Randy explained it, which made sense, on a rear steer system (which includes the bulk of rack-and-pinion systems, too), the Ackerman Angles were more perfect. Hence, better handling and steering precision AND slippage. On a front steer car, the Ackerman Angles are not quite so good, so each front wheel slips a bit in a turn.
AT the time, the 1979 WS-6/7 Firebird TransAms were right behind the Corvettes as the acknowledged best handling cars made in the USA. Yet they were front steer! This was explained in an article on such in an issue of CAR AND DRIVER, about how a front steer car could have such good transient handeling but possibly not the highest skidpad G readings. With the more mis-matched Ackerman Angles, ANYTIME the tires turned to make a change of direction, they were in "slip mode", which means that each tire was quickly developing "grip" due to the fact they were already in "slip mode". By contract the rear steer car's front tires went from "no-slip" to "making the corner", when the front steer car's tires were already in that mode. So, more responsive handling.
Personally, I feel a rear steer car will always be the most-neutral handling car (which is validated by the 1970s Corvettes), even with more weight on the front end. Tire wear can be better, too.
I'm sure there is a "window" of how much the front wheel can move up/down before toe-in changes enough to affect directional stability. Just that that was NOT mentioned in the video! More research needed on that point. Still, bump or extension of the suspension sends the wheel in different directions. Just as when doing a front end alignment, the LAST thing to finalize is the toe-in, for this reason.
In a super-touring vehicle, which might be capable of running 160+mph, with its stiff suspension calibrations to tolerate such, having toe-in change on a small bump is not very desirable. Hence the concern with bump steer. Which then generated the front frame structures needed to get rid of it as much as possible for safe and easy "super-touring".
Now, our '66 Newport Town Sedan w/factory a/c (this is important as the factory a/c cars got the same torsion bars as the HD suspension cars did, but not the law enforcement cars, as I recall), with normal shocks (later upgraded to Chrysler parts HD Monroe Supper 500 equivalents) had a normal "feels good" cruising speed range of 75-95mph. It liked that on any smooth highway that it was on, that was reasonably straight, for hours on end. Slower, it was bored. Faster, not quite as enjoyable, more throttle to increase speed a few mph and the shocks were getting out of their "good" range. But otherwise, it was happy. Front end alignment was set to factory specs and tires were inflated to 30frt/28rr and "normal load". By comparison, my '70 Monaco Brougham 383 "N" car felt a bit softer, as did our '72 Newport Royal 400 2bbl. All were at factory ride height, too. Still, NO direction stability issues, even on bumpy roads, that better shocks would not have fixed.
As I said, I always questioned the alleged "need" for a different front suspension, torsion bar-less on the A,B,E-body super-touring cars. I felt it was because "Chryslers were different" more than anything else, which might also still be operative. The "headers" issue did not make sense, for the same reason, to me. BUT the issue of "bump steer" CAN make sense, in those vehicle uses.
NOW to discover at what wheel movement change levels bump steer can become an issue with the stock suspension.
Enjoy!
CBODY67
