The Dodge Challenger Message Board

I am looking into tubular suspension parts and I am really considering getting a kit from Cap Auto Products ( http://www.capautoproducts.com/kfarms.p ... 9952eb4f4d ). I was wondering if anyone had any knowledge about the adjustable torsion bars and how they work, and if they're worth it.

If they're not then I'm going to keep my lower arms and upgrade to hemi torsion bars.

I got offered a similar set up from XV Motorsports a couple of years back. It was an excellent price via a mate of mine who imports parts, but I went with advice from board regulars and sunk money into Hotchkis E-max
springs and bars and poly bushings, decent shocks etc. Very pleased with the results, handles lovely, sits 2" lower and brushes off the weight of an all iron 440 easy. Even when all the other stuff I plan on like sway bars and tubular uca's it still won't cost anywhere near the cost of that K frame

You already have adjustable torsion bars.

Or do you mean adjustable LCA strut rods?

I think it was the CAP tubular UCAs that got a bad rep for failing. The forces on the upper ball joint were only being supported by a tube butt-welded each side of the ball joint. Some of the welded joints failed.

If I was installing tubular UCAs I would bite the bullet and go with the expensive Hotchskis versions. They look well engineered to me. Combined with the CAP adjustable strut rods you should be well on your way to a great handling car.

I thought the torsion bars were the 41" long bars that run from the LCA to the floor support. I would have also guessed that you could call them strut rods.

I am looking to lighten up the car a bit, and get a strong suspension for the occasional road course like Limerock Park in Connecticut, or Lightning at New Jersey Motorsport Park. Ive already planned on an XV chassis stiffening system. It seems like its the strongest kit out there from what I've seen, and should help the entire car ride better. I am open to suggestions and any input you have on different parts to improve the handling while maintaining the stock style suspension.

GibDTD wrote:I thought the torsion bars were the 41" long bars that run from the LCA to the floor support.

The struts run from the LCA, forward, to the front of the K-frame. Solid mounted adjustable is the way to go with those.

The torsion bars are indeed the long bars running from the LCA rewards. They are already adjustable which is why I was wondering what you meant?

The XV stuff is very expensive and designed around the size of many of their customers wallets.I strongly doubt that in reality it would improve the handling of the car any more than say the Hotchkis system or a combo of the Hotchkis and CAP parts. Also consider the suspension parts sold by Firm Feel. Most of the chassis stiffness is derrived from the addition of subframe connectors. After that it is the stability of the LCA that is most important. Next is having the correct balance of spring rates between front and rear. After that it is the caster and camber angles of the UCA.

Get those three things sorted and you have a very good handling car.

Daves right about the cost of these bespoke K members, frightening amounts
Do some research, people like Firm Feel and Hotchkis actively race thieir products, I wouldn't have thought that you could get much better results than those two

Check this link to a discussion we had a year or so ago, excellent info in there, Drew and Fabien use their cars on a road course/circuit, some impressive stuff


viewtopic.php?f=14&t=9156

I don't remember what the diameter was for hemi bars, but it is only marginally better than standard big-block bars.
Someone pointed to the discussion we had about this some time ago, and the bar diameters used for autocrossing can be impressive.

You can either use the original K-member along with some fat torsion bars (don't go for hemi bars, just check the diameter, if what you're after is racecar-handling).

The current offering from Hotchkis is really great, with rear bars, hollow sway-bars, and the best upper A-arms on the market. It's a bit expensive though.
Good reasons to go for a custom tubular K-frame now that the Hotchkis kit exists :
- weight reduction
- better steering feel than OEM (with the RMS kit and its rack and pinion)
- or specific needs like a big-block and headers in a A-body.
Other than that, the hotchkis kit pretty much sums it up.

You can have a real good steering feel with the stage III steering box from Firm Feel (I helped a friend install one last month, it's really good, much tighter than the Stage II).

You should go check this page (I just found this web site by the way) :
http://www.protouringmopar.com/showthre ... -evolution
This guy has been talking on moparts for years about tuning the OEM suspension for racetrack use, and he knows that stuff.

@Dave : I too thought Capautoproducts were not that good, but since QA1 just bought Capauto, I guess at least the stuff sells well, so it must have some merit after all.

On the 1970 E-body, Hemi bars are the same as 440 bars @ 0.92 inch. My understanding is the the 1971 440+6 might have got 0.90 diameter bars. Remember the 440 4bbl was 1970 only.

GibDTD's Challenger will have come with 0.86 bars unless it was optioned for HD suspension in which case they will be 0.90 inch.

The factory bars on my 72 were the very thin ones, now replaced with Hotchkis Emax 1.03" bars, can't remember the spring rate but this car even with a 440 doesn't pitch or roll, just rides flat and low