Need advice, what parts to use for an A body open track car

I'm building up my Demon to be an Open Track/ Autocross/ Optima car. I have quite a few spare parts lying around and could use some advice on what would be best to use for the build. I planned on using the Hotchkis TVS system (rather than mixing and matching parts), w fox shocks, and1:06 Firm Feel T bars.

For brakes I wanted to use either the Dr Diff kit (13" Cobra) or the 11.75 with Viper calipers. Which brake system would be better?
For the rears (BBP) I have a set of B Body 11" drums already, but wanted to go with the Dr Diff rear disc kit.

Here's where I could use some advice on which parts to use:

1) I plan on using a 73 spool mount K frame, but do have a 72 340 K frame too. Spool mount the best choice?

2) Control Arms (will be reinforced) with sway bar tabs. I have a set of 73's and 71's. (I also have several drag links too: v-8, 6cyl, 73+v8, etc) Is there any advantage to using either one?

3) Spindles. I have a set of 73+ A Body discs, or 70 E body Drums. Can you use the Cuda spindles on an A body, if I went with the Viper calipers?

4) Factory disc proportioning block (73+ disc A body) or use an adjustable one?

When it comes to tire availability is it better to run 17's or 18's?
I plan on using 275's in front and 315's in the rear (The rear is mini tubbed and the front will be modified as needed).
Thanks for the advice ahead of time.

If I were to do it again, I'd probably would have gone with the Viper front brake kit, but still kept the Dr Diff rears in the back. The Viper kit uses pretty thick truck rotors and since it is smaller, it should have less rotational inertia. Plus, the Viper calipers are pretty decent. Your problem is finding an affordable Viper caliper used.

As for wheels and tires, I'd go with 18" wheels. At least 9" wide if not a tad wider in the front. Try to find a lightweight wheel. I was trying to find a set of Enkei's that fit my car, but since my wheel tubs were so small and my offsets were different, it didn't happen. When I get the fenders rolled and my offset shackles installed, I should be able to fit 18 x 9.5" wheels all the way around with 275/35/18's all with the same backspacing so I have rotatability.

Would like to know first what kinda of power are we looking at here, as that kinda tells us kinda the speeds you will be braking from and how hard/deep you will be braking from, next what are your goals at the beginning of the project, and then what at the end? The 1.06" TB gives me a idea what level you are on, just want to make sure advice is in sync with your thinking.

Quick thoughts:
1. Add power later
2. Forget LCA reinforcement
3. Go square on tires
4. Go two steps higher on TB for starts
5. Go with the least investment Discs you currently own, cool/duct the heck out of them, drive them until you get seat time and they start to fade, THEN upgrade, same for rears but after upgrading fronts, repeat
5.1 definitely add adjustable brake bias, it will change with every other change you make
6. Ditch ANY weight you can, its really cheap
7. Get seat time, ecen with a slant six
8. you can never go too big on tires, 18's have a better future
9. Kissing the Beauty queen in the winners circle will take time.

I've got a mild 360 and a 4spd to use for now. I'd rather get the car sorted out handling wise before going big on the motor.
Putting the car on a diet is already in the plan. So 1:10 on the Tbars?

Can you run the E body drum spindle on an A body?

Good points on the 18's

I believe you can run the E drum spindle on the A. That said, the later A spindle is beefier and takes the better later 11.75" rotors if you go that route... plus a bunch of others. I'd start with the later A spindles personally.

I run the 13" Cobra based brakes on an E with late A spindles and like it. Service parts are readily available which is nice. One consideration is piston size and area. The Cobra fronts have relatively small piston area and need a good bit of brake line pressure. I went with a dual 8" booster and 15/16" master to get enough. Hydroboost is another option. With the high line pressure it is really hard to get the brakes balanced with rear drums. Best to go with the Cobra style discs on the rear with the Cobra fronts. With that you may not need any prop valve. This setup survived a full track day on a heavier E with no fade and no failure. 3 heavy braking events inside 90 seconds, 1 from ~125, 1 from ~90 and one from ~80 for many laps.

If you run rear discs, best to use a style like Dr Diff offers that allows you to keep the tapered bearings. Usually it is necessary to slightly lengthen at least one axle with this kit by welding a hardened washer on the end and machining to correct length so you can set the end play.

The 11.75" fronts with good pads should work OK on a lighter A if you go that route.

Go all the way to 1.18 on tbars, it will save you from having to buy them later.

I agree. Tim Werner's red Valiant has 1.24" T-bars and iirc, rear drums.

K-member is a mixed bag. 69-72 has more room for Milodon road race pan. 73-76 had less room but has narrow sway bars for the high backspace rims you'll need with 275 or 315 18" front tires and rims.

Tim's red Valiant had Dr.Diff rear discs on it when I owned it. Here are a few links to the cars build. Having driven it on track I can say that it was an awesome little car but was still in the "sorting out" phase. I was pacing with a few 3 Gen Vipers the day I took it around the Spokane Road Race track, it was seriously fast but more HP and more tire would have made it more competitive with some of the serious track cars out there. I would put as much money into a safe roll cage, invest in the best brakes you can afford, and plan on dealing with front end aero issues as well, lift makes things "interesting" at around 150mph in a tin can A-body.

http://www.moparmusclemagazine.com/techa...p/photo_04.html
http://www.moparmusclemagazine.com/techarticles/suspension/mopp_1210_stock_suspension_upgrades/
http://www.moparmusclemagazine.com/proje...r_friendly.html
http://www.moparmusclemagazine.com/techa...27_engine_swap/

Thank you all for the replies. I will go with the bigger bars. Great point about using the narrower sway bar. I'm doing a cage similar to 72Swingers with a removable X bar. I have followed and taken notes on most of the builds on here and other forums for years now. I have a really good idea of what I want to do with the car as I've been building it in my head for years.

If you use Hotchkis front 67-72 swaybar, you will not have any clearance issues. 18x9 on a 275

How well do you want this thing to handle? I agree with the big Torsion bars, I would recommend the 67-72 Hotchkis bar, no matter which k member you use. What are you doing to the rear end? If you are going with leafs, you need at least a 200# spring rate, and the biggest rear bar possible. If you really want to run against the big boys, go custom 3-link...

I'd like it to handle as good or better than my 89 Saleen did, if I'm comparing it to something. The area around me has some incredible twisty mountain roads, as well a road course (fernley) and autocross events. So I'm not building it for one set class to compete in.
For now I planned to use the Hotchkis rear leaf springs. I am not opposed to piecing parts together for what works best, as thats what I've done in the past on builds. I just thought using the TVS kit would be a great place to start. I have looked at the Control Freak products ( http://www.freakride.com/product/mopar-4-link-coil-over-rear-suspension-systems-copy/ ) and would probably go that route for the 4 link rear end down the road if I really wanted to get serious.

I daily drive my '73 Dart with 1" torsion bars from JustSuspension, Hellwig swaybar on the front and adjustable shocks all around (Hotchkis front/ QA1 rear).
7 leafsprings per side.

Looking at my own torsion bar 'step-up' from .89" to 1", I think 1.06" or 1.10" would have worked for me as well.
For all racing and competition, I would follow the folks here saying go with a more serious torsion bar.

I raced with the Hotchkis leafs all year, and they are a good compromise of street and track. I end up tracking the Valiant more than street driving so I need more spring rate to keep rear roll under control. I also need to lower the rear another inch to get the roll center optimum for racing. I have added helpers which helped, and the rear roll bar is on full stiff, but ideally if I was starting over with a leaf based system I'd start with circle track 200-250 lb rear springs (Hotchkis are 130lb). THE HIGHER RATE REAR LEAFS WOULD BETTER MATCH THE 1.18 rate TORSION BARS up front. The goal is to get the roll center front to rear working correctly. That weld in 4 link is not serious for this if you want to compete at the highest level. If you look at the photos notice how short the link rods all are. Remember it is a compromise of design to work around a back seat and all sorts of other fitment issues. You need a Custom 3-link or torque tube if you want to truly take it to the next level on a road course. The shop that is helping to build my next car will build and install a custom 3 link for $1500-$2000 that is much, much more effective at putting power down while turning, and the spring rate is easily adjusted with coil overs. In hindsight knowing how much tracking I'm doing, I wish I would have just started with the 3 Link on my Valiant.

For the street, the 1.06's are fine with the Hotchkis/Fox shocks, and 18's. The ride is actually pretty good. I have some ESPO 6 leafs in the back, MP Offset shackles, and the hotchkis front and rear sway bars. 275-35-18 all the way around. For a street setup, it's pretty good. I think you'd want more rate for a track car.

I use a Hellwig E body rear bar .:)

72 Swinger, why did you use the E body rear bar?

Because its 7/8" instead of 3/4" for the A-body version.

What is the rate compared to the 3/4 bar? Thicker doesn't mean stiffer.

I have no idea the rate. The bars look identical though other than diameter. I know it works really well autox'ing on the stiffest setting. Open track its good on its softest. This could change with new tires but its nice to have 4 different settings to play with, 3 holes plus unhooked.

It looks like they mount in a similar fashion at the axle, however the action arm on the Hellwig units looks substantially longer in pics. Do you have a bar you could measure? Distance at all 3 mounting holes would be good. I could do the same when I get home. All the A bodies are at the house right now.

I got 12" from center to center of forward most hole and 10" rear most hole so the middle hole must be at 11". My bar is Hellwig #6908 and the A-body model is #6807.

Went out to check, forgot the 68 had a custom bar. When the sun is out tomorrow, I'll see what I can see. Wife was already yelling at me for wondering around the yard in my socks with a flashlight in the dark

??????, are we talking rates, or material properties?

For simple reference, our A-body sway bar is stiffer than the B-body bar.

A-body rates:
- 230 lbs/in
- 265 lbs/in
- 310 lbs/in

B-Body:
- 150 lbs/in
- 180 lbs/in
- 220 lbs/in

Also, material choice does not affect the rate of the bar; a chromoly bar will have the same rate as a mild steel bar. Different materials are used for their bending properties for when the bars are shaped on the bender.

Does not matter what the Hotchkis bar does in my case because it wouldn't work with my inboard springs, where the Hellwig does.

Jon, the three rates you listed for A-body front bars are 63-66, 67-72, 73-76 ? Or is that different bar diameters? Are those rates wheel rates or bar rates? I am changing to the 73 K-member on my 70 Swinger, and want to replace my old PST front bar. I don't care for the 73 set-up, because it is about 50% as installed, using the original tabs. I want to get out to my added tabs on the shock mount bolts. (aprox 70%) My current bar is around 340lb installed. Rick, Sacramento.

Rick I think those are the rear sways in each of the three adjustment holes. Jon do you have rates for the two different front Hotchkis A Bars?

Tommy is right, those rate I posted were for the rear.

Fronts are a bit of an apple to oranges comparison really since they mount and attach differently:

67-72: 700lbs/in.
'73+: 375lbs/in.

Unfortunately I do not have the motion ratios for the lower arms in front of me to calculate the wheel rates.

When Aaron and I talked about this, then different mounting locations equalized the rate; however, the earlier bar allowed more control because of the longer action.

That sounds about right from the arm lengths and attachment points.