73 challenger

[Jc66]

Hey everyone first time poster here.

So recently my my uncle has approched me about purchasing his 73 challenger, he has owned the car since I was about 6 years old and I’m 26 now. In that time he’s only put 4000 miles on the car and 1000 on the 440 he found for it about 12 years ago. Car started as a plum crazy purple with a white top and had a 340 six pack in it.

I have big plans for the car but I first want to address the suspension, I know about the Hotchkis system but not sure about any other companies that support the mopar E body platform, are there any coilovers systems out there? I guess I’m looking for someone who can point me in the right direction on where to look for suspension systems. Real world experience would be appreciated.
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[elwaupo]

I’d check out the show ‘Graveyard Cars’ on the Velocity Channel, I saw an episode where he addressed the terrible handling of those model cars. They replaced the old suspension with a ‘K Member’ with coil overs which is a night and Day comparison to the old Tortion bar suspension. I don’t know which brand it was but I’m sure if you do a Google search you’ll find one.

[mikedc]

The aftermarket setup you saw was probably the RMS AlterKtion setup. It's a well-sorted package that uses aftermarket Mustang-II based stuff.

The Hotchkiss deal is for improving the stock setup. Still very good results.


My two cents:

Don't sell the Mopar T-bar setup short. It gets a bad rap from GM/Ford guys because it's so different from a GM/Ford. People don't like messing with unfamiliar things.

The T-bar deal starts working fine once it has a bunch of fresh parts and a few smart tweaks. The geometry & native handling traits are good. It's not intentionally hobbled just to slow down bad drivers (like early GM stuff). It's still not the BEST thing out there but's all that most drivers can handle. Pretty fast and very predictable.

Give the stock setup a fresh overhaul if the bushings aren't good. Give it modern spring/shock/bar rates. Set the alignment for radial tires. Add a few degrees of caster into the front end (either offset bushings or aftermarket UCAs). Check to make sure the factory steering box is adjusted right. With this stuff done you may be quite happy with it. The front end won't be so floppy on bumps. The body won't lean much in corners. The steering will start pulling itself back to center when you let go of the wheel like a modern car. Etc. (There's a few more things that can be done but this is just the lowest-hanging fruit basics.)

[superbee6]

I've been looking into the same issues with the suspension. You actually have some very good options for either keeping the torsion bars or going with the coil overs. I just purchased a Superbee pro touring project that had been sitting for a while unfinished. The car came with an Air Ride triangulated 4 bar in the rear and a coil over conversion with K member for the front from Control Freaks. So, I didn't have any of the stock suspension. It was a bit of a mis-matched set up, air in the rear and coils in the front. There are no air options for the the Control Freaks so I've decided to sell the front set up. I believe the K members for B and E bodies are the same. If you are interested, let me know, it's a complete setup with power rack and pinion, QA1 coils and sway bar, spindle to spindle. You can get a nice wilwood brake setup for it for about $700 or a bit more.

The advertised advantages of the coil over conversions you get better caster angles, less bump steer, rack and pinion (better feeling and tighter steering), better header clearance (torsion bars are usually in the way), better roll center, better bump steer, and weight savings (although probably not that much), eliminates the strut rod that allows some play. Probably a few other things.

The torsion bar set up is pretty tuneable now if you get tubular upper control arms, there are more torsion bar sizes available these days, sway bars, box in your lower control arms etc. If you keep the torsion bar setup you are stuck with the pitman arm style steering linkage and that style power steering. There are a couple options for improving the feel and operation of that system, Borgeson steering box, and Firm Feel steering box. there have been a couple Valiants that kept the torsion bar set up and were very competitive in autocross. There's a lot more available these days for improving the torsion bars.

The good thing about the coil over conversions is that they're bolt on (for the most part) and you can revert back to the torsion bars with minimal effort.

Anyway, here's a list of your options. There may be more out there.

Keep the torsion bars:
QA1: Performance Handling Kit: Tubular K member, tubular upper arms, tubular lower arm, heim joint strut rods (I've heard that a strut rod that's mounted too rigidly gets' the suspension in a slight bind state through the range of motion) They sell a kit for about $3000.

Hotchkis: Uses you stock K member and lower control arms. They add better sway bars, hardware, bushings, upper control arms, rear springs, strut rods, frame connectors, NO shocks. They also sell kits, one for the front and one for the back or what they call the TVS (Total Vehicle System, For E body it's about $3300).

Coil over conversion kits:
RMS (Reily Motorsports) AlterKtion: One of the originals, great service, great reputation. Biggest complaint I read about this system is increased turning radius. Expensive, completer front suspension $5000.00, includes shocks, and rack and pinion, sway bar, motor mounts, NO brakes. in my opinion, this system looks stout and well built.

Magnum Force: They sell a few kits for the front end. Also one of the originals, they have a tubular version as well as a welded version from flat stock called Transformer (and that's what it looks like, a Transformer). I live around the corner from them, I have no personal experience with them. However I've heard of customer service issues. Systems delivered with two right side arms and then 6 months to get it corrected, ignored the customer's calls for support. Part failures and no support. I've heard the owner is hard to deal with and the sales people that answer the phone don't know the product very well (maybe they were new to the company?). Again, expensive, no brakes, $5100.00. They do give you lots of options, you can get the basic system for $3100 but that's bare, not even powder coated. But having the options is nice. They would be last on my list

Control Freak Suspensions: They have Front and Rear systems. Their front kit is complete minus brakes for $3600.00. I have talked with one of the owners personally and he was great, very helpful. They have good records and were able to look up the kit that came with my car that was originally purchased in 2010. I had heard they had good customer service and I experienced that first hand. He was very knowledgeable on the brake kits available and suspension geometry.

HDK Suspensions (Hemi Denny): Their kit looks very nice and stout, nice details. I've heard great customer service from him. His kit is a bit more Ala-Carte, you have to buy some stuff separately, rack and pinion, spindles, etc. However, he has them all available through him so they might as well be options for a complete kit from him. Not including the options, his kit starts at $3000. I wish he had a few more pictures on his website.

Gerst Tubular Suspensions: I've heard good customer service from them and I've experienced that first hand. I've talked with Carl Gerst personally a few times and texted with him about his systems. Great guy, very knowledgeable and helpful. I've seen his system in person and it's very well built. I like the way he structured his cross brace. While speaking to him we discussed the turn radius issue and he said he had to add a turn stop to his system because without it he had so much range of motion available the wheels could be turned too tight. Another common issue that's been discussed in the forums regarding these systems is track width. His system keeps the track width right at the stock width and is adjustable. They have three levels of kit, Basic, Drag and Eliminator. Basic is a complete kit including brakes powder coat and sway bar for a hair over $4000.00 The eliminator kit is an upgrade to wilwood brakes, power rack and pinion, and upgraded hardware and joints for $4800.00. In my opinion, the Gerst Eliminator is the best bang for the buck comparing the coilover conversions. Well built and more complete for the price, great customer service.

There may be more out there but these are the ones I've found.

Lots of options for 4 bar rear ends too. Most of these companies also have the rear systems.

Hope this helps. Sorry for the long reply but there's a lot to take in.

[BMR Sales]

Start by going back to Plum Crazy and drive it for awhile!

[jvike]

First of, when going Coil Over, your first mission is platform stiffness. You need a firm platform for any suspension system to work. You'll need sub frame connectors, inner fender bracing, lower radiator support bracing, and maybe an engine bay ("Shock tower") brace, and torque boxes. US Car Tool and XV Racing Products sells stiffening kits.

Great info on the suspension options there. I do not know much about the later additions Gerst and HDK, but as you can see they are all pretty similar and are all based on the aging Mustang II.
Control freak is a straight copy (rip off) of the RMS Alter-k-tion. They ordered up one of his suspensions and reverse engineered it and sendt it back when they built their GTS Darts. Ask Bill Reilly about it. Also a local shop had problems fitting it to a 71 Cuda, the lower arms where shorter(!) than the upper. But since it is a copy you should be be able to get air shocks for it, since the RMS can be had with them. It's all Mustang II.

I would like to add another option in the Coil Over department.

https://xvengineering.com/ (XV Racing Products) sells a Corvette C6/C7 based front suspension that is all aluminum. They also offer a 3-link rear suspension with a panhard bar. I have this system on my 70 Cuda, and have had it since 2010. Real deal handling. I can assure you. The front sells for $5595. It has second-to-none engineering behind it. Done on 4-post rig by Multimatic. It was developed by now defunct XV Motorsports. But employee Chris Reinhardt continued the effort.
I have a playlist from Dream Car garage about the development of this system here -->https://www.youtube.com/watch?v=12rAF7CTtEw&list=PLZZAq_SZNwEiY5G3fAxrmaqxMTtXoFdGv

As for brakes you have endless options since it's Corvette based. I have Stop Tech. Also there are a huge aftermarket support for anything Corvette, I have drop spindles from LG Motorsports on mine.

https://static1.pt-content.com/images/pt/2017/12/12527422645_3819d9e8ed_b-1.jpg (https://flic.kr/p/k61jiB)

https://static1.pt-content.com/images/pt/2017/12/12527433535_ec014c9e26_b-1.jpg (https://flic.kr/p/k61nxn)

[High Plains Mopars]

Budget and goals?

A coil over suspension on both ends will cost $10,000+ An upgraded stock set up from Firm Feel or Hotchkis will run $around $5000.

Will you be racing? What sanctioning body? What rule sets will dictate your set up for compliance to rules or weight penalties for variations from stock??

Do you know how to set instant centers and do other suspension adjustments that come with a multi adjustable coil over system? Its entirely possible to adjust yourself right into an ill handling vehicle if you are new at this.

[rrunner68]

Fastest Mopars in the country are running Hotchkis. Despite what someone posted earlier, they have a complete shock package that is tuned for the chassis. The setup has won numerous Mopar autocross events across the country and also won a regional SCCA CAM Championship in the most heavily attended region (15-18 cars on average an event).
All the rest is fighting for second, and are way behind.

[GMachineDartGT]

I enjoy a t bar setup and have done 2 Optima events along with numerous track days. There is a lot of misinformation on the web. I also manufacture the fast ratio steering kits as well as being a dealer for qa1. Let me know with any questions, Bergmanautocraft.com.

[jvike]

Here is an interesting article on a guy who took the stock stuff to the max!
http://www.hotrod.com/articles/1970-plymouth-barracuda-aar-cuda-road-america-test/

[High Plains Mopars]

Overall the stock Mopar suspension isn't bad. Its biggest issues are lack of caster, bump steer, and limited rates available for the t-bar suspension. Improve these the caster and bump conditions, balance the suspension rates and you can have a design that is more capable than many drivers.

Look at it this way, the stock based racing suspension of the 1970 Trans Am racing season for Challengers and Cudas had these car turning faster laps than many modern cars. Can you make them even better, sure, but you had better be prepared to spend a fair amount of money as well as put in some effort to get there.