70 charger suspension upgrades

[chrisbinks]

Hey all, can anyone name a good suspension upgrade ,  one that handles awesome on the road and also great on the track?

I'm building a charger to use for both and wondered what you guys have used and recommend.

thanks

chris

[HPP]

What kind of track and frequency of use on that track? Budget of upgrade? Single upgrade or a package approach? What constitutes awesome?

[chrisbinks]

What kind of track and frequency of use on that track? Budget of upgrade? Single upgrade or a package approach? What constitutes awesome?

Be looking at track a couple of times a year. Be driving it on road more.   About $1500 probably. Or maybe less. Im not sure. Depends whats out there. Im looking for something thats gunna take corners better than normal suspension does. Im based in the uk an as you guys can imagine. Roads here arnt as perfect here as they are in the US

[HPP]

$1500 is a tight budget, even by US standards. I'm sure you will incur some additional costs along the way since you are  shipping across the pond. 

What are you starting with now?  Do youhave an original suspension, pieces and parts of unknown age, nothing at all?

If your in UK, are we talking Santa Pod or a road course? Good hanlding road suspensions are not the fastest at the drag strip, but they are much more consistent than a dedicated drag style suspension. Road course suspensions translate well  to street use as long as you don't go too heavy  on spring rates.

[myk]

Hotchkis sway bar set and their shocks.  That's like $1200 or so.  You could then weld on the Mopar Performance subframe connectors and your car will be worlds better than stock.  Wait...what wheels, tires and brakes are you running?

Honestly though, you're going to have to at least double your budget if you want to execute your upgrade properly.  I spent around $4K on the Hotchkis TVS, larger wheels, tires, disc brake conversion and I'm not even DONE yet...

[chrisbinks]

$1500 is a tight budget, even by US standards. I'm sure you will incur some additional costs along the way since you are  shipping across the pond. 

What are you starting with now?  Do youhave an original suspension, pieces and parts of unknown age, nothing at all?

If your in UK, are we talking Santa Pod or a road course? Good hanlding road suspensions are not the fastest at the drag strip, but they are much more consistent than a dedicated drag style suspension. Road course suspensions translate well  to street use as long as you don't go too heavy  on spring rates.

ok cool, supposing cost wasn't an issue and i want to keep standard height,what would you guys suggest  ill be using boys c5 wheels front and back, 18'' .   the tyres I'm not overly sure on yet I'm not at that point,  it will be having dual callipers on each wheel also. I'm basically buying a car one that needs restoring, when i can find one, its got to be the 1970 one as i love the look of that model. always wanted it since been a kid. i mean is there a suspension system out there thats adjustable for road and track use ?   you guys are the experts I'm still learning,
so sites to go on or suggestions are all helpful . many thanks
thanks chris

[HPP]

Here are my thoughts. I'd avoid getting something that is uber adjustable as it becomes way too easy to mis-adjust and end up with a worse than stock situation. There are some adjustability that needs to be built into some of the hard parts which is why I suggest the following two companies. I'd proceed down this path using Firm Feel or Hotchkis parts as they can be bought one at a time to facilitate the evolving you car will go through. The very first thing to do is rebuild the suspension. $300-1000 depending on if you do it yourself of have a shop do it. If you have to do this step first, then  opt for the Moog  offset upper control arm bushings. Install these opposite the instructions to  obtain more caster instead  of more camber.

An early stage that is the need to create a solid foundation for all the improvements to work off of. You need to shore up the flex in the car to allow the suspension to do its job. As such, the minimal starting point for this would be sub-frame connectors or a set of torque boxes. You  can get as fancy with this as you want from basic 1x3 tubing to contoured connectors. If you want it to all look stock, the  torque boxes can impart a stock look that helps firm things up over nothing at all. I'd say these are minimum to start with  body bracing. You  obviously can add even more pieces in more areas to really step up creating a solid car, but you  need at least this first step.  Firming up the body also has the side benefit of reducing squeaks and rattles, allow panel gaps to remain constant, improving window seal and reducing wind whistle. Costs for this can be as low as $20 if you cut and fab and weld your own to a few hundred for custom fit contoured units that someone else installs.

Wheels and tires are obviously the biggest improvement you can do. They also are the most expensive single purchase of the entire process and will consume a large percentage of your budget. So this would either be the very first thing or the very last thing I'd do. Typically I do them last. If you do them first, it will help some with grip, but it is still dressing up a turd as the systems underneath it all can make the 14"  tire set up feel significantly better while 17" tires on a tired suspension  will still feel floaty, wander, and  bottom out.  Probably will be even worse as most guys step up width in  addition to diameter, so you get the double whammy of bad suspension combined with wide tires that will make the wander even worse. So $2000 budget for this update and it can be thrown in at any time during the process.

Along the same lines as tires are steering boxes. Again, first or last, but I'd do it last. Steering boxes don't do anything for actual performance increases, but they  do make a world of difference in road feel. They also are expensive as a Firm Feel  units will run around $500 exchange or the  ultimate box approach may be a Borgeson  box and related  hardware. This is a late model style box that will really change the feel but will also set you back $1000.  IMO, there is a shim trick that can reduce pump pressure which gets rid of the over-assist and swap out the box  much later down the line.

Depending on your choice of doing the above changes, the next thing I'd do is get a radial friendly alignment. While this  may need to be done again after some other changes, sometimes simply doing this entirely changes the  personality of the car. If you have a good shop, they  may have already done this, but odds are, they probably didn't. Ask for 2000 Mustang specs to simplify the process. These keep your  shop tech from being confused about the uniqueness of the mopar set up and putting  the OEM specs under, especially if they don't do custom work. OEM  alignments are  for skinny bias ply tires. Unless you are using Firestone Wide Oval repops, avoid  factory specs. If your shop does do custom work, you want  5-7* positive caster, -.5-0* camber, 1/16" toe in, or maybe  .08* toe in.  The reason for this is positive caster increases stability, creates more dynamic tire orientation during suspension cycling, and  helps increases road feel. The  negative camber also increases the tire's ability to stay in touch with the road surface, especially with softer torsion bars. The toe  minimizes wear while  keeping the tires as straight forward facing as possibly with all the  joints in the  steering system. $40-100 depending on your local shop rates.

After that, better shocks. Since you want a good handling street car and are doing minimal racing, there is no need to get crazy with adjustable units. The RCD Bilsteins would be  great for this. $400 for this update. If you are really in a pinch, Monroe Gas Magnums can make do and can support  increased torsion bar rates under 1" if you go there later. These are only $100, but the Bilsteins are a huge improvement so I'd encourage you to  use them instead.

Next, a  stepped up front  sway bar. The tubular units are a nice step up in performance. $300 here. You can  add a control arm strap or plate to  help apply some of that force as well as the bigger bar imparts a  big increase in force on the lower arm. Compared to the stock  .875" bar, a 1.125" solid or  1.25" tubular  bar  is going to do a lot of controlling body roll in  corners and imparting a more confident feel.

After the front bar comes the addition of a rear sway bar.  New Hellwig and Hotchkis models can be adjusted to further dial in feel, so that is a nice position to be  in, but is not a requirement. This saves you a couple hundred bucks.

After sway bars, if you still want to  add improvements, then this is where some stepped up  torsion bars and leaf springs come into play. Moving up to 1" diameter  t-bars will match nicely with the previously selected shocks and provide a big step up in wheel rates that are much more late model in feel. Hotchkis does suggest 1.12 for their components and it certainly can be felt.  Torsion bars may be found as cheap as $200 but will most likely be $350+

Stepping up the front without a comparable step up in the rear will typically produce an unbalanced car that  understeers worse than  stock.  I'd suggest changing  leaf springs to match the torsion bars are the same time or  at least in stepped replacement with each other.  This is where the matched sets provided  by Firm Feel or Hotchkis are help full. There are several sources for these. Expect to spend around $400-500 depending on how customized you want these to be.

Part 2 to follow. This info is too long for a single post...

[HPP]

Part 2 from above...

So there is the basic formula for a solid cruiser:

suspension rebuild $400
sub frames $150
alignment $100
Shocks $400
front s-bar $300
rear s-bar  $200
t-bars $350
leafs $400
Wheels & tires $2000
total  $4300

Obviously you will have savings if you don't need a  rebuild from start, get a complete car with good wheel and tire package already, or pick up any deals along the way and this goes up if you decide to pull in steering box swap or substitute tubular control arms for items you don't need as part of the package.

Out beyond that are incremental improvements that are going to produce that Nth degree of feel that most drivers can't differentiate and certainly aren't pre-requisites for the biggest step up in improvements,  but can certainly help improve things further.  Among these would be  tubular control arms - biggest gain, extra caster, $400+. Some would argue that these should be part of the list above. I might conceed that if your alignment specs are really crappy right out of the gate. One of mopars achilles heels is the  lack of our ability to get decent caster numbers. Tubular upper control arms are built with extra caster in them and combined with different adjustment features and the stock eccentrics, can easily achieve 5-10* of caster . This is one part I'm  kind of torn on not recommending right out of the gate but it is really a variable  form car to car. 

Solid tie rod sleeves or stepping up to 11/16 tie rods- $200 for reduced deflection under heavy corner loads.

Welded K frames -$ is variable if you can do it yourself or have to pay. This falls under flex reduction which is always a good thing, but unless you're tearing your car apart, this is a tough one to accomplish without  putting your car out of commission for several weeks.

Pitman arm bearing/brace - $135, again, flex reduction and  more pointed steering response. IMO, this is a  decent upgrade if you never plan on welding up your K frame. This bolt in very easily on completed cars.

Idler arm bearings - $125, part of a smooth steering package.

Fast ratio arms - $300 this does speed up steering response. Great for low speed parking lot racing or tight  confine parking, but not a prerequisite. If you do a lot of high speed autobahn type driving, I'd actually recommend against this.

Adjustable strut rods or  fixed pivot  strut rods - $200. These can help fine tune caster and do help reduce toe changes under heavy breaking. Not bad things to have  and certainly necessary if you ever push the car through cone racing but not required for a cruiser or causal bracket racing.

Other changes like offset springs, drop spindles,  special brake compounds, so on and so forth get into the  how far and how hard do you want to push improvements or any individual quirks we have about having something we fancy.

So, my opinion on spending your money. I'm sure others  may agree or disagree. Your mileage may vary as well.

[BLK 68 R/T]

 

I just went through this on my car.  I did everything above, with the addition of the tubular upper control arms, drop spindles and disc brake upgrade. Depending on what upgrades and wheels and tires you decide on, expect to pay as much as $5000 or more before you are all said and done.

[nicjasno]

What about Rack and pinion steering systems like these:
http://www.summitracing.com/int/parts/uis-8010630-01/overview/year/1970/make/dodge/model/charger

And a polyurethane bushing setup (especially for the strut rod)?

And what are your thoughts on a 4 link suspension with coilovers in the rear, instead of leaf springs? I have seen a bolt on kit, that just requires you to weld in 2 brackets for the upper links because the lower links use the front leaf spring mounts. This way you could use either the stock setup with leafs or the 4 link setup.

[Mike DC]

               
Stay away from that R/P conversion.  Bad geometry, etc. 

The only good R/P conversion I know of is the entire RMS front suspensions changeover.


But if you run a decent rebuilt stock steering box + additional caster in the upper front arms, it will probably fix most of what bothers you about the stock steering.  It makes the steering do more to center itself when you let go of the wheel instead of "floating".   

[nicjasno]

               
Stay away from that R/P conversion.  Bad geometry, etc. 

But when increasing caster, you inevitably have to change the position of the stock track rods, so that they stay paralel with the swingarms, otherwise you get massive bump steer aswell, no?

[Mike DC]

The method of changing caster on these cars we typically use is to only move the upper arms.  The spindle snout location is much closer to the lower arms than the uppers so there is very little impact on the static wheel location this way.  The lower arms stay put, so the steering geometry does not see a major impact from it. 

[nicjasno]

I see. Me being a perfectionist, it does bother me a bit. I know that the lower ball joint is basically right in line with the wheelaxle, so when moving the upper ball to the rear, the wheelbase remains unchanged, but the spindle snout still travels downwards a little bit.

The steering knuckle and the lower swingarm planes are very close together, but if they aren't paralel, the arcs they travel on are not the same and bump steer occurs. There's bump steer as is in the stock setup, but without adjusting the steering knuckle after changing the caster, the bump steer is increased even more.

Arent there any methods to remedy this? Like shims or different endlinks? Or even a different spindle?

[myk]

You can either use upper control arms that are built to add additional caster to the suspension, or you can buy offset bushings on the stock control arms that will add caster. 

I suggest you go to the Hotchkis website and look at their products.  I am using their upper control arms.  They are high quality, bolt-in pieces.  With them I was able to get 6 degrees of positive caster and I have ZERO bumpsteer.  I didn't have to change the spindles or anything like that and the car handles better than I could've ever hoped...

[nicjasno]

That is awesome to hear! Thanks.

Maybe in adition to the added caster, this fixes the factory track rod geometry, which was made for soft bias-ply tires.

[Mike DC]

    
Some amount of bump-steer is inherent in the stock suspension design.  The torsion bars occupy the ideal space for the center steering link to be.  It's always a compromise.  We just set up the front end to minimize the effect and make the outside cornering wheel's bump-steer happen in an under-steering (safer) way.


The stock chassis is considered a very good setup for its day and not really bad even now.  The unibody was very stiff for the era, the geometry is more modern than many cars of the era, etc.  

Add radial tires, front disc brakes, a little more caster & camber, a little less toe-in, and the chassis really wakes up.  




BTW: somebody (HPP?) pointed out that you can ask the shop to align the car to 2000 Ford Mustang specs.  It may require upper arm changes to get it there, but the point is those numbers are a good place to end up.  It's a set of instructions that a modern alignment shop can deal with.  

[nicjasno]

Also, regarding steering, i heard people swap in c-body tie rod ends and sleeves and police spec (from diplomats/polaras) steering boxes.

[Mike DC]

                
The "police" steering boxes were just a standard box that the factory assembled with tolerances as good as they were designed to be in the first place.  That made it better than average, as most of the produced boxes were a bit sloppier.  

Getting a standard one rebuilt by Firm Feel Inc or Steer & Gear will give you a better result than hunting up an old police car box.  They can also do a couple different levels of reduced power assist if you request.  That makes it feel a little more modern also.

There is an adjustment on the box itself that needs to checked once in a while, rebuilt or original.  



The steering arm thing doesn't hurt but you won't really feel a difference.  Do it if you are already going to rebuild the front end, but don't bother taking the front end apart right now just to add it.    

 

[nicjasno]

The steering box info is very interesting. Didn't know that bit.

Thanks for the info!

[HPP]

As MikeDC points out, some bump steer in inherent with a mopar simply because the tie rod and torsion bar compete for the same pivot location. It can be improved to a point you can't feel it while driving, but it cannot be totally eliminated if measured with a dial indicator.  The Hotchkis solution for this is a bump steer kit that will drop the location of the outer tie rod end. They use a tapered shaft with a threaded sleeve that mount into the stock steering arm and their tie rods to allow you to improve the bumpsteer. They have measured a number of cars and derived this kit as means to improve all cars within a range. It isn't exactly precise, but is an improvement. If you are very detailed oriented about bump steer, the Mopar Chassis Manual details very precise information on measuring and changing the bump curve.

Mike also nailed the R&P steering issue and I agree with that assessment. If you really want to improve precision, the later model Borgeson steering box is a further refinement over stock boxes in more precise on center control and lighter weight. However, it comes with a hefty price tag as well and this conversion will be double (around $1400) compared to using a FF or S&G box. I've heard rave reviews of this improvement, but it is not a straight bolt in either as you need to modify the method of connecting to the steering column as well. I'm very happy with my FF box and the additional caster alignment. These two items significantly changed the feel over the OEM steering. There are also other ways to reduce the OEM over-assist that comes with power steering, but I won't get into those right now as there are several topics in the forum regarding those changes.

Also, 2000-2005 Mustang GTs have alignment specs that are much more compatible with wide, radial tires. They are pretty aggressive specifications compared to the stock mopar numbers so you may not be able to meet them using all stock components in your mopar, but they are a good spec to target if you have to use a shop that is not very knowledgeable about classics.

Yes, stepping up to C body tie rods and ends is a popular improvement.  The biggest improvement from this is reduced flex. However, this flex is pretty minimal and hardly noticeable. The original size tie rods ends are capable of 5gs worth of loading, which you will never achieve. IMO, the same improvement can be achieved by using solid tie rod sleeves instead of the factory slotted units, but many times the larger units can be found for the same price or less, so it isn't a huge price tag for a minimal improvement.

The OEM strut rod, or track rod, is a fixed length. This means the lower control arm location will not change at all with any alignment changes. The exception being if you replace the originals with an adjustable unit. However, even in this case you need to be careful with altering the length of the strut rod. It should be used to fine tune the location of the lower arm. If you simply crank in a lot of caster using this bar, you will introduce the potential for biding the suspension motion and prematurely wearing the lower control arm bushing. This also is where alignment with later model mustangs is helpful. Mustangs have had adjustable strut rods for decades and most alignment techs are familiar with them. Along with this, if you aren't using an adjustable rod with a bearing, then using urethane with the stock rod is an improvement. The strut takes a lot of compressive loading when hitting the brakes. Urethane will deflect less than rubber and will reduce toe change during braking. Even if you use rubber everywhere else, urethane strut bushings are an improvement.

Four link in the rear...its very nice and its design allows you to isolate each component to its dedicated function, unlike a leaf spring that performs multiple tasks. However, leafs can be made to ride and perform very well. IMO, if you are not racing where you need to quickly change spring rates and/or re-adjust geometry to optimal, there is not a huge benefit to using them in a cruiser. Additionally, depending on the type of racing you are doing, the conversion may not be legal or may put you in a much higher classification where you may not be competitive. They are lighter and look good though so if that is important to you, they may be a good selection, but will be much higher priced than decent leaf springs.

[nicjasno]

Yeah.

Every small improvement on its own may not be a lot, but they do add up in the end.

I have abandoned the thought of doing a 4 link. Too much hassle for too little benefit. Good leaf springs combined with good shocks and a thick anti roll bar will be good enough.

My goal is to have a crusier that can confidently negotiate twisty european roads, not a racecar.

[Mike DC]

   
The biggest real-world benefit of the 4-link is probably just ditching the heavy unsprung weight of the 6-leaf R/T springs.  You can also run fiberglass aftermarket leaf springs and get some of that benefit. 

[nicjasno]

One of the benefits would be to use a 4 link in combination of adjustable coilovers.

But a 4 link in itself necessitates to weld in brackets for the upper arms and will probably require some mods to the shock mounts aswell. But i like to keep things as stock as possible. Kinda making stealth improvements.

[Mike DC]

As HPP is fond of pointing out, the adjustability is more useful for a track car than a street car. 

A good known set of aftermarket spring/shock/anti-roll parts can leave the car 8 or 9/10ths of the way to perfect right out of the box.  You'll never notice that last 1-2 10ths on the street. 

On the other hand, when you start switching parts around, swapping coils, playing with shock valving . . . next thing you know, you might end up at 4/10ths.   Potentially worse than stock. 

Coilovers are more popular for cheap/easy installations & adjustments than anything else.  If you compare coils to leafs or torsion bars at exactly the same wheel-rate, the performance of the coils does not shine any brighter. 

[nicjasno]

Yeah, that's what i thought.

What kind of anti roll bar setup is recommended front/rear?

[myk]

Most if not all front sway bars are an inch thick at least.  There may be a difference in how the different bars mount to the suspension.  Same deal applies to the rear bars, although some would argue whether a rear sway bar is necessary or not.  DC.com member MSRacing89, who actually races his orgasmically beautiful '68, has been known to disconnect his rear bar if he felt he didn't need it on certain courses.  There are many brands to choose from, so it's largely a matter of preference.

I've turned into a Hotchkis fanboi, so I'll recommend their quality, but expensive parts all day long...

[303 Mopar]

Firmfeel's rear anti-sway bar actually goes up over the rear end like stock, all others that I know of go under.

[nicjasno]

One question about behaviour under breaking... how does one prevent rear axle hop during heavy breaking? Are the suspension upgrades we were talking about before already the fix for that (too little damping in the stock suspension, better leaf springs, front not diving as much..) ?

Or is a brake bias adjustment also needed?

[HPP]

The asymmetrical design of a mopar leaf spring naturally resists brake tramping, however, if it is a concern you can add a half leaf on the top of the pack from under the axle housing up to behind the spring eye.  Hotchkis springs already have this modification made to them. They also are made using berlin eyes to accomplish some ride height reduction over regular leaf springs.

[Kern Dog]

Their eyes are German made?
maybe you meant Delrin?

[HPP]

No, delrin is a bushing material, like rubber, poly, or bronze. Berlin eye is a style of wrapping the eye and its location in relation to the spring centerline. See below.

This is the decieving aspect of leaf springs. While many poo-poo them as antiquated and simple, there actually are a lot of variables involved in making performance leafs and they are much more complex than a coil spring. Eye style, leaf count, leaf material, leaf location, interliner material and length,  tapered method, rounded, pressed or diamond cut ends, degrees of camber, banding method and location,  metalurgery, etc. In the mounting area there is anti-squat, instant center, roll center and and roll steer characteritics to consider. There is a lot of detail to a good set of leafs. The biggest drawback to leafs is simply their size and weight. Otherwise they are a very capable method of suspending a vehicle.

[Kern Dog]

Thank you for that. I really did think he meant the bushing material. I do enjoy learning new stuff. 

[Mike DC]

 
I'm fond of saying it - show me somebody who makes a big point of hating leaf springs.  I will probably show you a GM or Ford guy who never had a leaf setup that was designed right. 

[HPP]

Bingo!

Most guys don't know it, but the whole Cal-Trac system was created by a Ford racer who was trying to emulate the Mopar SS spring action on his symmetrical Mustang springs.

[nicjasno]

What about having more leafs on one side, like on hemi cars, to counteract the driveshaft torque? How does this affect the overall handling?

[HPP]

The XHD bias design springs used under our cars does not have a significant impact on handling. The additional half leaves in a bias spring design have a direct impact on the control ratio of the pack, and a minor impact on load rate, but it does not have an appreciable impact on the spring rate.

However, if you are a finely tuned driver who is very familiar with the car, you may feel a slight difference on corner exit as a result of the different control ratios left to right. I'll put it this way, the difference are so slight that the changes in weight that a 1/4 tank of gas difference produce may be comparable to the difference in bias springs control function.

Now, having said that, the usual approach for performance handling is have equal rates between right and left so most people tend to put identical springs on both sides. Although one could argue that the additional control of torque needed in the right spring could be equaled by additional load rate that should be installed on the left spring to support the driver. Which gets us back to nearly equal rate springs. Like I said further up, there is  a lot of technology in a good set of leaf springs that is hidden in its design.