Rear Sway Bar Opinions

[Scooter]

Well I was close to getting those MP springs. I'll look at the other options for sure. I would hate to do all this and have a terribly rough ride.

Not just a rough ride, they dropped the rear end bout 2 inches as well. I like the look, but it presents other problems sometimes.

Brad, just read your thread and noted you swapped your composite 175 rate composite leafs for a stiffer 225. Why did you change and how did it effect the ride stiffness? The Hotchkis I'm looking at are rated under where you started at 165lb.

[Brads70]

Well I was close to getting those MP springs. I'll look at the other options for sure. I would hate to do all this and have a terribly rough ride.

Not just a rough ride, they dropped the rear end bout 2 inches as well. I like the look, but it presents other problems sometimes.

Brad, just read your thread and noted you swapped your composite 175 rate composite leafs for a stiffer 225. Why did you change and how did it effect the ride stiffness? The Hotchkis I'm looking at are rated under where you started at 165lb.

I found they were just too soft I could quite easily push the rear end down on the trunk lid/ bumper with my hands.  Might be the ticket for drag racing?

[70 Challenger Lover]

I doubt I'd ever be on a track competing but I'd like more of a modern ride with modern handling. Will I need 17-18" wheels to get there? It sounds like I might. The 165 lb Hotchkis leafs might be what I'm looking for. They look like an easy install too.

[Brads70]

I doubt I'd ever be on a track competing but I'd like more of a modern ride with modern handling. Will I need 17-18" wheels to get there? It sounds like I might. The 165 lb Hotchkis leafs might be what I'm looking for. They look like an easy install too.

I've never had them but have read lots that say they lower the rear end quite a bit over stock even.    ( Hotchkis leafs)

Problem with 15"  is no one make really good tires for them anymore, 17" and more in 18" but that is not everyone's cup of tea either so...?

[70 Challenger Lover]

I looked up the Hyperco leafs and information seemed lacking on their site. Under Chrysler, they had different rates but what about length and height? I thought A, B, E body cars used different length springs. Do the Hyperco ones attach just like regular leafs? I like the idea of upgrading to better technology but I don't know if I want to re-engineer or redesign everything in my path. Seems like all this is a slippery slope.

[MOPAR MITCH]

Well... where should I begin?... starting from the late 70s, then heavy in the 80s... and still playing/enjoying today!  Amazing handling that surprises all observers... street/highway... and autocross/road race track activities.

Here's my setup:  Overall intention is national competition-level of SCCA Solo II autocross, street legal and driveable (within reason to avoid street potholes, railroad tracks, etc.).  In other words, smooth roads.  Most importantly, following racing class allowable "rules".

Small block ... conservative and reliable power; trans.. 727

Torsion bars: I've tried many progressive sizes... settled with size 1.24" (425#/inch).. largest that will fit through factory hex of 1.25".  How many times have you guys heard me say... "Don't be afraid of larger TBs!"  Get some good shocks for these, as well!   I would NEVER give up my 1.24 TBs... best single handling improvement ever!  I say, don't go below 1.12 or better yet, compromise at 1.18... Firm Feel will supply them.  Anything smaller... and you'll be guaranteed to say to yourself... "not bad, not stiff enough... should've gone larger/stiffer!"... mark my words!

Rear leafs: I've tried many kinds and progressed towards the light-weight FLEX-A-FORM mono-leafs (same company that had been making Corvette factory leafs)... they worked with me.. tried three different sets.. settled at 225 #/inch... with a 5" unsprung arch.  NOTE:  In determining leafs, you must know the rear corner weights of the car.  Your goal is a nearly flat compressed weighted leaf spring... any arch after compressed... it weakens the rear handling.  AND... this should be determined for your common and desired driving weight (trunk filled or empty? passengers?, etc).  IF I'd replace them again, I'd consider 250#/inch.. 4" unsprung arch.  YES, you can go too stiff in the rear, and regret it,  but what/where will your driving be?  In my opinion, the Hotchkis rear "steel" leafs are pretty good, just too soft... have them stiffened a little by adding another leaf at a spring shop.... or try them first for a while... then decide later.

Shocks:  With today's choices, its a no-brainer to simply go for double-adjustables... QA1 or Vikings... look at the variables you can play with to "tune" your ride?   Just get them and forget it....and spend the time "tuning" your ride.

Sway bars:  simply, 1.25" diameter hollow front... its actually 1-5/16" as I've measured from Firm Feel, some other brands might be slightly different (for light weight); and NO LESS than 3/4" rear.   I run a 1" rear solid, same shape as factory OE... custom made long time ago... Then, play with "tuning" these sway bars with the end-link bushings... all poly? not so desirable.. pending your driving style.   DON'T be afraid of a larger than 3/4" rear bar... this 1" rear bar equalizes the balance so much needed with our cars!!!

Upper control arms:  Anything other than factory stock will give you the more needed positive caster, and a little negative camber.  Advantage to the "adjustables" are an alignment with greater caster/camber;  the non-adjustables are fixed... limited to what they are made to be.   An alternate consideration is the Moog offset UCA bushings... installed reverse.. if your $$$ funds run low.

Lower control arms:  stiffening them is a good idea... but... the factory race AAR/T/A SCCA cars never had them stiffened... perhaps due to rules... but in today's world, get them braced, and with poly or Delrin lower bushings.

Subframe connectors... yes yes, yes... determine local allowable designs from club rules, if needed.  The full-contoured floor shaped designs may not be allowed, but most all others are typically allowed.

Steering: must have power steering, and add the "fast ratio" longer pitman and idler arms (clearance/ding your headers if needed.. make them fit... I know a few guys with BB engines/headers that simply ding their headers for clearance.  ALSO, ONLY use the SAGINAW pump... toss the FEDERAL in the recycle bin.   NOTE: The longer idler arm is/always has been just a ~70 C-body idler arm... that matches the length of the longer Fast Ratio pitman arms.

Get a smaller steering wheel... helps quicken your steering.

Get some better supporting bucket seats... high side bolster!!!!   sit in some for your desired comfort... take your time in selecting these.

Lighten your car ... fiberglass hood?  Aluminum engine components?... physics... lighter = faster.. acceleration, deceleration, cornering... FUN!

Wheels and tires:  a great simple choice, in my opinion, are the YEAR ONE 17x9... installed FRONT AND REAR... with 275-40-17 tires... they have the CORRECT backspacing...  NO worries front or rear (maybe just fold the lips little for peace-of-mind).

Yes... 18" have broader tire size selections... backspacing of rims are critical.. 8" (4.5"); 9" (5"), 10" (5.5")

Finally, engine... OIL PAN... get a baffles pan... MILODON has what we needed .. get the road race/touring pan.

Hope your project gets all the love and attention it deserves!  Take the time... do it right!

[Brads70]

I looked up the Hyperco leafs and information seemed lacking on their site. Under Chrysler, they had different rates but what about length and height? I thought A, B, E body cars used different length springs. Do the Hyperco ones attach just like regular leafs? I like the idea of upgrading to better technology but I don't know if I want to re-engineer or redesign everything in my path. Seems like all this is a slippery slope.

They are close to super stock dimensions , so they require different front hangers, here is a post I made/copied from our old site. They will force you to get good shocks, I went with QA1 double adjustable and they have been great.
https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/composite-rear-leaf-springs-on-an-e-body/59/msg353#msg353

[HP2]

Rough spring rates based on observation:
MP Oval track 120#
OEM XHD 160#
Super Stock 180#
Adding a rear sway bar will enhance the roll rate of a leaf spring and turn that 180# into a 230# when in a corner.

I'm actually surprised that Mitch and Brad are running springs over 200#. Based on the calculations for my car, I needed 180# roll rate which was a 120# oval track spring with a 1" rear sway bar.  Haven't tracked it yet to validate the calculations but they were based of my years of competition experience.

Roughness of a ride is often lack of spring control (inadequate or mis-matched shocks rates)  unless you are bottoming the spring constantly. If you are bottoming out, then you have inadequate spring rate. Its important to think of shocks like you think of a camshaft to an engine. They create the parameters in which the rest of the suspension performs. Low, mid, and high speed valve circuits are all part of shock technology that create control.

Double adjustable shocks are a great tuning tool if you like to tinker with them, keep records, and change the tune for conditions of driving. If you are a set it and forget it type or only use your car for a cruiser, double adjustable shock  create twice as many ways to get the adjustment wrong and not only destroy the ride, but can actually make the car dangerous if you go too far the wrong direction. A quality non-adjustable, or single adjustable  reduce the potential for mistakes.

[70 Challenger Lover]

Thanks for all the valuable information. I have to ask though...when people say, "I wish I went with heavier leafs and/or TBs," are they saying this because they want a package that's more competitive on the track or because it feels too soft on the road during normal driving?

My goal is to build a cruiser that has lots of modern upgrades, some convenience and comfort while also trying to improve overall performance and handling that is more comparable to a typical modern daily driver sedan. It might find it's way onto a willow springs track someday just for fun but that would be rare and maybe never. I just don't want to shake my fillings out on long cruises.

My vision once was having 15" chrome road wheels on the car because I love the look and the rest of the car is going to be a flat hood sleeper in a subdued color. I really don't care for the look of larger aftermarket wheels but I guess I can live with them if they match the handling performance of the suspension.

I also prefer rubber bushings everywhere for comfort and less vibration but I assume rubber bushings defeat the advantages of a good suspension system. Is this correct. I want comfort first with improved handling if I can get it. I think the stiffening components I added will make a difference no matter what I do.

[HP2]

I'm sure there are a myriad of opinions about stepping up springs rates and overall ride comfort vs performance. Mitch and Brad and myself tend to be more competition oriented. Others more cruiser oriented. Generally speaking, an average car today is sprung 30% higher than our classics. Add performance use and those rates can be even higher.  More rigid uni-body structures to better utilize the rates, increased shock control and precision, as well as consumer expectations of handling have all changed what we expect out of a daily driver compared to what was the norm of 1970. So even just a baseline of what constitutes a nice cruiser means that the .88 t-bar that was stock in your car should be a 1.0 minimum.

Rubber bushings do not defeat the advantage of stepped up rates. New cars still use rubber bushings in many places. Granted the rubber is a different compound and may be thinner to reduce deflection, but you can make a big step up in comfort and control with stepped rates and rubber bushings. Remember the shock comment above. The shock is the heart of it all in the suspension. If the budget is tight, I'd recommend significantly more capable shocks ahead of suspension upgrades.

For 15" tires, yes the choices are very limited and are pretty much only available in what the industry calls "cosmetic performance" tires. They look fast with raised white letters but are hard compounds designed for cool running and for long mileage. There are still two decent units out there, Maxxis Marauder and Mickey Thompson SR. Both are H speed rated with softer compounds. The MT is the softer of the two with a newer carcass design based off their 18" performance line. But neither are available with raised white letters. If you want a broader range of speed ratings and compounds, you need to step up to 17" or better yet 18". However, I will caveat stepped up tires sizes with the observation that the industry keeps changing diameters and widths so if you choose a very specific larger diameter and width you will eventually not be able to get the exact size you want unless you chose a size that was an OEM option on some vehicle, ergo Viper, Vette, Camaro, or Mustang sizes. OEM sizes on these vehicles will continue to be available longer after custom sizes disappear.

I'd also add that with the leaf rates I provided above, all those different leafs have different mounting configurations that will require other changes to hangers to use them. Chrysler in the day tended to make things application specific and not a general one size fits all. Everything impacts everything else and sometimes one change may necessitate six supporting changes. Unless you want to get into the nitty gritty of changes, details, and keep accurate records of the changes, I'd recommend sticking with OEM configuration stuff.

The simplest solution for good handling and ride comfort is to call Hotchkis and order their kit. Bang, your done. If you want some tech advice along the way or want to discuss possible alternatives, call Firm Feel and tell them your goals and buy their  list of recommended pieces. If you really want to dig in the details and specifics of why and what for, we can help you with that here.

[Scooter]

I doubt I'd ever be on a track competing but I'd like more of a modern ride with modern handling. Will I need 17-18" wheels to get there? It sounds like I might. The 165 lb Hotchkis leafs might be what I'm looking for. They look like an easy install too.

Just ordered the 165 lb Hotchkis sport leaf kit which advertises an approximate 1 inch drop over stock and their heavy duty shackles. My flattened Mopar Performance springs have me at 24 inches ground to fender lip in the rear, good chance I'll gain an inch or so back with this kit. I'll let you know how it goes in and what the ride feels like when I get it installed.

[MOPAR MITCH]

To add a little more, regarding tire selections, your ride comfort will change pending sidewall height.

Tall 70 or 60-series have more sidewall to absorb the bumps, but will flex more during cornering.

50-45-40-35 series have shorter sidewalls and don't offer the absorption like the taller sidewall tires.  I other words, shorter sidewall tires will give a progressively firmer ride... you'll feel more of the road bumps.... and potentiall damage your rims easily if you hit some bad pot-holes in the road.

Tire pressures can be adjusted and will also make a difference in the ride comfort.

For my "street/hwy" cruising, I have 15x8 rims using BFG T/As  275-60-15 rear, 255-60-15 fronts.. providing good road comfort.. and reasonable grip, but they are a hard compound for mileage and truly not a track/performance tire.

For my track events, I'm using 16" diameter rims... two sets of rims... 16x10 for my Hoosier A6/7 competition events 275-45-16 f/r, or else my 16x8 using BFG G-Force Comp T/As... 255-50-16 f/r.. for lapping sessions (HPDE/HSAX)... and cruising on the highway to/from the distant road race tracks.   I plan to get some 18x10s and run 200 TW tires 275-35-18 f/r... although I also like the YearOne 17x9 Ralley rims... would easily fit f/r with 275-40-17 tires ... but a relatively small overall diameter (those 15" 255 and 275 60-series BFGs fill the wheel wells much better for appearance).

PS:  Yes, as said above, I favor my comments towards serious handling setups.. competition and street... if comfort is what someone wants... then you're compromising... and will give up performance.... individual's choice (even I've made a few compromises with my setup).

PSS: M/T tires are actually pretty good performance tires... 15" available.

[gzig5]

Good info there Mitch.
On  the tires, are you satisfied with the performance/grip of the 255-275 wide DOT tires?  Or is there grip or better braking to be had if you were to run a 295-315?  For now, I'm not too worried about class rules.

[70 Challenger Lover]

Thanks for those photos. I really like the lower stance and way the 15" wheels fill the wheel wells there. I am very strongly leaning towards all Hotchkis stuff using my 15" chrome road wheels with maybe MT tires if they are good performers. I'm okay with shorter tire life since it will never be a daily driver. I'm going to have to compromise in a few areas and wheels are probably one area. I just feel like if I go with a bigger aftermarket wheel, I won't get the look I really want and will always be a little disappointed. The look and the comfort are definitely important to me just like improving performance where I can.

[dodj]

They claim to be "Geometry Correcting" as well.

I wonder what this means when talking about the leaf springs. I understand the front end 'geometry correcting' relating to caster. But what are they correcting on the rear?