WHY DO WE UPGRADE OUR SUSPENSION

Bergman Auto Craft

  1. BergmanAutoCraft

    BergmanAutoCraft FABO Vendor FABO Vendor

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    Too often I see people purchasing parts without understanding why. I'll focus on most guys who want more modernized handling for the street, not all out Pro Touring or Drag guys. I'll give my take on each part. The Mopar Performance Chassis Manual touched on some interesting points which make a lot of sense even today. They claim the geometry of the front suspension was pretty good. This refers to camber curve, roll center and bumpsteer. They compromised miserably in the amount of tire, spring rate (roll couple). They elude to mild lowering of the ride height, but too much and the moment arm becomes very long inducing body roll.

    UPPER CONTROL ARMS: The factory arms have limited caster and camber adjustment because bias pliés were the order of the day. With radials, increasing the adjustment range can be done to some degree by offset bushings. Tubular arms have more caster built in, so it can be an easier starting point for a modern alignment

    LOWER CONTROL ARMS: Simply boxing the lower arm when a sway bar is used helps prevent twisting the arm. Its a great design, and the box plates work well.

    LOWER CONTROL ARM BUSHINGS: The originals were good in the day. They are were designed to dampen the road and worked for mass production. They were cheap and didn't last long. Alignment shops loved Mopars. Upgrading to harder bushings creates precise movement of the lower arm. Since arms were designed to move up and down only, this can be viewed as an upgrade. Some get concerned about the arm sliding off the bushing. To prevent this, the T bar must be pushed all the way forward during installation. They usually stay put unless another force is acting on them.

    STRUT RODS: The originals were long, to reduce arc and came with a soft bushing. Even Moog upgraded the bushing to have a tougher material and a larger footprint. This goes hand and hand with the lower arm. Today we have solid bushings to limit unwanted movement along with adjustable length help "dial" in the exact load on the lower arm during assembly. The technical term is brake reaction support which is its job. Keep the lower arms in line when braking forces are driving them backward.

    ANTI SWAY BAR: Just about everyone knows what they do. Combined with the t bar rate, the resistance to twist have is called roll couple. The current bars are very beefy and should be matched with torsion bar rates and the width and type of tire.

    SHOCKS: There are 2 types of shocks on the market, mono tube and twin tube. Generally, twin tubes are cheaper which makes them popular. Mono tubes are regarded as a higher quality design. Good shocks are matched to spring rate for proper damping of the suspension. Bigger t bar, more energy, more damping.

    TORSION BARS: Back when Direct Connection was around they produced their own bars. Mopar recognized the need for more spring rate as cars modernized. Some type of upgrade is pretty much required at this point. How far you go really depends on the purpose of the car.

    I hope some of these basics help people understand why they may need something. I don't want to get into reviewing other vendors products but happy to explain reasoning behind my offerings.
     
    Last edited: Apr 26, 2020
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    • Cranky

      Cranky Banned and proud Staff Member FABO Gold Member

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      I've always been one to go a little bit bigger on the sway bars but not so much on the T-bars and also not to stiff on the shocks. This usually makes the car still ride decently while getting better handling characteristics. I'm I doing something wrong? Never did like my everyday drivers riding like a 3/4 ton truck.....
       
    • 12swinger

      12swinger Well-Known Member

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      The Challenger is reaching a more modern feel on the road through a Borgeson conversion.
      it’s not perfect, as on bumpy roads I still feel some flex. Lower arms may be a factor, and a brace could help.
      I’m also considering a piece I believe you offer for the coupler on the gearbox as opposed to the one Borgeson uses. I’m not sure it’s a factor?
      Never thought of adjustable strut rods for alignment of the lower arm. Hmm
      The other day I pulled it back on the alignment lift, as it was recommended to increase caster with the new box, and I’m just now getting around to it.
      I had a slight caster split and a slight camber split. Overall looked good 2-3 degrees of caster on both sides.
      So I maxed all 4 cams for caster and the camber fell at near zero on both sides, and I had 3.8 left and 4.0 on the right.
      Went up a good degree or a little more actually.
      So much more pleasurable to drive.
      Any recommendations on good shocks I typically look at Bilstein or KYB for a driver.
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      Most do it because they see talked up magazine articles or forum gods doing it. Most people don't realize you can do just about anything you want with a Mopar suspension not far from stock. I would wager over 90% of people who mod their suspensions will never drive the car in a way that takes advantage of it.
       
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      • Cranky

        Cranky Banned and proud Staff Member FABO Gold Member

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        Oh man, I push mine hard, stock or not! lol. My alignment specs are never anywhere close to stock settings.....
         
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        • BergmanAutoCraft

          BergmanAutoCraft FABO Vendor FABO Vendor

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          Not doing anything wrong. It can be a matter of preference as long as you know what your options are. This philosophy has been shared by many. The combination of t bar and sway bar = Roll Couple. However, even cars with heavier bars (like mine) don't ride like trucks. I see lots of people overspring the rear. This degrades the ride quite a bit.
           
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          • BergmanAutoCraft

            BergmanAutoCraft FABO Vendor FABO Vendor

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            Sounds like a lot of this going on here. Cutting your column and putting a solid joint in is never a good idea. However, you cannot go back to my plunge (OE) coupler without an uncut column shaft. I don't know how you are detecting the lower arm flex, but I recommend the boxing for the torsional load the sway bar puts on it when turning. The strut rods do not act on the lower arm. They aren't meant to pull or push the arm. They are a locator. Alignment sounds good but usually when you max the cams (front all the out, rear all the way in) you are increasing negative camber at the same time. Be careful with too much caster as the more caster, the inside tire wants to lift in turns. Think of a steep rake on a chopper. When it turns it lifts at the same time. There's a limit. I sell Bilsteins as they are a good go to. They are high quality mono tube and last forever.
             
          • BergmanAutoCraft

            BergmanAutoCraft FABO Vendor FABO Vendor

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            Its true, many are trapped into marketing. As long as you know WHY you are buying something, its a free country.

            Peter-Bergman-1971-Dodge-Dart-GT-DriveOPTIMA-NJMP-2016_423.jpg

            Lime Rock 3 30 13 022.jpg
             
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            • BergmanAutoCraft

              BergmanAutoCraft FABO Vendor FABO Vendor

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              And they shouldn't be. You wouldn't belive how many people call me saying their old school alignment guy set their car up with neg caster and positive camber. Then cant figure out why the car feels strange. Having been in the business the better part of my life, I can't understand what the mystery is about alignments. Very simple concepts to understand. Making adjustments can be tricky in some cases, but alignment guys should always have a firm understanding of what they are doing and why.
               
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              • abodyjoe

                abodyjoe Well-Known Member

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                way too many don't though. its hard as hell to find that guy in many areas anymore. a good portion see a mopar come and and look at the cams and all and don't know what to do with them. they are used to sticking a shim in there to correct alignment. then you have the ones that all they know is how to bring up the car in the racks computer and turn things until the screen shows green which are stock specs. then you got the other guys that know what they are doing and want to argue with you when you bring in your own alignment specs and they end up putting it where they want it over where you wanted it. its a real pain in the ass anymore dealing with alignment places. after my good friend stopped working in a shop years ago i think i have finally found two places local that can and will actually do what i want and understand why.
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  Then, there are alignment guys that do understand, cannot get enough caster and have a customer that won't spend the money to make it happen and blames the alignment guy. Many sides to the same coin. It's not always the alignment guy's fault. There are some cheap bastids out there. Then, after they get done blaming the alignment guy, they spend 3K dollars on an aftermarket suspension and still caint get it right. I've seen it. Right here on this forum.
                   
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                  • abodyjoe

                    abodyjoe Well-Known Member

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                    oh i agree. i'm only speaking my my personal experience on my stuff and dealing with the clowns in this area.
                     
                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    Trust me, "your area" ain't the only area where clowns exist. lol
                     
                  • abodyjoe

                    abodyjoe Well-Known Member

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                    lol
                     
                  • 12swinger

                    12swinger Well-Known Member

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                    I have high expectations when I set up a car.
                    I drove a buddy’s SRT Charger the other day and down the same roads it’s not much better. I was in a BMW yesterday took a ride to the lake, I wasn’t impressed on washboard roads. So I’m picky.
                    I’m probably feeling the intermediate shaft dancing up and down affecting the gearbox input shaft, maybe. The car has Hemi torsion bars, and front and rear sway bars, Moog everything, C body tie rods, it’s just I like going down backroads and everything drives like crap.
                    Never had to cut the sector shaft, and the length was perfect when done. Though I understand it shouldn’t be a fixed shaft.
                    I believe camber was zeroish on left and .17 positive on the right. Looked perfect, though modern cars I try and run a little negative camber when possible.
                    Maybe I could get a estimate on 4 shocks?
                    Thanks
                     
                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    So do I! Because I know EXACTLY how much the stock suspension is capable of, so when I spend a lot or a customer does, I make sure they get as much for their money as possible.
                     
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                    • abodyjoe

                      abodyjoe Well-Known Member

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                      • ir3333

                        ir3333 Well-Known Member

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                        i would disagree with the comments on lower control arm bushings.Most i've dealt with last years and yearsThey are hard vulcanized rubber and when installed properly and tightened at ride height offer some torsional resistance to lower A arm travel and can be plenty firm.The poly or or hard plastic is avoided by many the second time around...i've seen that plastic crack and distort after only a couple of years.
                        I have never had any problem getting enough caster on the front end when rebuilt with new bushings..maybe i've been lucky.
                        I don't auto cross.
                         
                      • RustyRatRod

                        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                        Well, we all knew you were in that small percentile that's crazy anyway. lol
                         
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                        • RustyRatRod

                          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                          Speaking of sway bars, do you have a diagram of how your early A body rear bar mounts to the frame? I see it listed on your site but I cannot envision it.
                           
                        • 12swinger

                          12swinger Well-Known Member

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                          What I get out of it is enjoyment and a sense of satisfaction when a vehicle drives as perfect as possible. That’s why I’m in this business.
                          I expect sometimes to much out of a 50-60 year old suspension with inherent weaknesses. So I have a tendency to experiment till it’s as nice as possible.
                          Thousands of cars have passed through my shop, and I’ve made them all safer handling and better driving.
                          I can sit in a parking lot, or a car show and count the cars I’ve worked on. It’s a good feeling.
                          if your in it for just the money, your in the wrong business. Cause you have to care.
                           
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                          • RustyRatRod

                            RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                            I plan on upgrades to mine. Sway bars on both ends and a good set of torsion bars. Whether I re-power the car will dictate if I go further. It runs so good, I kinda hate to mess it up.
                             
                          • 383Scampman

                            383Scampman Well-Known Member

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                            The reason I upgraded to poly bushings is : My car is only used in good weather . I needed bushings that didn't need to be replaced as often . I've seen rubber bushings go bad just sitting there . Next : I wanted a tighter suspension because I have a big block .
                            I have hd bars and springs because the oem's were shot .
                            I tried modern alignment and my car was dangerous to drive . Went to factory specs and is now straight and true .
                            My car doesn't ride like a baby carriage because that's the way I designed it 15 years ago . I wanted the experience of driving a 60/70's car with modern braking . Safety was my goal . good luck to all a-body builders out there . It is worth it .
                             
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                            • ir3333

                              ir3333 Well-Known Member

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                              I don't know why you guys have problems with rubber bushings..they last years and years.
                              If you don't tighten your suspension at ride height you will ruin them because you are keeping the rubber permanently twisted...and then you will be blaming the off shore supply.
                              Rusty,be careful with rear sway bars.I have read that they are not always a good idea.
                               
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                              • 72bluNblu

                                72bluNblu FABO Gold Member FABO Gold Member

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                                Peter, I agree with pretty much everything you've said here. I would like to clean up a couple things you said though.

                                First, the torsion bar thing. This doesn't make sense, and it's easy to explain why pushing the torsion bars all the way forward isn't necessary.

                                If you assume that the LCA socket can't move on the hex end of the torsion bar, then the torsion bar doesn't need to be bottomed out in the LCA socket to keep the LCA from moving back. If you assume the opposite, that the LCA can in fact move on the hex end of the torsion bar, then the reverse is also true- the torsion bar can move in the socket. Which would also mean it can move in the crossmember anchor, so the torsion bar can't be assumed to be holding the LCA from moving back. Either way, there's no reason to bottom out the torsion bars all the way forward. If they can't move then the LCA can't slide back, and if they can move it doesn't help.

                                Second, the strut rod thing. Yes, the strut rod is a "brake reaction support" and that is its primary reason for being there. Because they are basically a solid link, especially with an adjustable strut rod, they prevent motion in both directions, both forward and back. So they will keep the LCA from sliding back off the LCA pivot if you have a poly or Delrin bushing, just like the originals kept the LCA from walking back and tearing the rubber bushing at that location.


                                People have "issues" with the poly bushings because they install and maintain them like they're rubber bushings. They are not. With the OE LCA bushings there are no surfaces that slide on each other, the motion of the suspension is just the flex in the rubber (which is built in binding at the extremes of suspension travel, BTW). So there is no need to lubricate the OE bushings, and no way to do so. With a Poly LCA bushing, the bushing actually rotates on the LCA pivot pin. So you have two surfaces sliding on each other, which requires lubrication. And it requires re-lubrication. That's why people complain about the poly bushings squeaking. Well, if they're squeaking it means you need to lubricate them. And if you don't, they will fail. This is no different than any part that requires lubrication. If your ball joints started squeaking you'd lube them, and if you didn't do that immediately they'd wear rapidly and fail.

                                The other change from OE is that the poly has less flexibility. That's the improvement, but it also has consequences. Namely, the fit of the bushing on the LCA pivot pin, and into the existing LCA outer bushing shell (depending on which poly bushing you're using) has to be tight. These parts have to be a tight slip fit. If there is any play, the bushings will wear out prematurely. Because people install the bare poly bushings into old outer bushing shells and onto original LCA pivot pins with the inner shells the fit is not always what it needs to be. And guys assume the bushings "just slide in" and it doesn't matter. Well, that fit is very important. If you went to install an OE rubber bushing and the pivot pin was loose in the inner shell you wouldn't install it. Same with a poly bushing. No, it isn't a press fit, but the fit still has to be correct.

                                If you install the poly bushings correctly- lubricate them and make sure they have the proper fit, they'll outlast rubber every time. I always use greaseable LCA pivot pins with poly bushings. They fit the bushings with a higher accuracy than the OE pins, and you can lubricated the bushings as needed. The small grease hole is negligible for the strength of the pin, and the greaseable pins from Firm Feel are a higher quality than the OE pins were to begin with.

                                If you use Peter's Delrin bushings (I do, they're awesome), the fit is even MORE important because the Delrin has less give than even the poly. So the pivot pin tolerance must be exact. I tried three different pairs of original pivot pins with mine, none fit correctly and all three pairs of original A-body pivot pins and inner shells had different diameter measurements. That tolerance is critical with harder bushings, they must be a tight slip fit with no play.

                                The OE rubber bushing quality is abysmal now. There are several threads about them not even fitting into the LCA's or onto the pivot pins. None of them will last like they used to, even with proper care. The quality just isn't there. Here are a couple threads where multiple different members talk about Moog and other brand OE style bushings not fitting.

                                LCA pivot pin loose in bushing problem

                                Lca bushing help.

                                Lower control arm bushing

                                As for the rear sway bar, that depends entirely on how your car is set up. From the factory the front's were undersprung and the rears were ok, but if you do something like add SS springs out back then the rear end is very stiff and adding a rear sway bar makes that worse. If you upgrade the front suspension and have the proper rate rear leaf springs a rear sway bar can be very beneficial. It's not a matter of "rear sway bars are not a good idea". Like any suspension upgrade you have to consider the whole suspension system, some need rear sway bars, others won't, it depends on set up.
                                 
                                Last edited: Apr 27, 2020
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