Posted By: cudabitten
Anti-Swaybar theory. Quick Lesson please. E-body. - 02/18/12 02:43 PM
Hey, just looking for some knowledge on how they work. Front and back.
Thanks.
Thanks.
Anti-Swaybar theory. Quick Lesson please. E-body.
Posted By: Mattax
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/18/12 08:17 PM
A 'sway bar' is more correctly called an 'anti-sway' bar, and also goes by some other names.
They provide no additional load carrying capacity, but reduce lean in corners. However in doing so it also puts more load on the outside tire, and on rough pavement may reduce traction by lifting the lower wheel.
Generally add or increase the front bar first, and or increas a rear bar second.
It is generally safer to have a front tire exceed its traction than a rear tire. Because..
When front tires exceed traction the car keeps going forward,
When rear tires exceed traction the rear of the car goes forward faster than the front (fishtail and spin)
Off roaders (four wheeling) usually disconnect them if the vehicles have them. Street use, and most dirt and paved racing use them to some extent to reduce roll which helps many things.
For the How and Why, go grab one of those books recommended in the post "Where to start, A reading list"
They provide no additional load carrying capacity, but reduce lean in corners. However in doing so it also puts more load on the outside tire, and on rough pavement may reduce traction by lifting the lower wheel.
Generally add or increase the front bar first, and or increas a rear bar second.
It is generally safer to have a front tire exceed its traction than a rear tire. Because..
When front tires exceed traction the car keeps going forward,
When rear tires exceed traction the rear of the car goes forward faster than the front (fishtail and spin)
Off roaders (four wheeling) usually disconnect them if the vehicles have them. Street use, and most dirt and paved racing use them to some extent to reduce roll which helps many things.
For the How and Why, go grab one of those books recommended in the post "Where to start, A reading list"
Posted By: EV2DEMON
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/18/12 09:02 PM
Ideally, sway bars will be used as a tuning device once you have the proper spring rates. Throwing a big sway bar at a car that is too softly sprung will generally lead to and amplify the issues mentioned above (overloading outside tire and often lifting the inside).
Not sure how your car is set up, but if you have a stockish E body, a mild sway bar increase can help, but don't just stick a huge bar on it and expect the handling to get better.
Not sure how your car is set up, but if you have a stockish E body, a mild sway bar increase can help, but don't just stick a huge bar on it and expect the handling to get better.
Posted By: 5spdcuda
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/18/12 11:44 PM
The proper use of anti-roll bars can help handling quite a bit. Keep in mind that the stiffest end of the car tends to loose traction first. This is why Chrysler often used front bars, but seldom rear ones. When the front breaks loose first we get understeer which is generally felt to be safer, more predictable and easier to deal with than oversteer which is what happens when the rear breaks loose first. I would agree with this so long as the understeer is moderate and builds up gradually. When you really overcook a corner and the understeer comes on abruptly all bets are off.Just as a side note one of the classic definitions of the difference between understeer and oversteer among racers is that understeer scares the crap out of the driver and oversteer scares the crap out of the passenger. One of the advantages of anti-roll bars relative to simply using stiffer springs is that you can increase the roll rate considerably without loosing compliance or adversely affecting ride quality. True one wheel bumps are a bit harsher with a stiff bar, but still not bad compared to what you would experience with stiffer springs. When using stock springs on an "E" body I tend to use a stiff front bar and leave the rear bar off on 'Cudas. I would be more inclined to try a rear bar on a Challenger since they have a 2 in. longer wheelbase and bit more rear end weight. Ideally I would prefer softer rear springs and a light and adjustable rear bar so I could trim out the car's balance. Normally as stated earlier the stiffest end of the car washes out first. This would seem to contra-indicate a stiff front bar, but experience often proves otherwise. The reason is that while the stiff front bar does increase the front roll rate it also limits body roll which in turn reduces an undesirable camber [ positive ] change. This often times outweighs the effects of the increased roll rate. A rear bar can make it more difficult to put the power down early on corner exit since a bar always tends to lift the inside wheel. When it's all said and done NO ONE has all the answers, I know I certainly don't. In the end you do what works. Driving style definitely enters into this. Some people prefer a bit of understeer, others want the car to be neutral or don't mind a bit of oversteer. Personally I REALLY want the car to turn in and if there's a trace of oversteer, I'll deal with it. Of course I am not driving an Indy car going 175mph thru the "kink" at Road America either. Good luck with your project.
Posted By: AndyF
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 12:12 AM
Quote:
Hey, just looking for some knowledge on how they work. Front and back.
Thanks.
They are basically just a cross ways torsion bar.
Posted By: autoxcuda
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 01:22 AM
Quote:
... Of course I am not driving an Indy car going 175mph thru the "kink" at Road America either. ...
I found that out the hard way with just a 75 mph kink and bump.
http://youtu.be/XJW-YvipFYE @1:40 min
F-that! I completely unhooked the rear sway bar after that off track excursion.
Now that I'm a little more used to it, I hooked it back up on the weakest setting. Seemed ok on the tighter and slower track.
Posted By: 5spdcuda
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 03:42 AM
That 75 mph kink might not have been so bad if the bump hadn't been there to unload the suspension. I'll bet it got your attention though. I tried running a rear bar in the 'Cuda, but it was just too "busy". I can see where with your level of experience using a light rear bar on a tight circuit could be beneficial in getting some rotation. As for going flat through the "kink" at Road America, I think those guys must have to get size xxx large when shopping for athletic supporters. Not sure what the gals wear.
Posted By: autoxcuda
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 03:59 AM
Quote:
That 75 mph kink might not have been so bad if the bump hadn't been there to unload the suspension. I'll bet it got your attention though. I tried running a rear bar in the 'Cuda, but it was just too "busy". I can see where with your level of experience using a light rear bar on a tight circuit could be beneficial in getting some rotation. As for going flat through the "kink" at Road America, I think those guys must have to get size xxx large when shopping for athletic supporters. Not sure what the gals wear.
Yes it got my attention! I was in the wrong placement on the track. Plus I got on it too much, too early with the new big motor.
I really needed to be more over to the right where the bump is not so pronouced. The bump actually fans out to the left. It's a notorious spot on Big Willow that bites quite a few. The instructors go over this every time.
I certainly got bit!
Posted By: Kern Dog
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 05:35 AM
Quote:
They provide no additional load carrying capacity, but reduce lean in corners. However in doing so it also puts more load on the outside tire,
I see it differently. The stiffer sway bar makes the car sit closer to level in a turn, which spreads the cornering force some FROM the outside wheels to the inside.
Posted By: Mattax
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 03:01 PM
You can see it differently but the physics doesn't change 
edit When taken too far the inside wheel will lift off the ground. This is the big bar, soft spring as described by 5spdcuda. It's not just theory, this actually happens in some instances during competition. For street most people just notice the flatter more predictable driving.
In all seriousness, at your level of interest Frankenduster, you would really enjoy any of those books on the reading list.
I'm going to add a magazine article to the reading list which involves adding a sway bar to a circle track car. It doesn't do the physics, but describes what is happening based on the data (photos, tire temps and lap times).
edit When taken too far the inside wheel will lift off the ground. This is the big bar, soft spring as described by 5spdcuda. It's not just theory, this actually happens in some instances during competition. For street most people just notice the flatter more predictable driving.
In all seriousness, at your level of interest Frankenduster, you would really enjoy any of those books on the reading list.
I'm going to add a magazine article to the reading list which involves adding a sway bar to a circle track car. It doesn't do the physics, but describes what is happening based on the data (photos, tire temps and lap times).
Posted By: amxautox
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 06:48 PM
Yes the right rear tire is off the ground, about 1/2". I have a 22" x 32" picture of it that the photog gave me for helping him - safety car spotting during the event so he didn't get run over in case of a spinout - ..
New but stock spring rate for a Go Pack car, rear leafs. 300# per " coils up front. .750" dia rear bar and 1.130" dia front bar. 3,100 car weight, 97" wheel base. Bars made by the guru of AMC and designed for the AMX. Called Gymkana Bars.
New but stock spring rate for a Go Pack car, rear leafs. 300# per " coils up front. .750" dia rear bar and 1.130" dia front bar. 3,100 car weight, 97" wheel base. Bars made by the guru of AMC and designed for the AMX. Called Gymkana Bars.
Posted By: 5spdcuda
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 07:40 PM
I've got to go with Mattax on this. Weight transfer causes body roll, but body roll dosen't cause weight transfer. The main factors influencing lateral weight transfer are center of gravity height and track [ how far apart the wheels are from left to right ]. A lower the center of gravity and a wider track will reduce weight transfer. Since body roll dosen't affect weight transfer, why do we care about it? The reason is as I mentioned earlier, to prevent an undesirable camber change which reduces traction. Speed also affects weight transfer. Going slower will reduce it, but that's sort of self-defeating. Amxautox has given an excellent demonstration of both good grip, driving skill and how a rear bar on a rear drive car can make putting the power down early difficult. It's actually pretty common to see front drivers lift the inside rear in hard cornering.
Posted By: Mattax
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 09:15 PM
The wheel lifts I was thinking of were RWD cars lifting inside front. Mostly in autocross with 'prepared' class cars that are nationally competitive. If I come across a picture I'll post it - most were in print magazines like North American Pylon and Sports Car.
Key words here are 'sort-of'. You touch on one of the great secrets of serious driving.
Most beginers and many experienced drivers have a tough time sorting out the trade off of forward speed for cornering bite. That said, slowing down is not design goal, which of course is 5speedcuda's point. I only add this point because too too often our friends hit the track or autocross and waste time and tires ploughing on corner entry 'cause they didn't slow down enough.
Quote:
Speed also affects weight transfer. Going slower will reduce it, but that's sort of self-defeating.
Key words here are 'sort-of'. You touch on one of the great secrets of serious driving.
Most beginers and many experienced drivers have a tough time sorting out the trade off of forward speed for cornering bite. That said, slowing down is not design goal, which of course is 5speedcuda's point. I only add this point because too too often our friends hit the track or autocross and waste time and tires ploughing on corner entry 'cause they didn't slow down enough.
Posted By: 5spdcuda
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/19/12 10:48 PM
I know what you're saying about lifting an inside front wheel with a rear drive car, but it takes a lot of grip to do it along with good speed. A good deal more of each in fact than what the OP is ever likely to achieve given a basically stock car. You're absolutely right about the speed part. Most racers are familiar with the truism that slow in, fast out beats fast in, slow out every time. Knowing it dosen't make easy. I know that when I need a few extra tenths I am still tempted to brake even later and harder and then I wind up coming in too hot and plowing down a few cones. Oh what the h$%^, if it was easy it wouldn't be nearly as much fun.
Posted By: feets
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 03:46 AM
Posted By: amxautox
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 03:59 AM
.Targa Challenger.
Posted By: feets
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 05:24 AM
Dropping the road out from under the car is cheating. 
Posted By: amxautox
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 05:25 AM
You weren't supposed to notice that.
Posted By: Jim_Lusk
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 06:35 AM
I think I'll put it another way for the OP. Gravity is pulling the car DOWN, cornering forces are pulling (or is that push?) the car to the outside of the turn. The forces that pull the car to the outside transfer weight pushing the car down on the suspension on the outside of the turn. The sway bar tends to lift the inside suspension toward the body. If this lift of the inside suspension is NOT enough to overcome the gravity on that side of the car you have flatter cornering. If the lift is enough to overcome gravity you have the situation where the inside tire is LIFTED off the pavement.
Posted By: Kern Dog
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 06:46 AM
My understanding in the simplest terms is the following:
In a right turn, weight transfer results in the left side of the cars suspension to dive and the right side to rise. The sway bar works to equalize the reaction from one side to the other. If one side moves up or down, the other side follows. This is why, in most cases, a sway bar usually doesn't make a cars ride degrade in the way that larger torsion bars can.
In a right turn, weight transfer results in the left side of the cars suspension to dive and the right side to rise. The sway bar works to equalize the reaction from one side to the other. If one side moves up or down, the other side follows. This is why, in most cases, a sway bar usually doesn't make a cars ride degrade in the way that larger torsion bars can.
Posted By: EV2DEMON
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/20/12 02:01 PM
Which gets back to what I originally said, a sway bar should be used as a tuning device once the car is properly sprung.
A car in corner will still want to compress the outside suspension as a result of weight transfer. The sway bar doesn't magically undo the laws of physics, so the body will still want to roll to the outside as well. When that happens, the sway bar no longer allows the inside suspension to sag (or, at least not as much). When the inside suspension can't droop, the inside tire is unloaded.
The only reason that a sway bar makes a car appear to run flatter is that when one corner is compressed, the other is forced to compress as well. To what degree depends on the sway bar, but ultimately it results in the inside tire unloading.
That is why spring rate is ultimately a better way to control body roll.
A car in corner will still want to compress the outside suspension as a result of weight transfer. The sway bar doesn't magically undo the laws of physics, so the body will still want to roll to the outside as well. When that happens, the sway bar no longer allows the inside suspension to sag (or, at least not as much). When the inside suspension can't droop, the inside tire is unloaded.
The only reason that a sway bar makes a car appear to run flatter is that when one corner is compressed, the other is forced to compress as well. To what degree depends on the sway bar, but ultimately it results in the inside tire unloading.
That is why spring rate is ultimately a better way to control body roll.
Posted By: cudabitten
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/21/12 04:26 AM
Thanks, this is the discussion I was looking for.
Some things I learned;(correct me if I'm wrong)
The front anti sway bar acts like a torsion bar from one lower control arm to the other.
The front bar prevents the outside tire/body, from diving too much, while lifting the inside tire at the same time.
A front bar tries to prevent body roll but will actually cause one of the front tires to break free of the road surface during understeer, and a rear bar could cause a rear tire to loose traction during oversteer.
Front sway bars are available as a bolt on after market part.
EV2DEMON, tell me more about "spring rate". How does that apply to me with front shocks/torsion bars and rear shocks/leaf springs?
Some things I learned;(correct me if I'm wrong)
The front anti sway bar acts like a torsion bar from one lower control arm to the other.
The front bar prevents the outside tire/body, from diving too much, while lifting the inside tire at the same time.
A front bar tries to prevent body roll but will actually cause one of the front tires to break free of the road surface during understeer, and a rear bar could cause a rear tire to loose traction during oversteer.
Front sway bars are available as a bolt on after market part.
EV2DEMON, tell me more about "spring rate". How does that apply to me with front shocks/torsion bars and rear shocks/leaf springs?
Posted By: ThermoQuad
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/21/12 12:37 PM
I have found that the rear bar needs to have some adjustabilty to get the car to handle [read rotate] properly. Think different material end link bushings and how much tension on the end link bolts. This is for every car, but if you have no testing grounds like a road course or deserted highway in the mountains it's hard to determine if you have arrived at the point of max rotation.
Posted By: Mattax
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/21/12 02:38 PM
Quote:
The front anti sway bar acts like a torsion bar from one lower control arm to the other.
yes. and its's attached to the chassis at the K frame. Rear bar is same idea.
Quote:
The front bar prevents the outside tire/body, from diving too much, while lifting the inside tire at the same time.
Basicly yes. Simplest description is that it helps fight body roll. That's not usually described as 'dive', but it sounds like you have the concept. Rear bar does the same thing but on the rear.
Quote:
A front bar tries to prevent body roll but will actually cause one of the front tires to break free of the road surface during understeer, and a rear bar could cause a rear tire to loose traction during oversteer.
You're mixing things here.
Understeer: When a vehicle doesn't turn even though you're turning the steering wheel. Plough.
Oversteer: When the when the vehicle turns more than you think it ought to. Begins a 180.
A Sway bar will increase the load on the outside tire and reduce the load on the inside tire. This will reduce overall grip when the tires are already near their limit of grip. However, this is often ofset by things like better tire geometry in relation to the road. For street use, you are not driving at the limit, and the car will feel more stable and predictable.
Too big of a front bar in relation to the rest will result in noticible understeer.
Too big of a rear bar in relation to the rest will result in noticible oversteer. If you get into an oversteer situation on the street, especially on wet, downhill or curve, you're pretty much guareteed at least 180 into the curb or ditch.
Quote:
Front sway bars are available as a bolt on after market part.
Yes. But there is some variety to how they address the attachment to the control arm. There also is variety in bar diameter. You want a diameter that is the in the ballpark of the rest of the package.
Posted By: EV2DEMON
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/21/12 03:38 PM
Quote:
EV2DEMON, tell me more about "spring rate". How does that apply to me with front shocks/torsion bars and rear shocks/leaf springs?
A spring is a spring is a spring. The car doesn't care that it has torsion bars on one end and leaf springs at the other. For all intents and purposes, they both do the same thing. Shocks are dampers that have no effect on spring rate, though spring rate will determine what shocks to use.
Sway bars can be used to limit body roll, but a sway bar big enough to make a stock sprung car corner flat will lead to excessive understeer, even more than what the car was originally built with. By increasing spring rate (stiffer torsion bars in this case) to limit body roll/suspension compression, the sway bars can be used to tune under/oversteer based on the rest of the combination.
Now, obviously a classic Mopar has it's limits and will never be a Viper, but by matching components (springs, shocks, sway bars, alignment...) you can end up with a reasonably neutral driving car that will hold it's own against many more modern rides.
Posted By: Mattax
Original E-body Sway bar packages - 02/21/12 03:49 PM
Below are roughly what the factory offered in the better handling packages
for the e-bodies. These can serve as reference points.
'Cuda with rear sway bar:
0.90 T-bar (111 lbs/in)
0.94" front anti-sway bar
0.75" rear anti-sway bar
Heavy Duty rear springs with 4.5 Leaf (132 lbs/in )
Although non-rear sway bar package seems to have been more common:
0.90 T-bars
0.88 front anti-sway bar
heady duty rear leafs.
A slightly larger t-bar came on Hemi 'cudas and maybe other options.
A stiffer 150 pound/in rear spring came on Hemi and maybe other options
A .88 T-bar and 115 lbs/in leafs came on 2 barrel 383s
Someone who is into restoration will know exactly the options and what came with what. But this should give you some idea of what you're aiming for. Most important, if you stiffen the rear with more spring rate or rear sway bar, you definately want to increase the front t-bars and sway bar at the same time. You pretty much can't go wrong increasing the front t-bars to .90 -1". But if you're staying with smaller t-bars than that, be conservative on the front anti-sway bar.
edit: Fixed decimal places!! See AMX's post below
for the e-bodies. These can serve as reference points.
'Cuda with rear sway bar:
0.90 T-bar (111 lbs/in)
0.94" front anti-sway bar
0.75" rear anti-sway bar
Heavy Duty rear springs with 4.5 Leaf (132 lbs/in )
Although non-rear sway bar package seems to have been more common:
0.90 T-bars
0.88 front anti-sway bar
heady duty rear leafs.
A slightly larger t-bar came on Hemi 'cudas and maybe other options.
A stiffer 150 pound/in rear spring came on Hemi and maybe other options
A .88 T-bar and 115 lbs/in leafs came on 2 barrel 383s
Someone who is into restoration will know exactly the options and what came with what. But this should give you some idea of what you're aiming for. Most important, if you stiffen the rear with more spring rate or rear sway bar, you definately want to increase the front t-bars and sway bar at the same time. You pretty much can't go wrong increasing the front t-bars to .90 -1". But if you're staying with smaller t-bars than that, be conservative on the front anti-sway bar.
edit: Fixed decimal places!!
See AMX's post below
Posted By: feets
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/21/12 06:16 PM
These guys have given you good info.
There is an easy way to think about (anti-)sway bars.
They are indeed a spring running side to side. Being springs, they don't want to be twisted. They want both sides of the suspension to be at the same height.
If you compress one side and they try to compress the other side to match.
Pull one side down and they will try to pull the other side down.
As for how they affect handling, think of them as tightening up the other end of the car.
The front bar makes the rear tires bite harder. Rear tires don't turn so you're going to go straight.
The rear bar makes the front tires bite harder. Front tires turn so you're going to turn too much.
Too much of either bar can cause trouble. it's all about balance.
There is an easy way to think about (anti-)sway bars.
They are indeed a spring running side to side. Being springs, they don't want to be twisted. They want both sides of the suspension to be at the same height.
If you compress one side and they try to compress the other side to match.
Pull one side down and they will try to pull the other side down.
As for how they affect handling, think of them as tightening up the other end of the car.
The front bar makes the rear tires bite harder. Rear tires don't turn so you're going to go straight.
The rear bar makes the front tires bite harder. Front tires turn so you're going to turn too much.
Too much of either bar can cause trouble. it's all about balance.
Posted By: amxautox
Re: Original E-body Sway bar packages - 02/21/12 07:00 PM
Acually that would be the following;
.940"
not .094" front anti-sway bar. .094" is about the dia of 7 strands of red hair.
.750"
not .075" - same thing as above
.880"
not .088" - same as above
Gotta watch those decimal point placements.
.940"
not .094" front anti-sway bar. .094" is about the dia of 7 strands of red hair.
.750"
not .075" - same thing as above
.880"
not .088" - same as above
Gotta watch those decimal point placements.
Posted By: shakerjoe
Re: Original E-body Sway bar packages - 02/21/12 07:46 PM
not to hijack the OP - but if adding a stock rear sway bar setup from say a 340 cuda to my 440-6 cuda (which I was planning on doing) would I benefit on increasing the torsion bar size from .940 to say a 1"? My friend put 1" torsion bar on his 440-6 Challenger and the front end seems very very stable - actually quite comfortable driving wise - would there be a noticable change on front sway bar diameter increase or would rear sway bar, larger t-bar and stock size front sway bar suffice - car is only street and highway driven - looking to make as safe and comfortable as can be - thanks, Joe.
Posted By: feets
Re: Original E-body Sway bar packages - 02/21/12 09:58 PM
Treat it like tuning an engine. Only make one change at a time unless everything's blown up or used up.
Many times you can find what you're looking for without throwing thousands of dollars worth of parts at the car.
What do you want?
Firmer ride with less squish to the suspension? Go for T-bars.
Ride is fine but you don't want to lean? Go for sway bars.
Ride and roll are okay but you want less bounce? Go for shocks.
Take a step here then a step there until you get where you want to be.
Many times you can find what you're looking for without throwing thousands of dollars worth of parts at the car.
What do you want?
Firmer ride with less squish to the suspension? Go for T-bars.
Ride is fine but you don't want to lean? Go for sway bars.
Ride and roll are okay but you want less bounce? Go for shocks.
Take a step here then a step there until you get where you want to be.
Posted By: Fury Fan
Re: Original E-body Sway bar packages - 02/21/12 10:52 PM
Here’s something that I don’t think has been mentioned yet. I feel a bit nervous mentioning it amongst some obviously experienced and knowledgable people, however I read it somewhere, either in Martin’s book or Puhn’s book, and it kinda stuck in my brain.
As the car leans thru a turn, a solid-rear-axle car (or is it a leaf-sprung car???) will actually experience some dynamics where the inside of the car experiences a shorter wheelbase as it rises, the outside of the car shows a longer wheelbase, so the rear axle starts to point slightly toward the outside of the turn. The rear axle ends up steering the opposite direction of the turn. A rear swaybar will help reduce that.
The more I think about it, a leaf-sprung car should theoretically exhibit that worse than a coil/trailing arm system because the change of arch in the leaves changes the length also.
As the car leans thru a turn, a solid-rear-axle car (or is it a leaf-sprung car???) will actually experience some dynamics where the inside of the car experiences a shorter wheelbase as it rises, the outside of the car shows a longer wheelbase, so the rear axle starts to point slightly toward the outside of the turn. The rear axle ends up steering the opposite direction of the turn. A rear swaybar will help reduce that.
The more I think about it, a leaf-sprung car should theoretically exhibit that worse than a coil/trailing arm system because the change of arch in the leaves changes the length also.
Posted By: Rick_Ehrenberg
Re: Anti-Swaybar theory. Quick Lesson please. E-body. - 02/21/12 11:04 PM
Pretty much everything covered -- well! --above. Just my 2¢...understeer is reduced with speed, and any oversteer increases. For the 99%, you want enough understeer so that there's always some. Yes, a neutral or slightly tail-happy car can be loads of fun (and fast) if you have the skill (and runoff room...), but for general use, as I said...
Rick
Rick
Posted By: amxautox
Re: Original E-body Sway bar packages - 02/21/12 11:05 PM
Leaf spring car as the leaf will 'bow' more on the inside as the weight is taken off, same as when you jack up the rear of the car with the floor jack under the center of the pumpkin/differential/ rearend, the leafs will bow and pull the rearend forwards a little, and yes it is a measurable amount. As the front of the springs are bolted to a non-moving anchor.
That will still occur with an anti-sway bar as the links will still allow that shift as the link bushings will 'pivot' in their holes and the link will move forwards and rearwards somewhat.
That will still occur with an anti-sway bar as the links will still allow that shift as the link bushings will 'pivot' in their holes and the link will move forwards and rearwards somewhat.
Posted By: Fury Fan
Re: Original E-body Sway bar packages - 02/21/12 11:08 PM
Quote:
Leaf spring car as the leaf will 'bow' more on the inside as the weight is taken off, same as when you jack up the rear of the car with the floor jack under the center of the pumpkin/differential/ rearend, the leafs will bow and pull the rearend forwards a little, and yes it is a measurable amount. As the front of the springs are bolted to a non-moving anchor.
That will still occur with an anti-sway bar as the links will still allow that shift as the link bushings will 'pivot' in their holes and the link will move forwards and rearwards somewhat.
But the rear swaybar should reduce lean on the rear of the car and reduce that phenomenon, no?
Posted By: amxautox
Re: Original E-body Sway bar packages - 02/21/12 11:11 PM
Quote:MAYBE a little, but I wouldn't count on it as the strength of the flat large spring is greater then the hardness and friction of the link bushings pivoting in the hole in the ends of the bar and around the link shaft.Quote:
Leaf spring car as the leaf will 'bow' more on the inside as the weight is taken off, same as when you jack up the rear of the car with the floor jack under the center of the pumpkin/differential/ rearend, the leafs will bow and pull the rearend forwards a little, and yes it is a measurable amount. As the front of the springs are bolted to a non-moving anchor.
That will still occur with an anti-sway bar as the links will still allow that shift as the link bushings will 'pivot' in their holes and the link will move forwards and rearwards somewhat.
But the rear swaybar should reduce lean on the rear of the car and reduce that phenomenon, no?
Posted By: amxautox
Re: Original E-body Sway bar packages - 02/21/12 11:28 PM
Yes I can see where it could/would be reduced as the bar twists, and the links/bar/bar arms try to hold up the that end of the rearend, but I can't see it being eliminated. 
Gotta think about these things sometimes while visualising what can happen.
Gotta think about these things sometimes while visualising what can happen.
Posted By: Mattax
now Leaf Springs and rear axle steer - 02/22/12 02:44 AM
Re: Leaf Springs and rear axle 'steer'
Although pretty well answered, the steer of the axle can be changed. For passenger cars, Chrysler set the springs up flat at normal ride height so the rear tracks in on a turn. You may find this MTCS pamphlet from 1968 interesting. http://www.imperialclub.org/Repair/Lit/Master/253/Page02.htm
Probably should start a new thread on leaf spring suspensions...
Although pretty well answered, the steer of the axle can be changed. For passenger cars, Chrysler set the springs up flat at normal ride height so the rear tracks in on a turn. You may find this MTCS pamphlet from 1968 interesting. http://www.imperialclub.org/Repair/Lit/Master/253/Page02.htm
Probably should start a new thread on leaf spring suspensions...
Posted By: amxautox
Re: now Leaf Springs and rear axle steer - 02/22/12 03:41 AM
VERY interesting read. Thankyou for posting that. 
Posted By: cudabitten
Re: now Leaf Springs and rear axle steer - 02/23/12 02:52 PM
A lot of easy to read info there Mattax.
Thanks.
U-joint angularity, slip angles, etc...Thats why even as a young driver back in the day, I always left things "stock" on my cars right down to the hub caps.
Thanks.
U-joint angularity, slip angles, etc...Thats why even as a young driver back in the day, I always left things "stock" on my cars right down to the hub caps.
Posted By: Mattax
Re: now Leaf Springs and rear axle steer - 02/23/12 07:22 PM
Your welcome.
There's a lot of good stuff in the MTSC series. It was written mostly for the Chrysler dealership techs.
The e-bodies have a lot going for them. Structurally they've got good shape and safety features the earlier cars didn't have. Wide track, leafs angled in, fairly low CG and roll for a production car. They can be a bit nose heavy compared to a similarly powered a-body, but other than that, they're a good basis for sports driving.
Your bit of wisdom on sticking with stock is one it took me a while to discover. Starting with stock, you have a good baseline. On my Barracuda I didn't and that made things really hard as I had no good refernce pints for a long time.
There's a lot of good stuff in the MTSC series. It was written mostly for the Chrysler dealership techs.
The e-bodies have a lot going for them. Structurally they've got good shape and safety features the earlier cars didn't have. Wide track, leafs angled in, fairly low CG and roll for a production car. They can be a bit nose heavy compared to a similarly powered a-body, but other than that, they're a good basis for sports driving.
Your bit of wisdom on sticking with stock is one it took me a while to discover. Starting with stock, you have a good baseline. On my Barracuda I didn't and that made things really hard as I had no good refernce pints for a long time.