rear leaf bushing bind

[ks71z28]

For years I have put up with rear leaf bushing bind on my 71 Camaro. When jacked up off the ground and set down the suspension must be compressed to return to ride height. I believe they also contribute to my lack of traction, forward and lateral because they inhibit the supension from doing its work. I have been advised to NOT go with Del-alum because they still won't allow the leafs to articulate. The car is an occassional roadcoarse runner. Any ideas guys????

[chicane67]

I dunno.... I have been running and designing leafs for years and dont have the problems you state. Maybe.... just MAYBE, if someone was paying you to drive your car on a track for a living and you were looking at cutting your lap times down to the hundred thousandth..... it might make a real difference to go away from leafs..... but then what would you have ?? Packaging problems, perhaps ??

And to comment on not running a rear sta-bar.... and why Global West doesnt recommend one, goes far beyond a simple answer of an increase in roll stiffness. A leaf spring rear chassis DOENST NEED ONE to begin with. The rate of a spring has more to do with roll control than anything else. A sta-bar and the shocks are compliments to the spring package. Besides, a sta-bar is more resistive to articulation anyway.

Maybe.... just maybe if someone had a properly designed and built leaf spring, the aforementioned problems wouldnt be as bad. But how bad is it really ?? I am not however, saying that all of it will go away, but..... if you were to do something like a min-tub and use the offset shackles, about 80% percent of all associated, and speculated bind, goes away. Look at your actual running suspension window. How much travel vertically do you really have in that window ?? This isnt a rock crawler..... so you might be looking at four - - maybe five inches at an extreme of total travel ?? Those are not 'extreme' angles.... or really enough to 'bind' like so many are suckered into believing. Dont believe the hype... and dont discount a correctly designed and constructed spring.

Do some research before getting suckered into believing something that isnt of real concern for a street driven chassis.

[ks71z28]

If you read closely I was mearly stating that my rear suspension movement has a lot of bind. Case in point, I must push on suspension to get back to static ride height after being jacked up. I like the idea of the AFCO articulating or shperical front eye, but those aren't for stock type leafs. You are correct, the rear sway bar adds bind to the rear, but it also adds roll stiffness and mine is adjustable, so tuning the rear is possible. Infact the range of adjustment is very wide. My rear leafs are 150# and the sway bar can make them work like 250# on max adjustment as far as roll stiffness. I guess I was really looking at bushing choices. I have ben advised to ditch the urethane in the front and switch to rubber, any thoughts?

[yody]

I think landrum makes a rear spring slider. THe rear spring eye will slide back and forth, a lot different than bushings. check it out

[Mean 69]

Delrin better than rubber, which is better than poly, which is completely unacceptable for any suspension bushing in the first place (okay for sway bar link spacers, but that's about it). If you do some searching, you can find folks that have fitted spherical bearings, up front mainly, and it seems to work well.

If you have bind on a leaf setup, it is virtually always the silly poly bushings. You'll NEVER be able to keep them greased. Tom is right, you'd be surpised how little suspension travel articulation the cars use. Also, a pillowblock bearing will reduce/eliminate the bind (which is significant) in the rotating sleeves for the sta-bar. In a perfect world, the sta-bar should not add ANY wheel rate in pure bump (both wheels same rate/distance).

Start with the bushings, and then leap larger if you need to.
Mark

[79T/Aman]

chican! what hype? leaf springs camber when one at a time is moved up or down period! that is no hype, Herb Adams was a suspension engineer and came up with a spherical bearing to deal with the problem, another fact , GW came out with their CAT% shacle the also deal withe the same problem (if only a 1/2 azzed solution), next a sway bar can follow the springs articulation as the sway bar end can slid in and out of the end bushing! as well as rotate, as far as Del-a-lum bushings they are nothing more than solid aluminium with a nylon sleeve ( oh sorry Derlyn ) one last thing and I'll get off my rant, if improperly designed leaf spring are the problem please design us a perfect leaf spring, after all you have been doing it for years!!

[Steve Chryssos]

When jacked up off the ground and set down the suspension must be compressed to return to ride height.....Any ideas guys????

Let's see if we can get this one back on track:

Your shackles should swing freely. Open the trunk and have a friend bounce the car up and down while you watch the shackles from underneath. They should swing as the springs compress and then swing back freely. If not, then you are missing the sleeves that fit between the bushings and the bolts. Or the sleeves are too short. In either case, the shackles will press against the bushings when they should be butting against the sleeves. Take it apart and check both ends of the shackle.
https://static1.pt-content.com/images/noimg.gif

[79T/Aman]

everyone is still missing the point , leaf springs bushings don't just rotate around the bolt they must also tilt as the rear end housing rotates about the rear roll center, this would be all good and fine if we didn't have to have the rear wheels able to move independently of each other as you go in to turns and up driveways or dips and bumps in the road.

[Mean 69]

everyone is still missing the point , leaf springs bushings don't just rotate around the bolt they must also tilt as the rear end housing rotates about the rear roll center, this would be all good and fine if we didn't have to have the rear wheels able to move independently of each other as you go in to turns and up driveways or dips and bumps in the road.

No, actually this is not completly true. At all. A leaf spring can, and will (thank heavens) move in torsion. Still not ideal, but they can, do, and MUST move to allow angular movement of the stiff rear axle assembly. Not pretty, but necessary...

(BTW, that's the other source of bind on a leaf car, but fret not, at least not too much, the strain on the leaf's is nowhere near fatigue levels....)

Isn't this fun?
M

[79T/Aman]

that is exactly my point whoo hoo! :thankyou:

[chicane67]

chican! what hype? leaf springs camber when one at a time is moved up or down period! that is no hype, Herb Adams was a suspension engineer and came up with a spherical bearing to deal with the problem, another fact , GW came out with their CAT% shacle the also deal withe the same problem (if only a 1/2 azzed solution), next a sway bar can follow the springs articulation as the sway bar end can slid in and out of the end bushing! as well as rotate, as far as Del-a-lum bushings they are nothing more than solid aluminium with a nylon sleeve ( oh sorry Derlyn ) one last thing and I'll get off my rant, if improperly designed leaf spring are the problem please design us a perfect leaf spring, after all you have been doing it for years!!


Send me $1250.00 and I'll put them in the mail to you.

[David Pozzi]

79T/Aman,
Please don't provoke chicane67, I don't like sweeping up the mess! :)

If you have polly bushings front and rear there is much more friction from them than the Del A Lum bushings have. There is also inter-leaf friction that you can reduce with plastic pads but not eliminate, your springs should allready have the pads. Some shocks have very tight seals that can hold the static ride height up. If the shackle bolts are too tight, they can bind.

Why don't you call and talk to Doug at GW and see if the Cat 5 spherical bearing setup will help you. I believe he sells a kit to convert your springs. When I talked to him he said they help the car put the power down on corner exit. It may not be all that helpful for an autocross only car, but for a road course car it should be great.

The twist of the spring yields an anti-roll bar effect, so you can get away with no rear bar usually, but many things vary in F/R tire sizes, HP, RC heights, F/R weights, and F/R roll couple that could change that.

I haven't checked with Doug, but a Cat 5 rear spring may require a rear bar.

[baz67]

chicane, you can do better than that! Slacker.

[chicane67]

chican! what hype? leaf springs camber when one at a time is moved up or down period! that is no hype, Herb Adams was a suspension engineer and came up with a spherical bearing to deal with the problem, another fact , GW came out with their CAT% shacle the also deal withe the same problem (if only a 1/2 azzed solution), next a sway bar can follow the springs articulation as the sway bar end can slid in and out of the end bushing! as well as rotate, as far as Del-a-lum bushings they are nothing more than solid aluminium with a nylon sleeve ( oh sorry Derlyn ) one last thing and I'll get off my rant, if improperly designed leaf spring are the problem please design us a perfect leaf spring, after all you have been doing it for years!!

Please use 'spell check'. Learn it and live it.....whether or not your on a "rant".

I know who Herb Adams is. I have met him personally. I am also more than familiar with the spherical bearing design. But, there is more, to the "Hotchkis" rear suspension than your proposed bushing limitations. There is also, more to the design of a leaf spring and how it can be tuned around much of what you seem to think, are problems SO MAJOR.... that for some reason you think that what you have read is hammered into stone. This, is far from our reality today. That is what the "years" have taught me.....

I really dont understand your point. But, remind me which point is your again.... your original comments OR the comments that Mark provided, that are contradictory to your own ??

The sta-bar thing, I believe, has already been constructively discussed by both David and Mark, and how its use is and/or would not be required. Tortional loading of the independant leafs, in and of a multi leaf spring design, and the available tuning within this alone, negates any real requiremnt for a rear sta-bar alltogether.

As I previously stated, you can negate near 80% of related bushing bind by taking the angle out of the spring, forward to aft. Secondly, Mark did reiterate just how little suspension travel articulation, the cars use or how much it actually occurs. Like I said, if you were on groomed pavement on a track somewhere, running slicks, or had the ride height at about two feet in the air..... the load factors just might become a factor. But not on a street driven (non 4x) chassis..... you wont see near the loading that you would on a non street surface.

Most of our chassis, here in our little circle, have reduced ride heights that really limit the articulation window to make this, the "hype" it has been built up too with some of our younger or lesser informed audience. Nor does it require, an incessant "rant", without 'real' defining TECH.

David, no biggie. Some of us just need to take the blinders off. :)

Brian :getout:

[79T/Aman]

I'll be the bigger man here and apologize if I offended anyone but as you say Brian "the blinders need to come off" as an leaf spring expert you should know the short comings of poly and del-alum bushings in leaf springs right! ,I do understand that a car with limited travel will put less tortion on the leafs, (you did agree that it does occur), but that is enough to bind the bushings and this is why GW and others say that you may not need a sway bar with their bushings all they are doing is turning a negative into a marketing benefit of their product, that is the HYPE I'm talking about and too many people are falling for it, sorry for trying to help people see the light,so a sway bar is a chassis tuning device, you may have to run one or not but too many variables involved.

[SHANE 73Z]

Chicane,

I retracted my original post after reading yours. I must say that I have bought into the hype as well. I myself have a few questions that hopefully you can address.

1) You mention designing a chassis (using leaf springs) and some of the criteria. Where does this leave people who do not have the money, skill, desire to stray away from the stock locating points? Can the same attributes be designed into a spring for a stock application?

2) Most folks myself included should be insanely intrigued at the springs you are offering. The price you stated, is that a custom spring tailored to my vehicle & needs? Just for my own curiosity what kind of bushings would I get with that spring and how would the spring rate compare to what is commonly available from the mainstream aftermarket?

These questions stem from my lack of knowledge as far as leaf spring design differences/methods goes. I am certainly not asking you to give away any secrets so feel free to pick and choose.

Thanks,
Shane

[Mean 69]

One other HUGE reason that a leaf sprung car sometimes doesn't need a stabilizer bar is the roll moment. The RRCH of a leaf car is bascially of the order of the radius of the tire, and of course because the spring moves up and down, it is dynamic in nature. The center of gravity of a lowered car is basically around 17 to 18" or so, leaving the roll moment to be pretty modest at a few inches. As such, lateral forces applied to the rear of the vehicle won't roll the body terribly, for more on the physics look in the archives under the stabilizer bar thread, it's a good one. Further, as the car goes into bump, the roll moment decreases more, and the roll tendancy is further reduced (kind of a dynamic anti-roll feature). Obviously in roll one wheel drops while the other wheel rises, so it gets a little complex, but this secondary dynamic effect is not as important as the roll moment issue.

Simple. Use good bushings, grab the correct spring rate for your application, and leave it alone.

Mark

[ks71z28]

OK guys I have listened to your debates and have decided to go with rubber bushings in the spring eyes, urethane on the shackle to reduce flex

So whatch think?

[baz67]

Better. I am leaving now.