Front AND Rear Spherical Bushings?

[hardline_42]

I'll jump in here and tell you what I found during my Bad Ast research...
Leaf springs can be made to work just fine. As a road race suspension OR a street driver suspension. This is straight from Mark Stielow and his experience with Thrasher. What you don't want to do is make it too complicated which is exactly what you are doing with your design. Keep it simple. Build some height adjustablity into the front spring mounts. Run a compliant bushing in front with high durometer rears and get yourself some GOOD adjustable shocks...
Don't use sliders on a street car. All they will do is wear out quickly and cause maintenance problems.
Here is what a spring manufacturer has to say about Pivot Bushings. This is quoted from the Landrum Spring web page...
"Pivot bushings are bushings that were designed to remove the bind between the chassis and the spring. However, the negative effects of these bushings greatly outweigh their intended purpose. Our extensive testing has proven this component to produce very erratic handling characteristics. When the front bushing is allowing the front leaf spring to pivot, it transfers all the side loads and lateral forces to rear portion of the leaf spring and shackles or sliders, which were not designed to handle the additional stress. This leads to bent shackles, warped sliders and misaligned axis points. Furthermore, because the front eye is allowed to pivot, it does not have any solid displacement to drive the car forward."
Here is their site...
http://www.landrumspring.com/pages/technical.html

Leave the spring angle alone also. I looked into angling the forward mounts for Bad Ast and everything I read said to do it for turning left only... Circle track cars do this a lot. It's kind of touched on in the Landrum site and, if you look at the diagram, you will see the LEFT spring is the only one angled...
http://www.landrumspring.com/pages/technical6.html
Here are some articles to look at. Maybe you have seen them, maybe not but they are good reading and informative...
http://www.circletrack.com/techartic...h_terminology/
http://www.smithees-racetech.com.au/leafspring.html

The decision I came to was keep it simple. A street car does not need all of the race car "tricks" to handle well on the street AND on the track. Granted it will not be perfect for road racing but that is not the intended end result right? A very nice handling suspension can be built with off the shelf, easily replaced OEM or aftermarket parts.
Just something to think about.
Mark

Mark, I appreciate the info and the links. I'm now more confused than before, though. I read all of the landrum information and they seem to want to steer you away from spherical bushings and promote the use of solid bushings in the spring eyes. But most of my suspension design ideas came after reading this article (http://www.afcoracing.com/tech_pages/leaf.shtml) from AFCO who also makes leaf springs, but happen to sell both spherical bearings and sliders which they recommend (they also recommend using the spherical bushings in the front eye). They also recommend locating the front mounts further inboard of the rears. Naturally, I don't really know which piece of information to put stock in. Chicane says the best setup is solid bushings up front, pivots out back with sliders and recommends the Gulstrand FIA leafs with the Cat 5 setup. GW says the Cat 5 setup has pivots front AND rear with a solid frame bushing. Landrum says no pivots. Can anyone shed more light on the situation?

[astroracer]

Stop.... Take a breathe... Go outside and look at your car.

Now, tell us EXACTLY what you are building... A race car or a street car? If you are building a RACE car fine, all of those sites, even the Landrum site, are geared toward ALLOUT circle track race cars. There is no consideration taken for turning right, hitting speed bumps, potholes or steep driveways...
You are making this much to difficult, as I did when I was developing Bad Ast... It is really a simple thing to make your car handle well on the street. Poly bushings, good shocks and a matched sway bar. That's all you need. The race car tech is just that, race car tech, and it does NOT apply or work well on a street car... Sperical pivots, sliders, angled springs and all that rot will not live on the street. Mud, water, grit and extreme conditions will eat them up and you will be putting stock stuff back on inside of a year.... quaranteed.
You have to come to grips with the end use of the car and you said yourself it is a street car. Build a street suspension and you will save yourself a lot of time, money and lost effort...
I am not trying to flame you here. I just want to think about what you are actually building.
Mark

[hardline_42]

Stop.... Take a breathe... Go outside and look at your car.

Now, tell us EXACTLY what you are building... A race car or a street car? If you are building a RACE car fine, all of those sites, even the Landrum site, are geared toward ALLOUT circle track race cars. There is no consideration taken for turning right, hitting speed bumps, potholes or steep driveways...
You are making this much to difficult, as I did when I was developing Bad Ast... It is really a simple thing to make your car handle well on the street. Poly bushings, good shocks and a matched sway bar. That's all you need. The race car tech is just that, race car tech, and it does NOT apply or work well on a street car... Sperical pivots, sliders, angled springs and all that rot will not live on the street. Mud, water, grit and extreme conditions will eat them up and you will be putting stock stuff back on inside of a year.... quaranteed.
You have to come to grips with the end use of the car and you said yourself it is a street car. Build a street suspension and you will save yourself a lot of time, money and lost effort...
I am not trying to flame you here. I just want to think about what you are actually building.
Mark

I agree that most people over estimate the purpose of their build so let me give you as much detail as possible. I plan to go full pro-touring with this thing within the constraints of my budget. It will have to pull double-duty as my daily driver from the spring thru fall of next year, so I have all winter to build it. The drivetrain consists of an EFI Vortec 406 that EA's at 511 pk HP and 497 pk TQ (I know, I know, what do desktop dyno's know?) and either a 4L80E, 2004R or T-56 trans depending on what I can find. Rear end will be a stock 10 bolt narrowed with welded axle tubes and no higher than 3.42 gears depending on which tranny I use. A minutub is planned to go with the narrowed rear. Up front I'm planning on using SC&C UCA's with del-a-lum's and stock LCA's with del-a-lums, and rubber bushings everywhere else. Front coil rating and sway bar diameter are dependant on the overall suspension design. Eedelbrock IAS or Bilsteins at all four corners. An 8-point cage and sfc's as well as the pro-touring f-bodies g-braces will hold the chassis together. After the cage install, the car will be lightened as much as possible and "aredynamicised(?)" with a front-breather set-up through the stock grill and out of hood vents. Wheel well vents will be installed and a full belly pan, if I can figure out how to make it work with a leaf spring suspension. Please keep in mind that although it seems wildly ambitious for a street car, it will only be on the street 'til next winter at which point I would like to try my hand at some road racing. I don't want to invest now on parts that will come off in a year's time.

[chicane67]

Chicane says the best setup is solid bushings up front, pivots out back with sliders and recommends the Gulstrand FIA leafs with the Cat 5 setup.

Well.... not exactly. I never said anything about the Guldstrand FIA springs. Now my own design..... that is a whole 'nother subject. Nor would I choose a slider type of pivot for the rear.

On the other hand, my spring design takes a few pointers from Guldstrand spring but they are completely different.

The primary reason I used the spherical bushings on both ends was to try and eliminate torsional loads on the spring. Perhaps I'm just being overly paranoid, but it's my attempt to keep the possibility of spring failure to a minimum.

I wouldnt say paranoid.... Id call that, damn smart. Composite spring technology still has a long way to go and the implimentation of your design does much more than meets the eye. Lessening the possibility of failure is just plain common sense considering that you are one of the very few that put your chassis through the ringer as well as you do.

What is the purpose of using stiff bushings in the shackles and rubber in the front eyes?

Id have to say ride quality, less noise transfer and lateral stability within certain expectations.