Front AND Rear Spherical Bushings?

[hardline_42]

I'm in the process of designing my rear suspension and I've come across some conflicting information (at least it seems that way). I plan on using a custom rear leaf setup with fiberglass leafs (say what you will) mounted inboard of the frame rails with the front mounts angled in further than the rear and modded Herb-Adams style. The rear shackle will be replaced with a slider. The confusion comes up in bushing selection. The front spring-eye will definitely have a spherical bushing in it ( http://www.suicidedoors.com/SuperPivotBarEnd.php (http://www.suicidedoors.com/SuperPivotBarEnd.php)). My understanding was that for best handling the rear should be a solid bushing of some sort and the slider I'm going with (http://cmwraceparts.com/Springs/springs32.html (http://cmwraceparts.com/Springs/springs32.html)) already comes with a solid aluminum bushing, but I've read in recent posts that some people are putting the spherical bushings in the rear spring eye as well. What are the effects of adding another spherical bushing? Just at a glance it would seem like this would allow lateral movement of the rear housing, but as long as the springs are torqued tight to the spring pads, I guess the leaves would only twist tortionally without bind. Would I need a lateral location device? How about a sway bar? Also, for anyone who has rear sliders, would there be enough clearance for the leaf to rotate about the spherical bushing without hitting the slider rails? Thanks.

Brian

[hardline_42]

Is this too easy for you guys? Just curious why GW (whom everyone hails as the be all, end all of leaf spring suspension components) offers one setup and all the leaf spring suspension gurus seem to recommend another.

[chicane67]

If it were as elementry as you think it is, then why are you even asking the question ??

A sperical insert in both the front and rear eyelet's of the spring itself are unnecessary. Unless your suspension travel requires an increased amount of articulation. Most street and race suspension have a very limited range of travel and that negates such a need.

A solid bushing in the front eye acts as, for lack of better words, a solid location device (a mechanical single pivot) is the anchor of the rear suspension. Since any and most of all movement in the spring itself is in the rear half of the spring (a mechanical two pivot), it would be the only end of the spring that would need the mechanical means to twist and control a change in length from the suspension movement. A slider would change that into a single pivot, and from there, that would be the pivot that should recieve a spherical insert. But a solid rear with a spherical front ??.... I dont see how that is really going to be any real help at all.

GW utilizes a single pivot in the rear spring eye with a solid frame insert. This was calculated to be enough to combat the small amount of 'camber' induced in the solid axle mechanism without the extra need for a lateral location device. If you were to use an insert in both the spring eye and the frame insert, the rear end as a whole would require a lateral location device so that you didnt run into location issues like that of tire rub or unwanted rear suspension movement. Using a slider by itself would not.


You know those rock crawling JEEP dudes? They use them because one side of their axle needs to climb up on the side of a boulder. If that's not smooth side to side axle pivot, what the hell is?

And why do you think that is ?? Why do they only do one side of the bar if they require 100%++ more travel and articulation than that of a street car ?? Answer: We dont require near the same amount of articulation and we dont have 1/4 of the suspension travel that they do. So why do you think you need them on both ends ??

Would you require a lateral location device... yes.

Do you need a stay bar... dont know.

You have yet to expound on what it is that you are building. But, if the spring build is done correctly, there is no need for a rear stay bar, what-so-ever. If it did, it would most likely be something small, like around 1/2" OD. A hotchkis style axle suspension does not require a stay bar for optimal performance, if the springs are designed correctly.

Since you have also stated that you are going to utilize a composite type leaf, that spring type itself has the natural ability to combat the induced camber during suspension movement. So for someone to use spherical inserts in both ends would be beyond over kill and unnecessary all together.

Is there enough clearence to pivot around the slider ?? Well, the one shown in your provided link.... maybe. Maybe not. It depends on the rear eye material thickness of the springs you purchase. I would go as far as to say, that I think that you will have enough room. Most of the rear eye material, in thickness, that I have seen over the years is about half of what a normal spring steel build would be. it would also come down to the over all width of the rear spring eye itself.

I have delt with your question many times before in the 15+ years I have been doing custom leaf builds for my clients. The best set-up so far, has been Doug's rear CAT5 shackle set-up with an FIA type spring build.

If you feel that you can live with the increased ride harshness and transfered noise.... then go for it. I have seen a few done in my time and they showed negligible results over what most have already done in the past 25 years or so.

But dare to be different I say.

[hardline_42]

Thanks for the response, you're the one I was hoping to hear from.


If it were as elementry as you think it is, then why are you even asking the question ??
I was only referring to the fact that 30 people looked at the question and no one took a stab at it. Sometimes, it's hard to get answers on this forum that are easy for you guys but not so for some of us. Also, searches aren't always fruitful.



A solid bushing in the front eye acts as, for lack of better words, a solid location device (a mechanical single pivot) is the anchor of the rear suspension. Since any and most of all movement in the spring itself is in the rear half of the spring (a mechanical two pivot), it would be the only end of the spring that would need the mechanical means to twist and control a change in length from the suspension movement. A slider would change that into a single pivot, and from there, that would be the pivot that should recieve a spherical insert. But a solid rear with a spherical front ??.... I dont see how that is really going to be any real help at all.

Wow. That is the exact opposite of everything I have heard (or misunderstood, I guess). Everything I have read states that the front spring eye should have either a rubber or spherical bushing and the rear should be solid or poly. Then I read this thread:https://www.pro-touring.com/forum/showthread.php?t=18924&highlight=flex-a-form and my question about spherical bushings at both ends came up. But, as I visualize the axle's movement during cornering it makes sense that the rear of the spring would both slide back and twist torsionally on the inside wheel and do the opposite on the outside.


GW utilizes a single pivot in the rear spring eye with a solid frame insert.

I have never seen the Cat 5 setup in person. However, the quote from the blurb under the picture of the articulating shackle:
https://static1.pt-content.com/images/noimg.gif
makes it pretty clear that "the spherical bearings in both ends of the leaf spring allow for the tilt." That's partially what brought on my confusion. I'm still not sure if it's a typo or not considering what you just said.


You have yet to expound on what it is that you are building.
Sorry, no sig on this forum. It's a 1981 Camaro with a Vortec 406 EFI sbc and an overdrive auto trans that is yet to be determined. My goal is not for an all out road racer but very spirited commuting and the ocassional track day would be right on target. It's going to be a daily driver that sees 99.9% highway driving (average 80 mph for an hour and a half each way) on the Garden State.


... Doug's rear CAT5 shackle set-up with an FIA type spring build.

I'll have to look this up. Thanks for taking the time.

[astroracer]

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/techarticles/ctrp_0602_leaf_spring_tech_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

[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/techarticles/ctrp_0602_leaf_spring_tech_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

[David Pozzi]

My 67 Camaro used Guldstrand "autocross' leaf springs, they came with solid bronze bushings front and rear. The front spring eye bolts egged out the holes in my front spring brackets from the harsh ride and twisting of the leaf. The car rode VERY harsh over freeway tar strips or pot holes, like re-adjust-your-mirrors rough. On smooth roads, it wasn't bad.
David

[CarlC]

OK, that's me in the link.

I too looked at the Suicide Doors part. However, they are only available with a 2-5/8" OD. They are too big to use unless special springs, spring brackets, and shackles are made. By that time, it's too much work.

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.

As some point I may try using a homemade del-a-lum bushing in the front.

Many of the sliders, including the AFCO part, utilize a single row ball bearing for the rolling component. However, these bearings were never meant to be used this way. The outer rings are far to thin to be used without a housing, and the load ratings are too low. In other words, they won't last long.

[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.

[hardline_42]

OK, that's me in the link.

I too looked at the Suicide Doors part. However, they are only available with a 2-5/8" OD. They are too big to use unless special springs, spring brackets, and shackles are made. By that time, it's too much work.

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.

As some point I may try using a homemade del-a-lum bushing in the front.

Many of the sliders, including the AFCO part, utilize a single row ball bearing for the rolling component. However, these bearings were never meant to be used this way. The outer rings are far to thin to be used without a housing, and the load ratings are too low. In other words, they won't last long.
Carl, you were running the setup with the Flex-A-Form springs IIRC. What were the results of using the spherical bushings front and back? Were you afraid of spring failure due to torsional loading or were there handling concerns? Thanks.

[astroracer]

My goal is not for an all out road racer but very spirited commuting and the ocassional track day would be right on target. It's going to be a daily driver that sees 99.9% highway driving (average 80 mph for an hour and a half each way) on the Garden State.

I'm sorry if I misunderstood this statement. I THOUGHT you were building a street car... My bad.
Mark

[hardline_42]

I'm sorry if I misunderstood this statement. I THOUGHT you were building a street car... My bad.
Mark
Guess I should've given you the whole story. The car was always meant to be a road racer and not my daily driver. Unfortunately, my daily driver is on the out and since my wife and I are shopping around for mortgages, we decided that now was not a good time to take out a new car loan. She suggested that I spend the money to make the camaro "road worthy" for my daily driver in the meantime. Not being one to disregard my wife's request (how often does your wife ask you, nay TELL you to dump money into your project?), I now have to build a road racer that will see constant highway duty for 6 months. I don't want to have to do the suspension over again later on but what I know only skims the surface, so I need all the help I can get.

[CarlC]

Torsional loading, but as Tom stated, dare to be different....

[jaybee]

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

[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.

[Rick Dorion]

And, to add to the options, I've been very pleased with the GW delalums front/back in my leaf springs. Tom had commented on this como a while back.