Coil over rear suspension options

[RonR]

Shad, I am not using stock trailing arms. With the tubular arms that I’m using, the heim joint bolts directly to the outside bracket. I’m referring to the plate to which the spring plate would normally bolt. On the arms that I’m using this plate is 3 ½ inches longer with the threaded coupling for the heim joint weld at the end. Therefore, there are no bolts are spring plate to get in the way of the tires. Also, this plate is slightly inboard compared to the stock arms and the heim joint is much more inboard compared to the Eagle Products kit. I have the heim joint located very close to the point at which the inner bushing axis intersects the axis running through the center of the torsion tube. I think that is important.

Ok, now I’m going to show my ignorance again. What are "isolation" heim joints?

Thanks again Shad. I really do appreciate you taking the time to educate me on this subject. I’m looking forward to getting my suspension completed so I can start on the engine with a set of those Biral Babies.

[Panelfantastic]

An isolation hiem doesn't have the "trapped ball" steel pivot point, instead it looks.... well, sort of like the end of a shock absorber ... with the steel sleeve the bolt goes through, then a rubber bushing, then a steel outer ring/housing with a threaded post like a regular hiem. Morrison has them in his 2003 catalog for $32.50 each in 3/4" and 5/8" (stainless steel).

[Shad Laws]

Hello-

Shad, I am not using stock trailing arms. With the tubular arms that I’m using, the heim joint bolts directly to the outside bracket. I’m referring to the plate to which the spring plate would normally bolt. On the arms that I’m using this plate is 3 ½ inches longer with the threaded coupling for the heim joint weld at the end. Therefore, there are no bolts are spring plate to get in the way of the tires. Also, this plate is slightly inboard compared to the stock arms and the heim joint is much more inboard compared to the Eagle Products kit. I have the heim joint located very close to the point at which the inner bushing axis intersects the axis running through the center of the torsion tube. I think that is important.

Ah, gotcha. I thought you had the Eagle setup, so I was confused by what you said. It all makes sense now :-).

Ok, now I’m going to show my ignorance again. What are "isolation" heim joints?

What Panelfantastic said is correct.

Thanks again Shad. I really do appreciate you taking the time to educate me on this subject. I’m looking forward to getting my suspension completed so I can start on the engine with a set of those Biral Babies.

No problem! Sorry I didn't get back to you sooner... life is quite hectic right now... <sigh>

Take care,

[RonR]

Panelfantastic, by “Morrison” are you referring to Art Morrison? In Art’s online catalog I only see one design of heim joint. Also shown, are what appear to be non-spherical rod ends which look very similar to but are not heim joints. Unlike the heim joint, a non-spherical rod end would not be able to swivel about it axis. I think that we may be talking semantics here. I think a heim joint, or spherical rod end, could be referred to as an “isolating” rod end. But the similar looking non-spherical (non-isolating?) rod end should not be referred to as a heim joint. Unless there is some variation to the original heim joint that I’m not aware of, which is of course a good possibility, all heim joints by there basic design are “isolating” (assuming I understand what is meant by “isolating”). The Eagle Products coil-over conversion kit utilizes heim joints not non-spherical ball ends.

[Panelfantastic]

Ron, yes Art Morrison is correct. I'm not sure on the exact labelling of one product as "isolation". I simply took that to mean a generic description of a style of rod end that "isolated" the vibration of the moving chassis. Maybe Shad can clear up the exact terminology we should use in reference to each style. I would also like to hear opinions on how important the on axis pivot of a spherical rod end is to street use as opposed to poly ends.
Also, I think "Heim" is a generic term used to describe spherical rod ends of all types, after the German inventor of the same name.

[RonR]

I’m not sure I exactly understand your question on the importance of “on axis pivot of a spherical rod end” as opposed to "poly ends”, but if you look at Art’s web page, there is a section that explains which one you should use for different applications. The bottom line is that if the joint has to move other than radial about its axis, the normal poly end joint will not work. That is the situation when replacing the spring plate, you have to use a spherical joint end (or a heim joint). Unless, you don’t care about putting a strain on the suspension and likely having something break. The spring plate is able to twist, if you replace it with a non-spring plate either it or the joint will have to also twist, or break. I don’t think chassis vibration is a consideration. Otherwise, I generally agree with your comments.

[Panelfantastic]

Art suggests sphericals are not best suited for street use and has the poly's listed as an option. Obviously he intends they can be interchanged even though the poly only has axis movement through deflection of the poly insert. Much the same as the mounting on the front of the control arm at the torsion housing. I was only curious as to your opinion of ... should we call it hard mounting as opposed to poly isolated. And would you also consider changing the front control arm mount to spherical ends?

[BerT3]

Hello,

Reading all the options and was wondering if the uni-ball setup will suit my air suspension setup.

Currently have a free floating setup with a cutted torsionbar in an Erthalon bushing. Note this is on a T3, they have longer torsionbars so I just cutted the splined ends from the springplates and the torsionbars.



I can move trough the complete suspension range and found the setup I used too binding. The springplate bends a lot through it's own axe.

Will the uni-ball setup (heim joint) suit my goal (stock swingaxle setup) ?

Van der Jeught Bert,
BELGIUM

[kenfyoozed]

shad,

i think im hearing from you that torsion bar setup is as good as a basic coil over set up. the reasons you gave i understand. i am re-evaluating what i want my car to do. it will be a everyday driver , with possible 1 day a year track time. so i dont think i will need coilovers for the fact of adjustments. but, if they ride better and i can lower my car wouldnt these be better in aspect? low ride and somewhat smoother than just lowering the rear torsion?

and the new dodge trucks with ifs now use a torsion bar setup on each side. so torsion still works.

neil

[Panelfantastic]

Originally posted by RonR
The bottom line is that if the joint has to move other than radial about its axis, the normal poly end joint will not work. That is the situation when replacing the spring plate, you have to use a spherical joint end (or a heim joint).

Sorry Ron, I only recently had an opportunity to lay under a spring plate car and move the suspension through a full arc. I knew the plate was slightly twisted under load but did not realize how much it twisted during travel of the full arc. My idea was completely unusable and now I see what you were trying to tell me. I suck at geometry and didn't understand the forces you were trying to convey.

[RonR]

No problem man, sometimes you have to just see it for yourself. Thanks for the reply and good luck with your project.