4 Link owners, please chime in

[Highveelocity]

For those of you that have 4 links with rod ends, without rubber or urathane bushings, what is the noise level like in the car? Does it transfer the road noise into the car?

[55fazzi]

Hey CT-Dummy,
In a word yes. With rod ends your likely to get noise from other parts of your car vibrating from the extra rigid suspension or........You may not get any additional noise at all. Keep in mind rod ends don't flex and give like the rubber or poly rod ends do making them less friendly for a street car turning corners and entering/exiting driveways. If you do choose to run rod ends....you must check them often for damage and to see that the adjuster nuts havn't vibrated loose. Hope this helps.

Tom

[Highveelocity]

So maybe I should run a non adjustable 4 bar, since I don't plan to drag race?

[55fazzi]

I dont know of any four bar or four link set-up that does not adjust. If you plan on running adjustable coil overs or an air bag/shock system, changing the ride height ocassionally, the adjustability will be helpful in keeping the correct pinion angle. It also assists in final adjustments after installation. Just remember to set the pinion angle then install the bars parallel to each other and level to the ground, or close there too, at ride height and you will be fine. Mild steel or 4130 rod ends are for drag cars who's adjustment, integrity and torque are checked after every pass. Rubber or poly rod ends will give a firm yet less harsh ride.

Tom

[JLS]

I am with Fazzi, unless you're building a drag car (and it sounds like you're not) stay away from rod ends. They are noisey and clunk when there is a shift in motion [entering driveways, going from reverse to forward, etc]
Stick with a Parallel 4 bar and not a 4-link. You don't need all the adjustments of a 4-link.
And also Like Fazzi said, set those bars up so they are parallel to the ground at ride height.

My car has a 4-link, but over the big block's crackle through dual 3" exhausts, the least of my problems is noise from the rod-ends. :)

http://i117.photobucket.com/albums/o49/joesander/50%20FORD/4-link-9-inch-ford.jpg

Joe

[Highveelocity]

Thanks for the info guys, just what I was looking for.:D Why is it important to keep the bars parallel to the ground at ride height. The goal is to have the pinion angle correct through the entire suspension travel, right?

[JLS]

Yeah, with a 4 bar, the pinion angle wont change much as it travels up and down. This is because as the rear axle travles up and down the axle will go up and come down, while the axles angle relative to the ground remains the same thus keeping the pinion angle the same as the angle coming out of the tailshaft (assuming you set your pinion angle correctly, of course)

The reason you want the bars set parallel at ride height is because as the axle travels up and down during suspension, it will swing in a slight arc. The radius of this arc is the same as the length of your bars. This arc will slightly move the axle back and forth essentially during suspension travel. By keeping the bars parallel you are limiting this back and forth movement as much as possible by placing the axle in a relatively calm spot of the arc.

In my attached diagram you can see a simolified and exagerated view of a 4 bar and it's suspension travle. You can see the difference between the X's are the same virtically. But you can see the difference between A and B is greater. If your car was set up at #2 ride height the axle would "walk" a lot more than if your ride height was at position #1.

Joe

[Highveelocity]

Very well illustrated! I plan to make my own 4 bar out of stainless steel, should I use urathane or rubber bushings?

[55fazzi]

Slight pinion angle changes occur during accelereation and braking and thats good for a street car. You don't want a super rigid set-up (rod ends) like a drag car which is designed to deliver all the power to the rear tires immediately with little or no change in pinion angle. Pro chassis builders/engineers recommend the bars be installed parallel to each other and the ground at ride height, on a street car, for the same reasons you should use rubber or poly rod ends. To ensure there is ample suspension travel for street applications....cornering, driveways, speed bumps etc. Starting at parallel accomplishes this.

Tom

[55fazzi]

Rubber or poly???
Personnel preference. You might not feel any performance difference between the two if you were to test them. Rubber will "give" a little more than the poly. Poly is supposed to last longer than bubber. Some poly brands tends to squeek. Rubber can squeek also. To maximize the performance benefits from a four bar suspension I'd go with the poly bushings. Have fun!

Tom

[Highveelocity]

Thanks Tom. I will have fun! I bought my engine and trans last week and I am just about ready to fit it to the frame, then I'll start on the rear suspension.:D

[55fazzi]

You're very welcome.

Tom

[NickP]

http://pic20.picturetrail.com/VOL1600/2283636/6394656/99300295.jpg

You might give consideration to AME's (Art Morrison Enterprise) Triangulated 4 link. You have no need of a Track Locator/Wishbone Link/Panhard Bar and the associated cost/issues.

[Highveelocity]

I was shying away from the triangulated 4 link because I heard they bind when there is articulation. Is that true, and if it is, is it really an issue?

[NickP]

Try and recall, this type of suspension has been on Chevys since 1958 - Review the AME (Art Morrison) catalog and look for their 1955, it has the very same rear suspension in my pic and works very well - read about it http://www.artmorrison.com/tri5/perf/index.cfm

[Highveelocity]

Yeah, and the late model mustangs have them , also. Maybe I will go with that after all. Now I just have to order some Stainless tubing! :D