Topic: Long arm?

[bigchelis]

No doubt this question has probably been asked,  but will a long arm really make the Jeep smother in the street.
This is now my daily driver and I Keep reading that a long arm conversion will smooth the ride among other things.

This is an expensive approach, which is why I would probably lower the control arms with an inexpensive kit.

Is this a myth or has anyone actually done it and noticed a much smoother street driving machine?

[jagular7]

The links themselves don't make the ride better or worse. Its the combination of spring rate, shock, tire, and the air pressure.

What holds the weight of the vehicle up is the strength of the springs. They are usually given a rating, 350#/in, representing the amount of compression per inch for a given weight. The shock's valving has to work with the spring rate to make it smooth riding. The shock's purpose is to minimize the amount of oscillation from the axle movement. Given a spring rate, it will collapse to a point based on the amount of force it received. In return it will push back and probably go beyond the static point, push/pull till it stops oscillating. The shock is to minimize the amount of force the spring itself uses to get back to static. Tires play a very big role in a good or comfortable ride. The amount of space between the lugs, the size of the lugs themselves, the weight carrying capacity of the tire, etc. all are important to a smooth ride. Last but not least, the amount of air pressure in the tire.  A load range E tire generally is designed for high pressure (up to 60psi or more) load carrying tires. Load range C are a compromise to ride to carrying capacity. Load range E tires will also have better side wall strength through steel belts due to the higher weight carrying capacity. 

The links can be involved but not the links, just their ends. The ends have to be able to freely move without restrictions. Leaf springs with rubber bushings will usually have a rough ride as the mounting bolt is usually over tightened, causing the mount to rub on the rubber bushing. This causes friction. Same for the way the leafs are secured to each other. If there is a spring clamp on the leafs, I usually open it up to let the leafs rub against each other versus being pressed together.

[bigchelis]

Thanks for the imput.
I have a 4in superlift kit with 33in superswampers Mudd tires on 15in rims. (The TJ came with them).  Im definitely going to change the tires and rims for Rubicon style OEM's with 33's A/T. 

[Mr_Random]

Well from what I've read, and it does make sense to me is that the control arm angle, not the control arm itself, will change the smoothness of the ride.

It's all physics and trigonometry really, when the control arms have an angle relative to the body approaching or past 45* (technically -45 since they face down), the transference of energy from the ground to the body is increased across the arms.

Most lift kits, up to about 4", offer adjustable and/or extended control arms, most with only adjustable bottoms, some with top also. By lengthening the control arms, the angle of transference is lessened, and therefore produces a smoother ride, but this becomes negligible at anything past four inches, because extending the arms from stock mounts will eventually just push your axles too far forward/back to be anything practical.

Drop brackets, nowadays, are just cheap insurance. There are alot of Long Arm suspensions out, but many people just fab their own, as the LA's are NOT cheap. The Major advantage of LA's is that they extend your control arms by FAR, in an attempt to be as close to parallel as possible, allowing as much, if not all, of the energy to be absorbed by the springs and shocks. Most LA's, also, incorporate both top and bottom CA's into one long arm, allowing MUCH more flex to the axle without changing, making them wonderful for rock crawling and such.

The only disadvantage, I'm pretty sure (I haven't really read anything about it, but I'm good with visualizing mechanics and such in my head), is in high droop steering situations (how often does that happen anyways?), because your camber angle goes all to the pooper, as your axle is only following the angle in relation to the one long arm, ie; the long arm goes angle-down, the axle follows that same angle... as long as there isn't some remedy to this in the LA's design, it could be a problem. It's hard to wrap my head around this thought, let alone explain it to someone else... but in some, strange, more practical world, I'm sure it makes sense to someone.

Well, thanks for your time, and I hope this helps (and I pray I'm not just giving bogus info, it's not like I have some "mechanics and physics of long arm suspensions versus four links" manual on me).

[Mr_Random]

Most LA's, also, incorporate both top and bottom CA's into one long arm, allowing MUCH more flex to the axle without changing (something is supposed to go here, but I neglected to put it and now forgot what it was), making them wonderful for rock crawling and such.

I want to edit this statement, it doesn't make sense... but I'm not even sure what point I was trying to get across... oh well?

I guess good luck trying to understand what I was saying, not even I am making sense of myself at this point...

[neale_rs]

When you hit a bump the front tire moves up and forward.  Up is good for a smooth ride and forward is bad for a smooth ride.  Assuming the same 4" lift, with short arms there is more forward movement than with long arms.  So long arms should in theory be at least a bit better.  Enough to notice, who knows?  Softer shocks and lowering the tire pressure would probably help more and be a lot cheaper.