Long arms should handle better and not have any quirks. You should expect a more comfortable ride both on road and off as you reduce the amount of axle shift that occurs during articulation. You can however get more brake dive and squat during acceleration depending on where the frame side control arms mount and you can get pinion angle issues on kits that use too short an upper arm. For rock crawling most long arm kits create some clearance issues because the arms hang down so low.
As for lift size vs axle width if you want to stay low and maintain full steer with a good scrub radius 72" wms axles with 4.5"x9" wheels are the sweet spot if you are running 40"x13.5" tires.
In my opinion you need to have the lower frame side mounts as close to the output shaft u joint. The uppers should be at least 80% the length of the lowers and the closer they get to the same length the less union change you get. If you have the mounts in this location your pinion will stay pointed at your transfer case thru out the articulation range
So, is the goal (to reduce driveline vibration) to keep the front diff pinion flange and the front t-case pinion flange as parallel as possible during full articulation? If so, I think the four-link would better accomplish this.
If it is to keep the front diff pinion flange pointed at the t-case then I think the lock-n-load would do a better job of that.
Am I visualizing that correctly?
Which should be my priority?
It really depends on the overall set up. Tire clearance, shocks travel, what you are going to do with it, budget. Frame side mounts and upper to lower arm lengths will determine pinion change. Either set up can be done to keep the angles lined up to prevent vibration or bind. You have to realize how a u-joint gets weaker as the angle increases.
Because of the design of the JK and the trend to have LCG and 40" tires driveline angles are often ignored. Most companies concentrate on long travel instead of looking at the overall and typically give too much droop to gain that long travel. Metal cloak is the only company that I know of that addresses this by the use of the high clearance fenders and 6 pack shocks (even though I don't recommend the 6 pack). They build that set up for up travel as well as overall long travel that keeps the driveline angles in check.
I see you have a pretty complete set up and not sure what you are wanting to accomplish with a long arm but really if you are not having any issues you are throwing away money with a new kit. You are not going to see much improvement from a long arm in terms of performance. If any it would be better ride on the road.
I'm primarily concerned with belly clearance in the bigger rocks.
The 3-1/2 kit is working great as is.
So the smarter choice may be in tires and strengthening the axles? That could keep the center of gravity lower...
There is always a bigger rock to get over. Tires are the best route as you get actual clearance under the axle as well but creates issues with axle strength and gearing which can be costly. Excessive lifts lead to handling issues and the increased need for a caster corrected front axle and a close look at your driveline angles at full droop.
Looking for comments and observations on these two kits. Going to 5-1/2" with rocksports and want to hear some real world comments about both styles. I like that the lock n load doesn't require welding and addresses binding but it looks like it puts all the stress on the two mounts. Any feedback is appreciated, still trying to make up my mind :dunno: