Spring Under XJ

[LhcAzXj]

Okay, so I have searched and searched threads containing information about spring under XJ's and with the exception of 1 or 2, everyone frowns upon it. The no.1 complaint is less ground clearance, followed by expensive springs, then too much rear travel for what the front is capable of. Lets say I don't care about ground clearance or the cost of springs, but I'm more interested in being able to slam whoops harder without compressing my spine.

I currently have 4" Deaver Jeepspeed Packs, Full Traction 1.5" boomerang shackles, and Fox 2.0 x 14" shocks through the floor all bolted to a Ford 8.8 axle. I only have about 5" of uptravel before the spring plates nearly contact the unibody frame, with about 5-6" of down travel. Now I understand that my shocks could be valved slightly stiffer on the compression side but anything I hit thats moderately sized my rear end will bottom out, followed by a buck afterward.

My buddy has SUA on his 1st gen 4 runner and is pulling around 19-20" of travel, would it benefit me to go SUA with HDOR spring hangers and custom shackles or am I just going the wrong direction with valving and travel?

 

[DieselSJ]

SUA >>>> SOA. We have been advocating for that change to the JS rules ever since we started. Even Deaver admits that we are overworking the springs and says that SUA with a longer spring will work better and let the springs last longer. And if you have a true Deaver race spring in the back, your rates are WAY too high.

Better travel.
Longer springs.
Better spring rates.

The biggest problem is getting a long enough shackle to allow the spring to fully flatten out. Also, you will need to control axle wrap because the springs will twist...a lot.

Alternately, swap to rear coils with a 4 link. Coils >>>> SUA >>>> SOA.

 

[LhcAzXj]

SUA >>>> SOA. We have been advocating for that change to the JS rules ever since we started. Even Deaver admits that we are overworking the springs and says that SUA with a longer spring will work better and let the springs last longer. And if you have a true Deaver race spring in the back, your rates are WAY too high.

Better travel.
Longer springs.
Better spring rates.

The biggest problem is getting a long enough shackle to allow the spring to fully flatten out. Also, you will need to control axle wrap because the springs will twist...a lot.

Alternately, swap to rear coils with a 4 link. Coils >>>> SUA >>>> SOA.

^^^^ that is exactly where my thoughts were, I just can't seem to find much information on it I'm assuming because JS rules don't allow it so it isn't a popular conversion.

Regarding my spring rates, I bought my deavers off of a guy who bought them new from deaver, used them for 6 months then sold the jeep, so I have no idea what my rates are. Like I said though, if I hit anything big they just blow through the compression damping and bottom out. That being said you would assume the rates are not that of a true JS Deaver pack huh?