Let's get this out of the way up front: I'm pretty dumb. I drive too fast for the XJ I've got, and I end up breaking it a lot. Most recently, I shot the stereo out of the dash, jammed the seatbelt for good, and blew one of the seat mounts through the floor. I'm pretty dumb.

After asking for some advice here, helpful forum members pointed out that I have exactly the wrong suspension for what I'm doing. There aren't any rocks where I wheel: I don't rock crawl. There are a lot of trails where I wheel: I trail run. I drive as fast as I possibly can down rutted, potholed, washboarded, hummocked dirt, mud, and sand trails, two-tracks, and fields. And I mean big holes: it's not uncommon to hit something that's a lot like a curb, and I'm hitting it at 30, 40, 50 MPH. And my 3.5 inch RE lift kit has the highest spring rate out there, hence the shooting of the seat through the floor. So I need to make some changes.

What kind of suspension setup would you recommend for the kind of high-speed, tall obstacle offroading I'm doing? I'm hoping to gain some articulation, as well - the RE springs are so stiff it's like I still have a anti-sway bar - but mostly what I'm interested in is smoothing out the surface a little so I don't break everything all the time.

 

wow. yeah 40-50mph with small objects without breaking your neck from the bumpiness is expensive. sounds like you're ultra-fouring the damn thing

3 link/ radius arms
front axle trussed to hell with a good diff cover and C gussets
beefed upper and lower control arm mounts
rear axle also trussed (probably swap to a bigger axle)
full circle snap rings and upgraded ujoints
keep the coils/leafs and run really good shocks. bilsteins or better
BUMP STOPS
FRAME PLATING. roll cage tied really well to the frame


^^that's like bare minimum. otherwise it's going to fall apart in a matter of months at the rate you drive it. the faster you go the more it costs. the less $$/time you spend prepping it the more often you will repair it. check out some pre runner threads on naxja

 

LongArms
Bilstien 7100 Series (pricey, but you can rebuild and change the valving yourself)
Adjustable Coil Spacer Pro
Keep the 3.5" coils, they'll help your stability'
Currie Anti-Rock

 

Look up prerunner xj builds to get ideas.

 

Hmm. I've been doing this with stock XJs for years, without exploding everything in sight. I guess all I'm really looking for is springs with a rate not quite as ridiculous as the RE coils and leafs I have, and appropriate shocks - and I think the Bilstein 7100s fit that bill - so I'll definitely check out some prerunners and see what springs they're using. Thanks, all!

 

if you're going 40-50mph through bumpy terrain without bending everything in sight then you probably arent going as fast as you say you are.

you're going to want to keep the slightly stiffer coils and such. if you were looking to change the ride quality its going to come from better shocks and long arms

 

Yup. If you did it stock, you aren't doing anything close to what you think you're doing. Change out your shocks for 7100s... 360/80 valve up front and 275/78 valve out back.

I can do all that you say you're doing with a cup of soup between my legs and it won't spill... But it'll cost you. Ok maybe not really but I have a ton of cash into my suspension and it shows when I get crazy.

 

Deaver springs front and back

 

Well, I don't know how your XJs are set up, but on mine, there's this big dial in the middle of the dash that gives me a pretty accurate idea of how quickly I'm traveling. It's pretty sweet: you should check it out!

Seriously, I think I've given the wrong impression, like, "I hit 100 curbs going 50 every day, and never broke anything!" It's a bell curve, centered around 30 or 35: sometimes I hit stuff at 50, sometimes I hit stuff at 10. I would expect if I hit a big hole at 50 that it'd shake me up a bit: I can't tolerate running a two-mile-long pitted dirt trail at 35 and having my seats break. So maybe adjust your sights downward a bit: 50 is supposed to be the boundary exception, not the rule.

Really? That surprises me. On my last two "can't handle the rough stuff" Jeeps - set up for rock crawling and not for trail running - the culprit has seemed to be way-too-stiff springs, that won't allow the suspension to give when it needs to. Is that really a shock-and-geometry problem, then, and not a spring problem? Remember, these are the RE 3.5 springs, which are the stiffest on the market at that size: they're not "slightly stiffer," they're "exactly like having a sway bar." My articulation posing pictures are very disappointing.

That definitely seems like great advice. Given that this is also a daily driver, and I'm not flush with cash, and if I'm lucky I get to wheel it a couple times a month, do you think it's worth remote reservoirs, or would the standard 7100 do the trick?

This is a common refrain I hear from high-speed runners - I note that's what 93XJLI has on his cup-of-soup-between-legs suspension, for example! I suspect cost is going to be a factor, but I'd rather drive slow for six months and save up for the right thing that put more money into something that doesn't do what I want.

 

My word. It'll cost me more for 4 Bilstein 7100s than I've spent on several of my Cherokees. Maybe I should just buy another $850 Cherokee and just drive it until everything shatters.

 

A Purpose-Built rig is going to cost money.

You can't have it both ways so you need to pick one or the other, built right or built cheap.

Not bashing you or anything, just pointing out the cold truth. Based on your descriptions, you are going to have to start re-thinking your budget.

 

Lol. I have more than twice that into just springs and shocks.

 

On your advice, I've been looking at trusses, and I definitely think they're doable in the short-ish term. Before I run out and start welding stuff, let me ask: what are they for? Obviously, to strengthen the axle, but to what end? Just to keep the axle from breaking, or to keep gears meshing? I'm more curious than anything else. And do you have any particular suggestions for whose truss? Looking at the ones I've seen, I think I could probably fab my own; is there a reason not to go that route?

As I go, I've been replacing my u-joints with Spicer 1310X u-joints, the no-grease-fitting style. Is this sufficient, do you think?

Yeah, I think this may become a priority. Besides the floors, this XJ body is in extremely good condition for its year [drove to MO from MI to get it, but it spent much of its like in IL], but looking at the frame design, and other people's builds, it's clear I need to reinforce the control arm mounts. If I'm going to put a long arm on it, that seems like the logical time to do all that, obviously.

Anyone's long arm / frame reinforcement you recommend? That's another one of those things [minus the arms themselves, obviously] that I probably could fab, but I probably shouldn't.

Yeah. This was a bad one. I didn't realize the PO had removed the rear bump stops, and hadn't lengthened the fronts, and I'm sure I did some damage to the seals on my Bilsteins this last time out. [When I broke the seat and floor and subwoofer box, et cetera. Derp.] I've got some picked out that I'll be picking up before I run again - I have a new floor to weld in next week; rust belt XJ, not too bad, but bad enough - so hopefully that's taken care of. Would love ACOS, but a couple hundred bucks more than I'm willing to spend at the moment. Which I'll be saying until I have to replace twice that in shocks, so that might be something I'll want to reconsider.

 

I don't disagree at all. But I think people have this distorted idea of what I'm looking for that involves taking it out every day and racing it down mountains.

Well, that's excellent for you. I don't have that kind of money to throw into what is ultimately a hobby, so maybe let's look at it this way: how can I make it faster over broken terrain, without dumping $4000 into suspension upgrades? Maybe I won't be able to hit 100 curbs at 50 MPH every day for a year, but I'm not really looking for that, anyway. What inexpensive options are there that will allow me to go faster than I currently can?

Like, let's say tomorrow someone replaced your Jeep with a normal 3.5" lifted XJ, and then took all your money away, so you couldn't solve problems with dollar signs. If you only had a couple grand to upgrade the whole thing, what would you do then? Consider it a thought experiment for the less fortunate.

 

The more I think about it, the more I feel like that's the question I should have asked to start with: given ~$2000 and an XJ with a 3.5" RE lift, Bilstein 5100 shocks, SYE, and HD tie rod, drag link, and track bar, on 31x5.5 tires, how would you modify the Jeep to be faster over trails without falling apart?