Ideal shock lengths

[Jared]

Okay, I'm building a '96 XJ with an 8.5" lift. I'm not interested in hearing how this is too much lift, or that your buddy's setup would work better so if that's all you have to offer, please move on. Most of my wheeling is in Moab, but I very much like going fast on desert roads and plan on cruising more in the dunes.

I am ordering a full set of Bilstein 5125's, one at each corner. They will be 255/70 valving (medium). 12" travel fronts and 10" travel rears will bolt up and sit exactly halfway through the travel of the shocks. For example, at rest the front 12" travel shocks will have 6" of exposed shaft. Is this where I want the length of the shocks to be - right in the middle of their travel? Or would more compression travel be better? More extension travel instead? I need to build my bumpstops to match how I mount the shocks.

I do hit a lot of bumps hard, and will certainly be doing more of that at the dunes, so I'm leaning toward having the shocks at rest with more compression travel available than extension (meaning the shaft would be out further at rest. But I'm new to this and would love to have a 2nd opinon.

Any experts out there? Any old desert buggy builders with some insight into this?

Thanks!


Thought it might be important to add... the front lift is a Skyjacker RockReady subframe and lower arms. The lower arms are appx 4" longer than stock lowers. Johnny Joints throughout. The rear is BOR 8" springs and extended shackles.

 

[GOAT]

Okay, I'm building a '96 XJ with an 8.5" lift. I'm not interested in hearing how this is too much lift, or that your buddy's setup would work better so if that's all you have to offer, please move on. Most of my wheeling is in Moab, but I very much like going fast on desert roads and plan on cruising more in the dunes.

I am ordering a full set of Bilstein 5125's, one at each corner. They will be 255/70 valving (medium). 12" travel fronts and 10" travel rears will bolt up and sit exactly halfway through the travel of the shocks. For example, at rest the front 12" travel shocks will have 6" of exposed shaft. Is this where I want the length of the shocks to be - right in the middle of their travel? Or would more compression travel be better? More extension travel instead? I need to build my bumpstops to match how I mount the shocks.

I do hit a lot of bumps hard, and will certainly be doing more of that at the dunes, so I'm leaning toward having the shocks at rest with more compression travel available than extension (meaning the shaft would be out further at rest. But I'm new to this and would love to have a 2nd opinon.

Any experts out there? Any old desert buggy builders with some insight into this?

Thanks!


Thought it might be important to add... the front lift is a Skyjacker RockReady subframe and lower arms. The lower arms are appx 4" longer than stock lowers. Johnny Joints throughout. The rear is BOR 8" springs and extended shackles.

I would measure the mounts at ride height and provide deminsions to bilstein.

8-9" of lift is usually requires 31-32" extended front shocks on an XJ.

 

[waynehartwig]

x2
Or set your ride height and measure what it is. Figure out how much up travel you want and that will give you your compressed length. Add your 12" (or whatever) and then you have your extended length. Depending on if you have bump stops or not, will depend on how much up travel to leave. I'd leave at least 3-4" available (with bump stops).

 

[Jared]

I would measure the mounts at ride height and provide deminsions to bilstein.

That would have been great counsel to follow a week ago before I ordered the shocks!
___________

I already know what lengths I need - in fact I already have them... I determined the length by taking the Jeep out and flexing it with no shocks installed. I measured the lengths and found the best match on Bilstein's shock length charts. I just looked for the compressed/extended shock lengths that encompassed the compressed/extended lengths I measured on the Jeep.

I need to fabricate lower shock mounts front and rear. So, my big question is this - Where should the shocks should sit in their travel at rest? Meaning... when the vehicle is sitting on level ground do I want 6" of up travel and 6" of down travel available for a 12" travel shock? In other words, when it's parked should I have 6" of shaft exposed? Or, would 7" of up travel and 5" down be better? Or...?

I know I stink at explaining this! The best way I can sum this up is "Where do I fab my lower shock mounts?". Where I install them will determine where my shocks rest in their travel.

Thanks again!
Jared

 

[Jared]

Okay, I just read my last post and I don't think it conveys what I'm asking here.

Alright...

- I'm not just going to bolt these on to stock axles using the stock mounting locations. I have some room to set it up how I want, as far as where I locate the lower shock mounts.

- IF I fab mounts in the stock locations, the shocks I have will be sitting at dead center of their stroke at rest. Meaning that my front 12" travel shocks will have 6" of exposed shaft, and my rear 10" travel shocks will have 5" exposed. This means that from rest they have half their compression travel available, and half their extension travel available.

- My question is this... Is the above scenario, where the shocks rest in the center of their travel, ideal? Or, would it be advantageous to lower my mounts 1", giving me more compression travel and less extension travel? Or, by raising the mount 1" doing just the opposite? Regardless of where they end up, the bumpstops and limiting straps will be built to keep the shocks from fully bottoming or extending.

I guess I just wanted to know which is better for fast, desert style driving - a suspension that has more droop, more compression, or an even amount of each.

Thanks for reading my long post.
Jared

 

[Lifelong Jeeper]

x2
Or set your ride height and measure what it is. Figure out how much up travel you want and that will give you your compressed length. Add your 12" (or whatever) and then you have your extended length. Depending on if you have bump stops or not, will depend on how much up travel to leave. I'd leave at least 3-4" available (with bump stops).

I haven't ever set up a desert racer but I agree with what Wayne is saying here and I do understand, or at least I think I do, what you're asking. Let me see if I can explain his counsel in other words.

Compress the suspension sufficient for your tire to clear and not hit the body. In the front compress it and rotate the tire full crank to full crank. Measure that and set your bump stops there. Add 1"-2" to that and that should be your fully compressed shock length (1-2 inches of stroke to go before bottoming out the shock for really hard compression). Then do the opposite for setting your limiting strap lengths. Ride height IMO is irrelevant since it rests anywhere between these two points. It may be important to note that since you may be jumping this quite a bit that the suspension cycles differently with equal side to side up/down travel versus opposite side to side up/down travel (articulation). You may want to remove the springs so that you can compress/extend the suspension equally on both sides to make your measurements. Pay attention to pinion angle at this time too so that you don't break UJoints while fully compressed or extended. I know the rear has leaf springs so that may prove difficult since you can't just disconnect it.

 

[waynehartwig]

Kind of, but you want the bump stops to hit before the shock bottoms out.

I haven't ever set up a desert racer but I agree with what Wayne is saying here and I do understand, or at least I think I do, what you're asking. Let me see if I can explain his counsel in other words.

Compress the suspension sufficient for your tire to clear and not hit the body. In the front compress it and rotate the tire full crank to full crank. Measure that and set your bump stops there. Add 1"-2" to that and that should be your fully compressed shock length (1-2 inches of stroke to go before bottoming out the shock for really hard compression). Then do the opposite for setting your limiting strap lengths. Ride height IMO is irrelevant since it rests anywhere between these two points. It may be important to note that since you may be jumping this quite a bit that the suspension cycles differently with equal side to side up/down travel versus opposite side to side up/down travel (articulation). You may want to remove the springs so that you can compress/extend the suspension equally on both sides to make your measurements. Pay attention to pinion angle at this time too so that you don't break UJoints while fully compressed or extended. I know the rear has leaf springs so that may prove difficult since you can't just disconnect it.