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Front Suspension Cycling Results


Impact LJ

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So today I tried to cycle the front suspension to set bump stops and see what shock I'm best off going with.

As of this morning, I have no bump stop extension with a 3.5" lift installed. After my most recent wheeling trip, I realized I had enough rubbing to damage my front fender from the up travel.

The original plan was to add 2 hockey pucks bolted into the spring pad with a 1/2-13 bolt in case I needed to go with the Currie setup.

tempImageFVSAQ1.png


After realizing the jounce bumper does very little in terms of stopping up travel, I needed to add more. About 1.5 inches more the way I see it.

Here is where I need the up travel to stop and how much shock shaft I would have showing when that happens. It seems like quite a bit and something I could stop with a spacer on the top of the shock under the mount.

tempImageIwcdaJ.png

tempImagexNdqs3.png


What are you guys using as a spacer on top to maximize shock travel? Or am I better off going with the longer version?

These are the measurements of the shocks and mount:
tempImagegJA2q9.png
 

freedom_in_4low

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probably wouldn't hurt to fill out your profile so we have more info about your rig.

I have 3" of total bump stop extension which matches perfectly with Rancho RS55255 front shocks in factory mounts and nothing else makes contact before the bumps, including 33" tires.

This photo is from my TJ...I've replaced the springs and the rig itself lol but same axle, shocks, and bumps.
20200422_220944.jpg


You are correct about the jounce bumper - it collapses completely into the cup on a hard bump so bumps are checked with the jounces removed.

20200419_214534.jpg
 
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The shuggs

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You should remove the jounce bumper, and re-cycle the suspension. While you can measure the distance, and add to the bumpstops, you won't be able to tell if anything else is contacting before full bump.
 

Blackjack

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As been said start by taking the bumpstop out of the cup so you do not have to fight compressing it and then jack it up until your spacers hit the cup. Also you can move the brake line mount down the frame to pick up some travel out of it.
 
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Impact LJ

Impact LJ

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So the only thing not connected is the sway bar, springs, and shocks depending on if you are checking them at the time?
 
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Impact LJ

Impact LJ

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I have 3" of total bump stop extension which matches perfectly with Rancho RS55255 front shocks in factory mounts and nothing else makes contact before the bumps, including 33" tires.

This photo is from my TJ...I've replaced the springs and the rig itself lol but same axle, shocks, and bump

Good eye on the profile.

So theoretically it should be at least pretty close to the same story for me then eh? Maybe your fenders have something to do with it?
 

jjvw

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At the end of the day, the shock is the limit to up. The jounce is there to slow the last bit of travel.
 
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LONGJP2

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If you have to limit the travel that much to clear your tires, at what point are the tires not worth it.

However, that seems to be the trend. Really big tires, less travel.
 
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Impact LJ

Impact LJ

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If you have to limit the travel that much to clear your tires, at what point are the tires not worth it.

However, that seems to be the trend. Really big tires, less travel.
33" tires with a 4" lift is what is recommended by most people on this site, I can't imagine 35's with this lift.
 

jjvw

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It looks like you have the Currie bumps, do they replace the top jounce cup or add onto it?

I'm thinking that's going to be the way to go...
They both replace and add. Without the included spacers, Currie bumps are intended to keep Currie 4" springs from going solid. But they are not intended to stop travel, only slow it. The shocks do the final stopping.
 
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Impact LJ

Impact LJ

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They both replace and add. Without the included spacers, Currie bumps are intended to keep Currie 4" springs from going solid. But they are not intended to stop travel, only slow it. The shocks do the final stopping.
I thought the shocks weren't to be used as the final stop in order to preserve their life? A body lift might also be a solution.
 

jjvw

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I thought the shocks weren't to be used as the final stop in order to preserve their life? ...

I'm guilty of saying that for many years.

The reality is that if you use the right size shock with an appropriate lift height for the desired tire size, then the shocks can be used as the final limit to travel. And you get to use the entire travel of the shock. This means finding a shock that will closely divide it's travel in half from ride height. This gives the shock enough distance (and time) to slow the suspension travel before the shock fully compresses. Extend the bump stops so that the jounces add cushion near the end.

From this, you can infer some of the reasons why a low up travel LCoG build is dumb. The shocks aren't allowed to work properly.

... A body lift might also be a solution.

There are many good reasons to add a small body lift.
 
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Blackjack

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I thought the shocks weren't to be used as the final stop in order to preserve their life? A body lift might also be a solution.

If you are into the go fast thing this would be some truth to that but for the average recreational wheeler you just want to make sure you are not just crashing into them.
From this, you can infer some of the reasons why a low up travel LCoG build is dumb. The shocks aren't allowed to work properly.



There are many good reasons to add a small body lift.
I have never understood that either. Why spend the money to run 14" coilovers and run only four inches of up travel? Makes zero sense to me.

I agree that a 1-1.25 inch body lift is always a good plan.
 

Rubicon John

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I'm guilty of saying that for many years.

The reality is that if you use the right size shock with an appropriate lift height for the desired tire size, then the shocks can be used as the final limit to travel. And you get to use the entire travel of the shock. This means finding a shock that will closely divide it's travel in half from ride height. This gives the shock enough distance (and time) to slow the suspension travel before the shock fully compresses. Extend the bump stops so that the jounces add cushion near the end.

From this, you can infer some of the reasons why a low up travel LCoG build is dumb. The shocks aren't allowed to work properly.



There are many good reasons to add a small body lift.
Do the LCoG builds emphasize down travel while limiting up travel? In other words, is the shock 2/3+ of the way compressed at ride height?

If so, that would seem to be counterproductive to utilizing the shocks’ full travel.
 

freedom_in_4low

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Good eye on the profile.

So theoretically it should be at least pretty close to the same story for me then eh? Maybe your fenders have something to do with it?

The fenders don't add much. They get rid of the flange that the flares mount to but that's like 3/4". 2" bumps were enough to keep 32s out of the stock fenders before I cut them off the TJ, and though I didn't cycle before tearing the LJ apart, I havent found any signs of contact between the 33s and the stock fenders with the 2" of extension it had.

I'll know for sure later in the week, my Currie bumps are supposed to be delivered tomorrow. I was fine with what I had except for this happening when I put on the Currie 4" springs.

IMG_20210111_150706_319.jpg


I'm admittedly at a loss how you're getting tire contact with 3" of extension and what looks like 2" of air still in between with 33" tires. Where exactly are the tires making contact? And what specifically are you tire and wheel dimensions?
 
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