Front shock upper mounts - stem vs. eye?

[anthrax323]

Now that my XJ is running a measured 5.5" of lift, I really need to install longer shocks up front. The 5-6" lift Bilstein 5100s for the XJ appear to be the perfect length (adding 4" of downtravel), however, I got to thinking about it as I always do...

Are there any obvious advantages in converting the upper stem mount to a traditional eye mount? I've seen a handful of people do it, but I'm not sure if it was necessary due to the shocks they chose, or if there's a notable mechanical advantage to doing so.

If there's no real reason to do it, I'll just stick with the stem style for now. Thanks in advance!

 

[Cherokeekid88]

The only difference is running a shock conversion kit on the front allows you to run shocks not built vehicle specific, such as fox, kings, bilstein etc. I have bilsteins that have a stem....I did run a shock conversion kit, but I found it to be annoying when chaning out shocks.

 

[anthrax323]

Right on, that's what I figured. I want to step up to 5160s (non-vehicle specific) but can't justify the coin associated with them at this point. Not to mention I've been extremely happy with my 5100s on everything but washboard surfaces.

Thanks man!

 

[bcmaxx]

It alsoopens up a world of shocks to you and allows you to completely dial in shock lengths using compressed/extended measurements

 

[anthrax323]

Quite true, but for now I don't think it's necessary. This is the last suspension work for a while (hopefully), as 5.5" is way more lift than I wanted in the first place. The next investments include gears, lockers, and new tires.

The next pass at suspension work will hopefully be on a new XJ (my current body has rear frame rail damage from an unreported rear-end collision involving the PO), at which point I'll be stepping up to OME LTRs or Bilstein 5160s. For now, I just want to maximize articulation.

Given the stiffness of my RE 3.5" front coils, I can no longer fully stuff the fronts after installing the JKS ACOS setup. I have a set of JKS bump stops sitting in a box waiting for installation, which will go in once I install the new shocks (I'll only be losing 2" of uptravel so bumpstopping should be an easy way to ensure the shocks are protected).

When it comes to the rears, I found I'll be gaining less than an inch of stroke if I go for the 5-6" lift 5100s (running the 4" models right now). I'm just going to make a weekend project of raising the axle-side shock mounts in the rear to gain what little droop I'm missing out on without having to replace the shocks.

 

[anthrax323]

Pics of current articulation:

 

[gpnmoab1]

I did try the eye conversion for some time and they worked fine only I lost uptravel with this setup. I decided to go to Bilstein 5160s and went back to the stem as they had a perfect length to eliminate the eye conversion. I prefer the stem only because I did not want to lose any uptravel.

 

[xj9140]

Stims are better.

 

[xcm]

Conventional eye conversion brackets eat up about an inch and a half of shock length, not the end of the world, but something to consider.

There are at least a couple of top tier shock mfg's that make a stem top shock, such as fox.

Its complicated, between bilstein, bilstein short bodies, and fox, you have a spread of over 3" in lengths. Obviously pick the shock that fits best.

 

[sunburned]

I wanted 7100's, so I bought the eye mount from Poly. They seemed to be really long, so I ended up drilling another hole in them higher up and trimmed off the rest so they wouldn't kill all my shock travel. I also made new lower mounts that were lower than stock, so it all evened out, just dropping the whole shock lower instead of killing uptravel.

 

[anthrax323]

Good points, thanks guys - ultimately I will have to measure if I don't go with the 5100s for 5-6" of lift (the dimensions appear to be perfect based on what I've seen flexing it out).

I did try the eye conversion for some time and they worked fine only I lost uptravel with this setup. I decided to go to Bilstein 5160s and went back to the stem as they had a perfect length to eliminate the eye conversion. I prefer the stem only because I did not want to lose any uptravel.

I'm now seriously considering the 5160s for the front, but the only "direct fit" options I've seen from Bilstein are for 4" of lift. I'll get on the phone with them to discuss it further, but are these the ones you're running, or did you get longer ones?

I ask because I'm about to re-valve my dad's 5160s (5165s, really, as he's had them converted) for his Suburban, and he's offering to buy me a pair of 5160s as a "thank you" for doing it. If you've got model numbers and dimensions handy that'd be awesome, but if not, don't sweat it - Bilstein's support/advice gurus are extremely helpful every time I've called.

 

[gpnmoab1]

Good points, thanks guys - ultimately I will have to measure if I don't go with the 5100s for 5-6" of lift (the dimensions appear to be perfect based on what I've seen flexing it out).


I'm now seriously considering the 5160s for the front, but the only "direct fit" options I've seen from Bilstein are for 4" of lift. I'll get on the phone with them to discuss it further, but are these the ones you're running, or did you get longer ones?

I ask because I'm about to re-valve my dad's 5160s (5165s, really, as he's had them converted) for his Suburban, and he's offering to buy me a pair of 5160s as a "thank you" for doing it. If you've got model numbers and dimensions handy that'd be awesome, but if not, don't sweat it - Bilstein's support/advice gurus are extremely helpful every time I've called.

Oh man I'm sorry... I have the 5100's for 6" lift, not the 5160. The 5100 is perfect and I run 7 1/4 in lift. I seem to remember they make some 5165 in custom lengths but they have an eye on top. I was looking at the 5165 part # 25-187700 27.4 x 16.1 valving is 170/60. You would need to be careful and bump stop them.

 

[markw]

Oh man I'm sorry... I have the 5100's for 6" lift, not the 5160. The 5100 is perfect and I run 7 1/4 in lift. I seem to remember they make some 5165 in custom lengths but they have an eye on top. I was looking at the 5165 part # 25-187700 27.4 x 16.1 valving is 170/60. You would need to be careful and bump stop them.

You also don't want that valving. Go with the 255/70 or 275/78.

Also, quite a few guys are going to the prothane coil inserts for bump stops then shoving a measured 1.5" piece of delrin inside as a hard stop.

http://www.amazon.com/Prothane-19-1...65472651&sr=8-1&keywords=prothane+coil+insert

thread here:

http://www.naxja.org/forum/showthread.php?t=985677

 

[anthrax323]

Right on, awesome tips as usual. I've got a JKS bumpstop kit waiting to go in up front, and will be grabbing a set of the Currie rear bump stop plates in the next couple weeks, so bumpstopping is taken care of right now.

Looks like the payment for revalving my dad's 5165's has ballooned to a full set of 5160's for my XJ (ridiculous overpayment in my opinion, but he won't have it any other way)... So now it's time to look at the rears as well.

At 5.5" of lift, would you guys think it'd be wise to go ahead and raise the axle shock mounts (likely by either cutting and re-welding the factory ones, or buying the JKS tabs) and throw in a JKS upper shock hoop? Or should I just go with upper bar pin eliminators? I still don't fully understand the effects of steeper shock angles out back beyond being able to accommodate longer shocks. If what little I know is correct, the shocks will provide more damping/resistance when angled than if they were perfectly vertical, correct?

 

[Brent T]

You got it backwards. They will provide less damping / resistance if they're angled. The more you angle them, the less effective they will be.

 

[anthrax323]

Ahh, gotcha. With that in mind, I take it I should just go with BPE's in the rear? The JKS shock hoop bolts to the original upper shock mounts, meaning the mounts are a minimum of 3" further inboard. If I was to take this route, I guess I'd need to buy more aggressively valved shocks?

From what I've read this morning, the rule of thumb seems to be 10% loss of damping per 10° of shock angle. Sound about right?

 

[PahlMc]

It's not just that it decreases the damping, its that as the axle travels up, the shock gets even steeper, and you progressively decrease damping (which is called a regressive rate).

So- when you hit a huge bump and need maximum damping, you actually get less and less damping. Its horrible as far as going fast over bumps (I race desert trucks BTW).

However, with VERY limited shock mounting options for the XJ other than going through the floor, if you want the max travel from your set up, you may have to mount them more inboard.

So if you crawl a lot and go fast a little, run the longest shock you can to the center of the jeep. If you want better damping for go fast...well just do the first option and valve it to the moon! Its too expensive to go fast!

 

[rocknxj]

I had the same decision back in January. I bought some 5165's at the advice of Bilstein themselves, only to find out I would need to buy stem conversions. The conversions I bought with the 5165's were not the right type (made for stems, but they sold me eye type) so I returned them on my own dime. I'm still pissed at the entire transaction.

After searching for the correct eye conversion for a few days and failing to find what I needed, I decided to go for the Bilstein 5100's and they have been pretty good so far.

On a completely unrelated note, I believe I saw PahlMc's vehicle at Space Park at El Segundo today. I was catching the shuttle bus back to LAX and saw a red XJ with stickers on the side. Odd coincidence.