Thought I read about a formula for this somewhere and how it effects shocks dampening ability but can't find it anywhere. Anyway this is on my 89 XJ, putting in a 8.8 and figured I would weld the shock stud so it wasn't hanging below the axle. Now my shocks of course are too long so I was going to move the upper mounts to the middle of the jeep but was curious what this would do in terms of their dampening and ride.

I don't see the problem w/ the hi-clearance lower mounts and the relocation of the upper mounts. Cross Enterprises makes a "shock hoop" for the rear that relocates the upper mounts inwards, which provides more shock travel. I don't know about the dampening of the shocks though. With the upper mounts moved closer, the shocks would have less binding and way more travel.

http://www.crossenterprises.com/Image3.gif

Just my $.02 :flipoff2:

You lose dampening when you set it up like pictured. You also gain like yah said though more travel. Is a gain with a loss. As for the math of angle to amount of loss I recall seeing it while going thru coil over searches on this board.

my brother has the shock hoop on his XJ, and yea the wheel travel gained is great. he didn't lose any dampening b/c he simply bumped up his 9000's one notch. my point, easy fix if you have 9000's, if not maybe get new rears w/ a little stiffer valving, or "give and take" like all other mods... :D

Its a pretty slick idea for sure, but I don't know about spending that kinda cash on that CrossEnterprise thing.:eek: I saw a tech article somewhere a while back where somebody used the rear swaybar mounts as bar-pin eliminators. He had them mounted towards the middle of the rear crossmember, just in front of the XJ fuel cell. Pretty good setup, but it required some exhaust modifications to clear the shocks.

Edit: btw, that Cross thing is somewhere in the neighborhood of about $250.:shaking:

Cool, I was looking to soften up the ride in back anyways so that is a plus. Kinda high for that crossbrace especially for what it is, oh well. I'm just going to make up some mounts, bolt them up where it looks good and call it done.

I'll see if I can dig that link up Ath, I think I might know where its at.;) It was a minor mod that somebody did along with a homebrew rear coil conversion.

Originally posted by JS-Economos
I'll see if I can dig that link up Ath, I think I might know where its at.;) It was a minor mod that somebody did along with a homebrew rear coil conversion.


I'd like to se that article also, i recently broke and punctured a 9000 at Paragon.

I used the rear sway bar brackets at upper/rear in the stock location, but this idea sounds good if i can relocate the mounts on the tube and still reuse my existing shocks.


$250 for the shock crossmember is high!

Well, I couldn't find that article, but I'm still lookin'. I did find this little nugget off of BillaVista's webpage. He's got some very good XJ tech on his page.

Bill's rear BPEs (http://www.rightcoastcrawler.com/billaVista/BPEs/BPEs.htm)

BillaVista's Homepage (http://www.rightcoastcrawler.com/billaVista/Tech_Index.htm)

I'm still lookin' for that tech page though...

Take a look at the rear shock angles on this EB 14 Bolt.:eek: :eek:

Shot 1 (http://www.rightcoastcrawler.com/tech/Bolt14Shave/P6140556C2E2.jpg)

Shot 2 (http://www.rightcoastcrawler.com/tech/Bolt14Shave/P6140558C390.jpg)

Done deal, was really easy just made up some brackets out of angle iron and bolted them into a good location. I'll snap some pics tomorrow, didn't need to alter the exhaust or anything.

Originally posted by AthlonAJ
Done deal, was really easy just made up some brackets out of angle iron and bolted them into a good location. I'll snap some pics tomorrow, didn't need to alter the exhaust or anything.

Sweet, did you ditch the bar-pins? Lookin forward to some pics, better get some flex shots in there boss.:flipoff2: :flipoff2:

That cross enterprises thingy is $175 not $250. Still too high for a $20 hoop though.

Ben

Originally posted by jeepboyben
That cross enterprises thingy is $175 not $250. Still too high for a $20 hoop though.

Ben

Thanks, I stand corrected, but thats still an ankle-grabbing price.:D

Originally posted by JS-Economos


Sweet, did you ditch the bar-pins? Lookin forward to some pics, better get some flex shots in there boss.:flipoff2: :flipoff2:

Yup, no more barpins and it cost about $2 for the hardware and scrap I had laying around. Here's a pic of the angles and lower mounts. The left side of the axle is jacked up a little higher than the right so the angles look a little "off".
http://tellico.off-road.com/wwwthreads_uploads/871261-back.jpg

Outstanding work Ath, looks good all snugged up in there w/ the 8.8.;)

Damn, you've got both shocks mounted on the same side of the tubes, how does that work?

Here's the mounts, left side is the passenger side. I welded the nuts to a plate to slide in behind the area I fastened to to strengthen the area up and make them easier to install. They are not perfectly even with each other but close enough for me.
http://tellico.off-road.com/wwwthreads_uploads/871263-shocks4.jpg

Looks good, only about 1/2" off, if even that. I doubt it would make any difference at all. Nice work.

And last pic gives a better idea of where they are sitting. In the pic it looks like it could hit the exhaust but I removed the spring and jacked up the axle to the bump stop and it was close but didn't hit. I'll still probably change the exhaust as a "just in case":p , no big deal though. I've gotta finish everything tomorrow and then hopefully next weekend I can go out and see how it twists up!http://tellico.off-road.com/wwwthreads_uploads/871264-shocks3.jpg

if you are worried about the dampaning ability run 4 shocks in the rear....... and angle them more... just my .02

Click here form last week. (http://www.jeepsunlimited.com/forums/showthread.php?s=&threadid=279362&highlight=shock)

I just covered this....

Originally posted by JS-Economos
Take a look at the rear shock angles on this EB 14 Bolt.:eek: :eek:

Shot 1 (http://www.rightcoastcrawler.com/tech/Bolt14Shave/P6140556C2E2.jpg)

Shot 2 (http://www.rightcoastcrawler.com/tech/Bolt14Shave/P6140558C390.jpg)

WTF was that guy thinking?

Originally posted by Scout Dude


WTF was that guy thinking?

How could they possibly provide any sort of suspension control? I mean, fawk, they're 6" apart and right in the middle of the pumkin...:shaking:

Probably gonna get skulled for this, but I gotta throw my $0.02 in. No such thing as dampening. The term is damping. There is no stiffness to shock absorbers, there is only stiffness to springs. With a spring, force is equal to spring stiffness x deflection.

Damping only occurs when there is motion, velocity. Force from your shock absorbers is equivalent to rate of compression/expansion x damping coefficient. Damping force is purely rate dependent and is only dissipative in nature (that is it turns velocity energy into heat ~ absorbs). Springs on the other hand disspatte nearly no energy, 'cept the Coulomb friction of leaf springs. They store energy dependent upon the amount of deflection or extension and will release it as quickly as damping will allow it.

The fact that a shock wants to extend when you compress it is because the accumulator is pressurized and that pressure seeks to reach ambient (atmospheric) pressure. That pressure force is dick relative to the dynamic loads the shock is designed for during operation.

Geometry and triginometry will tell you how different angles effect damping forces. The relationship is linear for both springs and shocks. Manipulating the shock's geometry will impact the vehicle's ride. It strikes me that there are two main degrees of freedom with a rear axle: rotation of the axle relative to the fore/aft direction of the vehicle, and vertical translation (up and down) of the axle relative to the vehicle.

A rock crawler may want lower rotational damping forces on the axle to get more freeedom of articulation. This would be achieved by decreasing the distance between the roll axis of the axle and the shock (assuming same shock use). If the shock were to be moved inboard, the vertaical component of ride quality would remain unchanged, but body roll becomes more prevailent. That is the initial goal.

Another approach is to move one end of the shock to achieve the same purpose. As was discussed by ashmanjeepXJ, the change in angle impacts damping forces at the vehicle level. The steeper the angle of the shock the greater amount of travel of the shock is required to achieve the same vertical axle travel. Damping force is decreased by the same sine/cosine relationship of the angle.

Good luck, hope I don't wreak too much of engineering:(

Originally posted by Geesh

A rock crawler may want lower rotational damping forces on the axle to get more freeedom of articulation. This would be achieved by decreasing the distance between the roll axis of the axle and the shock (assuming same shock use). If the shock were to be moved inboard, the vertaical component of ride quality would remain unchanged, but body roll becomes more prevailent. That is the initial goal.

I dissagree with this statement? It would support this mess (http://www.rightcoastcrawler.com/tech/Bolt14Shave/P6140556C2E2.jpg)

for all types of wheeling stability is important, and contorl on the articulation is especially important, the inertia of a falling fast axle can take the whole jeep over with it......