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Unread 09-10-2013, 10:33 PM   #16
COLOUXJ
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Alright here is an update to setting up a suspension to any Jeep JK. I want to say that what I post here can be done with any setup whatsoever. This stuff here is what I have done to help everyone out there when they ask "will this work"

I have discovered through this that a high majority of offroad parts out there are trusting/assuming that you have atleast 2.5" of bumpstop. We saw that in how the JKS adjustable front trackbar hit the diff without the 2.5" being added. I also encountered problems with a component that I will talk about more below.

First I will start with a few comments about my particular setup and how it has treated me through the summer.

This setup has been great so far. I have taken it on 12+ hour wheeling trips and never been uncomfortable or ready to get out of the driver seat.

Tires: The Duratracs keep surprising me even after owning them for the last 4 years. They take abuse like any mud tire out there and never slip up. The most damage that they got was getting the outer treads chewed up a bit when trying to rescue a hydro locked JK out of the bottom of a canyon by spinning all my wheels up a gravel inline of about 30 degrees.

Bilstein 5100s: During the first 500 miles or so I thought that the Bilsteins were really stiff, that changed however after they broke in and now these puppies absorb everything. Taking them on forests roads is a breeze and they make the ride seem like your cruising down the street in front of your house. Can't say enough about these. One drawback that I do have for them though is the amount of down travel that they have. I know this is not anything that they can help but if I had to be picky thats what I would say. I am looking at either shock extension now, or maybe even swapping the shocks out for a p/n 2" longer if it exists.

OME HD 2" lift springs: These things are great. Even after about 7k miles on the Jeep they have only settled about 1/4".

Clayton control arms: I love these control arms. There is nothing that is going to bend them. They are massive. I highly recommend them. I was concerned that they only had one JJ at the axle end, but these things flex like no other. I can only say good things about these arms.

Now, let's get to the informative stuff. While doing the lift the bumpstop measurements were taken, you can read about that in the first couple posts.

FRONT:

The front bumpstops were the most involved. The install started with tearing down the front end again. The shocks where removed the trackbar disconnected from the axle end, and for good measure the front lower control arms were disconnected from the axle end as well. Finally, with all this disconnected I was able to just pull the springs out, no need for spring compressors!

First step was to prepare the bumpstops themselves. For the front Zone Offroad body lift pucks 3" tall by 3" in diameter were purchased. The spring perches on the JK axle are 3.5" wide so a 3" diameter puck works perfectly.

Since only 2.5" of bumpstop were needed the pucks were trimmed down by 1/2".

To attach the pucks to the perches grade 8 1/2-13 bolts 3" long were used.
The spring perches were then drilled and tapped.

And lastly the pucks were installed.


REAR:

We did not end up cycling the suspension in the rear, thus we did not remove the springs, shocks, trackbar, or control arms. The setup in the rear actually allows for bumpstops to be installed with the Jeep sitting on the ground at ride height.

The rear were far easier than the fronts. On the rear axle of JK's there is a spot that is flat with two holes already on the flat. Perfect for bumpstop extensions (maybe Jeep knew people were going to install aftermarket parts on their product?)

For the actually bumpstop 3" tall x 4" wide x 1/4" wall sqaure tubing was used. the two holes were traced onto the tubing and then holes were drilled on the tubing and the bumpstops were installed.




UNFORESEEN PROBLEM:
While crawling around the front of the Jeep it was discovered that the lower control arms were rubbing on the top of the control arm brackets. Time to bring out the angle grinder to fix this problem.




TESTING:
So after reinstalling the control arms and reattaching the trackbar the front suspension was cycled to check to make sure everything was clearing. TIme for lots of pictures.



Full Bump:







On the last picture you can see how close the tire gets to the tub mounts and the front swaybar. Because of this I recommend anyone with 35's to atleast run 2.5" of bumpstops to avoid hitting anything under the front end under full flex.

Now, in the first post I showed the interference between the front tires and the stock bumper. To fix this I ordered the VDP stubby endcaps. Eventually I want to upgrade to an aftermarket bumper, but as I want to get the suspension and drivability of the Jeep up to where I want it, a bumper is just not in the budget quite yet so these will work for now. The install on this was very easy. More pictures to show the process.






The color on the endcaps is different when you install them, but it get a lot less noticeable after you get them a little dirty.

Finally I have some flexing pictures while out on the trail.






As you can see these pictures were at almost full bump, still had maybe 1/2" of uptravel but did not feel safe getting out of the jeep when I had the back tire off the ground.

Everything works well and I get no rubbing, except for one little spot that was not tested.


Looks like it will be a stubby bumper that I upgrade to when the time comes.

Finally a fun wheeling shot at a trail in the area that I did this weekend.


So, that is all for now. I hope this write up helps someone out there when they are researching their lifts. There will be more to come, but I might move that stuff over to a build thread since most of it will not be relevant to a proper suspension setup.

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Quote:
Originally Posted by cyberpyrot View Post
is it a plink plink kerrrrdunk? or more of a brrrrrconk doc doc miiiidge pang!!!? or is it a badonk ka donk? if it is the latter its just the normal fat *** of the JK

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Unread 09-10-2013, 10:34 PM   #17
COLOUXJ
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Quote:
Originally Posted by SoK66 View Post
Well done. That's precisely the way to fit a custom suspension build. Never assume that every kit out there has been as carefully engineered and tested for fit.
Thank you, I really believe everyone should do this. It is the only way to know what you suspension is doing and if you are going to run into any problems on the trail. Its better to know in the driveway than it is out in the middle of nowhere.
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Quote:
Originally Posted by cyberpyrot View Post
is it a plink plink kerrrrdunk? or more of a brrrrrconk doc doc miiiidge pang!!!? or is it a badonk ka donk? if it is the latter its just the normal fat *** of the JK

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Unread 09-11-2013, 01:17 PM   #18
SoK66
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No sweat, really nicely done. I'm amazed by how poor some of the fitting and setup instructions are that come with many of the JK lifts.
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Unread 09-11-2013, 07:52 PM   #19
Remmy18
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Very well done and thanks for sharing
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Unread 09-13-2013, 05:46 AM   #20
bhoch
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Nice write-up! Nice mods too!
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Unread 09-13-2013, 08:39 AM   #21
jwmbishop
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Thanks for the time you spent and sharing!

One question - can you plot the suspensions geometry before/after for roll center, roll moment and roll axis with your software? My license for performance trends expired (I have not been active in Racing for about 10 years) and I can't!
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Unread 09-13-2013, 01:20 PM   #22
COLOUXJ
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Quote:
Originally Posted by jwmbishop View Post
Thanks for the time you spent and sharing!

One question - can you plot the suspensions geometry before/after for roll center, roll moment and roll axis with your software? My license for performance trends expired (I have not been active in Racing for about 10 years) and I can't!
Not sure what you mean by plotting them?

In this setup my roll center actually decreased, have not looked into why as I thought it would increase. The link to the calculator/excel sheet in in my first post. Just need to get under your Jeep to get the measurements. What you see is what it will output.
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Quote:
Originally Posted by cyberpyrot View Post
is it a plink plink kerrrrdunk? or more of a brrrrrconk doc doc miiiidge pang!!!? or is it a badonk ka donk? if it is the latter its just the normal fat *** of the JK

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Unread 09-15-2013, 09:22 AM   #23
jwmbishop
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Quote:
Originally Posted by COLOUXJ View Post
Not sure what you mean by plotting them?

In this setup my roll center actually decreased, have not looked into why as I thought it would increase. The link to the calculator/excel sheet in in my first post. Just need to get under your Jeep to get the measurements. What you see is what it will output.
Plotting is what the diagram does - plots the points and shows the angles... thanks! I did go back to first post and see the link you referred to - but also see the end results on the upper corner of the side plot (usually roll uses a front facing plot in conjunction with the side plot as you showed) so I did not see or look for the values shown in upper right of plot sheet. Its already there!

So lifting takes us from a 41 inch roll center to a 40" - actually LOWERING the roll center... and raising the CG. The dynamic that makes a vehicle roll is the distance from the two (roll moment) - if the CG was passing BELOW the roll center the vehicle would BANK (transfer weight inboard of the turn) as opposed to ROLL (transfer weight outboard of the turn). Watch an Indy car - they are either very close to neutral - or slight bank. Also seeing the roll axis (amber line) level out more - so have to wonder - without inputs for REAR suspension points how well does this plotting tool work as a before and after...
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Unread 09-15-2013, 10:48 AM   #24
COLOUXJ
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Quote:
Originally Posted by jwmbishop View Post
Plotting is what the diagram does - plots the points and shows the angles... thanks! I did go back to first post and see the link you referred to - but also see the end results on the upper corner of the side plot (usually roll uses a front facing plot in conjunction with the side plot as you showed) so I did not see or look for the values shown in upper right of plot sheet. Its already there!

So lifting takes us from a 41 inch roll center to a 40" - actually LOWERING the roll center... and raising the CG. The dynamic that makes a vehicle roll is the distance from the two (roll moment) - if the CG was passing BELOW the roll center the vehicle would BANK (transfer weight inboard of the turn) as opposed to ROLL (transfer weight outboard of the turn). Watch an Indy car - they are either very close to neutral - or slight bank. Also seeing the roll axis (amber line) level out more - so have to wonder - without inputs for REAR suspension points how well does this plotting tool work as a before and after...
Ok, that makes sense about the roll center. I used this tool as another means of seeing how everything changed. From the thread on Pirate it has gone through a couple of Revs so I would think that it would be fairly accurate. Even though they make some assumptions for some of the calculations as a worst case scenario. This program did have me measure the rear arms, not the front.
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Quote:
Originally Posted by cyberpyrot View Post
is it a plink plink kerrrrdunk? or more of a brrrrrconk doc doc miiiidge pang!!!? or is it a badonk ka donk? if it is the latter its just the normal fat *** of the JK

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Unread 09-26-2013, 10:57 AM   #25
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Quote:
Originally Posted by jwmbishop View Post
without inputs for REAR suspension points how well does this plotting tool work as a before and after...
the calculator he used does take into account most rear suspension mount points. i think he used the 4-link calculator, but there's also a 3-link w/ panhard that could be used to account for the track bar. either way background calculations figure out the geometry from there, but you do have to make some rather big assumptions, like where the CoG is. On a TJ, most people put the CoG someplace around the top bellhousing bolt, not sure what people are using on 4 dr JK's.

that calculator also has a neat built in suspension cycle function where it automatically calculates the geometry across the suspension cycle...so for a given droop or bump travel point you can find anti-squat, roll center, etc. It's kinda useful as a reference, but how much time do you spend under power at full bump or full droop?

a big downside is that calculator doesn't take into account anything on the front end - which has it's own set of characteristics (anti-dive when stopping, etc), and one can even argue the front has it's own additional set of characteristics when under power (front pulling...FWD or 4wd). it also doesn't look at how the front and rear interact together under power, stopping, etc.

I still think it's interesting to see the difference - see what was measured at stock height, and see how lifting the jeep changes geometry. Neither may be accurate, but at least the difference is precise. Good for brainstorming, but not really an all encompassing tool.
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Unread 10-03-2013, 10:26 PM   #26
aTX427
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Good write up. Curious if you ever pulled the fender flares? Looks like the tires tucked up in the pocket before you added the 35's. Probably needed less offset to compensate for the extra tire width, but that also created interference with the bottom of the flare, hence the need for so much bump stop. This weekend I am going to install a set of .75" coil spacers with a 1.25" body lift and XRC armor all around on the stock suspension. I have not been able to find anyone with that exact combo, but have a feeling I can make it work with 35's without adding bump stop with enough shimming and trimming. I would like to go with 37's since this is an over landing rig, but I don't think they will clear without adding lift. I may try finding someone who will let me borrow a wheel or two to test it out.
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Unread 10-04-2013, 12:46 PM   #27
COLOUXJ
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To run the wider tires you need to run larger backspacing to let the wheel turn in the wheel well. That is just part of the larger tire problems. With that setup I would run ateast .75" bumpstop extensions. Simply because if you are just adding spring spacers if you do not add that bumpstop you can overcompress the springs if you do not. If you are doing this setup just to drive on the road then you will be ok, but this is not the best way to go if you plan on taking it offroad.
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Quote:
Originally Posted by cyberpyrot View Post
is it a plink plink kerrrrdunk? or more of a brrrrrconk doc doc miiiidge pang!!!? or is it a badonk ka donk? if it is the latter its just the normal fat *** of the JK

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Unread 10-06-2013, 06:52 PM   #28
aTX427
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Makes sense - after looking at the numbers for so long it's easy to overlook the obvious. I installed the body lift and XRC armor this weekend and there is no way 37's are going to fit, so I will stick with 35's, which are fine for overlanding.
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Unread 03-18-2014, 04:46 PM   #29
Bradyjones02
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Finally a fun wheeling shot at a trail in the area that I did this weekend.



I just recently moved to Monument, CO and bought a 2008 Unlimited Rubicon. Where is this trail, as I've been dying to do anything other than Mt. Herman.
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Unread 03-19-2014, 06:21 AM   #30
COLOUXJ
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That trail is Wheeler Lake. It wont open up till June or maybe even July with all the snow we have been having. Granted it is just outside of Fairplay so maybe earlier? It will be a good challenge for a stock Rubi. You will definitely get to use your lockers on that trail.
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Black Jeep Society
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Quote:
Originally Posted by cyberpyrot View Post
is it a plink plink kerrrrdunk? or more of a brrrrrconk doc doc miiiidge pang!!!? or is it a badonk ka donk? if it is the latter its just the normal fat *** of the JK

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