Design-a-lift (and help a newb!) -
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post #1 of 7 Old 05-09-2013, 08:46 PM Thread Starter
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1991 XJ Cherokee 
Join Date: Apr 2013
Location: Nashville
Posts: 54
Design-a-lift (and help a newb!)

I'm not sure if this should go in the tech or non-tech forum, move if i've mis-located it.

Basically, i just want the re-assurance of having some people double check my shopping list and point out whatever i've missed or what terrible decisions i've made without realizing it. Also a few related questions

So first, the question on control arms -
I notice some LCA's (pretty much all the fixed length and a few of the adjustables that i've seen) have a slight curve to them to ensure they wrap down under the mounting point. However, i've also seen the straight adjustables which then require a control arm drop bracket be installed.

The question is thus: why would i ever select the straight arms w/ drop bracket instead of a curved option? It seems like i'm just adding something else to potentially damage or hang on rocks if i use a drop bracket but maybe i'm overlooking something?

Next question: suspension bushings. Mine are in really rough shape- they're dried and cracking. Not to mention i have no rear bump stops and my fronts are only halfway there. Anyone got an opinion on energy suspension vs daystar? price is basically the same and unless daystar is just hugely inferior i'll probably go that route since i can pick up the bushings + bumpstops at the same time. How hard are they to replace in a 91 XJ? Will i need a press or are C-clamps going to be sufficient? Last bit - do i need to bother with a master set or not? I'm wondering if i should just do my leaf spring bushings and the front sway bar... especially if i replace LCA / UCA / trackbar?

On the topic of bump stops - do the fronts just push into their mounting on the front? And are daystar extended rears worth the price or should i just get OEM and build an extension bracket to go under them?

And finally, on to the meat 'n taters of this post, the suspension 'plan' / shopping list:

4.5" Coils
From my research, it seems like the rockkrawler are just a bit stiffer than the stock springs. I suspect these probably give some of the best offroad performance - soft enough that you can get the jeep into a squat to get more rubber in contact with the ground, but not so soft that you're constantly bottoming out.
I think second choice would be Teraflex TJ front springs - they'll be a bit stiffer and will require additional convincing to be the proper height--- 4" TJ will require spacers, 6" may be the way to go as, the combination of not giving full rated TJ lift + heavy winch / bumper [future] should help level it out @ 4.5"

Extended bump stop

LCA- goes back to the above question. Also, i know that the LCA length is really important - is there a chart of aftermarket fixed LCA lengths? I know there is a chart for what length LCA / UCA i need, but i didn't find anything that tells me lengths of my aftermarket options. I guess that makes the case for adjustables though doesn't it.

UCA - do i need to do these? seems like the answer is probably yes but i did find mixed opinions in my quick research. What is the effect of having UCA's that are too short?

Trackbar - adjustable - seems they're all pretty well created equal so i'm just looking for a deal on one with good bushings here, right?

Swaybar - probably do homemade quick discos for now

Bastard pack leafs - S10 or Dakota - are they about the same or is one more supple than the other? My stock springs are pretty saggy I think so i'll probably need something with some backbone but i'm afraid that's really going to hurt my flex.

Shackles - how do i determine what length shackle i need to maintain proper shackle angles? I know that the lift will be 50% of the shackle extension but that doesn't speak to the angle any.

Front & Rear

Shocks - I don't even begin to know... I guess i get the lift sans shocks put on, let it go full droop and full tuck and just measure eyelet to axle lengths to determine compressed and uncompressed lengths of the shock?

BPE - depends on whether the shocks require them; if so i'll probably just fab some myself.

Brake lines - I'm guessing i just let it go full droop and get lines long enough to reach from the hard line mount to the calipers.

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post #2 of 7 Old 05-09-2013, 10:14 PM
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1999 XJ Cherokee 
Join Date: Apr 2010
Location: Colton
Posts: 2,236
Springs, most springs are uprated for larger bumpers and winches and stuff, my RE 3.5in XJ coils put me at about 5in installed. There is a lot of advanced tech that goes into picking "prefect" springs and most manufacturers dont publish enough info to make a proper assessment, but if youre not building a competition rig it likely doesn't matter. Shock valving will play more into performance than the springs will.

LCAs, adjustable vs non isnt a big deal, the LCA mount has a adjustment in it to make caster adjustments from. Adjustable arms are nice, but not wholly necessary. The bent or curved arms dont make much if any difference either, pick some. Bent arms are technically weaker but that's never been an issue for anyone AFIK, also the bent arms do allow for more tire clearance at full lock.

drop brackets are nice cause they allow for more droop and wheel travel as well as smooth out the ride quality some, long arms will do the same at a higher price point while staying out of the way.

Mine with drop brackets.

There arn't any rocks in FL obviously, but the drop brackets have never gotten me hung up on anything.

Trackbar, pick one, just not Rustys unless they've started using something other than that week TRE on the end of it. Also double shear mounts are good to have.

The rear shackle angle will be more determined by the eye-eye length of the spring while loaded than the shackle its self. easy way to get good shackle angle is the shackle relocation brackets kits, rough country and HD offroad sell them. They also add a variable amount of lift, so add that into your final height calculations. changing the shackle angle can really change how the rear end behaves.

UCA arent a big deal until you start doing serious wheeling, lots of us are still running stock uppers, same with many TJs.

You've got the right idea with shocks. Figure out your bump stops first, long enough to keep the tire out of the sheet metal, then measure for shocks, also remember that bump stops do compress about an inch or so. Ideally at ride height the shock should be between 40-60% compressed, mine are closer to 75% compressed, makes the ride harsh as it hits the bump stops sooner.

On the bumpstops, i have the OEM ones, Daystar and Energy Susp. are both good to go, pick one. The fronts should just pop in and out by hand, a little grease makes it easier. The rears either way will work, get the extended and cut them down to fit if need be, or block the OEM ones down to fit. Skip the master kit unless you want to do every suspension components, since you're looking at replacing most of them with aftermarket parts no its a waste, just order the ones you need.

BPEs can be made with the old rear sway bar parts, you'll be removing them during the lift install.

Brake lines, go ahead and get the longest ones you can find, they're usually the same price as the shorter lengths, and if you go higher you wont need to replace them then too. and if they end up being to long you can keep them out of the tires with zipties or light springs or bungee cord.

One more thing to consider, the slip yoke, all the lift parts are going to be useless if the rear drive shaft falls out constantly.
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post #3 of 7 Old 05-10-2013, 06:59 AM
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1998 XJ Cherokee 
Join Date: Oct 2009
Location: Florida
Posts: 273
Lots of good info

98 XJ 4x2 to 4x4 converted
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post #4 of 7 Old 05-10-2013, 10:03 PM Thread Starter
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1991 XJ Cherokee 
Join Date: Apr 2013
Location: Nashville
Posts: 54
Thanks for the really detailed reply Chris! I've re-visited the chart i was using for spring rates and checked some vendor sites and found the rubicon express coils to actually be down around 160 for the 4.5" lift so they've moved into my #1 slot. Been troweling the forums for a deal on them; maybe i'll get lucky soon! It sounds like, for control arms, my best bet is to get some adjustable lowers for now. I can later add drop bracket and adjustable uppers, or if i decide to spring for it i can go long arm and, because my LCA are adjustable, they'll be easier to sale at that point.

To throw a bit of a king in this plan though - i was talking to another local jeeper (CJ5 and CJ7 are what he's built) and he was telling me he thought a common approach was to keep the stock lowers and use an adjustable upper since that could be used to adjust how the tire moved in up-travel. Thinking about the geometry of it, it seems to make sense to me too - you could keep your tire coming up in the center of your fender better with an adjustable upper than with an adjustable lower. Thoughts? Is this a viable option or are we replacing the LCA due to strength issues or because of interference?

When you say that the shock valving has more to do with performance than the springs will, can you expound on that or direct me somewhere that explains in more depth what you're talking about? I really don't know anything about shocks other than I need them; they need to fit my extended and compressed dimensions; bottoming them out is bad; and i can either spend not much at all or sell a testicle to pay for them.

SYE is planned for use in conjunction with a front AW4 driveshaft (I think @ 4.5" this will work won't it?) - I felt confident enough in that portion of the build that I didn't mention it in a thread that was already a huge wall of text I'm glad you put some pictures in to make it more bearable lol.
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post #5 of 7 Old 05-10-2013, 10:41 PM
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Read up
I know you're not looking for coilovers, nor need to be at this stage, but the physics is the same and the first half covers general shocks and springs later on, the part about springs also has some heavy math, that if you're not ordering custom spec coils and ordering off-the-shelf instead you can more or less ignore. there is a ton of info in that article, enjoy.

The Bilstein 51xx series shock are great, many valving options, and come in many different lengths at about 80-100$ each. Other than those, the "white shocks", or cheap twin tube shocks that come with most lift kits are all the same, made in the same factory, feel the same, look the same, just with different stickers slapped on them. they're not bad, but not spectacular either. Also when looking for shocks, everyones opinion of what a "good" ride is is different, some like a "caddy like" soft, spongy, body rolling suspension, while others like harder, stiff, ultra responsive, "sports car" like rides.

Most of the reason for replacing the stock lowers is they are weak stamped sheet metal and are in a vulnerable spot, they get banged up easily. generally the upper is used to position the tire in the wheel well, the lower is used to adjust pinion angle and caster.

About mid way down the page is a chart for control arm lengths vs lift heights
for the uppers at 4.5in of lift there is 0.11in (<1/8in. aka not much) of difference between stock. At the same height there is ~3/4in difference in the lowers.

The SYE with a stock auto front shaft will work fine, i run one, many others do to.
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post #6 of 7 Old 05-12-2013, 06:04 PM Thread Starter
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1991 XJ Cherokee 
Join Date: Apr 2013
Location: Nashville
Posts: 54

I went to the junkyard today and got some stuff - only a portion was lift related but still some really good stuff (I think)! Picked up some leafs from a 2001 blazer - they arch about 7.5-8" off the ground and deflect an inch or so when i stand on them (about 220 lbs). I'm excited to put together the bastard pack and get the *** end up a bit! I also got everything for my rear disc conversion but i've got to see about having one of them turned. One rotor is great, I didn't notice it but the second was not in such great shape - very light scoring. Pads on both calipers look to be evenly worn and guide pins / boots are in great shape. I also pulled a beefy tie rod from a v8 ZJ which will need a new TRE boot. And last, I grabbed a trans cooler off a grand cherokee and a ford taurus electric fan.

I've got some RE uppers and lowers along with a single shear trackbar on the way from a guy on another forum. Once they get here, i'll need to replace the superflex joints and i'm going to see about modifying the arms from fixed to adjustable as well. I figure since i'll be ordering some form of superflex joint to get everything i need to rebuild them, i might as well go ahead and get the rod end version. I can then hack the arm and weld in a tapped plug (assuming the arms are hollow; otherwise ill just take them in to work and tap them there.

Here's to hoping some appropriate coils get posted up soon! And i'll be checking another junkyard later this week hoping for the automatic front drive shaft - probably had 20 ZJ's on the lot and only 3-4 XJs. I wasn't sure if the ZJ shaft was the same or not so i chose not to risk my money on it and just come back to do some research. I also was unable to pull any chevy fullsize shackles due to complications with my, i bought from harbor freight and was inappropriately trying to use an 18" long 1/2" driver with an adapter down to a 3/8" driver 13/16 socket... i spun the adapter right in half. The last thing i looked at but didn't get was a longer rear soft-line that runs from the chasis to the axle from a dakota. I looked at it for about 15 minutes and never came up with the answer of "how the eff do i get that off without destroying it." I figure brake lines are one of those items I can afford to outright buy new anyway for safety's sake.
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post #7 of 7 Old 05-13-2013, 02:14 PM
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2000 XJ Cherokee 
Join Date: Aug 2009
Location: Portsmouth
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Track bars: Rough Country uses hollow tubing. IRO uses solid round stock.

My build thread has pics again.
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