What's a TK?
...it's a TJ running 33's that rides just like a JK with 33's.
I remember running into a bloke in his fifties about a year after I bought my first TJ in 97, he was considering a TJ but he went on to say, "I need more comfort these days", I didn't get it, twenty years later I get it and let's face it, a TJ running a three inch lift and 33's is a punishing experience when compared to a JK on 33's. I'm reluctant to part it out for the more refined JK so I set about trying to achieve the same ride quality from my 2001 TJ without spending a fortune - not to feel every bump and corrugation in the road - even it meant losing some off road prowess. So this is what I did.
The theory
I would need to match or better; the suspension geometry, curb weight and unsprung weight of the JK to achieve the same ride quality using similar 3" higher springs and JK shocks.
Tires
The JK runs a 255/75R17 coming in at 32. 47 lbs (32x10x15), our good old friends at BFG have provided us with the perfect fifteen inch equivalent 33x10.5x15 at about an inch taller, a little wider and comes in at a very lean 55 pounds, the equivalent in a metric size is a 285/75/17 that weighs in at just shy of 62 pounds, quite a bit heaver which is strange considering it has less sidewall. I am told that's because they use heaver compounds in the construction of metric sizes, nevertheless, based on the JK running 285/75/17 and my TJ running 33x10.5x15 we are well under the JKs unsprung weight with respect to tires by seven pounds a corner
Springs
First thing is a set of suitable soft springs, I used the Black diamond three inch springs but you can use whatever as long as they are fairly soft. Stock JK springs will do the job but you will need a front spring spacer and a little modifying to make them fit, there is plenty of info inline if you want to do that to save some money.
Shocks
The stock OME JK shocks fit up to the TJ mounting points with minimal modification, the lower rear shocks are too wide to fit inside the axle mounts but you can use a grinder to slim down the eyelets on either side of the shock, if necessary, the lower axle mounts can be pried opened a small amount.
With the front we went with the JKS bar pin eliminators and fabricated a sleeve to take up the space between the pin and shock eyelet
Control Arms
I guess any long arm kit will do the job but I chose teraflex because they have a budget kit replacing only the lower arms that's cheaper than doing upper and lowers, if need be you can add upper arms latter.
Result
With the control arm geometry overcorrected and all the relative unsprung weight very close to that of the JK - with 100 kilos or so of winch, bar work and tire carrier making my TJ very close to a JK's curb weight - together with the JK spring rate and shocks, if you close your eyes and hide the trusty roar of the 4.0L you could easily think you're in a JK running 33's. It's a very smooth ride and it takes some time to get use to, you keep bracing yourself for the bumps that never come.
As for handling, At an intersection near my home has some corrugations that use to cause my TJ to lose traction turning right - that's left turn for you guys - when mashing the skinny peddle in second gear but after fitting the JK shocks that no longer happens. The tires maintain contact with the road and refuse to let go, it's truly amazing how much better it performs then the shocks that came with the original Black diamond 3" lift kit or the Rancho 9000 adjustable shocks I upgraded to about year ago.
I've driven a stack of TJ's with fox and ARB shocks to name just a few and although the ARB kit is nice, there's no comparison on or off road if you're looking for a comfortable surefooted ride.
Downside
I have lost a bit of articulation when compared to the Black diamond shocks and to be fare to the Ranchos you could say I have lost a lot of articulation - you really notice it when trying to climb up big rocks - but I plan on fitting an air locker up front to match the ARB in the rear and I'm hoping that will help offset the articulation downgrade.
Rancho
JK Shocks
I'm also expecting the shocks to fade when pushed, partially on a hot Australian summer days but if I mitigate my driving to suite the conditions I should be fine.
Future
I would like to upgrade the upper control arms to the TF four link with a high steer but I'll probably just install a Falcon stabilizer and call it done. Drop ratios from 4.10 to 4.56. Install a double DIN touch screen entertainment system with TPS, nav and a few other goodies. Move to the KO A/T treat pattern, add some sound reduction methods I've learnt over the years and fit a Bestop Twill Supertop to reduce highway noise.
Hindsight
Would I do it again? Well Hell Yeah! In fact I couldn't own a TJ as a daily driver without a similar setup unless it was near stock, (OEM) my back couldn't take it. If you're looking for a setup that you can feel comfortable and confident with, not just on the street but down the highway at 110k then this is it.