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linked rear + stretch questions

5K views 23 replies 9 participants last post by  Rock Krawler Suspension 
#1 ·
been poking around thinking about gathering parts to start changing the rear suspension on my 2 door and doing some research. currently im running 2.5" TF coils, raised axle side trackbar bracket in the back, and some fox shocks. other than that the rear suspension is still virgin. this is my DD and weekend warrior. pic for reference of what im working with from last weekend. 37" old MTRs that measure 35"



I know going triagulated 4 link would require removing the factory gas tank. that leaves me the option of a fuel cell which I cant do because we have state inpsections here in WV, or a genright tank but im not dropping $1.5K for a gas tank. I know a TJ tank is plausible but I really just don't want to move the stock tank unless it was for a fuel cell. I know I want to push the rear axle back a few inches whatever I do. I don't mind doing some tub trimming but cant do a full stretch/comp cut, again due to state inspections. RKs 3 link conversion and stretch seems really interesting. but can I use the stock lower arm frame side mounts with it? where would the upper shock mounts move to? or would it be easier to just run basically 3" longer arms in the stock location to push the axle back and move the TB? if anyone has done the RK 3link + stretch I would really love to see some detailed photos of where everything moved to and how it was done. ive had a hard time finding anything more that some flex shots or side profile shots of this setup. id like to see actual suspension shots if possible. any help or guidance is appreciated.
 
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#4 ·
You might as well ask that the kit add 300 hp allow you to run 54" tires on dana 44's and make the jeep hover.

You make it sound so simple to do. RK will make custom arms for you if you wish

You don't see much in the 3" stretch because it is not worth the trouble for the gain and 3 link rear set ups are not that great either. I have run a long arm 3 link and know several others that went that route just to scrap it after a year and go full comp double triangulated..

Far a daily driver I would just keep it they way it is and find a buggy to have fun in.
 
#5 ·
Thanks Marcus.

Dirtman, ive read several of your post that argue that point (3" not worth the work) and the more i sit and think about it...i believe your right. Ive been talking with some friends in a neighboring club that run trail only rigs, and they all say 4 link over 3.
 
#6 ·
I wish that I would have stopped at 35's with some lockers and 12" coil overs and built a buggy for the money I spent building what I have now. At least I would have a nice street friendly jeep to pass on to my son to drive now that he is getting his DL.

The limitations of the JK are enough of a hassle (clearance, fuel tank, lack of hp) but throw in emissions test or full on safety inspections and modding the jeep becomes nearly impossible to do extreme builds properly.

If you are just looking for around 3" of stretch you could always do some front and some in the rear. It would give you better approach and decent angles, a bit better climbing ability, better ride on the road and if you are running aftermarket driveshafts you should have enough length in them so you won't have to get them lengthened.

You would be still looking at a full set of arms and I would look into metal cloaks or an arm with 1.25" shank johnny joints that would allow you to gain the length without doing custom arms. The RK shank is too short to dial out and is designed to have a minimal amount of threads sticking out of the arm.

You would also need to move the frame side track bar brackets and likely the sway bar mounts.

You can also buy new axle coil mounts and offset them to line up the upper mounts.

Good luck with whatever you choose and am always glad to help if you have any questions.
 
#7 ·
Dirtman - Keep up son, keep up. Our 1.25" shanks have the same shank length as the others in the industry. No, we do not advise having a boat load of threads hanging out of an arm for structural reasons of course, but people can do it if they want at their own expense.

As far as 3 link with track bar versus triangulated or dual triangulated 4 links, that is a matter of opinion. JP Magazine stated the 3 link with a track bar is the best suspension ever, but again, that is their opinion. The 3 link with track bar does allow for use of the stock gas tank so that expense and head ache is saved by the consumer. For a trail rig it is ok to move the gas tank behind the rear axle like Genright does, but for street use, it opens you as a consumer up to a hole new can of worms. It is not street legal and if you ever got in an accident where it became an issue, the consumer is responsible and ultimately liable. That would not be a lot of fun...

We also have (2) 6" stretch versions coming out very soon. One with an independent 3 link and track bar and another with a reverse 3 link design. Neither of which require removal of the OEM gas tank. The reverse 3 link design uses the reverse wishbone we will be offering in our Rock Racer System. We feel it is pretty cool stuff.

RK
 
#8 ·
The OP has a short arm set up. As far as I know your 1.25" shanks are only offered in your long arms. Please correct me if I am mistaken. What are the lengths of the threaded sections of your 1.25" shanks as there is no industry standard and vary by manufacturers.
 
#10 ·
clearance, fuel tank, lack of hp
all but the last one lol. im happy with the 3.6 in stock trim with my 4.88s. anything over a 38" shoe and I wont DD it anymore (that's a long ways off.) luckily we don't have emission testing in WV just a stationary inspection, that I already technically fail based on bumper width and tire coverage. good thing being a mechanic for a living I can get by with "just a little illegal."

You would be still looking at a full set of arms and I would look into metal cloaks or an arm with 1.25" shank johnny joints that would allow you to gain the length without doing custom arms. The RK shank is too short to dial out and is designed to have a minimal amount of threads sticking out of the arm.
RK arms are what im running up front for upper/lower right now. I haven't checked how far I can push them out. but with hydro assist a future goal while staying at 2.5" lift I know things will get tight.

with a reverse 3 link design
ive looked into this just a little too. im assuming you guys are using the rear bumper cross member to mount off of? ive long since cut out the rear cross member and using a Crawler Concepts stubby rear bumper.

TJ gas tank mod is an option.
not ruling that one out yet either, but I need to look into the legal side of it.

thanks for all the info guys. kinda sucks trying to make your DD the trail rig you want it to be, but its fun at the same time. or maybe im just weird.
 
#12 ·
I have zero issues with my three linked JK and it is inspected and registered for street use in Texas. It works well offroad and handles well on road too. Everyone is entitled to their opinion, but I can't *see how you could say that the three link is not a viable option in our platform. ESPECIALLY for someone who wants to keep the stock fuel tank.

What you're asking for is sitting right here. If you don't want the whole kit it is possible to only buy the rear setup. It uses forward spring pads on the axle and the three link long arms to move the axle back and keep the geometry mostly flat and smooth. It works and will do everything that you're looking for and it even comes with a fancy instruction book. Ha ha!

http://www.rockkrawler.com/ProductDetails.asp?ProductCode=JK35XFLA-3S

My Jeep is pushed out about 4" rear and 3" front in the final stages and you can see how much body has been removed. If you aren't ready for the type of commitment then put the X-Factor mid arm in it and go have fun. The X-Factor gives you a little more adjustment without requiring any welding or relocation of your factory control arm mounts.

Based on your pictures, it looks like you're going where you want to as is, so I don't see four linking and losing your tank and all that to take you where you haven't already been. At that point you're going to be destroying the Jeep for what it is and as others have mentioned, you'd be better off DDing it and buying a buggy.
 
#15 ·
but I can't *see how you could say that the three link is not a viable option in our platform
im not ruling out the 3 link (unless this was ment for someone else), just in the research stages of this process.

you'd be better off DDing it and buying a buggy.
no buggy for me. that would entail getting rid of the jk and purchasing a trailer and tow pig. I like my jk too much to do that and have always drove what I wheeled. maybe not the smartest thing in the world but it makes the challenge that much more fun.

Marcus I didn't see it mentioned in your build thread but going by one picture your using the stock rear upper shock mounts with the stretch/3 link correct? (or at least were, theres a lot of cool changes in your build thread.)
 
#16 ·
The rear upper mounts are stock for the coils and the shocks. Its kind of crappy right now, but I will run it like it is until I feel like doing some rear coil overs next month. lol

EDIT - Let me clarify...it is kind of crappy because of A the axle I am using and B I have the axle moved back further than RK intended. I was going to use Synergy upper mounts but I decided to not waste the effort on it since this setup is somewhat temporary back there. :)
 
#17 ·
I know going triagulated 4 link would require removing the factory gas tank. that leaves me the option of a fuel cell which I cant do because we have state inpsections here in WV, or a genright tank but im not dropping $1.5K for a gas tank. I know a TJ tank is plausible but I really just don't want to move the stock tank unless it was for a fuel cell. I know I want to push the rear axle back a few inches whatever I do. I don't mind doing some tub trimming but cant do a full stretch/comp cut, again due to state inspections. RKs 3 link conversion and stretch seems really interesting. but can I use the stock lower arm frame side mounts with it? where would the upper shock mounts move to? or would it be easier to just run basically 3" longer arms in the stock location to push the axle back and move the TB? if anyone has done the RK 3link + stretch I would really love to see some detailed photos of where everything moved to and how it was done. ive had a hard time finding anything more that some flex shots or side profile shots of this setup. id like to see actual suspension shots if possible. any help or guidance is appreciated.[/QUOTE]

Why exactly can't you run a fuel cell? Mine conforms to all FMCSA requirements. I reused the stock pump, evap, etc. Properly vented. And used a fill hose from a GM vehicle so it still has a flapper valve to limit fuel spills. I'm not very familiar with the inspection process, but curious what the issue would be? Or is it an arbitrary process not based on actual codes?
 
#20 ·
Don' forget a new or rebuilt driveshaft, swaybar relocation, some trimming, and maybe some frame modifications depending on the set up on arms. There are some cross members that cause clearance issues on the rear.


To RK, I was trying to help the op not bash on you guys. I even recommended to the op that RK could make custom length arms for him. You guys seem to have pretty thin skin if anyone says anything recommending another company of if someone gives an op another option other then RK. You jumped in and made a snarky comment and stated your joints 1.25" are industry standard in length. I was asking a question about the specific length and I guess you say they are the same as the standard currie johnny joint? So 3.2" of threaded length.
 
#21 ·
Dirtman

Here is a link to the dimensions for the 1.25" shank joints.

http://www.rockkrawler.com/ProductDetails.asp?ProductCode=Krawler_Joints_1.25

You may or may not take offense to this as we have all been around the forums for a long time, and a lot of times you seem to genuinely seem to be trying to help people, but tell the to use the search function. The data is on our site for everyone.

You also tell people to "build it yourself" all the time. You may have the skill set for that which is awesome, but for most people that is not the case. We find a lot of irony in your statement that now in this string of posts, you are stating you regret your build and wish you would have kept it simple and built a buggy.

We try to think about the average Jeeper and help them to the best of our ability. We feel we have products to offer all kinds of budgets, but it is not about products or sales or anything like that. It is about helping Jeep people achieve their goal. If that is a budget boost, then so be it, even though we do not offer one. As long as that individual achieves their goal, the entire Jeep community is stronger....

RK
 
#22 ·
Well this thread escalated quickly. I will chime in, as I have run similar. I ran an RK 2.5" max travel, then built a custom long arm three link front and rear with 3" rear stretch that was based loosely on RK dimensions. This kept the 2.5" springs. The setup did well, but I felt that I still got hung up too much on the undercarriage and links. It also had too little antisquat. Since then I have built a double triangulated 4 link rear with 4" stretch and outboard coilovers. I could not be happier with the current suspension. I have ran it for two years and it performs flawless Offroad and rides like a Cadillac on road. I'm not saying the custom route is for everyone, but if done right the results are awesome. The RK system is great as well, and I feel the 102" wheelbase I have now is right where I want to be. Good luck with the build.
 
#24 ·
There are many ways and styles this can be done.. You have to choose the best one for you that meets your needs and are within your abilities or resources to get it done properly. At the end of the day, achieving your goal is what is most important.

From what we have learned, a 3" rear stretch is a nice all around performer for all conditions, more like a "stealth stye", street-able stretch.

A 6" rear stretch suits much more hard core applications and for 37-40" tires, a small flare can cover the backside of the rear tire maintaining a street-able rig.

Longer than that, you will loose legal street coverage in many states, but that is up to you of course and your build.

Good luck...

RK
 
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