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Shock question for RK rear coil conversion

SwampDonkeyXJ

NAXJA Forum User
Location
North Carolina
I'm looking for input from anyone who has done the RK rear coil conversion on their XJ. What shocks do you run on the rear?

From RK:
Shock Notes: It is recommended that high quality shocks be used with all Rock Krawler Suspension Systems. At a very minimum an adjustable dampening rate shock such as a MX-6 or RS9000 so you can choose your ride quality!

Rear Shock - 14.5" Collapsed to 24.5" Extended
Reference MX6027 with Daystar EVS Jounce Stop for 6.5" lift systems


Just wondering if you guys have gone with the "minimum recommended" Pro Comps/Ranchos or if you coughed up the cash for something more extreme like Bilstein or Fox...
 
i think you may be the first person on the bord who will be doing the conversion. i want to do it as soon as i can afford to
 
I thought that conversion came with coilovers? I've only seen two, and they had coilovers.
 
I thought that conversion came with coilovers? I've only seen two, and they had coilovers.

I was under the same impression. I've only seem them with coilovers as well.
 
They do offer the kit for normal shocks and TJ rear springs. I installed one this Fall on my 90XJ except that I modified the install so that I got a 7 inch stretch out of it too.

Im using Rancho 9000XL adjustable shocks.



You didnt ask this but FWIW:

I moved the forward brackets back as far as I could to where the front leaf spring box starts bowing out from the frame, and then I mounted the Left upper coil support on the right side and the right on the left side. Again pushing them as far back as I could.

I ended up making custom shock mounts upper and lower and used angled Ballistic Fab lower control arm mounts on the Axle instead of the RK ones.

but really ? 10" shocks. all that work for 10" shocks. no thanks. and certainly not 10" coil overs :)

I will say the ride is way different than Leafs !

YMMV
 
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I'm using the RK brackets on my build .... but I am making my own shock mounts because I felt the 10 inch was a bit "short"


Travel is relative to lift height too, of course.


My XJ will only have about 5 inches of lift ... so it's hard to "easily" squeeze in longer shocks without major surgery (into the cab).



I'm planning on 12 inch short body Bilstein 7100s for the back. Thinking 4 up and 7 down should do the trick.



Joe
 
I'm using the RK brackets on my build .... but I am making my own shock mounts because I felt the 10 inch was a bit "short"


Travel is relative to lift height too, of course.


My XJ will only have about 5 inches of lift ... so it's hard to "easily" squeeze in longer shocks without major surgery (into the cab).



I'm planning on 12 inch short body Bilstein 7100s for the back. Thinking 4 up and 7 down should do the trick.



Joe

When you say 4" up, I assume you mean 4" of shaft showing so 4" of compression/up travel?

I'd think you'd want more than that, only 4" would let it bottom out pretty easily.
 
When you say 4" up, I assume you mean 4" of shaft showing so 4" of compression/up travel?

I'd think you'd want more than that, only 4" would let it bottom out pretty easily.



Rich,


4 inches of uptravel (probably 5 inches of exposed shaft on the shock).


Factory TJ and ZJ have less than 3 inches of uptravel from Pad-to-Bumpstop .... so I *think* I'll be okay with 4 inches



I'm not driving it like you, ya know. :roflmao:



I haven't figured out my coil spring frequency yet .... but the rate is higher than factory, which I'm hoping will keep the rear end level when my mother in law is in the cargo area.



Joe
 
Ha!

If you're even thinking about calculating frequency I'd think you'd want the performance of more bump travel. The spring rate and shock valving would need to be stiffer to keep from bottoming hard, which could promote more rear kick up. Also, hitting the bump stops hard and rebounding will contribute to rear kick up.

Of course, if the rear links are just for better traction while crawling, then it doesn't matter. But, with the work of putting in that kind of suspension, it's nice to let it do what it's capable of doing. Once you can go faster, you'll never go back......... :D
 
Ha!

If you're even thinking about calculating frequency I'd think you'd want the performance of more bump travel. The spring rate and shock valving would need to be stiffer to keep from bottoming hard, which could promote more rear kick up. Also, hitting the bump stops hard and rebounding will contribute to rear kick up.

Of course, if the rear links are just for better traction while crawling, then it doesn't matter. But, with the work of putting in that kind of suspension, it's nice to let it do what it's capable of doing. Once you can go faster, you'll never go back......... :D


Well ... frequency is important for fast on the street too. I have no desire to pogo around at 70 mph down the highway. Hence the analytical approach. :yap:


Take a peek at my rear suspension numbers in the build thread -- if you have some time. I'd be curious to what you think. I have 6 mounting choices for my upper control arms ... so I can change the characteristics quite easily depending on how the chassis reacts to input.



Maybe someday I'll try the speed thing. Right now ... I'd be happy to wheel it at all.



Joe
 
Let's see if this will work this time. I'm in Afghanistan and my internet is a POS so I can't always get on here.

Since I'm out here I have someone doing the work for me. From the pictures I have seen, the shock mounts are behind the spring perches so it's not set up for coilover.

Been out here for close to a year now and have had everything from the "frame" down completely stripped and replaced. No more worrying about my fragile little D30 sponaniously combusting on the trail, haha.

Can't wait to see how it handles. I was at 6" with short arms, AAL, and blocks in the rear before it went under the knife. It will be nice to finally have some flex in the rear.

I'll be home in just over a week so I will get some before and after pictures.
 
RK recently switched to coil and shocks instead of coilovers. When we done the RK rear link on the crawler it had some like 8.5" C/O's. Im not sure the reason behind the switch though but like goatman said, go for more bumptravel than down with your shocks, I recently made the switch from rocks to prerunner and I'm not going back anytime soon so if you have a crawler that has decent bumptravel you can still go fast and have the best of both worlds.
 
I'm stuffing 38's with 6.5" lift. Trying to keep low COG. I'm going to have to spend a lot of time with the sawzall to make enough clearance for decent bumptravel. Trying to cut as much as I can, but with the four-door I might be forced into a comp cut with a stretch.
 
. From the pictures I have seen, the shock mounts are behind the spring perches so it's not set up for coilover.

on my RK rear coil conversion kit the upper shock mounts are about 6 inches behind the upper coil spring mount and are actually a part of the same upper bracket, putting the shocks almost perfectly vertical from the lower mount (which sticks out a few inches past the axle) and rather then perpendicular to the lower control arms
 
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