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Old 09-23-2012, 03:44 PM   #1 (permalink)
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MJ Crawler

This vehicle is a semi-daily driver, meaning I have an FZJ80 that I drive most days, but I still drive this MJ to work once or twice a week when it's running. It has to remain streetable to an extent so I can drive it across the country to trails if desired.

Current Project: Shorten the bed, improve the departure angle, and shorten the wheelbase. Current wheelbase is 113", I prefer closer to the 101" that my XJ was when I had it.





Problem 1: My 57" long MJ springs hang out too far behind the rear wheels and don't fit my design goals.
Problem 2: I'd prefer to keep the gas tank underneath if possible to increase bed space, but will consider moving it to the bed.

Options:
1. 47" stock YJ rear leaf springs. Pros: Easy to setup, doesn't interfere with the gas tank even though the axle itself might. Cons: possible lack of articulation, rough ride. Any comments on long vs short leaf springs?
2. Radius arm rear coil suspension with panhard rod. I've read some that say these are OK, some that say these don't handle well. Pros: easy to setup, should ride good, doesn't interfere with exhaust or gas tank. Cons: off-road characteristics?
3. Parallel 4-link with panhard. Pros: better handling off-road than radius arms? stays clear of gas tank & exhaust
4. Double triangulated 4-link. Pros: best handling of all the options if setup correctly. Cons: Most difficult to setup, takes up all the room where the gas tank and exhaust would go. Where do most people route the exhaust when running a triangulated 4-link? From looking at it, I'd have to dump it under the bed, route it under the frame rail out the side, or drill a hole in the frame and route it out the side through that hole.


I will be cutting the frame rails right behind the crossmember.







I've just had all these options going through my head for a while now and would love to hear from you guys of any experience you have with this stuff.

Future projects: Install recentered H1 beadlocks, military 37" tires, and '79 F150 HP D44 front axle that I have already shortened to waggy width.
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96 4Runner, D44 SAS, ARBs, 35s

Last edited by cooleysix; 01-26-2015 at 03:01 AM.
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Old 09-24-2012, 12:04 PM   #2 (permalink)
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Quote:
Originally Posted by xjaz View Post
Options:
1. 47" stock YJ rear leaf springs. Pros: Easy to setup, doesn't interfere with the gas tank even though the axle itself might. Cons: possible lack of articulation, rough ride. Any comments on long vs short leaf springs?
2. Radius arm rear coil suspension with panhard rod. I've read some that say these are OK, some that say these don't handle well. Pros: easy to setup, should ride good, doesn't interfere with exhaust or gas tank. Cons: off-road characteristics?
3. Parallel 4-link with panhard. Pros: better handling off-road than radius arms? stays clear of gas tank & exhaust
1. Hard to go wrong with leaf springs, and they will probably allow for the most continued use of your bed space.
2. I think you'll get some crazy anti squat with a radius arm rear suspension.
3. If you decide to go with the 3/4 link w/panhard route, here is a MJ build thread with what you are describing. H3RESQ's Dream MJ, the build continues... - Page 20 - Your project MJs - Comanche Club Forums

Keep us posted on your progress.
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Old 09-27-2012, 07:24 PM   #3 (permalink)
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I decided I wanted a 4-link more than bed space, so I just ordered a bunch of joints and brackets from ballistic fabrication. Does anybody know of a good place to get steel tube in Kansas, around Topeka or Manhattan? I'll be using 2" OD 1/4" wall DOM for the lowers.
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Old 09-27-2012, 10:11 PM   #4 (permalink)
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I decided I wanted a 4-link more than bed space, so I just ordered a bunch of joints and brackets from ballistic fabrication. Does anybody know of a good place to get steel tube in Kansas, around Topeka or Manhattan? I'll be using 2" OD 1/4" wall DOM for the lowers.
CANCEL YOUR BALLISTIC ORDER IMMEDIATELY!!

their joints are shit. go with ruffstuff heims if cost is an issue. beefy stuff, plus they have a sale on their 4-link kits right now.
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Old 09-27-2012, 10:23 PM   #5 (permalink)
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Originally Posted by Johnny Quest View Post
CANCEL YOUR BALLISTIC ORDER IMMEDIATELY!!

their joints are shit. go with ruffstuff heims if cost is an issue. beefy stuff, plus they have a sale on their 4-link kits right now.
That makes me feel wonderful! Just ordered a complete set for my buggy!!
Ruffstuff is not bad though.

-----------------------------------------------------

OP... Have you thought about going the route of a flipped shackled chevy leaf style. Buddy of mine built a rig like that and it was very stable and had crazy flex on the trail.... Just my 2 cents...

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Old 09-28-2012, 12:26 PM   #6 (permalink)
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So what about their flex joints makes them crap? The design is the same as everybody else, the steel body is thicker than the RE superflex joints I've used in the past without issue. Are the poly inserts that the steel ball rides on bad? One of the deciding factors in my decision to use them was because their large 3" joint uses a 3/4" bolt and their prices are reasonable. The last rock crawler I had was an XJ using the small 10mm bolts on the upper links and it would always wallow out the hole and get loose. So I'm planning to use 9/16" & 5/8" bolts on the uppers and the 3/4" bolts on the lowers. I believe all the brackets I'll be using are 1/4" thick and everything should stay tight with that combination.
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Old 09-28-2012, 01:45 PM   #7 (permalink)
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For brackets and joints also check out artec. I run 3/4 bolts with all my heims from ruffstuff. 1.25 for the lowers, and 7/8 uppers. There's a reason people tell you don't run their joints. At one time they were wearing out within a run or two and very minimal miles. Poor customer service led to their demise on this site.
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Old 09-30-2012, 01:03 AM   #8 (permalink)
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I cut about 11" out of the wheelbase. That should put me at 102" when I'm done, and when I do the front axle I'll push it forward 2" for a 104" wheelbase.











Gaps will be filled in and large plates will be plug welded over this entire section to add strength.


My awesome helper.






What it looks like at the end of the day today.
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96 4Runner, D44 SAS, ARBs, 35s

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Old 10-05-2012, 06:20 PM   #9 (permalink)
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Looks good! did I miss the tire size you plan on running?

Doven tail perhaps?
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Old 10-07-2012, 10:20 AM   #10 (permalink)
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I'm planning to run either a 35" or a 37" tire. With a locked D44 front and spooled or locked Ford 8.8 rear I figure I'd be pretty safe on 35s as long as I upgrade the u-joints and shafts in the front. 37s would be riskier, but I like the price point I can get H1 double beadlock wheels and tires for. 5.13s would work better with 35s as well, since I can't get 5.38s for both the D44 and 8.8 and I'm just running a built 2.5L engine with an AX-15 and an NP231. No dovetail planned. I'll be happy just to not have a bunch of sheet metal behind the rear wheels for once.
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Old 10-07-2012, 10:49 AM   #11 (permalink)
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I did a little more welding to the frame this weekend, nothing major. I'm working on the template for the inner-frame reinforcing plates now. I'm thinking of just having a shop with a plasma cutter cut them out for me. I hate trying to cut curves with a 4.5" grinder and a cutoff wheel.


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96 4Runner, D44 SAS, ARBs, 35s

Last edited by cooleysix; 01-26-2015 at 03:03 AM.
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Old 10-08-2012, 08:09 PM   #12 (permalink)
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I added the inner rear frame reinforcement plates today, tied them to the outer side of the frame with some bolts welded through, then welded on the UCA mounts. Looks like my UCAs will be around 24" when I get to that, which means I'll probably make the lowers around 34".









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Old 10-11-2012, 02:04 PM   #13 (permalink)
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I am liking the build so far. I know you have already made up your mind, but did you ever consider flipping the springs?, I believe they have about a 3" offset center pin. Also, how much did you bob off the bed? It looks similiar to mine which was a little more than 15".
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Old 10-11-2012, 05:10 PM   #14 (permalink)
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Just whack off the shitty sheetmetal rear subframe all together,
And build a new frame. Itll be way better than patching together a chopped up sheetmetal job.

I capped off my frame stubs & started fresh
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Last edited by barillms; 10-11-2012 at 05:14 PM.
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Old 10-11-2012, 05:35 PM   #15 (permalink)
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Flipping the springs was my first consideration, but one of my major goals was to remove almost everything behind the rear wheels, and that still left too much hanging back there. I seriously considered YJ leaf springs. Swapping to a shorter spring would have fixed the overhang, but it would have hurt ride quality and off-road flex. The last XJ that I wheeled hard was always coming down on the quarter panels when I dropped off ledges or started climbing a waterfall. I got tired of it being in the way, so I'm doing this one different.

I bobbed 14" from the rear, but haven't cut in front of the wheel wells yet. Once the 4-link is done and the wheelbase is set, I'll cut a little out from in front of the wheel wells also. I'm going to try and get some work in on the rear axle truss and UCA mounts this weekend.

I thought it would be easier to get the bed level, lined up, and everything square by reusing the existing frame. It will also be a little easier to remount the bed. That, and it was cheaper. There isn't any rust on the frame and I feel confident it will be strong enough, especially how I cut it and had uncut overlapping sections top and bottom. A cage will be tied in down the road as well.
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Old 10-12-2012, 04:50 PM   #16 (permalink)
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I wouldn't have peace of mind knowing my rear half frame/base of my cage is made from cut & rewelded sheetmetal. It's only .120 thick man.
That's my opinion.

I build an entire buggied MJ and know what you're dealing with.

Why do u want a bed? It's just gonna get torn up & smashed in.

If you like the look of a bed... You can always hang bed skins on the back,
but you want have sturdy steel structure back there.
1. So your link brackets are welded to solid structure, not sheet metal.
2. In case you roll, your cage is solid with a solid base.
3. Overall strength & durability of your chassis.

Something like this:
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Last edited by barillms; 10-12-2012 at 05:24 PM.
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Old 10-13-2012, 04:30 AM   #17 (permalink)
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I went about it a little different and just chopped a foot off the back of the frame behind the rear crossmember. The only reason I kept the rear frame was for the same reasons, easier to align and mount the bed and I didn't want to chop it off yet because I want to wheel. It's been way too long! I plan on backhalfing it next winter similar to what barillms did but with all 1 3/4" DOM to tie into the front hybrid cage that will be built. Hi-jack off, carry on.
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Old 10-13-2012, 05:50 PM   #18 (permalink)
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I'll be taking a foot off behind the rear crossmember as well. I'm just leaving that for later. Once I mount the bed and determine where I want the rear bumper, I'll trim accordingly. I worked on my rear axle truss and upper control arm mounts today.



I finished the truss and one of the two UCA mounts. I also cut a circle plug out of 3/8" and used that to weld up the hole the sensor used to be in. I cut off the two big ears that normally protect the sensor also.



I used 3/8" thick 4" wide steel for the truss, bent it accordingly, and welded it to the top of the pumpkin as well as to the tubes. It sits right on top of the diff and the mounts are about as low as they can go.

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Old 10-19-2012, 07:23 PM   #19 (permalink)
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Got the upper control arms built and mounted tonight.
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Old 10-22-2012, 07:54 PM   #20 (permalink)
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Squeezed in some time after work before the debate. Finished one LCA, 39.5" long using 3" OD Ballistic Joints and 2" OD .250" wall DOM. Made it non-adjustable for the brute strength / simplicity factor.

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Old 10-23-2012, 06:12 PM   #21 (permalink)
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Got the upper control arms built and mounted tonight.
That sure is a lot of thread exposed on those joints.
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Old 10-23-2012, 07:29 PM   #22 (permalink)
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I noticed that as well and plan to correct it. I also used one RH joint and one LH joint, but I'm starting to be concerned about whether or not I'll be able to get the jam nuts tight enough to prevent the link from changing length while it's on the vehicle. Once I have the LCAs on and the pinion angle dialed in again, I'll double-check the length of the exposed threads and extend the UCAs if necessary to correct it. I may make one end non-adjustable to prevent unwanted length changes also (or change it up so both joints are RH or LH, which would prevent unwanted length change as well).
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Old 10-28-2012, 09:36 AM   #23 (permalink)
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Only minor progress this weekend, one more control arm built and I cut the leaf spring pads and shock mounts off the rear axle in preparation for the new LCA mounts. I used the tube coping calculator to notch the control arms with my angle grinder prior to welding.



I also found out that the coil buckets I bought previously were for front XJ/TJ springs, so I ordered a set of these from BTF to make life easier mounting my rear LJ coils.
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Old 10-28-2012, 11:18 AM   #24 (permalink)
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Nice work so far!
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Old 10-29-2012, 10:23 AM   #25 (permalink)
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Frame looks sweet! After plating my brothers XJ's frame I know what a pain it is to deal with sheet metal Uni-body rigs.
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