Need tips on HUGE conversion...

Okay guys, I got an HP44 and a Ford 9" out of a '77ish F-150 for $60 a couple weeks back. I know that some of you have put these very axles into an XJ. I know that they are wider (about 4-5" wider) than stock, so please limit the discussion here to how to install these beauties. I want to end up with a 2 link + track bar coil suspension front and rear. The rear radius arms will function as a "wristed radius arm" setup to avoid having to use Ford-style radius arm axle bushings. My plan is this...

- relocate the D44 radius arm/spring mounts (yes, they're welded on, not cast) to the correct spring perch width for an XJ.
- keep the Ford radius arms, and attach them with a home fabbed crossmember.
- fab a rear crossmember directly above the original rear axle position. It will include XJ style front coil "retaining pillars/bumpstops" and shock mounts, if you can understand what I mean - those round tubes your front coils fit over.
- use STOCK front coils for the rear. They will mount directly under the unibody frame rails, fitting to the above mentioned crossmember.
- weld on some factory front coil/shock perches from a stock XJ D30 to the Ford 9" to hold the rear coils in place.
- fab up some rear radius arms. One would be a "Y" shaped arm, with two bushings that mount to the rear axle. The other would be like a long control arm, with one bushing attaching to the axle. Both rear radius arms would be a similar length to the rear driveline to minimize the need for a long travel driveline. The rear radius arms would attach to the frame a little behind the t-case crossmember. The bushings throughout the rear radius arms would be those found in XJ front control arms.
- the rear would be held laterally with a track bar, similar to the one on the front of a stock XJ.

Whaddya think? Mostly, I'm curious to see how you'd build the frame mounts for the radius arms. Should they be crossmembers, tying the framerails together? Or, I could make one long frame mount for each side which would hold one front radius arm and one rear. Would it be stronger to make one crossmember for the rear and a seperate for the front.

BTW - I understand the pros/cons of rear coils. Better flex vs worse stability and all that have already been considered. I really want to know what you guys have done for consruction of the suspension components for installation of these axles, and also for rear coil conversions.

Any and all info would be helpful and appreciated, thanks in advance. I know this is a crapload of stuff to respond to, but I want to do it all at once. Good thing I have a spare lifted XJ to keep me going for a couple months...

Jared

Oh yeah, I want to end up with about 5-6" of total lift. It sits on RE ZJ 4.5" coils in the front right now, so it's lifted about 5.5".

just a point of clarification:

Rockwell 2.5s=HUGE
Mogs=Damn beefy
60s=pretty big
D44s=not even close to compensating for a small pee-pee

The general consensus from the built guys on this board is that rear coils and mucho rear flex is overrated. There is a lot of geometry involved in getting the rear anti-squat correct and coilovers into the cab via shock hoop is the only way to go. Stick with rear leaves, with the correct shackle position, they work very well. Even a buggy leaf set up will work.

SeanP

Sounds OK to me, you can work out the small bugs that come up and later convert to coilovers if you want to. Get a working suspension linkage done, you can use it with almost every type of spring.

as far as body end link mounts I think that building a crossmember front and rear would be the best way to go. after that you could possably attach the two crosmembers and have a small "subframe" this would also be a great place to mount some skids, belly pan.

SeanP said:

D44s=not even close to compensating for a small pee-pee

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The Dana 30 I have now is inferior in basically every way. Less gear options, smaller shafts, smaller joints, smaller carrier giving way to weaker lockers. Yes I could upgrade the 30, for many times over the price I paid for the 44.

SeanP said:

The general consensus from the built guys on this board is that rear coils and mucho rear flex is overrated.

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I could care less about "mucho flex". What I want is mucho smooth ride on the trail. I have a wife and 7 week old baby and I want them to enjoy wheelin as much as I do. Coils make the vehicle shake side to side over uneven bumps a TON LESS, plain and simple. A little extra flex in the rear never hurts either.

SeanP said:

There is a lot of geometry involved in getting the rear anti-squat correct and coilovers into the cab via shock hoop is the only way to go.

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With the radius arm setup, the axle torque will unload the rear suspension somewhat, not squat. The pinion will try to rise, and therefore push the axle away from the body. Coilovers are just a tad more expensive than the FREE stock front coils that we all have lying around. Cutting a hole in the back of the Jeep to accomodate outrageously long coilovers is simply not sane for a family rig.

I don't mean to shoot you down or anything, but everything you said is the exact opposite of what I think. No hard feelins.

Jared atriot:

EDIT - I just read my post here and I sound like a JERK. Sorry sean for my tone, I do appreciate your input. I just happen to disagree. I should have been more clear on my goals for this Jeep. I want a good trail machine, with good (not incredible) flex and a very smooth trail ride. I have stock control arms and drop brackets right now, and all the bangs and pops I get from them is driving me crazy. I want something **CHEAP**, simply designed, strong, and unique. Buying a full set of RE control arms only fulfills 2 of these requirements. Strong and simple.
I firmly believe that the ride would be improved with these looong radius arms over stock length control arms. Yes leaves are simple and can be made to flex, but again flex isn't really what I'm looking for. The rear coils will help keep the skin from wearing off my wife's back during long days of bumpy Moab trails, and hopefully keep the kid happy too.
As far as anti squat, am I correct on how I think the radius arms will work? The shorter arms the better for anti-squat properties if I am. Shorter arms won't hurt the flex much either, since this will be a wristed arm setup.

Any other ideas out there? Who else has done radius arms up front?

shizza-my-nizza said:

...I think that building a crossmember front and rear would be the best way to go. after that you could possably attach the two crosmembers and have a small "subframe" this would also be a great place to mount some skids, belly pan.

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I like the subframe idea. Do you think that it would add much strength over just having seperate radius arm mounts on each side? One option I had considered is having one long piece on each side, that attaches to one front arm and one rear. They would be a few feet long each and follow the bottom of the framerail. This would give some good attachment points to the frame, and I could even use the stock t-case crossmember. The radius arm mounts would act like a t-case drop kit. This setup would be a little easier to fab than the crossmember/subframe setup, but I don't know how it would compare in strength.

Jared

The stock front XJ coils will get you about 8" tp 10" of lift when used in the rear, so you might want to look around for a shorter spring. You could cut a few coils out of the stock coils but I'm not sure what that will do to the spring rate. Why a trackbar setup in the rear? Wouldn't a 4 link be easier/better? Do a search for rear coil conversion under the User name LED he has a real nice setup. Also check www.dandcextreme.com thats who made the set-up for LED. Good luck!

I like your idea of running some material to along the bottom of the frame rail to attach the front and rear arms But I think it could be a lot stronger if you also made crossmembers between the rails. Once you have your link attacment points made I don't think it would be that much more trouble to add the crossmembers.

Rockstomper over on the Pirates board did a wristed arm rear coil suspension and hated it. since the pinion rotation is only controlled by one side, that one side sees ALL of the squat/anti-squat forces, essentially lifting or squating just one side.

If you're after a very simple rear coil setup, I would recommend running 2 radius arms, not 1 radius and 1 wristed. This will give you a balanced suspension, easy setup, smooth coil ride, no silly flex, and the added insurance of 2 arms controlling axle wrap.

However, unless you're ready to get a little crazy and start chopping body and investing some money, I strongly believe that working with LEAFS is going to be your best bet. Get a good pack put together, get your shackle angle right, get some full-length poly leaf-spring liners, and spend the extra money on some Bilstein 7100s. I can all but garauntee that will ride better than a thrown together coil suspension running stock front coils.

Mine doesn't. It uses the little 260x's found on earlier XJ's. The D44 in my driveway DOES use the 297's (the one you are talking about). Even USED 297x XJ shafts will be over 100 bucks unless I'm lucky.

Jared

$270 + shipping on 2 heavy leaf packs is the retail price for RE 4.5" Extreme Duty leafs. This is already more than I would have to spend on materials to build this setup. I am still not convinced that this would ride better than coils. You guys with good soft rear leafs, which end of your rig is more supple -front or rear? My money's on the front. Now for the Bilsteins. I don't even know what they cost, but I would estimate about $60 each. So, leafs and Bilsteins together are ~$400 + shipping. Yeowch - especially when I already HAVE rear lift springs...

The 2 standard radius arm option is still being considered. The only problem being that I have none of the parts to complete it. I would have to purchase 2 radius arms, all the bushings, the frame mounts, and make them fit to the axle. This is probably about a hundred bones for used stuff. Not too bad actually, since I would have to buy at least 5 control arm bushings to make the wristed setup, also some tube. I do like the "sway bar" effect that the Ford axle bushings have. They would be a bit more stable. Perhaps this is the better option.

Jared atriot:

you don't have to use the ford radius arm wedges and bushing on the rear, just make 2 "Y" arms like the common XJ front long-arms. That's 6 bushings for the axle ends and arm intersection and 2 Johnny joints for the frame ends. (6*4)+(2*35)= $94 plus money for steel tubing. It would be a toss up between what would be cheaper, "Y" radius arms or Ford style radius arms.

also, radius arms can be made to have squat or anti-squat, it all depends on where they mount relative to your COG. Usually they will have anti-squat (lift the rear).

it sounds like you have more time than money, which I can totally appreciate. it will be much more work to setup a good coil suspension, but it may be cheaper. it may be even less work and less money to use junkyard leafs. search for norcalxj, he put 63" Chevy springs under the "frame" rail. flexes amazingly, cheap and super easy. you could do it with 57" MJ leafs too.

2 Y shaped radius arms wouldn't allow any real flex at all would they? Well, only as much as the bushings would compress, which wouldn't be very much. The ford bushings allow the axle to twist some inside the radius arms, which is why they allow any flex. There would be none of this with 2 Y arms.

Wait! Isn't the new RE long arm kit 2 Y shaped radius arms? I think that the longarm lifts on http://www.rockkrawler.com/pages/xjsystem.html (the 6.5" long arm kit) are a wristed radius arm setup like what I have been talking about making for the rear.

So if the RE longarm lifts ARE a double Y arm setup, how do they flex? It shouldn't be able to work, hmmmm...

Jared

They usually use johnny joints or heim joints at the frame end of the control arms. Along with the treaded part of the control arm this gives the flex on those type of arms. I use Rusty's arms in front with stock rubber bushings and the only thing limiting flex are the shocks and limiting straps.

I am working on a simaler set up. i will be using 71 ford hp44 and 9". using the ford radius arms in front with a set of johnny joints. for the rear i have not yet made my mind up yet. i do nto have a wife or kids to be worried about comfort and i do nto need to think of road manners.(a plus of haveing 3 xjs(braging)) so i can either do a 4link or leafs or 2link. i want a little more flex and am just not a big fan of 2 link. probley go with 4link and coilovers.

for mounting them. i am making a full under body skid plate. will start at engine and go all the way to the gas tank. will nto be one piece but will tie togeather. as a part of the skid play i am wraping the under body frame rails with either 1/4 or 3/8s steel. will be making my mount go off that.

just to make my project fun for the whole fmaily i am doing a 5.0L np435 swap.
to brag more i think. axles 100 bucks. not as cheap as you but still good deal. 5.0L 250 bucks complete. np435 50 bucks. then all i need is money for links, steel plate, a few joints, and set of coilovers.