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Those of you with home built long arms...

Try BDS. I bought the long arm upgrade, but you can buy just the crossmember kit. Also I do not have a picture, but they have a transfer case skid that bolts to the crossmember too.

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I used a 2x6 boxed section of 3/16 steel in my last rig with a single upper link attached to the box steel and it held up fine. I mounted it flush with the bottom of the frame and used ONE large bolt through a sleeve in the frame per side as well as four bolts through a plate into the stock crossmember mounting nut serts. My new rig is going to use a 2x4x3/16" boxed steel crossmember also mounted flush to the bottom of the frame rails. I'm not using a plate on the bottom this time though. I offset a plate into the ends of the crossmember so the bolt heads will be above the bottom of the frame rail. I'm also going to use a couple other bolts to tabs welded to the inside of a plated frame rail. Others have also used 2x4 boxed steel successfully mounted in various ways. Jeff
 
Have you looked into the TNT belly skid to start off of?
TNT is not a true 4-link.
Not only that, but isn't it quite expensive for just the crossmember?

There was a thread a few weeks back about a similar topic.
Anyway, I started with a section of 2"x4"x3/16" wall and cut and modified it to work. The end plates are 1/4" and have mount up using five 1/2-13TPI G8 bolts. There a a few ways to do it, all have been debated and have their pros/cons.
If I was to start again and I had not already had the 2"x4", I'd use 2"x5" to make it a little easier with the trans mount.

Here's how mine sits without the suspension mounts and the trans mount on top:
Crossmember_Step2.jpg


The ends are angled down in order for my skidplate setup to clear.



The lower arms will mount about 2" inward from the beginning of that slope.
 
wow nice stuff guys

i ended up tying my upper mounts ( i have a radius arm system -- RK WJ lower arms with daystar upper adjustables) which are for a WJ into my uni frame stiffeners... so they are welded to uni frame and tied into uni-stiffener... not as strong or cool as those crossmembers shown but they are beef --- ideally i should have started with a crossmember --- much strong and better placement for upper links
 
I know it's not a true 4 link I wasn't talking about getting it with mounts. You can get the skid with it not set for radius arms. Bill does have a point it is up there in price though.
 
Sweet ideas here! I like the BDS idea, pending price on the cross member, even still I think it's an excellent starting point to know the arms are in the correct positions!

Not cheap. I think it is about $350 with hardware. BDS will have you go through a local distributor to buy. You will have to call them to get a hold of pricing.
 
Not cheap. I think it is about $350 with hardware. BDS will have you go through a local distributor to buy. You will have to call them to get a hold of pricing.
Just checked BDS's site, $311 and some change, so plus tax etc you were pretty on the nose.

Not sure if correct here, but if I build my own cross member, the hardest part is going to be mounting options correct? Especially for me, since I won't be able to wrap the mount around the frame rail, because I've got TNT stiffeners and T&J tube stiffeners already in place. What are some options guys?
 
I priced out just the TNT crossmember with mounts about 2 years ago, they said it was about $450 for just the crossmember, without shipping.
 

I am making one very similar to this for a couple of friends, but using 2x5 x 3/16. My biggest difference is that the center will drop out like clayton's does. The system will be fully bolt on and also use mounting plates like rusty's off road.

My set up was bolted and then welded in.
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Damn, that is an awesome setup... VERY nice work Vetteboy.
 
With a set up like that, what's the geometry on the arms? I mean, how do you figure where to mount the uppers in relation to the lowers? Obviously a 4 link really wouldn't work well if the arms are all on the same plane etc. Is it just a guestimation?

On mine? No guesstimation there...that was all planned out way ahead of time.

all.jpg


Explained more here...

http://www.pirate4x4.com/forum/showthread.php?t=630589&highlight=suspension+design

I can't speak for the specs on the BDS kit, but on any longarm suspension, you're going to run into compromises. There are reasons why most of us who have gone with a custom 3-link end up going up through the floor, which is something a 'kit' can't really expect you to do. Between the 'wrong-side' axle, the oddball drivetrain, and flat belly I opted to entirely re-do the floor anyway so it wasn't an issue.

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So servicing the drivetrain is easy, because I can just pull it out through the top. I didn't crawl under the rig once to get the t-case out, and this was less than 45 minutes from pulling it off the trailer with the interior complete.

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That's the advantage of designing your own setup...you can pick and choose where you want your compromises instead of going with someone else's.

For the BDS one...it's a nice stout piece, but I don't see any advantage in having 4 long arms plus the panhard still (that's best described as an 'almost parallel 4-link with panhard' so it's not really a true 4-link anyway). Many of us on here are running some variation of the 3-link and it works really well. Having any triangulation at all in a 4-link with panhard is creating bind where there shouldn't be any.
 
For the BDS one...it's a nice stout piece, but I don't see any advantage in having 4 long arms plus the panhard still (that's best described as an 'almost parallel 4-link with panhard' so it's not really a true 4-link anyway). Many of us on here are running some variation of the 3-link and it works really well. Having any triangulation at all in a 4-link with panhard is creating bind where there shouldn't be any.

Interesting. But, does a three link keep the front end geometry "true" enough for high speed antics like JeepSpeed? I don't know, I'm asking.

I'm thinking that a three link will be less precise.

?
 
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