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4-link geometry? Double Triangluated.

Im trying to get back in gear and finish my rear 4link...

Im planning to do a double triangulated 4link, and run stokc ZJ rear coils mounted under the frame. My lower links will mount of top of the 14bolt axle tube as wide as they can. The lower will will triangulate to the drive shaft and be within the frame rails NOT below the frame rails. The upper link will be 8in of seperation from the lowers at the axle end, and about 4in of seperation at the frame end. The upper links will go though the floor, and the upper link at the frame end will be adjustable by about 3in.

Ill be running the 42s, not the 38s as pictured so that changes the angles alittle. How does the Center of gravity look?
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CG looks a bit too far to the rear. Ya, you've added a lot of tube, but you've cut a lot of sheet metal too. CG is always a crap shoot. Real tought to figure it out.

Sounds like you already know what you are doing. The upper links pretty much have to go through the floor to get decent angles. Good thing you are not attached to that sheetmetal.

Keep us informed!

Steve
 
YES!!!!


you guys see it!

Those uppers have to come through the floor to get optimal geometry.

I remember when ONE BUNG was helping me figure things out, I was placing things where they "had room to go" but I wasn't thinking outside the box yet.....when I compared his measurements with mine (his rig is different and without a floor) I suddenly realized I was ready to compromise everything I has researched, studied and drawn out becuase I was seeing the floor as a constraint.......

there is no reason to concern yourself with link geometry on an xj if you can't deal with cutting the floor!

awesome.

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it looks like using the instant center #2 configuration will give you an anti-squat pretty damn close to 100.......have you calculated that yet?

you have plenty of weight in the rear to get away with a healthy anti-squat.

you can also keep your lower links mounted ABOVE the axle centerline without problems. IT WORKS
 
Beezil, how much into the cabin are the upper links in your pic...meaning how high above the floor?

I'm building this cool cage floor for kiddie bucket seat mounts, and that could double for upper link mounts. I could just box in the holes to keep out water and noise....and the road vibration into the cage floor would be like one of those old hotel beds that take a quarter for 15 minutes of vibration. Their little butts would sleep the entire trip. Talk about two birds with one stone :D.

Nay
 
What about the horizontal seperation between the upper links on the frame side? I was looking under my XJ and it looks like they would be best right where the frame is. If they were inside the frame the seperation would start to get a little narrow, or is that even an issue??
 
Rather than taking a WAG on the CG location, I think it's easier to start with the stock location and make an educated guess at how your modifications have moved it.

The stock CG, based on an average of two 84's and one 97, 4dr, 4WD with driver seated is 26.34" above ground and 46.18" behind the front axle centerline. Apply those measurements to a stock XJ and you'll know right where they land on the door panel. Pretty close to where your triangle shows.

You have probably removed more weight in sheetmetal, interior panels and sound proofing than you've added in steel tube. You have also added quite a bit of weight to the front in steel tube, winch, etc. I would guess that you haven't changed the vertical distance much (not taking the lift into consideration), but your CG has probably moved forward by several inches.

Keep in mind that the preceeding stock measurement includes the wheels, axles, etc. You want to consider the sprung weight only. This raises the estimated height an inch or so.

As far as the anti-squat; based on your drawing, it looks to be at about 75% - 80%. Keep in mind that this method, popular on POR, assumes you are in 2WD.
 
I get mine at Speedwaymotors.com. Go for their "Heat Treated Chrome Moly".

I do have a question reguarding the strength of the 1/2" bolts you will be using (3/4" heim with a misalignment spacer gives a 1/2" bolt hole). Are they strong enough? I am just curious.

*EDIT* Just realized, those must be larger than 3/4 heims by the size of the bushings next to them. Where do you get misalignment spacers for big hiems? For that matter, what's the best source for the big heims? Speedway only stocks 3/4" ones.

Steve
 
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Ashman, are those standard heims, or are they the large Jimmy Joints?

Ary
 
Beezil said:
YES!!!!.....Those uppers have to come through the floor to get optimal geometry.......there is no reason to concern yourself with link geometry on an xj if you can't deal with cutting the floor!

Sorry to disagree Beez, but you could raise the axle end mounts fully above the tube for the same IC & AS without cutting the floor.

I like this solution better but it's not a this or that situation, the geometry is the same only the mounting points change.

I know, boo me.

-jb
 
vintagespeed said:
Sorry to disagree Beez, but you could raise the axle end mounts fully above the tube for the same IC & AS without cutting the floor.

I like this solution better but it's not a this or that situation, the geometry is the same only the mounting points change.

I know, boo me.

-jb

and if you try to maintain vertical seperation on the "frame" end, you run into clearance issues. You must consider the whole package when you are thinking link geometry.....you are over-simplifying....you can't just raise the links up and "have the same thing" because those are relative to your CG....

on our XJ's with 101-105 wb, you are making a compromise by NOT cutting the floor.

FREE YOUR METAL.
 
Willis said:
Where do you get misalignment spacers for big hiems? For that matter, what's the best source for the big heims? Speedway only stocks 3/4" ones.

Polyperformance.com FK or Aurora Bearings make good stuff.
 
Sorry guys, I kinda left my own thread hanging for awhile...

The rod ends I did buy from Dave at poly performance. About $75 each with the misalignment spacers for 3/4in bolts. He didnt have the spacers in stock so my order was delayed. I was charged $5 each for those jam nuts that I specifically didnt order. Dave is buzzy, I didnt complain about the mixup, he tries to provide good parts at good prices. I was not in a rush so the dealy didnt hold me back.

Bezil, The IC#2 synario will be less then 100% because it is below the blue diagnal line. Im guessing about 80% the height of the blue line.

I got all my bolts, and metal to start the 4-link.
Sounds like my CG is reasonable so my ideas should be reasonably close.

I built these coil buckets, but after building them I noticed that on compression the coil is gonna push down on the last piece of boxtube and will probibly bend the coil or brake the coil. Any Ideas for a coil bucket to retain the ZJ rear coils?
To re-use these Im thinking cut the box tube to half that height, cut off the last two of the three box tube retainers, and make the single retainer have a bolt threaded through it to keep the coil from spinning out of the retainer. The other side of the coils Ive made some nice mounts for.
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ashmanjeepxj said:
Sorry guys, I kinda left my own thread hanging for awhile...I built these coil buckets, but after building them I noticed that on compression the coil is gonna push down on the last piece of boxtube and will probibly bend the coil or brake the coil. Any Ideas for a coil bucket to retain the ZJ rear coils?
To re-use these Im thinking cut the box tube to half that height, cut off the last two of the three box tube retainers, and make the single retainer have a bolt threaded through it to keep the coil from spinning out of the retainer.

Your rearend is looking good Ash. :) I especially like the Swampers. :thumbup: Why not cut off the square tube retainers & run a single ubolt through the perch at the end of each coil. Either that or some stock XJ front coil retainer thingys?

-jb
 
your view is foreshortened, I was imagining the blue line wouldn't appear so drastically slanted skyward, if the picture was taken to show a true profile view.....

I think it will be more than 80 percent, but either way, have fun fine-tunin'
 
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