2X4 frame for my CJ2A

Chuck, Terry, Uncamonkey and Ryan are all right.

I will be extending the back 2 frame rails with this idea, either cutting 2" pieces of tube and butt welding it or something else. I spent last night thinking about how this is stupid to leave it wrong. That will also facilitate making a spare tire carrier. I was looking at cj rear shackle mounts and they are all about 3~4 inches in from the back frame. I wanted to have my mounts all the way back, but this will have to do. If for some reason I can't make this work I will build my own tank, but I would rather not.

I have thought about how easy this would be. With the rear mount tank i get 15 gallons, not 10, no firebomb under my rear and the #1 reason is I get to drop my seat down a little. I am average height but I have to either look at stop lights over my windshield or turn my head sideways, plus I get more storage. One of my mufflers is right under my tank and even though I left a space for heat dissipation between the tank and the floor pan, the fuel does get hot and expand and contract quite a bit. Thought about putting in 2a seats that are thin, but it might not be so comfy. I think its worth this effort.

 

Chris, Although I believe you are on the right track I thought I would throw this out. On my '45 GPW at a point 12" back behind the step up in the floor below seats, there is another rise in the floor. The floor rises at an angle of about 30 degrees an additional 1 1/2". The additional clearance this provides may help in solving your problem.

 

Thanks for contributing.

I already have a lot of body lift, 1.25". I want to have rear seat for my sons too an I don't want them to feel like they are in an ejector seat! I will make the required modifications tomorrow.

 

Got to work this morning.
As I measured it wasn't going to be as simple as just pushing the tank back 2 inches. I also needed to move the shackle down so that it did not interfere with the tank skid plate/mount. The side bands for the skid plate were exactly where the bolts for the upper shackle mount is. I made some 1.25 stand off out of the same tube as the frame.

I then cut some 2" pieces of tube and butt welded them on to the back of the frame rails.

Got those tacked up and tacked on the stand off shackle assembly.

as you can see the upper bolt head for the shackle rides in the area of the tank. It DOES NOT touch the tank though.

I put 640lbs of concrete on the rear end and then proceeded to put my 190lbs on the bumper and jump up and down. It is fixed. there wis zero interference between the differential housing and the tank. I did see that I need to have a minimum of a 5" bump stop between the axle tube and the frame though.
Low riiiiideeeerrrr rides a little Lowwer.


has to get a crow bar to pop em back out again. Booiiiinnggggggggg!!!!!!!!

 

Springs and parts get themselves in some pretty unpredictable spots when stressed off road. That shackle will repeat that lockup with half that weight when articulated. Looks like you could use some longer shackles, no? If you don't want the added lift, you could at least put little (like factory CJ?) bump stops here, to prevent the shackle from overextending. Its a boonie fix, but effective and hardly noticeable.

 

I had to move the axles too. I will have to carve out my well wells no matter what as they will not accept the 35'S

 

Those are just stock YJ shackles and I don't care if they go to the scrap heap. I guess its either longer shackles, boomerang anti inversion shackles or some sort of shackle stop.
http://www.fourwheeler.com/how-to/suspension-brakes/1310-what-now-fixing-shackle-inversion/
I bet you guys have a fix for this and would love to tell me how to make sure this doesn't happen. Now remember this is over 800lbs bouncing on the back of this chassis before this happened. I was trying to make the differential housing contact the skid plate. I tested it to failure in a sense.

 

Going up a hillclimb will transfer a ton of weight back there...

 

The inversion shackles are usually used to keep the shackle from flipping in, locking the spring in a moon-shape, usually from bashing the spring/shackle against rocks, or trying to force the tire up and over a vertical surface. (Or getting rear-ended in a race, as I found out the hard way.) If it locks out (like in your pic - and in that pic in the linked article on the J-truck), that is just too long of a spring for the shackle length and/or shackle mount location. Notice the pic they used showing the installed inversion shackle is to keep that spring from flipping in... not how they needed it on their truck.

I run stock YJ springs on my other Jeep and just ran down and measured the shackles. I'm running 4 1/4" on the rear and 5 1/2" on the front, eye center to eye center. My springs are flat, so they don't need any outward travel, only inward travel, but they use the full swing even at those lengths. I think your shackle mount location is the short side of ok; you might want to move it back a hair while you still can. You'll need more room to swing back than forward with springs that arched - droop will be limited due to the amount of arch. You at minimum need some longer shackles, IMO.

You are putting the extra time and patience in where it counts, trust me. It's looking good!

 

Ryan,
Yes I always thought that the inversion shackles were for INWARD inversion, not outward. I ran these springs on my old frame but never could get the articulation that i have in this test. Those 4" lift springs were almost flat when this happened. These are the shackles that came with the guys lift kit I bought. Maybe I should just make some new shackles. No big thing if that will solve my issue.

I have no problem cutting off these tacks again, but I am afraid that there may not be enough angle outward on the shackle at regular ride height. There is probably less than 10 degrees where they are tacked now. The last thing I want is inversion inward where I bend a spring. If the present inversion outward were to happen I can just pry them out, but inward could ruin a spring for sure.

If I were going to really run this thing off road much i would probably go flat springs on top of the tubes. I see why guys do that, but that also had its problems. Terry and his linked coils really has me thinking about that a couple years off.

I appreciate all the help I am getting from you guys. i really want the chassis to be something that is quality and useful to build off of for any future projects and changes that that might entail.

 

10* with the weight on the frame or with no weight? 10 seems like very little to me if there is weight on the frame. I would think somewhere around 20* would be good when the chassis is weighted. Just guessing. I never measured mine.

 

You need to get the right weight in there first at ride height ........if that has to wait a few weeks then so be it, don't rush the process..........the shackle end should be tack welded at a point of your choice in the rear.......that aligns with a point just ahead of the center of the wheel well........the fixed end of the spring hanger should then be moved fore or aft to get the shackle in the right orientation angle.........done.

 

Just went out and measured my cj5's rear shackle angle. I have about 22* +/-. It has about a half tank of gas in it and is otherwise unladen.

 

Yeah, 10* with about 160lbs in the frame. Thats probably the weight of the back end of the body. Its really not much but I can adjust the shackle end really easily. I expect there to be more weight than that with the roll bar, fuel, bed and rear seat. The angle will increase for sure to I hope 20* or so.

I really can't move the stationary spring mount. Go rearward and the housing will crash into the gas tank, forward and I will have to cut too much out of the body.


This pic was taken before I lengthened the frame rails, but the shackle mounts are in a very similar location. I am really happy that I solved the differential/ gas tank interference issue. Now I just need to solve the rearward shackle inversion. I don't need to finish weld the mounts, but I would like to finish weld the cross members and get some primer and paint on this thing. It will rust really bad pretty soon if I don't take care of it. No garage.Winter in the east. you get the idea.

What is the accepted method of keeping the springs from inverting outward? Ryan says stops or longer shackles. Either of those fixes are very easy....

 

"What is the accepted method of keeping the springs from inverting outward? Ryan says stops of longer shackles. Either of those fixes are very easy...."

What I just told you............your extension to raise your shackle mount needs to be carried rearward as if it was part of the chassis, that will stop your shackle. Correct weight should be known, If your overloading it you cannot correctly make the adjustment to the shackle angle. With the correct weight in place you then should be able to move the front and make the adjustment to the rear.......the front only needs to move a little to get the shackle at the correct angle..........I would wait till you have most done and weight in and make the adjustment......fix the height shackle extension.

 

Alright then. Thanks. I will continue the spacer all the way out to the rear of the bumper. That will stop the shackle and not allow an inversion. Got it.

 

As far as shackle length - measure your unsprung springs from eye to eye. Then load them as far as you think they will ever get compressed and take the same measurement. The difference in your measurements is how much minimum swing your shackles need to have. If it's 6" of difference, a 4" shackle won't work without inverting. From my own experience, a good place to start with shackle length is the same eye-to-eye length as the difference in your measurements.

What angle they sit at rest is almost irrelevant after knowing those beginning and end locales.

 

I assume you mean as long as the shackles have a degree of angle so they will not be inverting onto themselves. That would be bad.

Thank you. When I get to making my shackles I will take this measurement into account and make them that length. I assume this is also correct for the front end. The front has no provision for shackle stops as the rear does in this particular case. Is it imperative for frame mounted bump stops over the axle tube to prevent this inversion in the front? Or will correct shackle length suffice in the prevention of outward inversion? If this all seems a bit redundant, its because I have never built a chassis from scratch before and I want it to perform correctly. Well I did build one and it didn't work correctly, so here i am.

Thanks again!

 

Chris.

Some reading material............http://www.quadratec.com/jeep_knowledgebase/article-93.htm

Lift springs are always a PITA. Why? because the lift or Re-Arc of the spring pack is created to hold the vehicle higher and in doing so the effective spring rate is also much higher than it should be to obtain the lift......hence the reason most lift springs ride like a Mack Truck. Do to the re-arc the spring pack length also becomes longer and may either require a longer shackle to allow for the spring to go into full compression or full droop length which may also require a re-positioning of the brackets........I doubt that you would be hauling enough weight to collapse the spring to near flat , but I really don't know..........A flatter spring pack that carries the weight at ride height is a much friendlier animal , and a shackle angle at about 40-45 degrees is a much nicer ride and will hardy ever go inverted.

The only true way to test your springs would be to take them apart and just re-install the main leaves only. Now you can run them through the bump to droop cycle and add whatever length shackle is necessary so that in the extreme they can never compress and bend nor run out of room in droop.





Q: Will I need longer spring shackles?

A: Longer spring shackles are a relatively inexpensive and effective way to get the best performance out of lifted springs. Are they absolutely necessary? No. But because most lifted springs are arched higher than stock, they're actually longer than stock. And when the suspension flexes, the shackle end of the spring moves farther than stock. That's why shackles that are 1" to 1 ½" longer than stock often allow the new springs to work better.