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post #1 of (permalink) Old 09-15-2000, 11:01 PM
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3/4 ellipical suspension

I have a 1987 wrangler that has a rusted frame at the rear shackle . I been reading articles about 3/4 elliptical suspensions Would this system help my problem with the rusted frame? Is this system for daily driving and /or towing? What special modifications are needed for this ?system?

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post #2 of (permalink) Old 09-15-2000, 11:25 PM
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Re: 3/4 ellipical suspension

I don't have direct experience with doing this type of mod, but a 3/4 elliptic to my knowledge is basically a 'buggy leaf', where you take a main leaf from another spring pack, cut it down, and bolt it to the frame and have the shackle kind of hanging suspended between this buggy leaf and your main leaf. This allows more droop.

Generally speaking I think this setup is inherently less stable than stock, with a lot more side movement of the springs, and therefore I think generally not recommended for a daily driver.

That's what I've HEARD. I'm sure there are others with more direct experience.

Chad

post #3 of (permalink) Old 09-15-2000, 11:58 PM
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Re: 3/4 ellipical suspension

This web site has some great articles on the subject though I'm sure you'll get some good tech answers from the BBS surfers. Chad's pretty much on target from what I've researched myself some time earlier (thought about doing it to mine). The whole idea is for articulation of your axle when rock climbing among other things. It's also the much discussed option between getting the most from leaf springs vs. a coil conversion. If your entire point is because of rust on your frame, you need to consider repairs not modification.

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post #4 of (permalink) Old 09-15-2000, 11:58 PM
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Re: 3/4 ellipical suspension

if you fix it so that you can pin/bolt your buggy leaf up then i think it would be alright on the road. what do you think?

brian wilson
80 cj5 "high 5"
stretched to 100" wb
351w/np435/d300/d44/d60/detroits/4.56/35ss/bdlocks
post #5 of (permalink) Old 09-16-2000, 12:08 AM
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Re: 3/4 ellipical suspension

The suspension you suggest will permit a little more sway on the highway at higher speeds.

The one thing I question is your need for towing. You’re going to have to repair the tail of the frame to have something for the tow hitch to attach to. The tail frame will take the stress of the hitch, either directly connected t the frame, or to the rear crossmember (which is in turn connected to the tail frame area). It’s time to repair… weld and enjoy a few more years out of that frame.

Good Jeepin'

Larry
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post #6 of (permalink) Old 09-16-2000, 12:18 AM
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Re: 3/4 ellipical suspension

Do you know of anyone who sell a frame or frame reinforcement for a '87 wrangler ?Do you have any other ideals on fitting it? It look to me that if I cut the rust out , and weld in a new piece of metal. The shackle will not move back and fourth.

post #7 of (permalink) Old 09-16-2000, 01:07 AM
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Re: 3/4 ellipical suspension

You may want to visit M.O.R.E.'s site:

http://www.mountainoffroad.com/catal...tes/framep.htm

or, here's how I fixed mine:

http://vanevery.homestead.com/RearFrame.html



Good Jeepin'

Larry
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post #8 of (permalink) Old 09-16-2000, 03:01 AM
 
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Re: 3/4 ellipical suspension

3/4 eliptical suspension are completely different that a buggy leaf suspenion usin traditional leafs.
A 3/4 eliptical is basicly a thicker leaf pack cut in half and supported upside down from the what was previousely the front spring hanger area. So the leafs arch away from and downwards from the spring hanger. There is no conection at the back half of the upside down springs, so a 3 point or 4 point link set up up needs to be fabricated to keep the axle located. This is definitel not what a would call a dailky driver type of set up, but it can be made to ride plenty stable for road driving. They are very flexy by nature and allow you to reposition the axle further back or forward as you desire due to the fact that their is no limiting factor of being between the spring hanger and shackle. My 89 YJ will probably get this treatment in the near future as I plan to move my axle to a 101" wheel base position.

Jeff
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I take my Jeep "On the Rocks",usually "With a Splash of Addrenalin"
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post #9 of (permalink) Old 09-16-2000, 03:19 AM
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Re: 3/4 ellipical suspension

H8,
I think you got 3/4 and 1/4 elliptical mixed up. The set up you described sounds a lot like 1/4 elliptical. This set up yields incredible flex and requires a good 4 link or other means of positioning the axle. Avalanche Engineering, makers of the sniper, sell a nice 1/4 elliptic kit which would take a lot of the design work out of your conversion. As for the 3/4 elliptic setup there are tons of write ups all over the net about this conversion. I did it on my old 4Runner and was pleased with the results. But IMHO there are easier ways to get sick flex, that don't have all the drawbacks of the goofy leaf set up. I've been thinking of a full elliptic set up, basically and main leaf mounted to the frame bolted in the center with shackles on both ends connected to the conventional leaf spring. It would require a damn good 4 link to take adventage of all the flex potential. Then again spring overs with Wrangler springs seem to keep tires on the ground pretty good. Best of luck
Travis

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post #10 of (permalink) Old 09-16-2000, 09:53 AM
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Re: 3/4 ellipical suspension

AZJeeper called ot right on the difference between 1/4 and 3/4 eliptical.

And AZJeeper, I too have thought about the 2 leaf spring per side, but I think you would end up with a lot of slop in the suspension.

Have you considered a 4 link with shackles at both ends of the spring? I have a friend who did this to his CJ7 and it works awesome [img]/wwwthreads_images/icons/smile.gif[/img]

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