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1/4 Elliptical Springs

Discussion in 'Center Of Gravity' started by okie k5, Jan 27, 2005.

  1. okie k5

    okie k5 Registered Member

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    I was looking around at some suspension ideas. I am looking for something that gets good articulation and yet won't kill you on the way to the trail. Has anyone had any experience with 1/4 elliptical suspensions. They look like the articulate great, but I have never seen them on anything excepts jeeps and I would worry that they wander. Any information
     
  2. ntsqd

    ntsqd 1/2 ton status

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    Usually a 1/4 elliptic set-up uses a complete linkage system and all the springs do is hold the vehicle up. That is not to say that you can't use them as part of the axle locating linkage.

    The problem with using them to partly locate the axle is that they are a link member of variable length. As the spring compresses it gets longer and vice versa when it extends. What that typically means is undesireable pinion angle changes. It is possible to design the change in length to be small enough that it's not a problem, but I suspect that now you're talking really LONG springs.
    Also, to use them as locating links you'll have to fix them so that they only pivot in one direction. That means to articulate you'll have to twist the main leaf just like if you were running a semi-elliptic system.
     
  3. marv_springer

    marv_springer 1/2 ton status

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  4. Topdown

    Topdown 1/2 ton status

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    definitely dont want to Hijack... so I will keep this on-topic

    Marv, got any pics of the axle mounts for front and rear? Are you just running crossover on the front for steering? Did you 4-link your suspensions? What springs did you use?

    I have heard that you have to use a 1-ton leaf pack to run a 1/4 ellip rear because its only got 1/2 the spring to do the same work...

    I plan on running 1/4 ellip front and rear but need more info.

    I have a fair number of spring packs but I dont know if I have the right kinds.

    Thanks!
    -Ryan
     
  5. josh454

    josh454 Registered Member

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  6. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Hey Josh!

    Welcome to the Board! :thumb: Your 1/4-Elliptic pictures created quite a stir when they first got posted here a couple of years ago.... and people had all sorts of questions about how it worked, how you liked it, etc.

    Now that you're here, I'm sure you'll be getting plenty of questions!


    I'm living on the East Coast these days, so I look forward to meeting you at an event at some point. :usaflag:
     
  7. josh454

    josh454 Registered Member

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    i reserved a spot at the all-truck nationals in carlisle this year. looking forward to meeting some people. the truck is black these days - my neighbors got tired of looking at a multi-colored truck so i decided to spray it.

    josh
     
  8. sled_dog

    sled_dog 1 ton status

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    sweet, I guess I'm going to have to make the trip to Carlisle, to get a look at your rig up close.
     
  9. magnum4x4

    magnum4x4 Registered Member

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    I can't wait for carlisle. I was wondering if you could give me some perticulars on the rear 1/4 lip setup you have and maybe some more pics. What springs (1ton 2x4 or 4x4, what year, where did you cut them)? How much lift? Limit straps or not? What shocks and travel? I am working on setting up a 1/4 lip rear on my 73 Blazer. Thanks for any info in advance. Oh yeah are you gonna be at carlisle Fri-Sun. If not whick days are you planning on running the course?
     
  10. josh454

    josh454 Registered Member

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    you are going to have to cut them wherever you need to based on your mounting point on the frame, your 'bumpstop' location for the spring and how far rearward you want to push your axle. i cut a stock set of blazer rear springs (maybe from like a '80 or something) and added in a few others i had laying around for a total of about 8 i think (probably overkill but i would rather wheel than keep taking them apart). my 'bumpstop' sets my ride height and is located almost in the middle of the cut spring pack where the pin would go through the center. i would recommend setting up your front height and using the 'bumpstop' to set the rear ride height. i don't know how much total lift i have as the front is a custom setup with some revolver shackles i made. the only limiting strap i have is attached directly above the pumpkin to not let the driveshaft reach maximum operating angle. there is nothing out at the wheels, even though i probably should have something out there. no shocks, nothing in production comes with enough travel for my suspension. i drive the truck from ct to nj at 70 mph on the highway with no problems and will be driving it back and forth to carlisle from central nj.

    i know that a lot of people like reading books and are self proclaimed experts on suspension designs yet don't even have a running truck. you should just follow some broad rules of thumb and go for it. you could sit at your computer for hours trying to design and build models but at the end of the day wouldn't you rather have dirty fingers than carpal tunnel syndrome and bad eyes? ultimately you aren't competing in uroc/neuroc and can live with some rear steer and should be out wheeling your junk instead of cleaning clue off your fingers from building your rear suspension out of toothpicks on your desk. my setup is not the prettiest by any means but it works extremely well, i am happy with it (because i built the entire thing) and i am sure would flex with any truck around. plus the uniqueness factor of a 1/4 elliptical 7500lb blazer is priceless.

    i was planning to be out at carlisle only on saturday. i was going to park in the am and walk the swap meet and then maybe go back and hang out at the truck in the afternoon. feel free to climb all over it and check it out if i am not there - just don't unbolt and steal anything...my girlfriend is going to field all questions so make sure you ask her some good ones and would probably drive the course because it is just me and her going and i would have to spot if the course is decent.
     
  11. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I have no real experience with quarter ellips, so can't offer much there, but I do have a word of caution to add in reference to custom suspension design in general.

    There is something to be said for that "just do it" approach, and it generally works fine, until something goes wrong. :crazy:

    Frankly, I think there are primarily 2 categories of "reasons" people feel their "good enough" systems are "good enough" (including my own).

    First, the placebo effect. The same effect that makes people think that adding a K&N filter to their mostly stock motor gives more power and or mileage. We want to believe that the results of our efforts (time, money, physical work, etc.) are productive, so we tend to ignore evidence to the contrary and focus on or even (unconsciously?) enhance any supporting evidence. Nah, the rear steer had nothing to do with my problems on that obstacle. No way the excessive anti-squat contributed to my falling off the line and rolling. But look how much flex I have! And so on...

    The other category of reason is that what you have now is in reality actually better than what you had, but you don't realize how much better it could have been with a bit more design effort. Of course that is true of so many things that you can drive yourself crazy worrying about it. Built engines, transmissions, suspensions, chassis and so on all fall victim here. At some point you've got to say "enough".

    I guess what I'm trying to say is that "just do it" with a few "broad rules of thumb" may well result in a perfectly usable "good enough" system for many people, but I've also seen first hand where it results in an absolutely unusable POS that MUST be completely redone to get a usable rig. This includes rigs that didn't really look "obviously wrong", but will literally flop themselves on level ground; and I'm not talking about doing doughnuts! So don't get too bogged down in details and calculations to the point you don't make progress, but I think you should make sure to understand the risks and trade-offs that may/often/usually result from insufficient "engineering". Like a friend of mine says, "follow the principles of CEE" (Close enough engineering). But only you can define what is "close enough"...
     
  12. yunit

    yunit 1/2 ton status

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    Hey Josh, been a long time, maybe I will try to meet up with you on the way down or at the show. I know a bunch of the UCP run people are heading down this year. Check out Mid Atlantic Offroaders everyone is on that site. Later.
     
  13. 79k20350

    79k20350 3/4 ton status

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    where in norwich do you live? i have an aunt that lives across the street from where staples and kfc are (that little development) im in norwich all the time and have never seen yuor truck, would love to check it out. im in quaker hill (on the new london side of the montville border,l so im really close to ya
     
  14. Ten_Bucks

    Ten_Bucks 1/2 ton status Premium Member

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    I can only imagine the amount of flex a fullsize Chevy would have with 52s up front and 1/4 Elliptic in the rear. You'd definetly need limiting straps, to say the least.
     
  15. josh454

    josh454 Registered Member

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    a few minutes away from the high school - norwich free academy.
     
  16. Ten_Bucks

    Ten_Bucks 1/2 ton status Premium Member

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  17. sled_dog

    sled_dog 1 ton status

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    Josh's rig

    I took a bunch of pictures of Josh's K5 at Carlisle All Truck Nationals, so here are some.

    [​IMG]
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    [​IMG]
     
  18. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    what does that wiegh in at? that thing looks really good.
     
  19. rcurrier44

    rcurrier44 1/2 ton status

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    Hey Josh is your lower shackle mount for your 1/4 eliptical setup a johney joint or something? It realy needs to have the action of a full shackle there otherwise when the suspension cycles you are eather going to tear up bushings or main leafs.

    Your antisquat #'s look quite high too. Did you do the calculations after you built it to see whare you are at? You might be heavy enough those steep links work allright.
     
  20. rcurrier44

    rcurrier44 1/2 ton status

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    Here is another way to do it and use a full spring. I helped a buddy of mine put one together for his CJ5. He ended up buying a house and having a kid and decided to get rid of it before he got it finished. My girlfriends mother bought it and now its back in my shop getting finished ;)

    The CJ5 has been stretched to 110" wheelbase an uses scout axles. Its a double triangulated 4 link that uses YJ leaf springs with an aditional main leaf. The spring is designed to drop away but realy doesn't drop much before the limiting straps stop it. The axle bridge looks hack but is strong, the ag joints in the shackle will be replaced with johney joints soon.

    [​IMG]

    You can see some of the suspension in this pic. It has low antisquat and little roll steer but the lower links are low...especialy with the 110" wheelbase and 35's. They are sleaved DOM....so they shoulden't bend...just hang up.

    [​IMG]
     

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