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Discussion Starter #1 (Edited)
OK, someone has to start this. Here goes. I KNOW this has been touched on a LOT of times, but why not bring all the knowledge into one.

There are a LOT of different ways to 4 link the rear of your cruiser. None of which are a drop in the bucket easy... So here comes some tech. Grab a hold of your seat, because this is going to be a fun ride.

You may ask what makes you so damn good at a 4 link? Nothing really. I have not studied them in detail. You want book knowledge, go ask the Gen board, and someone will respond with a textbook answer. I have built a few, and yea, screwed some up. I built my first flatty with a 4 link and a 1/4 ellip. The next buggy was a 4 link with a 1/4 ellip as well. Only this time, the 4 link was different. Then I helped my bro with his 4 link with coilovers. Sure I read up somewhat, but quite honestly I can give a shit what anti-squat, or any of that crap is. I build it. If it works, great. If not, I rebuild. So lets get the tech started!!!!

First off... What is a 4 link? Well I hope if you are here, you at least know what a 4 link is. If not. Here you go. It is basically 4 bars that connect the rear axle to the frame. At least 2 of the links SHOULD be angled to limit lateral movement of the axle. The other 2 should be straight (but they can be angled as well). There are a variety of different 4 links. There is your basic w shaped 4 link. This one is shaped just like a "W" You have 4 connecting points on the axle. You build a bridge above the "pig" on the axle, and make 2 mounts off that. From there you have 2 links that connect to the frame. These will be pointing away from each other. The other 2 will connect from the outside points on the bottom of the axle, and move in towards the outside of the frame rails. What is so bad and so good about this design? True, this has been working for YEARS, but the design does have its flaws. SERIOUS rear steer. Will it work? YES, and well in my opinion, if you can deal with eh crab walking and rear steer. I ran my first comp with this rear design.

Now the other one I built was a bit better in my opinion. I did NOT run heims at all 4 corners. I ran heims at the frame end only, and bushings on the axle end. This limited my flex, but it was also more controlled. Soooooo.... How does this 4 link work? Well imagine "XX" if you will. This is called an inverted y design. All 4 links are the same length, so the axle can only move up and down in a straight line (minimal arc). Between the frame, you build a bridge with some link tabs. Most places are building these now. Off the top of the axle you mount the links the same way. Off a bridge V Off the bottom you go from the outside in. An upside down V if you will. You can even plate the bottom of the links and it can act as a driveshaft protection thingy...

So why even have a 4 link? What about suspension? I like 1/4 ellip. But the best part about 4 linking the rear is all the hard work is done. Now just mix and see what works for you. You can do coils, 1/4 ellip, dual shackle, coilovers, air shocks... Name it, you can do it.

As for the wheelbase stretch. Once you 4 link you usually stretch the wheelbase as well. I go to at LEAST 100", and some go more. Up to you. On the old flatty, I chopped the back of the tub off, and tubed it out. The last rig, I kept as a full-bodied rig. I like the look of the body on there. Now I want to have kids in the fairly near future... I have a full-bodied cruiser fj40. I plan to either sell this and build a 4-seater buggy, OR keep the cruiser and stretch it. Why stretch it? Imagine a CJ6 of FJ40's. Yup, stretched in the body right behind the front seats. This will allow me to sub frame the rear, and get a backseat in there with room for the gear.

OH BOY!!!! I am done. I got to go help Doug unload the buggy now. I will add more to this as I go along. I would add pics, but I can't use this fawking Mac.

Dima
 

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Discussion Starter #3
orangefj45 said:
man, for a math teacher, you sure use the "scientific method"! :flipoff2:

SHEEEET!!!! I use the guess method... "I guess it works" So when am I building your 4-link :flipoff2:

Dima
 

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Dima-
This wasnt even proof read. Sentence structure is poor. No formulas or illustrations. If you think you can just write your papers 10 minutes before class, your'e mistaken mister. How about if we give you a week worth of detention to polish this paper up. To the Principals office!

:D

-Dustin
 

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I was waiting for some sort of rebar scrap metal model pics for examples, but I guess you ran out of duct tape. :confused:
 

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Discussion Starter #8
OK, all edited for your pleasure...

Marc, Hell yea, I got duct tape. I never run out of that, but I am out of rebar. Maybe I can use a coathanger.

Come on guys, lets get some constructive criticism. Do you guys agree, or think I am smoking crack?

Dima
 

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Discussion Starter #9
choreboy2 said:
Dima-
This wasnt even proof read. Sentence structure is poor. No formulas or illustrations. If you think you can just write your papers 10 minutes before class, your'e mistaken mister. How about if we give you a week worth of detention to polish this paper up. To the Principals office!

:D

-Dustin
Dustin... I wrote this 15 minutes before class. The principal told me she is sick of seeing me in her office...

So when ar we going to 4-link your rear? Come on, you know you want to :evil:

Dima
 

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You may ask what makes you so damn good at a 4 link? Nothing really. I have not studied them in detail.


Not a good way to start a 4 link tech thread there Dima. :D But I have to give you props for trying to get one of the guys to sacrifice a rig for you to do a "how to" class.
 

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Discussion Starter #11
toploader said:
You may ask what makes you so damn good at a 4 link? Nothing really. I have not studied them in detail.


Not a good way to start a 4 link tech thread there Dima. :D But I have to give you props for trying to get one of the guys to sacrifice a rig for you to do a "how to" class.

I am just being modest. I kick ass at these things. I have mastered the lengths, and the flex aspects of one. Lets link up one of your POS's...

Dima
 

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this thread sawks :flipoff2:
 

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everybody has their own opinion on everything...especially suspension.

after learning about links and suspension geometry its way easy. read up on it. and learn from people who have built a few.

tri 4 links work the best in the rear imho. keep the rc roll center high and its all good.

double tri 4 links work good but would lower the rc.
single tri with the lowers tri and uppers straight will drasticly lower the rc. a few shops do it this way and fix the roll with a sway bar. it works so?????


everybody there own opinions.....that is all :flipoff2:
 

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Discussion Starter #14
I think the main idea to keep a good RC, you have to keep the top links as flat as possible. The flatter on top, the better. You really do not want the rear to rise too much when you get on the gas, but you don't want it to drop too much either. I would prefer the rear lift a little. There is a LOT of reading on roll center, anti squat,... Sure you can figure it all out with mathematical formulas, and if I was to daily drive it, I probably would, but I build rockcrawlers, not mall crawlers...

Dima
 
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