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2 link vs 3 link vs 4 link vs 8 link vs 20 link...

sirhk100

Well-Known Member
Okay, I know what a 2 link rearend system is (I think) but can someone explain the difference between a 3 and 4 link rearend. It seems like people are tossing the terms around as the same thing. I always thought a 3 link rearend was basically a 2 link rear with coils/coilovers and a draglink bar to center the rear end under the vehicle. Like what the McNeils do on their Explorers. And I thought a 4 link was what all of you do with the 2 outter links housing the coilovers (swingarm) and the triangular setup in the middle to keep it all centered in there. Am I right or can someone clarify this for me. Maybe Jeff (Aloha) since he did such a great job for that other guy on the radius arm explination? What other common setups are there. A tutorial on common rearend link designs for my own personal knowledge would be great. Me personally, I don't ever see doing anything more then a set of race packs and maybe a 2 link to control them if I have any problems with hopping.

Thanks in advance!!!

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart
 

Jerry Zaiden

Well-Known Member
This is a 3 link note top of the rear end.

Camburg Engineering from camburg web site.

This is a 4 link.


Stewart race works from "skunkz/ Race-Dezert.com
 

sirhk100

Well-Known Member
Thanks Jerry, you can't get any more obvious then that explination. Does that 2 link setup with the Drag link (that is rarely used) have a common name?

'99YZ400,
'92 Ford Exploder lifted work in progress,
lifted golf cart
 

Junior

Well-Known Member
Great question! I thought I knew the difference but was way off.


Junior
EJR Racing #244
 

Jimmy8

Well-Known Member
That 3 link with a wishbone you have a picture of is very similar to a 4 link, due to the fact that it mounts to the chassis in 2 different spots. 3 links may also only mount to the chassis in only 1 spot and be a single bar running from the top of the housing to the center of the chassis.

"We've done so much with so little for so long, we can do anything with nothing!"
 

ntsqd

Well-Known Member
Very similar in appearence maybe, but not in where the roll center is relative to where the axle is in it's travel path. A 3 link like the pic will always have it's roll center at the center of where the axle's lateral locator is mounted to the housing.
With the 4 link pictured it will move up and down relative to the housing during the suspension's cycling. It seems that short course trucks prefer the 3 link and dezert trucks prefer the 4 link. I have some ideas on why, but I'm not sure that they are right.

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee
 

Junior

Well-Known Member
This may be a dumb question.....................Do you have to use swing arms with a 3 or 4 link setup? It seems that the 3 or 4 link setup's in the photos would eliminate axle wrap, common with some leafs. Also, it appears that the nature of the link setup would cause changes in the pinion angle (driveline angle) throughout the cycle, since attached only to the top of the housing. Is this the purpose of the link setup?


Junior
EJR Racing #244
 

vwguy

Well-Known Member
technically the pinion angel DOESNT have to change throught the cycle of a 3 or 4 link setup it depends on if its designed to change or not it can be made to change for the good or not change at all.
if the top links were longer than the lower ones it would point the pinion up toward the transmission depending on how much longer it is, through its cycle.
it they are the same length for the top and bottom it would stay the same if the links were parallel and the mounting points were designed right such as height between the lower mounting point on the axle and the top mounting point
i will post a picture of what i am talking about later tonight

how ironic is it that most people slow down for speed bumps yet almost all of us here im sure pin it
 

JoeB

Well-Known Member
On our CORR Pro-2 race truck our 4-link was designed to change pinion angle through the suspension travel. Even though there is less wheel travel than a desert truck, the short-course trucks have shorter wheel base, with shorter driveshafts which keeps the driveshaft angles pretty extreme. Being able to change the pinion angle with the design of the 4-link keeps these driveshaft angles down, helping those u-joints handle everything.

As for the post that says short-course trucks prefer 3-link, I'm not so sure of that. I think CORR hosts the worlds best short-course trucks, and just about all of them are 4-linked.

Joe B.
 

martininsocal

Well-Known Member
the 3 link vs. 4 link debate is decades old. the 3 link with the Y upper locator is not very different than the 4 link shown. roll centers will vary very little with the upper housing mounts so close together. the 4 link seen off road developed from the 4/5 link of drag racing and sprint car design. those had a mostly 4 bar parallel design with a 5 link pan hard bar to center the rear ejd. on a sprint car, it would push the whole rear housing outward to help with roll center in the left turn. when offroad trucks started running so much horsepower, there were severe probelms trying to get it to the ground. a guy from the midwest started applying some roundy round technology to the offroad trucks he was building. a few modifications and wallah! the 4 link with floating shackle/leaf springs popped up. worked, but was very heavy. the next step was the 4 link with coilovers and the design wars were on. there were 3 links, 4 links, leading arms, leading trailing arms, cantilever, etc...the design has been refined to the standard 4 link with non- parallel links to do the job of locating th erear end as well as provide the upper links, saves weight of the panhard bar and is easy to fix should you break one link. with the 3 link/y link, you breal it your done. the 4 link will limp a little. pinion angle is not just about saving driveline angles, whether neutral, negative or positive, the pinion angle helps increase or decrease tire bite depending on traction surface. even with a shortbed shortcourse truck, driveline nagles with 20"s of travel are not severe, but on a dry track versus a wet track, bite is very important in the dirt.

If your gonna go, go BIG
 

ntsqd

Well-Known Member
My observation of short course trucks preferring 3 links was long distance. I stand corrected with regards to CORR trucks.

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee
 
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