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4link arm length question

O'neal

O'neal

?????????
Location
evanston wy
I'm looking at building a 4 link in the rear.This will be a single triangulated 4link (upper's attatched at the diff and out to the frame)

Lower's at 35"
upper's at 28"

Are these length's acceptable?
 
ROCKRUNNER

ROCKRUNNER

Active Member
Location
SLC
You can make almost any length link work well with the right geometry. If the upper Links are the only links adding triangulation then we would need to know how wide the frame is. The narrower the frame the less triangulation you have holding the rear axle center under the rig. I would try to get 40* of triangulation on the uppers.
 
O'neal

O'neal

?????????
Location
evanston wy
I read post's on 4 link's over on pirate last night until my head hurt! I'm back at it again trying to soak up as much info as I possibly can.
Anyone have any tip's on linking maybe a good link calculator?I would like to get it right the first time,thank's.
 
chadschoon

chadschoon

Well-Known Member
Location
lehi
JRYOTA said:
best to have the uppers at 70% of the length of your lowers
Click to expand...

and why is that? mine are about exactly the same in the rear. I know of a shop (BHR) that make them about the same. we were told that if you do this your pinion angle shouldnt change... I think its just preferance. I think people do it all different. is there a perfect way, I guess it just depends on you.
 
waynehartwig

waynehartwig

www.jeeperman.com
Location
Mead, WA
chadschoon said:
and why is that? mine are about exactly the same in the rear. I know of a shop (BHR) that make them about the same. we were told that if you do this your pinion angle shouldnt change... I think its just preferance. I think people do it all different. is there a perfect way, I guess it just depends on you.
Click to expand...

Exactly. I think Rockrunner hit on the head - it all depends on geometry. So link placement, not lengths. Lengths will change things like pinion angle and mounting points which will change geometry.

Get a calculator and throw numbers at it and see what works. With that, you can also get an idea of what happens when you change lengths/mounting points...

Keep in mind while designing it that you want the links to be parallel to the ground at ride height. You'll get better numbers and the rear won't try to drive under your rig.
 
spaggyroe

spaggyroe

Man Flu Survivor
Location
Lehi
I Lean said:
Why would that be?
Click to expand...


4-link folklore. :D

I used to think the same (after reading volumes of interweb 4-link propaganda). After actually learning how to use the 4-link calc, and trying a bunch of different scenarios, I came to the same conclusion that Rockrunner and Wayne have already pointed out.
 
JRYOTA

JRYOTA

Member
look for peterson's writeup on dual tri'd 4 links. When you have it set up correctly with your c.o.g. Etc In order your axle will react properly when power is applied. It's no folklore, there is a better way to build links
 
I Lean

I Lean

Mbryson's hairdresser
Vendor
Location
Utah
JRYOTA said:
look for peterson's writeup on dual tri'd 4 links. When you have it set up correctly with your c.o.g. Etc In order your axle will react properly when power is applied. It's no folklore, there is a better way to build links
Click to expand...

I've read it. I don't agree with a lot of the things that were stated as fact in that article.

They had to be careful to make sure than no matter how badly someone screwed up their link setup by reading the article, they'd still end up with something at least functional.

You're absolutely right, there is a better way. ;)
 
waynehartwig

waynehartwig

www.jeeperman.com
Location
Mead, WA
I Lean said:
I've read it. I don't agree with a lot of the things that were stated as fact in that article.

They had to be careful to make sure than no matter how badly someone screwed up their link setup by reading the article, they'd still end up with something at least functional.

You're absolutely right, there is a better way. ;)
Click to expand...

I had the same opinion when I read it too. While I'm no Twisted Customs or anything, I just fealt like what they were saying as fact was wrong.

I know for a fact that proper geometry is key. Granted it's not rocket science, but...

If you don't want to hear it, go look at comp buggies that are WINNING comps and see how their suspension functions. I would think they know what's right....
 
I Lean

I Lean

Mbryson's hairdresser
Vendor
Location
Utah
waynehartwig said:
If you don't want to hear it, go look at comp buggies that are WINNING comps and see how their suspension functions. I would think they know what's right....
Click to expand...

Either that, or they know how to drive to make the rig work despite the suspension? (just playing devil's advocate...)
 
UNSTUCK

UNSTUCK

But stuck more often.
I Lean said:
Either that, or they know how to drive to make the rig work despite the suspension? (just playing devil's advocate...)
Click to expand...

I like that. Some people are pretty good at driving in and out of their nasty rear steer.


Link length is not as important as link seperation. You just need to figure out what the seperation should be once you figure out how long you can make them. You should do pretty well with with your frame seperation at about half of your axle seperation. You axle seperation should be as much as possible for added leverage, but I think the 1/4 tire diameter is pretty good. Also if you can place your lower links below the axle center line, that will also help with leverage, but most people place them at the axle centerline and add a bit to the upper links.
 
O'neal

O'neal

?????????
Location
evanston wy
Here is the number's i've got so far.

Anti squat-72%

Roll center-27in

roll axis ---5 deg

inst center X-80 in

inst center Z-23 in

From what i've read i'm looking for around 80-100% anti squat and close to 0% in roll axis as possible...Right?
 
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