How to use a 4 Link Calculator, DIY long arm four link suspension on my Jeep Wrangler TJ

In this video I bust out the laptop and the 4-link calculator on a quest to fix my, at times unstable rear long arm suspension. There are a lot of other factors that come into play including wheelbase, track width and vehicle height (lift kit).
Get your 4-Link calculator here: Triaged 4 Link Suspension Calculator (.xls) (crawlpedia.com)
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[@Go4BrokeOffroad]

Been building my 4 links for 8 years now. Finally found someone to explain how to understand the calculator. Thanks man.

[@MuddyBeards4X4]

Glad it helped 👊🏻

[@Fix_It_Again_Tony]

Thanks for taking the time to go over this. The calculator is a great tool that is freely available, though I would guess that most people never use it.

[@MuddyBeards4X4]

I wish I used it sooner as well. 👍🏻

[@noidea4name1226]

Ive been following your build for awhile and will be setting up my own 4 link with a 9 inch within the next month, this channel's videos are always informative and I really appreciate the work you guys put into them. Thanks for the great and helpful content

[@MuddyBeards4X4]

Good luck with the build, glad i have been able to help

[@ssravernal4185]

My understanding of 4 link is sketchy at best, but you have helped me a bunch. now maybe I can figure mine out. Thank you.

[@MuddyBeards4X4]

Awesome, glad i could help

[@chuckkrumm6291]

Great video. Been building off road vehicles for 12 years. Can't believe the builders/people that don't use this spreadsheet.

[@MuddyBeards4X4]

Thanks man, it can be confusing and overwhelming to get started using it. Wish I used it sooner!

[@kshepthedrummer]

This is a huge help! Im about to tear everything out of my Jeep and build from scratch. so this will help a bunch with me setting it all up correctly. Thanks!

[@MuddyBeards4X4]

Hope it helps out on the build 👊🏻

[@rickmarquart3277]

Thanks Kelly, very helpful. Trying to wrap my brain around this. 👍🏻🇺🇸🇺🇸🇺🇸

[@jamesmoore8271]

Ive been trying to wrap my brain around link geometry for a long while now but this video really helped me understand .

[@MuddyBeards4X4]

Glad I could help🤟🏻

[@kyferez1]

THANK YOU VERY MUCH! I was so confused with where to start with that calculator!

[@MuddyBeards4X4]

Glad I could help👊🏻

[@kyferez1]

@@MuddyBeards4X4 I've since added a bit to the calculator, specifically around Link lengths and angles, coilovers, and notes to help explain things if you are interested in that.

[@Babarudra]

for the clearance issue on the lower links, you could go longer and tuck the brackets up higher. But with length, be sure to add some beef to them. The problem with suspension is you're always trading one issue for another. Especially on shorter wheelbase. Good video.

[@fishing_with_ryan2416]

Great video!

[@SWBCrawler]

Thank you for the tour of this tool! I was already aware of it, but man, so many numbers! It's been on my list of things to figure out, and THIS REALLY HELPED! Thanks!

[@MuddyBeards4X4]

Glad i was able to help even a little 🤟🏻

[@scottadvevture2022]

thank you for your time on explaining the in and out i too am setting up a 4 link and this help out

[@MuddyBeards4X4]

👍🏻

[@dolarmangr]

Thanks for explaining the 4 link program....that will help us a lot 👍

[@MuddyBeards4X4]

👊🏻 glad I could help

[@genoory5090]

I plan on doing something like this to my 2011 ford ranger by deleting the leaf springs, and add coil springs and links

[@environmenteller4442]

Nice got my front 44 in now gonna do the rear 4link 97 zj 6 inch lift 37s hybrid caged

[@martynewkirk8315]

Camshaft is center of motor 👍

[@scousetruth7298]

Thank you so much been looking for a vid like this for ages

[@MuddyBeards4X4]

Glad it helped 👍🏻

[@maxwellcard]

Awesome walkthrough Kelly, extremely helpful thank you!

[@MuddyBeards4X4]

Glad I could help👊🏻

[@joesears773]

Thanks for the video!!! Now I am going to go measure mine to see what I have!!

[@MuddyBeards4X4]

👊🏻

[@adamjohnston376]

Awesome information! Thank you!

[@SouthernEngineering]

Your tutorial is beneficial; thanks for sharing. I've been planning a YJ resto-mod for some years, been thinking about what to use instead of the leaf springs; since the doc retired me last Fall, it looks like I'll be getting in the shop soon; it may be a slow build, but one I will definitely do.

[@noahbartholomew932]

Lol 4 link calculator I just used a tape and a level seemed to work pretty dang good too 😂😂

[@johncranfordpersonal4146]

Extremely helpful, Thanks!

[@MuddyBeards4X4]

👊🏻

[@jean-philippebonneau6582]

Nice video man !!! simple, with visual exemple . the best easy way i found to learn fast how to use calculator and how to take mesure for calculator !!! i recommand, .. (sorry bad english, i'm canadien french gys) samurai strecht 98'' wheelbase 4link/3link suzuki j18 twin t case toyota axle (v6 welded) cromoly on irok 36. home made build, low cost

[@MuddyBeards4X4]

Thanks 👍🏻

[@jonathansullivan2424]

The four link calculator has confused me for years. I finally figured it out after watching this video. I have always built a 4 link using the three L's (Long, Low and Level). It works but I can see how the calculator can really help fine tune the performance. Could you please do a follow up video to let us know how you like the changes. I think it would be very helpful to know if how your changes actually changed the performance of the jeep. Mine is coming apart for a 4 link this week so the sooner the better.

[@MuddyBeards4X4]

I will, once I get some seat time with the new setup. But it is wet and cold here, no rock crawling going until it dries up. But I will be doing some trips here soon where I will be testing it out.

[@jonathansullivan2424]

@@MuddyBeards4X4 I finished building my TJ rear suspension back in The spring based on your your thoughts and Jake Burkeys videos. I finally got to really put it through the some serious trails last week and it performed flawlessly. My final numbers were 90% anti-squat, roll center at 26 in, -1 degree roll axis, with 100 inch wheelbase, and 37 inch treps. I’m still looking forward to your follow up video.

[@user-tk4fc5jw1t]

Man, giant thx you, for great explanation ! 🤝🏻

[@johnterpack3940]

The rolling radius is simple to measure. It's just the distance from the axle centerline to the ground.

[@kyridgejumper]

Very good job explaining this Great video man Love the tech

[@MuddyBeards4X4]

Thanks👊🏻

[@1187830]

Thank you!

[@DonziGT230]

I'd love to know what happens to your numbers with a corrected rolling radius. I believe the rolling radius in this application would simply be the measurement from the center of the axle to the ground. That would be the static rolling radius and since you're concentrating on low speed use it would be pretty accurate. Realistically, it'll be lower when climbing (more tire squish) but still closer than just using half the tire diameter. The dynamic rolling radius is the hard one to figure out, that's the radius at speed where the tire effectively grows. Since your actual radius will be much lower than what you put into the calculator it seems like it would make a pretty big change on the outcome, but I've never played with the calculator so I don't know.

[@seanday6127]

Pretty sure you got the tire size and rolling radius backwards. Pretty sure the tire diameter should be horizontal diameter of your tire (i.e. normal diameter) and the rolling radius would be your center axle to road height with the tire at your lower pressure. If you changes those inputs, you'll see your wheels become non circle like they actually are.

[@malibu294]

Awesome video dude

[@MuddyBeards4X4]

Thanks!

[@ConcreteSlabJackers]

Great Video.. I enjoy your channel for sure, I am also not an expert. I noticed your static numbers and travel are the same. if you go to the travel tab at bottom there is a field to enter travel increments and travel amount you have in inches... that dramatically changes the anti squat and roll axis numbers at bump. it will also calculate pinion angle change. I made it 1 inch increments for a total of 5 inches. it made your anti squat 45% and roll axis -9 degrees & pinion angle change 3.7 degrees. then i went back in and put your ORIGINAL NUMBERS in, shockingly at bump you had anti squat 102% and roll axis -2.7 degrees pinion angle change 5.6 degrees, again based on only 5 inch of travel. please give feedback after your next outing for handling.... my guess is somewhere between static and bump is where you actually are running on trails, if the true optimum target is 100% anti squat and 0 degrees roll axis. Should you set it up for average of static to bump.???

[@MuddyBeards4X4]

Hm... I definitely will have to look into this. Thanks for the info.

[@kushtrimhyseni8030]

great work man, cheers.

[@MuddyBeards4X4]

👊🏻Thanks

[@thumpstar12502]

This is awesome .!!! Thanks

[@UncleRayRayGarageEmporium]

Thanks a ton!

[@MuddyBeards4X4]

👍🏻

[@FabbinAdventures]

Hey man, thanks for making this video, it really helped me understand where to get my measurements from. I have a 1972 FJ40 project that im putting 1 tons under and going to 4 link and coilovers for the rear and 3 link and coil overs for the front! I will be videoing it for my you tube channel and would like to link your video if you dont mind. You do a great job explaining it, better than i could. Any ways, ive been watching your channel and Dirt lifestyles for a while and have watched this video a couple times already, keep up the good work!

[@MuddyBeards4X4]

Awesome man, thanks. Good luck with the project🤟🏻

[@FabbinAdventures]

@@MuddyBeards4X4 thanks man, hoping to get this FJ up and running for the fall, alot of work ahead of me with this frame off rebuild!

[@StormbornJKU]

I’m by no means an expert on this at all. But have you thought about stretching that wheelbase another 2” to get an even 100”, and then lengthening your links another 2” as well? Keep the mounting locations the same, just lengthen everything, and then mess round with the calculator? I’d imagine it’ll change the numbers slightly because of the different angles things will be sitting at just because it’s stretched a bit more.

[@MuddyBeards4X4]

I would love to stretch the Jeep even more. Right now the rear axle is stretched as far as it can with my genright stretch tank. If I went with a fuel cell I definitely could move it back more.

[@danielmagalhaes5739]

this is an interesting theme!!! but instead of low the lower link, why you don´t try to open or close more the upper links? or better, why you don´t try and do a double triangulated setup?

[@raywarner4704]

An anti rock in the rear would help stabilize your rig.

[@ninja63639]

This is definitely the best video I found explaining the 4 link calculator. Let me ask you this though... How do you calculate all this before your suspension is installed? For instance I want to 4 link my '49 Ford coupe and my YJ. Obviously I don't want to weld all the brackets in, take measurements and have to modify everything. I can't think of a solid way to hold all the brackets in place without being welded though, unless I tack them in, but then that's pain in the ass. Is that the only way to make it happen?

[@user-ws8ek5zm8f]

Спасибо! Отличное видео! Вопрос: стоит ли делать такую подвеску для микроавтобуса если не требуется огромных ходов подвески?

[@Mekhanic1]

Maybe I'm missing something or this is different but anti-squat higher numbers mean more lift under throttle. My background is drag racing however. Lowering the bottom arm always made the car bite harder off the line.

[@adamfowles1060]

Maybe a dumb question but is it possible to change your center of gravity? Thank you

[@Fix_It_Again_Tony]

It's best to think of the vehicle as three separate parts. The body and chassis and every thing attached (engine, trans, seat, dash, etc.) is one. The front axle with wheels and tires and the rear axle with wheels and tires are the two others. Each of these parts has it's own center of gravity and the three combine to result in the vehicle's overall center of gravity. The axles are know as "unsprung" mass and the chassis and body are the "sprung" mass. The springs carry the weight of the sprung mass. The sprung mass CoG is most important for understanding how the forces developed in the suspension links will act on the body and chassis. It is used to find vehicle anti-dive and anti-squat numbers. The calculator uses the complete vehicle CoG and then calculates the sprung CoG using the tire rolling radius, the front and rear unsprung mass and the mass of the complete vehicle. Easiest way to lower the center of gravity of the sprung mass is to reduce lift. Obviously you need to fit tires and have enough clearance of navigate obstacles, but lower is better for stability. The next way to lower the center of gravity of the sprung mass is to lower the heavy parts that make up the body and chassis. The heaviest is the drive train, but that might not be practical. A certain clearance needs to be maintained between the engine and front axle, and the angles of the drive shafts are critical for vibration and u-joint life. Next would be to take anything mounted high and mount it lower. Like a rooftop tent. Or if you have a roof top cargo rack with a 100+ lbs tire and wheel on it you can mount the tire and wheel somewhere lower on the vehicle. Aside from the lift, it's not easy to lower the sprung CoG unless you can move some heavy parts (like the tire and wheel example) lower, but even then moving a 100 lb tire is going to have a limited effect on a 3200 lb. body and chassis (4700 - 800 - 700). The best way to keep your sprung CoG low is to only run as much lift as absolutely necessary. If you have a high CoG things you can do to add stability to your vehicle would be to stretch the front and rear axles so they are farther apart. This will help with climbing and descending obstacles. Wider axles will help with off camber stability. This is why you see guys with short wheelbase jeeps and big tires talk about axle stretch. One ton axles also help where because they are wider. In summary, the center of gravity that is important is that of the body and chassis (sprung mass). This CoG is a result of where all the weight is mounted. Lowering any individual item mounted to the body and chassis will lower the overall body and chassis CoG. The most straight forward way to adjust the sprung CoG is with lift.

[@adamfowles1060]

@@Fix_It_Again_Tony thank you for taking the time to explain. Much appreciated.

[@cjwhite8109]

Funny rocks!

[@steelrides4462]

How did this turn out for you? Did it help with the body roll and tippiness?

[@heberrodrigues3903]

hi , nice video 💪💪 can you give the feeling after the new setup ?

[@miloganze3469]

that is all great info if you have a 4 link to start with BUT what if you are converting from leaf spring to 4 link and trying to get these numbers?

[@Little.R]

completely unrelated but I want to know about that Yellow TJ in the Outro...

[@MuddyBeards4X4]

@rubberduckytj on Instagram

[@xristoskaraolis4851]

very useful video, it will help a lot, I have a set of unimog axole 406, the program can give me accurate measurements, or because of the portal this will not be possible ?

[@rifleman7313]

I have been heavily contemplating about building a complete tube chassis for a 4x4 daily driver vehicle. Do you think that using one of these calculators would help me with the various tube lengths before I even start buying and cutting the tubes? I basically already know what axles, engine, transmission, tire size that I would like to use. Thanks

[@eldiablobiker]

I’m am trying to understand the tire diameter measurement. Nate @dirtlifestyles explained in his suspension video he has 40’s so went with 10” link separation. You have 40’s and went with tire diameter at 8 psi, 37.5” or 9.37” of link separation. Not sure if this makes a difference?

[@MuddyBeards4X4]

A 40” tire doesn’t actually measure 40”. so it would be more accurate to measure the actual tire size not just assume it measures 40”. 10” and 9.37” is so close it won’t make a difference anyways so either way will work it’s fine.👍🏻

[@dhrracer]

Maybe it has been answered but did you get the results you wanted on the trail? Is there a follow up some where?

[@MuddyBeards4X4]

I just got back from Moab and between this and removing my spare tire from the back, it made a big difference. I do plan on lowering the Jeep a little so I can move the frame side mount back to the original position.

[@wingcmdr90]

So you've set it up for the trail (trail tire pressure), how does it perform on the road? My trail rig is also my daily and I'm wanting to 4 link solid axle swap dana 60s into it

[@ShoddyRC]

Could you explain why you want anti squat below 100 percent? Is that always better for rock crawling?

[@purextacy3174]

The question I have is If I do a ford ranger then my buddy wants to do the same kind of truck would it be set up the same way?

[@MuddyBeards4X4]

All the same concepts 👍🏻

[@trevoratkins4639]

Where did you get your link mounts that’s welded to the frame

[@MuddyBeards4X4]

Barnes4wd, the link is in the description. It will automatically get you 10% off too.

[@jaredwhite4996]

What size coilovers do you have in the back for travel? 14" or 16

[@MuddyBeards4X4]

They are 14”

[@MrPasha-kq4tc]

I am not able to download the calculation sheet, can anyone please help me

[@rrebaza]

This calculations apply for a Trailer?

[@nickk4296]

How did you calculate your center of gravity

[@MuddyBeards4X4]

I used the centerline of my engine crankshaft. So just from the ground to the middle of the crank pulley on the front of the motor.

[@nickk4296]

@@MuddyBeards4X4 so you don't know for sure you are just guessing? I would of thought it would be higher then that. I think Nate said he used to top bolt on the bell housing. I wonder if there is a way to actually calculate this

[@MuddyBeards4X4]

There is a way, but it is very complicated. The article I used in “crawlepedia” the link is in the description, used the crank shaft as center of gravity. I have read of using the top bolt of the bell housing as well.

[@chadstevens8086]

Best video on this I’ve seen yet.

[@MuddyBeards4X4]

Thanks 🤟🏻

[@rileyletik9710]

I can’t seem to find that exact calculator could you post the link

[@MuddyBeards4X4]

Just google 4 link calculator, it should be the first one, crawlapedia.