Building a 4-Link Suspension to Conquer the Trails - Carcass S2, E6

hey guys thanks for watching our shows we're getting so close to a million subscribers and we'd love if you guys could help us out by hitting the subscribe button the like button and sharing the video too and be sure to follow us on instagram where you can stay up to date on all contests and giveaways and now stay tuned for carcass today on carcass rain sleet or snow project junk mail gets major suspension upgrades taking our jeep from a mail delivery vehicle to an off-road machine that can handle all the elements we'll show you how to set up a race inspired 4-link system that will conquer the trails and rocks [Applause] hey guys welcome to carcass now our 1978 jeep dj-5 that we're calling project junk mail looks a whole lot different than the day that we picked it up that's right we got the cab off the chassis stripped all the old suspension brackets off and we even went to a junkyard got a set of axles and got them all the way down to the housings now we slid our axles underneath our chassis to give us an initial look at what we're dealing with and we're going to be prepping for our four link suspension but we're going to add a set of axle trusses to give us a good foundation for that suspension so we got to slide these babies out set them on a set of axle stands and start [Music] prepping to clean up our axles we're using some wire wheels we just want to knock off the rust and grime to give our trusses a good clean surface to weld to with our axles all cleaned up we're going to be adding a set of artec industry axle trusses that we picked up from summitracing.com we're going to be doing this for two reasons one it's just going to help strengthen our axle and the second more important reason is it's going to give us a great mounting point for our upper arms and for our shocks so what we're going to do is just tack this into place then we'll set our axles back underneath the chassis keep rolling on our suspension [Music] [Music] all right that looks pretty good get her back under the chassis got it yeah got a little heavier that's for sure we now have trusses tacked to both axle housings but there's one thing we need to do before we start designing our suspension and that's deciding where the axles are going to land and in the rear it's not too critical but we do know we're going to extend the wheelbase a little bit for stability but on the front end it is critical because the position of our front axle solely depends on the position of our steering gearbox because we don't want our steering to bind under heavy articulation so the next step is to mount the gearbox on the passenger side [Music] we mounted our new gearbox using an existing hole from the original box now this is just for mock-up we're not sure if we're going to have to move the gearbox towards the back or toward the front of the jeep but this is just a good starting point now with our axle and our chassis set at right height i'm going to use a plumb bob and drop it down the center of our pitman arm and then we're going to mock up some steering and that should help us find the final resting position of our front axle [Music] well now that we have the steering mocked up on our front axle we now know that the stock location we chose for the gearbox should work out just fine what we also noticed is that the axle is now about three inches further forward than the stock location which extends our wheelbase and having a longer wheelbase well that always just helps out on the trail now this is the position of our front axle figuring out where our rear axle is going to sit well that's just a whole lot easier now the look that we're going for in the rear is pretty simple we want the tire to stick out of the back of the jeep just a little bit since we're running 37 inch tall tires all we did is measure in from the back of the chassis about 18 inches and we set our axle right here now that's eight inches further back than the factory location further extending our wheelbase now we're running a triangulated four link suspension and that is exactly what it sounds like we're going to be running a set of upper links and a set of lower links from the axle up to the chassis now what that's going to do is going to help center our axle from left to right it's going to give us some adjustability and it's going to give us better articulation when we're out on the trails now we gotta figure out where we're gonna mount all of this stuff and there's a couple of things that we need to know but let me show you what we're talking about what we're trying to do with our suspension is land on a value that value is called our anti-squat number to figure out our anti-squat we need to project some lines on our chassis the first line will be the center of gravity and for us that's basically the center of the camshaft which is about nine inches above our motor mounts the next vertical lines will be the center of our front and our rear tire also known as the contact patch the third line will be our anti-squat line which is run from the contact patch of the rear tire to where the center of gravity and the center of the front tire meet where those lines meet will help us choose where we put our mounts for our upper and our lower links the position of those bars will create a point that's called an instant center and where that point lands in relationship to our anti-squat line we'll determine how our suspension will handle as you change the position of your mounts that will change where the instant center will land and that will determine how your suspension reacts and knowing these parameters will help you guys figure out where to put the mounts for your suspension and for us and project junk mail it's going to be an all-around off-road rig it may see some rocks it may see some mud but it's going to see a lot of trail riding so we're going to try to land as close as we can to that 100 anti-squat line but if we're above or below it by 20 percent we'll be just fine now the next step for us is to just start laying out some lines we have a plan we'll show you how to build a heavy duty four-link suspension that can handle anything the trail has to offer now that we have the links mocked up on our suspension we can project the lines out to find our instant center and see how close we are to that 100 anti-squat line that we've been shooting for now to mount our suspension it's going to be pretty simple here on the rear axle we're just going to use a couple tabs but on the frame side we're going to have to build some mounts so we went ahead and used a piece of cardboard to help show where we're going to mount our lower links and for our upper links they're going to be pretty basic we're just going to weld a tab to the inside of the chassis here but this is just half of our suspension we're also going to need to build the links that connect the axle to the frame and now that we know where those mounts are we can actually start cutting some tubing and building our suspension [Music] for our links we're going to use two inch by quarter inch wall dom that we had laying around the shop it's super strong and should be able to take plenty of abuse we'll cut our lowers to 43 inches and our uppers to 38. this will give us a little wiggle room when we do our final mock-up now that i got some links cut out it's time to start assembly we're going to be using inch and a quarter by one inch rod ends now we're using these because of their strength and their flexibility these also come with some threaded tube inserts now there's a left and a right hand side to these inserts and we're going to be using both that way if we need to adjust our suspension when we're underneath the jeep all we got to do is give the tube a little twist and then we'll just lock down our jam nut but to get this whole party started i gotta tack in some of these inserts [Music] when welding these up you don't want to bottom out your tube insert you'll want to leave a little space to give you a nice channel to weld to [Applause] [Music] with our tube inserts tacked in we can install our rod ends now to go along with our rod ends we're going to be running some high misalignment spacers what these do is extend the radius of the ball and they give us more flex and articulation out of our joint they also add a little bit of width and they step the inside bore from one inch down to three quarters of an inch now with all this mocked up we can take our tubes over to our jeep keep rolling on our suspension all right let's see how this fits on the [Music] axle all right that'll work right there let's get a couple tacks on it to hold it in [Music] you got one corner done yeah the brackets you made down here on the axle are perfect but i'm going to need you to do one more thing and that's make this big guy oh see this is why i love cnc plasma tables right you can use a new table and uh i'll go ahead and get started on the other set perfect coming up we design and build some custom mounting brackets for junk mail's off-road suspension jeremy and i have made some pretty good progress on our full-length suspension system for our jeep but we're at the point now when we need some brackets to finish it out he gave me this template but there's a few more things i need to do before we can cut it out on our cnc plasma table i'm actually going to take a few measurements and transfer this into our 3d cad program and then we can start cutting some metal [Music] [Music] everything looks pretty good so all we have to do is transfer it to a usb drive and take it over to our plasma table to cut out our brackets we'll be using our cnc plasma table from premier plasma in a fab shop like ours it's the ultimate time saver this table can handle a 4x4 sheet of steel or any other metal which gives the potential to mass-produce small brackets or build something bigger like the back half of a chassis this table is built with heavy duty components to give smooth motion and ensure accurate cuts another optional feature is the torch height controller or thc by nature metal sheets are usually boater wavy the thc keeps the torch at the optimal height to improve accuracy premier plasma can accommodate any shop they offer tables from 2x2 all the way to 5x10 and even have router attachments available for those who work with metal and wood and it's all made here in the usa with the outside brackets done now i adjusted the original template to accommodate the bracket that goes on the inside of the chassis rail so i have that and a few more pieces to cut out and then our suspension mounts are done [Music] for our brackets we're using 3 16 hot rolled pickled and oiled steel the pickled and oiled version is better than normal hot rolled steel because it doesn't have the mill scale on it and the 3 16 material is going to be plenty strong for our suspension [Music] [Applause] i got a puzzle for you whoa those look just like the brackets on the axle yeah so like the trusses uh in the big pieces there's slots and then the internal pieces have a tab on them so that it goes into the slot and it's going to make it a little bit easier to line up and it's going to give it some internal support yeah i think this is going to be a whole lot easier to do this on a bench versus the chassis yeah i'm going to work on the inner upper mounts too all right i'm going to go put these together [Music] just like the axle trusses there's a few pieces we need to put together to make these brackets first i'll start assembly then i'll add a couple attacks and it's back over to the chassis for a test fit before attaching our mounts we'll grind away some of the rust on our chassis giving us a good surface to weld to now we can clamp in our mount and tack it in wow that landed on my leg because the width of our heim joints the inside of our four-link bracket extends past the chassis just a little bit so we designed this top plate to help strengthen the mount now when i put the two pieces together it doesn't leave me much of a surface area to weld to so what we're going to do is grab a grinder and bevel the outside edges of both plates creating kind of a trough now what that's going to do is give us better penetration and a stronger weld nothing too drastic just enough to give us good penetration for when we go back to finish weld it later with our lower mount tacked in we can move on to the upper mount that jimmy knocked out on the plasma table then from here we can cut the bars to length and finish up our rear suspension [Music] with our mounts in place we can measure our links [Music] cut them to length [Music] weld in our heims and bolt them up with our links installed that wraps up the bulk of our rear suspension and it's time to transition to the front and that's pretty much rinse and repeat with the exception of one thing and that one thing is a clearance issue i've already designed and tacked in the upper mount on the axle and pretty much wherever we put the other mounts on the chassis the four link bars are going to hit this crossmember but we do have a solution we're gonna end up getting rid of this cross member completely and we'll build two separate engine mounts and just weld those directly to the chassis now we're not too concerned about losing the support of this cross member because when we put the bumper on the front of the jeep we're just going to weld it to the frame anyways so the first thing we got to do is get that crossmember out of the way so we can keep rolling on our suspension [Music] just like the rear we'll clean up our chassis and weld in all our brackets once in place we can measure for our link bars and cut them out twenty [Music] then we'll tack in our rod ends and set them in place dude this thing's looking so trick and i am so glad that we got that plasma table yeah everything turned out pretty good all we got left now are the shocks [Music] junk mail gets a coil-over suspension that will help us crush any terrain when it comes time to picking out the shocks and struts for your next project you need to remember that they are key to ride quality and the foundation of your suspension system well summit racing has a wide variety of shocks and struts to choose from so let's take a look at a couple options a gas adjust shock has performance advantages over a traditional twin tube design like an increase in steering response and stability the monotube design responds instantly to driver's inputs and delivers an increase in handling an on the car adjustable shock makes it easy for you to dial in your desired level of comfort and performance quick bolt-in installation can be done in minutes and it's designed to be used with your stock style springs an integrated air spring and shock absorber system like this one replaces your car or trucks metal springs with a pressure adjustable air bag and these are great because you can adjust them from inside your vehicle a direct replacement coil over shock gives you the ability to adjust and re-valve to fit your needs they allow you to tune them to different driving styles plus their direct bolt in for a lot of vehicles making them a popular swap and lastly the universal coilover shock is designed to be used with dual rate springs they come in a wide range of travel lengths making them perfect for custom suspension setups and for us in our four link jeep these things are going to work perfectly with the suspension linkage all done it's time to move on to that last piece and to get the shocks installed it's going to be pretty basic what we're going to do is weld some tabs onto the axle and then we're going to build some shock hoops and weld those directly to the chassis but we're not going to use the shocks to do any of the mock-up and the reason for that is because the chassis is already at ride height so with the shocks fully extended they're not going to work for mock-up so instead we have this tube that mimics the length of the shock at ride height that way we can accurately place the tabs and the shock coup and to get all this started first we got to take a couple measurements to put on the tabs these measurements aren't too critical we just want the bracket inboard enough to clear our brake components and outboard far enough so that the shock body clears the chassis then we'll tack in our tabs [Music] now that we have the tabs on our axle it's time to figure out the hoop section and basically what we're going to do is we're going to take a tube and bend it 180 degrees and weld it to the chassis but we have to figure out what length of tube to cut so if i stand up this tube that represents our shock it stands up about a foot off the chassis and a little bit shorter on this side but it's best to have some excess and we know from experience using our bender the 180 degree section is going to take up about 18 inches of tube 18 plus 24 is 42 and that's the length we need to cut [Music] for our shock hoop we'll be using some 120 wall dom [Music] [Music] with our shock hoop bent up now the first noticeable thing is that our simulated shock does not fall in the center of it but the idea here is the shock hoop is going to fall on the box section of the chassis to maintain strength so the compromise is to lean the shock over a little bit and let the tabs fall right in the center but before we get to the tabs we gotta tack this thing in [Music] we'll give the chassis a quick grind before installing our hoop go ahead we'll make sure this thing is square and drop in a couple tacks [Music] then we'll head back over to our plasma table and cut out a few tabs to mount our shocks [Music] you know that plasma table came in pretty handy building all these brackets it's a great machine the suspension is all tacked in underneath our jeep and from what we can see everything should work out pretty good still got a couple things we got to do we got to tie the shock hoops in front and rear but we're going to do that after the body's on it so all we really have to do now is build up the axles put the drivetrain in the chassis and put the body on it so we can really see how this thing sits i think we'll save that for next time if you guys like anything you've seen on the show today why don't you check out powernationtv.com and uh we'll see you next time can't wait to get this thing on the trails it's going to be a good time yeah it's going to be awesome

Channel: POWERNATION

Views: 711,227

Keywords: Car, PowerNation, howto, how-to, diy, automotive, cars, trucks, automobile, do it yourself, automobiles, auto, powerblock, carcass, mail truck, suspension, postal truck, 4-link suspension, 4 link suspension setup

Id: eLlWRIHF3hI

Length: 21min 48sec (1308 seconds)

Published: Sun Mar 21 2021