4 link brackets 101

hey guys this is brad with 10 soldier race cars we get a lot of questions uh every day about our four link brackets and what the difference is between them and so i'm just going to go over some of the basics of a four link some of the terminology and then i'm going to go over our different styles of four link brackets and which one would be right for you [Music] uh starting off how to measure a four link and some of the terminology basically like a four link 101 you always hear people talking about instant center and anti-squat so what these two things are is your instant center is basically if you drew an imaginary line from this four length bar continuing on out and from this four link bar continuing on on out where they intersect is your instant center the way that i like to think about an instant center is a ladder bar so everybody's seen an old school lighter bar we dug this one out back from outback off of old rear end housing it's all crusty rusty old technology but lighter bars work i mean there's people that still run them they do their job but uh this is basically a great representation of if you drew your four link bars and you tied them together in the front this is your instant center so on a on a lighter bar car your instant center length is fixed instant center length is always measured from the center of the axle tube to your imaginary point where your two bars connect together so on a ladder bar your bars are physically connected together in the front so if you have a say 28 inch or 30 inch lighter bar well your instant center is always roughly 30 inches so you can move your instant center up and down but you can never make it longer or shorter so this is one of the disadvantages of a lighter bar is that you just don't have as much adjustability you can't adjust the bars one from another so they work but they're just you know old-school technology um but this same thing here so if you imagine these two guys connecting you together just like the lighter bar where they intersect that's our instant center like i said length is from the center line of the axle tube and height is distance off the ground and that's what the car's sitting at ride height so obviously these brackets would be a little bit up in the air if you were measuring it so that gives you your instant center length and height so the other thing uh that you always hear everybody talk about is anti-squat so what anti-squat is is basically uh the resistance to the car to squat and how we measure that is the neutral line or the anti-squat line um they're the same thing is basically a line basically from the bottom of your back tire to the top of your front tire roughly it has to do with the center of gravity and stuff so it's not exactly that but that'll give you a good idea of where the neutral line or the anti-squat line on your car is the bottom of the back tire to the top of the front tire and there's a line that runs through imaginary through the car so if your instant center falls below the anti-squat line then you will have less than 100 percent anti-squat and the car will squat on launch if your instant center is above the neutral or the anti-squat line then you will have over a hundred percent anti-squat which will make the car separate on the launch so typically any small tire car that we set up we want it to separate and you know to plant the tire on the hit and then it'll separate as the power comes in so basically when we're setting up a small tire car um we're typically a little bit looking for an instant center of 30 to 40 inches long it'll normally end up somewhere in the ballpark of seven to ten inches high depending on ride height tire size and then we want our anti-squat over a hundred percent so that the car separates and plants the tire um so you know obviously a hundred and one percent anti-squat isn't going to separate very much 200 anti-squat is going to separate a ton so um that has a lot to do your your anti-squat number has a lot to do with how the car is going to react at the release of the trans brake button on the launch so when you're measuring for your instant center there's a couple different ways that you can do this when you're measuring it obviously you want the car at ride height it's easier to get it up on blocks or uh something so that you can get underneath the car and take some measurements off the ground a four-pitch lift is amazing if you have access to one but for people that don't if you can get the the car up on blocks or something you want the car sitting at ride height but get it up in the air where you can roll underneath of it and take some measurements you're basically going to be measuring from the ground up to the center of the bolt on all your points and then from the center of the axle tube forward to your points and then if you want to be really cheap and easy about it you can actually lay this out and i'm going to pick on martin conley i've actually seen him do it on poster board or cardboard like let draw it out on the on the shop floor and connect your imaginary dots with a straight edge and you can actually plot out your instant center right there with a ruler and some paper or cardboard but there's also a lot of great tools online there's some free four-link calculators that can help you plot all this out and you punch in your dimensions up off the ground and forward from actual center line and it'll tell you what your instant center length height and your anti-squat are i think the baseline suspension one is free and it'll get you in the ballpark obviously you get what you pay for so the like the more expensive ones uh you know are going to have more features um mccamus and performance trends and a couple uh different ones that i've used work really well um the performance trans one is probably my favorite uh one of the things that it does is it actually um you can actually uh plug in your four link your instant center and everything it'll give you your instant center but then you can also do dynamic changes and you can actually see how uh the instance center changes as the car separates or squats and vice versa and that's where things drastically drastically change you can have a traditional four-link car or you could have a mustang with the same instant center length and height and the same anti-squat that's great and all but they are only the same at ride height as soon as that thing separates at all it they change completely different they act completely different and i'm going to show you guys why so this is a traditional four link and the upper and lower bars are the same length this four link right here in this example has 20 inch bars center to center that's pretty common we make a lot of them about this length especially for small tire cars a lot of your higher horsepower cars and your big tire cars especially like your pro mods and stuff might have a 22 to 24 inch length 4 length bar but they're all going to be roughly in that range normally 20 to 24 inches center center on the bar and so this four link right here works really really well for a high horsepower radial tire car like a radio versus the world car pro 275 car ldr car something making really big power is where this four link works really really well you could also use it on a big tire car or a slick slick tire car that's racing on a prep track or even no prep but this four link really really works the best for like a high horsepower radial tire car and the reason that is is that the four link the instant center um right now i have it plotted out at about 30 inches 38 inches long which is pretty normal for a car like this and when this thing separates the instant center will never grow in length because the upper and lower bars are the same length so it's just like the ladder bar i showed you guys earlier the instant center will only move up and down so the instant center is not only where your imaginary pushing on the car forward and the axle is rotating around but the instant center is also where you're pushing up on the car so when this thing separates you're pushing up your point imaginary where you're pushing up on the car is 38 inches forward of the rear axle so that's well behind the center of gravity so what it's going to do is it's just going to keep going up up up up and the anti-squat is going to keep going up and you're just going to pick the back of the car up and that's why you see all these radio versus the world pro 275 cars separating you know five six seven inches and the reason they're doing that is not for traction but it's a hundred percent for anti-power wheelie so they're basically trying to pick the back of the car up to drive the nose of the car down towards the ground to keep it from power wheeling and it works really well so that's where this four link shines really well the downside to this four link if you have a lower horsepower car is that with the four-length bars as long as they are that it's a little lazier on the hit so to compare it to like a mustang a mustang has a really really short upper bar this is actually one of our 9-inch mustang upper control arms you can see the difference and these are a short four-length bar for a four-length you can see how much shorter the mustang upper bar is so this short upper bar is going to cause the the four length to act a lot faster so when you let off the trans brake button a mustang you can watch it it shoots the rear end out you know smashes the tire real hard sticks the tire they work really well at getting off the starting line because they slam the tire into the ground really hard this thing is going to be a lot more mild on the starting line it's going to separate a bunch but it's kind of like a more gradual separation as the power comes in a mustang it fires the rear end out almost all at once and then it's done you know doesn't separate a whole lot it's boom and then just kind of holds it there so completely drastically different between the two so because of that you know like a mustang we found works really really well on low prep no prep mildly prepped tracks and a lot of the reason that is because of the shorter upper bar you know hits the tire really hard on the hit and they separate pretty quickly so because of that we've designed our radial tire four link you can see how it compares so as you can see here our my radial tire 4-link has a much shorter upper bar so it's basically a hybrid between a mustang and a traditional four-link you can actually see you know the difference here this is your mustang bar this is our uneven four-length setup and then this is a traditional four lengths you can see very short medium upper bar really long upper bar so what what our radial tire 4-link does is with that shorter upper bar is it allows you to hit the tire harder on the hit than a traditional 4-link but not as hard as a mustang if you've got a mustang and you're leaving on a lot of power it's really hard to control how hard it hits the tire on the trans brake release so this upper bar is a little bit longer than a mustang so it tames that down just a little bit but then after that um it still separates pretty quickly the other nice thing is because of the shorter upper bar you can get a lot more bar angle um downhill which will shorten your instant center up so the shorter that you make your instant center uh will make the bars act shorter it'll make the car separate faster the shorter the instant center is just like you shorten your lighter bar up the longer you make your instant center the lazier it's going to separate so this is going to speed it up a little bit like i said it's a nice medium between a mustang and a traditional four link and i had designed this originally for a lower horsepower radial tire car or a radial tire car on a mildly prepped track so when i say mildly prep i mean bracket prep to light radial prep something like that a lightly prepped track on a radial that's where this four link really really really shines and that's why mustangs work so well on those type of surfaces is the shorter upper bar allows you to separate uh quickly off the starting line plant the tire and drive so this guy and when i say lower horsepower i mean uh i'm talking like ultra street cars you know 50 000 to 1500 horsepower uh you know cars like that um x275 is kind of those cars are kind of a weird bird because they're kind of stuck in the middle of uh you know they're 2 000 horsepower or so but they're going really really fast so they're on the verge of needing uh to separate the car to combat wheelies um depends you know on the wheelbase of the car and a lot of other things but um an ultra street car is pretty easy to main is to maintain wheelies on just because they're normally 1500 horsepower or less so your your average 1500 horsepower or less car on a radial maybe on a lightly uh prep track is what these were designed for with that being said so we started trying these on a slick on no prep type surfaces and figured out really quickly that these things work really really well and so the slick on no prep that little small 28 10 5 slick it actually likes to be uh separated and stuck down to the track um just because the that little bitty slick doesn't like a ton of wheel speed it's not it's completely different than a big tire it'll take a little bit of wheel speed but you you got to try to keep it stuck for the most part so this shorter upper bar really helps plant the tire especially on the hit and uh work really well uh we've seen you know mustangs have done really really well in the no prep world and a lot of that reason is because of that shorter upper bar all right so i've actually plotted out three different four links i plotted out the traditional four link our uneven radial low prep four link and then i plotted out a mustang all three with the same instant centers and the same ana squat um i set them up at a 38 inch long eight and a half inch high uh instant center with a 128 percent anti squat and i'm going to show you how much different these are when they separate just three inches so when you separate this guy three inches this is my roughly three inch block of wood so as you can see before these two upper bars were on the exact same plane and they had the same instant center so now you can see with both uh the radial low prep four link and the traditional four links separated three inches this is the blocks of water representing the body of the car three inches higher than it was before um the traditional four four-link back here uh still has a 38 inch long instant center but it is now 13 and a half inches high and it went from 128 percent anti-squat to 188 percent anti-squat the low prep radial uneven four link went from 38 inches long to it is now 53 inches long and 18 inches high and has a 178 percent anti-squat so you can see the instant center now at three inches of separation is completely different so if you think of say you have a hundred inch wheelbase car with that's exactly 50 50 front and rear on the scales um that's going to put your center of gravity basically dead center of the car so we're going to call that 50 inches because it's 100 inch wheelbase 50 inches forward to actual center line so now with three inches of separation our low prep brackets the instant center is now 53 inches long and 18 inches high so our instant center now is actually in front of the center of gravity so now it is no longer even though the car is separating it is no longer trying to pick up the back of the car technically it's trying to pick up the front of the car but it's about three inches in front of the center of gravity so it's actually trying to pick up about right in the middle of the car which is really really good for traction because you're not just lifting up the back of the car now you're trying to lift the weight of the entire car and you're using that leverage to plant the tire now if we look at a mustang um if you imagined this little bitty upper bar and we separated three inches it would probably actually be going uphill you can see this one's about flat this one's still going downhill if this was a mustang four link it would probably be going uphill at three inches of separation it might not even get to three inches of separation and i'll tell you why at three inches of separation with this little bitty upper bar the instant center it went from 38 inches long to it is now 255 inches long and 51 inches high so it is way it's a car length in front of the car this the center is way out in front of the car and the anti-squad has dropped all the way to 109 percent so it would actually probably not ever get there the mustang with this instant center and anti-squad in it will probably not even separate three inches it'll probably separate somewhere around two inches and at two inches the instant center is still 90 inches long and 19 inches high with a 115 percent nano squat so even at two inches of separation on the mustang uh upper bar the mustang four link it's still 90 inch long instant center so you can see the traditional four length incident center is 38 inches long at three inches of separation the mustang four link is 255 inches long so they're completely different once the suspension starts moving it's not even close the mustang four link the anti-squad is going down as it separates the traditional four link the anti-squad is going up as it separates so that's why this uneven radial low prep four link works so good is it's a happy medium between the two um to where the instant center starts moving forward and up and so it gets aggressive it keeps one to separate it keeps wanting to plant the tire you're trying to pick up the entire weight of the car planted down on the tire so all of our brackets here that i've shown you guys today are radial low prep brackets and our traditional small tire brackets they both work with the same axle housing brackets they're set up for coil lever brackets back here the coil over goes the shock mount goes right on the back of the four link bracket all of our brackets are available in mild steel and chromoly the housing side brackets are available in three three and a quarter and three and a half inch tubes in mild steel and three and a half inch only in chromoly we also have four link bar kits available in inch and a quarter and inch and a half for higher horsepower cars so we have a lot of options for everybody whether you're putting for mild steel brackets on an 88 housing or you're building a chromoly fab 9 floater there's great solutions for everybody this is for your lower horsepower or a lower prepped track car and then our traditional four link is going to be for your serious high prep high horsepower radial car is really what is geared around you know or if you want to run them on big tires so i hope you guys enjoyed the video um you know giving you the differences between this four link and this four link and a mustang and uh all the different variations what their purpose is for be sure to like share subscribe and we'll see you guys next time

Channel: Tin Soldier Racecars

Views: 63,719

Keywords: Tin Soldier Racecars, TSR, drag racing, 4 link, drag racing and car stuff, drag racing cars, how to, 4 link suspension setup, 4 link suspension

Id: LECIF02_rCk

Length: 23min 44sec (1424 seconds)

Published: Tue Feb 15 2022