4 Link Top Bar Change with Level Lower Bar to stop crushing slicks | Understanding 4 Link suspension

4 Link Top Bar Changes with Level Lower Bar to stop crushing slicks will show you how the top bar can be tuned to stop from killing the sidewall of a big or small tire slick! 4 link tuning is not magic and these principles apply to all 4 links, at a high level. Understanding 4 link suspension is a great tool to have! Remember the anti squat line is a tuning aid and each drag car is unique. Stop crushing your slicks. Your instant center in relation to your car's center of gravity is very important.
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[@btadams123]

earlier videos you said to get rid of squat with slicks and here we are.

[@frankensteincreations4740]

All the difference between weight transfer, and making the rear suspension do all the work… Either the rear separates, smashes the tire into the track. Or let the weight transfer and gain traction the old fashion way! 👍 Awesome presentation of a very basic concept people way over think… Makes it even more clear how simple it actually is… I always tell people trying to tune a chassis, set up a camera! Tells you everything you need to know, frame by frame! 👍

[@Eddie_Bielak]

This deserves more attention this helped me a lot thank you

[@stevelangworthy9553]

That was really cool to see the difference after each adjustment. Thanks!!!

[@andyjones6361]

Kevin Great Video Kevin. You have helped so many racers!! God bless!

[@joebass2458]

Great video with video footage to show the changes thank you Kevin👍👍 keep up the good work!

[@BoWhiteRacing]

Love this please do more Iv learned so much from you. I have a ladder bar s10 and love watching your videos. Thank you.

[@Prismracing]

Thanks for making this vid. Getting folks to understand the essential value of quality shocks is important, and often overlooked. Having a little too much bar, controlled by shocks, allows you to add, or remove bite, and time to return to ride height simply by shock adjustment. So as the track changes, or the use of more , or less power adder changes, you don't have to play on the monkey bars. I made the change to inerters a few years ago, and I'll never go back. Thanks again for taking time to help people figure it out, without the usual bs in suspension vids

[@Brad355]

Great video Kevin, it’s awesome being able to see back-to-back runs with changes. Rarely ever it’s this well documented. Out of plain curiosity, it would be interesting to see the same video with the original IC at 113%, but trying to control the sidewall crush using the wheelie bars. On the first pass, it almost looked like the bars were too high so it just infinitely crushed the sidewall until they finally smacked the ground and unloaded the tire.

[@thebradnoyes]

Man, this video was bad ass and extremely educational. I know you did an IRS video a year or so ago, but could you go over something similar with IRS and double adjustable shock settings. Maybe different spring rates. I may be asking for a lot here but these videos are too good.

[@blackcoffeegarage]

Killer! We're doing a 4-link on our next build, with big tires (probably Hoosiers) swappable for slicks for track day. This may come in handy!!

[@truthboomertruthbomber5125]

The tires are springs but they are undampened. I remember a long time ago reading that a large percentage of an F1 car’s vertical “suspension “ travel was the tire’s sidewall deflection. This was probably the ground effects era -early 80s.

[@Anarchy-Is-Liberty]

Yes, that is cool!! Thanks Kevin, great video!! You're a great teacher, we need more people like you in the World!!

[@xaviersimmons1843]

Houston TX babe i love it great video

[@Azzy1016]

Loved the great content on progressively moving the top bar till it look good on track. Curious what the out come would have been moving top bar up again. Is that the wheelie zone?

[@jakefriesenjake]

Thanks a bunch Kevin! I'm converting my ladder bar, lowered 81 Camaro with 500 ponies and a stick shift tranny into a 4 link setup for better street-ability. This car won't be raced or auto-crossed at all, I just want it to drive nice, hook up the best it can with probably 100% anti-squat, with wide street tires. I'm designing the brackets and bars that will be installed. Question, some sites state for best street manners, you want a level to the road bottom bar, and a equal length, and parallel top bar. I will be adding a super beefy diagonal link. What are some do's and don'ts, for a street setup? I'm leaning towards a bottom bar that is as long and low as possible, with it angled up toward the front chassis mount probably 1", and having a top bar that is level with the ground and around 75% the length of the bottom bar. I seen a post where it said that you want to rear axle centerline to track perfectly vertical. What do you think?

[@sgvette707]

WHT was the front and rear spread in inches? 7 and 12 are standard and you started well below that in the front. That car will be faster with double adjustable shocks and the that rear bounce and wheelie bar bounce should leave when you keep the slicks planted. That was very informative and keep it up

[@shawnwieser7101]

Well done Kevin :)

[@bertmorlas3534]

Such a good video really hope Z knows how appreciated it is

[@williamchristine1384]

that was a great video i just wish you would of showed the 60ft time improvement you said the ending 60 was a 1.22 but not first and second thanks for the videos

[@henglish3398]

The first and second videos were like 3 seconds. He probably threw the ticket out the window

[@glenbrannon7224]

Awesome, thanks for sharing this with us!

[@earache_srt8790]

Great video. This clearly demonstrates how the science works . Demonstrating how the front and rear suspension have too work together. IMO

[@keithstarner]

Great presentation! I was wondering how much air pressure were you set at?

[@jasonstormoen]

Nice work! You are looking a lot healthier too.

[@KevinWilsonSBC]

Thank you! Go fast, go straight! Be SAFE!

[@deondimicks8159]

Your content is the best kevin keep up the good work... by the way it looks like you lost alot of woeght keep up the good work

[@LeonardGrawburg-qd1vn]

Can you share the 60ft times for each of the bar settings. Great video

[@koutros100]

Love your work brother Great info and vids to show real life reactions

[@stuartgriffin5.7]

Knew the car looked familiar. Kevin I've got a good video from it making a pass at Houston Raceway Park in late January at a track rental if he or you want it. (That's my truck at the 9:10 mark)

[@KevinWilsonSBC]

Would love to see the video! Go fast, go straight! Be SAFE!

[@stuartgriffin5.7]

​@@KevinWilsonSBCsent it in an email 👍

[@scottschwer5654]

Thank you so much for sharing your knowledge

[@Nobody-ld7mk]

A little more info as to Spring Rate would be helpful, any standard information on spring rates vs. weight? How much energy do you typically want a spring to absorb? Looks like the car could use a stiffer spring to slow downward travel.

[@KevinWilsonSBC]

Good feedback! I will update the description by COB tomorrow, 3/13. Go fast, go straight! Be SAFE!

[@Gregorybridgewater]

Thanks Kevin! Great video, always learning!

[@TheMoody876]

Great video. I'm having issues with my turbo s10 suspension im at the point I think I need to increase the bar angle on my caltracs

[@davidreed6070]

I listened and learned. Thank you

[@robblowe8525]

Congratulations on the weight loss your starting to look like a football coach good job

[@lazyhoundracing9621]

Thanks Kevin

[@stevenrumsey2534]

Would lowering the top bar on the rear end bracket done the same thing when your that far off to start with cool video thanks for the info

[@henglish3398]

I’m wondering the same thing plus even with the same IC, higher bar angles would hit the tire harder correct? So it seems like that could make the issue even worse than what it would necessarily be with the same IC and a lower bar on the top of the rear end

[@AbdulazizAlfaris-c8g]

Very informative 👍

[@MPbdy]

52” length, 8.3” height and flat lower bar has transformed our big tire roadster. What’s the significance of the IC being in front or behind the CG? That honestly seems to have made the largest difference on our car reflecting on our situation vs the video you just shared

[@MPbdy]

The four link on our roadster was deceptive what appeared to have been a flat lower bar was actually a 3-5* down angle. The chassis was designed for very short IC’s aggressive top down angles. Making an old Davis super gas roadster designed for throttle stop go straight out like a door car is not easy business. Many said it can’t be done.

[@truthboomertruthbomber5125]

What would happen if you raised the rear ride height enough to level the lower bar and then adjust the upper bar to lengthen the IC ?

[@MPbdy]

@@truthboomertruthbomber5125 we were able to raise the front of the lower bar to get it flat with a driver in the car, and the upper bar is maxed out. Luckily the car is very happy there. The IC is about 4” in front of the CG and 7” below it. It’s the first time we’ve been able to run wide open on the leave and the car doesn’t try to flip over backwards. It’s been as fast as 8.15 at 164

[@sanger440]

Running a 3 speed trans is making that car violent at the hit for sure. A PG would calm it down quite a bit and probably run similar ETs.

[@opeliac]

What is the fastest big slick tire, with Strange single adjustable rear coil overs?

[@dannyfasttcars8612]

I'm familiar with these shocks since i have them on my street/strip car which im just in the middle of dialing in. I may have missed it but where are the rear shocks set at(1-9way) loose/tight in the middle? Thanks

[@henglish3398]

This thing still kinda looked like crud leaving…so from my take moving out the IC somewhat bandaids the whole setup by slowing down the separation…to get it to actually hook, does it need that force driving down the tire on the hit but just a better shock to control it? We are about to start working with our 4 link car. Runs 6.0s big tire 87 dodge charger. Need it to hook on poorly prepped bracket tracks. It’s been good but I know it can be better.

[@BlessedMe11]

Extremely interesting and useful content. Well shot footage too! I wonder how this data would apply to a 2021 Dodge Hellcat Redeye Widebody Charger. Any thoughts on it?

[@KevinWilsonSBC]

Applies if it has a 4 link rear suspension. Go fast, go straight! Be SAFE!

[@Taras-Nabad]

I see it, big difference.

[@roudydog3063]

The problem with your analysis is engine height in chassis plays a huge part . How high in the car is the 4 link bracket in relationship to the camshaft height. Where is the bottom bar in relationship to the front spindle? So many factors in adjustment . Front shocks effect the rear , camber change caster, toe it's "all" 4 corners of the suspension that makes the difference especially with the HP numbers some of these guys are trying to harness. Tim Mc Amis has everything you need to solve problems in chassis

[@tommyborntrager-kj5pi]

What program do you use to plot your 4 link?

[@lorenmorelli9249]

Clearly shown.. Thanks~~

[@chriswise1232]

Isn't this the same geometry you would use on a radial? You mentioned big slick a lot, what's the difference in setup?

[@KevinWilsonSBC]

Slicks and Radials are definitely setup different on the 4 link bars.... My channel has so many videos to help with this and it is much deeper than a KZbin comment. This video actually helps demonstrate 1 key difference around slicks and radials with how the car interacts with the sidewall of a big tire slick. Go fast, go straight! Be SAFE!

[@garyrisley3781]

I was thinking that when the instnt cntr length went out 23" and out forward of the CG the car was going to wheels up a lot more?

[@KevinWilsonSBC]

At a high level it does/will, but with this car's current weight bias, it helped apply the wheelie bars more effectively. The wheelie bars are critical for this very reason. Go fast, go straight! Be SAFE!

[@rockinghamdragway]

Z is awesome

[@johnzeek4731]

When you speak of a radial, do you mean a drag radial or a radial slick?

[@KevinWilsonSBC]

Mainly a drag radial... I am doing more and more with "radial slicks" though these days... more to come on that very soon. Go fast, go straight! Be SAFE!

[@therocketshop]

This is a great video, thankyou ! One question if you please, do these things also apply to the factory 4 link on Gm G-body chassis ? I'm fighting with an 81 malibu small tire car running low 9's.

[@KevinWilsonSBC]

Yes it does... same principles apply, except the triangulated uppers also "locate" the rear end. Go fast, go straight! Be SAFE!

[@therocketshop]

@@KevinWilsonSBC Thanks for the reply, do you have any g-body rear suspension video's ? I've been considering some type of upper bar front mounts that allow the upper bars to be justed up or down at the front just like in this video. When you install a 9" rearend in these cars the back of the uppers gets higher which i'm thinking is not a benefit for high powered cars. So if i could raise the front of the bars i could move my IC forward if i'm understanding this correctly. Sorry for the big comment.

[@tomcoon9038]

Question from a newbie. What if you moved the lower bar up a notch. Wouldn't that reduce squat and push down ore? Or would that reduce traction because of reduced weight transfer aft?

[@KevinWilsonSBC]

There is a bunch to that question. Go fast, go straight! Be SAFE!

[@MrTommy954rr]

Is a triangular 4 link and small tire slick’s totally different from this setup?

[@KevinWilsonSBC]

Each car is unique and prep vs no-prep, along with weight bias and CG height have a bunch on the baseline setup I start with... Triangulated vs parallel behave the same way on the antisquat theories, but the upper triangulated arms also "locate" the rear end right to left. Go fast, go straight! Be SAFE!

[@ForceEngineering]

Nice video, Are you checking center of gravity height? or using a rough estimate?

[@KevinWilsonSBC]

Mainly the crankshaft centerline then based on that I use the camshaft centerline height as a rough estimate. The AS line is merely a reference from which I make educated changes. Go fast, go straight! Be SAFE!

[@ForceEngineering]

@Kevin Wilson i do the same. But the AS % then becomes useles to apply to other vehicles. I've want to determine my and customers' actual CG. Then, the AS % becomes something you can apply over multiple vehicles with a bit more confidence. Would have to be a lot of data though. SLR, shock/spring, wieghts, and hp just as a start. Obviously, you know this. Anyway, dig the video!

[@KevinWilsonSBC]

@@ForceEngineering O yes... I have used the following method with great success. Find the height of your car's Center of Gravity: brakepower.com/center-of-gravity-calculator.htm Go fast, go straight! Be SAFE!

[@FadetoBlack1463]

Have you changed your stance on getting slick tire cars closer to or above the anti squat line?

[@KevinWilsonSBC]

No. This is/was a single adjustable shock car. You have to setup the 4 link accordingly. Go back to what I said in the video about these shocks. Go fast, go straight! Be SAFE!

[@FadetoBlack1463]

@@KevinWilsonSBC So if you use your properly valved shocks to control the hit (because its too strong) why not make the correct bar angle change to so it does not hit the tire so hard?

[@SketchysGarage]

​@@FadetoBlack1463 That would be an interesting comparison video. Which would be faster and more consistent.

[@FadetoBlack1463]

@@SketchysGarageI'm not sure there would be much difference. I feel you do not want anti squat near or over 100% on big slick tire car. Especially in anything that makes a lot of power.

[@budd1814]

when tuning,, change one thing at a time..

[@alnix7250]

I just want to stop wheel hop on a stock chevy A body lol

[@engissler]

It would be great if you could put subtitles on your videos

[@motorfab]

Great video. Those shocks work very well for the price. I’ve actually run 7.60’s in the 1/4’ with the single adjustable strange shock in a 3500lb leaf spring car on 275 radials. Check out our channel.

[@rx3rotorace]

The 1st and only thing you would do to this car is buy proper big tyre dragracing shocks before you even turn up to test What a waste of time using that shock on a big tyre car 🤡