ROLL CENTER EXPLAINED by Jake Burkey- Tech Tuesday

This time on Tech Tuesday Jake Burkey of the Busted Knuckle Off Road Shop is going to explain everything you need to know about Roll Center and Roll Axis and how they affect your Triangulated 4 Link Suspension as well as a 3 Link or Parallel 4 link with panhard bar.
#RollCenter #4Link #RollAxis
Roll Axis/ Roll Center
The roll axis and roll center of a vehicle's suspension system determin how much body roll or sway the vehicle will experience when cornering. The roll axis is the imaginary line drawn between the two points made where the lower links would eventually connect and where the upper links would eventually connect. In the case of a suspension with parallel links the roll axis line is simply going to be parallel with the parallel links. The point along the roll axis that is directly above the axle center line is the roll center.
Body Roll
The distance between the roll center and vehicle's center of gravity becomes the leverage factor for body roll. In other words, the further above the roll center the vehicle's center of gravity is, the more body roll the vehicle will experience during a turn. The closer the roll center is to the center of gravity, the less body roll the vehicle will experience and, in theory, if the roll center is on the center of gravity line, the vehicle would have no body roll.
We hope you enjoyed Roll Center Explained be sure to check out the other videos in our 4 link suspension build series below.
4 Link Suspension Explained - • 4 Link Suspension Expl...
Anti Squat & Anti Dive - • Anti Dive and Anti Squ...
More Tech Info can be found here - bustedknuckleoffroad.com/page...

[@someotherguyy]

7 minutes in and I've learned more and had things explained to me that after countless conversations with people who actually do know quite a bit suddenly make sense, thanks much man this is incredible.

[@BustedKnuckleOffRoad]

glad it helped!

[@TrailTime.]

This was the one that hit it home for me. Thanks bud!

[@BustedKnuckleOffRoad]

Glad to help!

[@Arykperry]

This video changed my entire view on 4 link and a lot of things just clicked !!!! Thankyou very much !!

[@BustedKnuckleOffRoad]

glad it helped!

[@patrickschliesing1294]

Record a video of a clean slate design of a typical buggy using the 4-link calculator. Teach the ins and outs of the 4-link calculator. Use a screen recorder of sorts, and voice over? I'd watch it.

[@BustedKnuckleOffRoad]

Noted.

[@swstrand]

Agreed

[@gatekeeperoffroad]

the 4 link calc. is pretty intuitive itll make alot of sense once your start your project hands on and have some measuraments to work with

[@BeeftallicA]

Great tech. You are the new BillAvista Jake!

[@BustedKnuckleOffRoad]

Has big shoes to fill

[@jeffreydavis5506]

Well your still badass jake...in my book. Havnt been able to connect via koh yet but i will one day. Stay up player!

[@BustedKnuckleOffRoad]

Jake is not a fan of KOH LMAO

[@jeffreydavis5506]

@@BustedKnuckleOffRoad really....i remember years ago when i first called him "golden voice" he was going to koh and said to visit him him at the bk tent. No worries tho im still his biggest fan.... "RIOT"!!!!

[@SNAGEMNTAG3M]

When I watched the first 2 videos years ago my head was spinning got a migraine from thinking lol then I dove in head first and it wasn't as bad as I thought thanks again for those videos and all the other tech vids you guys post

[@bustedknuckleoffroadllc5060]

It takes a bit to understand but if you really understand the overall concepts of how everything works you can make some good educated decisions on what to do on your rig

[@SNAGEMNTAG3M]

@@bustedknuckleoffroadllc5060 I'm happy with how it acts on the trail so far maybe next year at koh I'll show ya guys if your around

[@BustedKnuckleOffRoad]

Suspension design is super important for being happy with your build in the end

[@mirhanadewi5242]

Good video thank you

[@bustedknuckleoffroadllc5060]

Your welcome. Thanks for watching

[@BustedKnuckleOffRoad]

Glad you enjoyed it

[@PandaOnSkis]

Thanks for all the great info, awesome series!

[@BustedKnuckleOffRoad]

Glad you enjoyed it!

[@papacapra1908]

I’ve been waiting a while for this. Well done!

[@bustedknuckleoffroadllc5060]

Thank you. Glad it helped!

[@BustedKnuckleOffRoad]

Glad we finally got around to getting it done

[@gatekeeperoffroad]

great video! very thorough and well put together!

[@BustedKnuckleOffRoad]

Glad it helped!

[@RevLimitRyan498]

I've been building crawlers for years. Your videos helped take setting up the suspension to another level. My personal crawler is four link front, one link rear and it flat works. The body stays level on obstacles and is stable at high speed. Uphill, downhill, side hill on coil overs it is very stable!

[@BustedKnuckleOffRoad]

awesome glad we could help

[@wanderingfrenchie]

Solid advice, as always 👍

[@bustedknuckleoffroadllc5060]

👊🏻👊🏻 i do my best!

[@BustedKnuckleOffRoad]

Glad you think so!

[@gafrers]

Greatly explained once again

[@BustedKnuckleOffRoad]

Glad you liked it

[@AUBREYTHOMAS1979]

Brilliant video. Well explained. Thanks !

[@bustedknuckleoffroadllc5060]

Your welcome Aubrey, thank you for watching

[@BustedKnuckleOffRoad]

Glad you enjoyed it!

[@GarageFab]

Very well explained. 🍻

[@BustedKnuckleOffRoad]

Glad it was helpful!

[@JasonHam41]

Brilliant Jake, such valuable information to the home builder. Thanks for your time!

[@bustedknuckleoffroadllc5060]

Your welcome sir. I hope this helps people out when they are building so they dont make the same mistakes i did

[@BustedKnuckleOffRoad]

Glad it was helpful!

[@woodchuck243]

Professor Burkey as always great job thank you for sharing your skills and knowledge keep them coming

[@BustedKnuckleOffRoad]

Thanks, will do!

[@richardf.dossii3900]

Love the way you teach

[@BustedKnuckleOffRoad]

Jake knows his stuff

[@kyferez1]

Dude! THANK YOU SO MUCH! Gives me a lot to have to figure out, but it will be so worth it. I knew there was more to this that I didn't know and I want to build this SASed Jeep WK right!

[@BustedKnuckleOffRoad]

Glad I could help!

[@randomstuff3672]

Great video. I ordered rear TB relocation brackets a couple of weeks ago knowing they were a solid 2 months out. I was excited to get them based on what I have "heard." Now I can't freaking wait!

[@BustedKnuckleOffRoad]

Great to hear!

[@simonbar7665]

Big like

[@off-roadingexplained8417]

Thanks!

[@BustedKnuckleOffRoad]

glad it helped and thank you for the support!

[@eliinthewolverinestate6729]

I run a parallel 3 link in rear. Wishbone upper and slight triangulated to lowers. Built a bent dom tube bridge truss. Jacked axle up till level driveshaft and added bump stops. Took measurements for tire full stuff too. Then measured squarely 31" and marked for mounts. My driveshaft is around 31" run length. So now have the 2 control arms and driveshaft moving parallel.

[@kululv]

this is absolutely great, I learned more about roll center/axis than I did in engineering school. i tried to download the 4 link calculator but did not find it on your website

[@BustedKnuckleOffRoad]

thanks, Jake has a good way of relaying information in an easy to understand way

[@rscustomize]

I’m going to buy some stuff of BKO just to thank you for the video ;)

[@BustedKnuckleOffRoad]

We appreciate it!

[@charliedee9276]

I could not get the calculator to work... so I took measurements off my Jeep and laid them out on Mylar by hand. I am a retired suspension designer, manually drawing out suspension geometry and articulation is relaxing now. Very informative video, clearly explained.

[@BustedKnuckleOffRoad]

glad it helped

[@jacobbutler1932]

I think it would be neat to get your opinions on chassis design. Not necessarily the riot chassis that y’all make but maybe an explanation on basic, important structure designs. For the guys wanting to build their own chassis with their own style, but still have a good understanding on how to make it strong/safe.

[@BustedKnuckleOffRoad]

Good idea, could wrap it up by showing how we use the though process to design our chassis

[@donkiejarretjie3338]

Oh that was a real “heads up” about the panhard bar - tnx. A question if I may: what about a Watt-linkage like on the Bucher Duro? How about a vid or comment about using this instead of the panhard bar? Thank you for taking the time and showing things the right way!

[@BustedKnuckleOffRoad]

watts link is a different animal

[@donkiejarretjie3338]

@@BustedKnuckleOffRoad Yup, thus my question, I can not wait for you to explore the pro's and cons - if any - of this system. Another question - if I may: From some videos about the rock racers it looks like some run a very negative caster (the steered wheels leaning "out" of a corner and not in.) is this true and if so, why?

[@williampankratz600]

I have a different scenario ,Model TT with transverse leaf springs , 126" wheel base and using model 44 and 60 axles , some of this will work but not all of the stuff your telling me will be used Roll Center will be necessary along with squat control but no coils and likely no shocks because I am way to much of a Ford Purist Great video and thanks for the input laying out dimensions that I knew I didn't know till now

[@BustedKnuckleOffRoad]

no shocks?

[@jaredbudzinski8434]

Five seconds in and I’m loving it😂👌 great intro

[@bustedknuckleoffroadllc5060]

Hahah we thought i was appropriate

[@BustedKnuckleOffRoad]

Glad you like it

[@eliinthewolverinestate6729]

High centered roll axis making a hard left turn with plenty of power will pull drivers tire up. It does happen.

[@travismayer33]

Is it possible to use the link calculator to find all these values running a front triangulated 4 link, and leaf sprung rear? If so is there any specifics other than what’s described in the videos? I have a toyota on dana 70 axles, 42’s and a full EXO for crawling. I’m looking at changing my front 4 link system for better performance while crawling through obstacles and to help reduce body roll.

[@BustedKnuckleOffRoad]

not sure how you would find a rear value with leaves

[@enduror-ce5166]

[@BustedKnuckleOffRoad]

Sure thing!

[@codymullins4523]

can you guys do a video on i beams? or solid front axle suspension?

[@BustedKnuckleOffRoad]

What would you like to know?

[@AussieBruteUte]

Hey mate, used the calculator (v3.0) you recommended and it says for my measurements that my roll centre is 17% (roll oversteer). Just wondering if you could clarify that for me as you only speak in 0-100%. Thanks

[@off-roadingexplained8417]

Yeah. I had mine leveled. Hated it... Lifted the rear and unleveled it to fix it. Way better handling.. even though it's higher up ! Very counterintuitive... I like a little bit of "downward dog" in my suspension.

[@BustedKnuckleOffRoad]

Right on

[@3ddirtmover]

So if I have a roll center of 44” on the v3.0 calculator, does this make the calculated roll center irrelevant if I have a panhard bar? 12:15

[@Dono.N]

I am really hoping to build a setup on my rig that can articulate on crawling but also be able to do faster driving and good cornering. I hate how the panhard bar shifts the whole diff over, I wish I could figure out a way to get rid of it while keeping all the benefits of the 4 link. Watts link seems like it would just over complicate everything.

[@BustedKnuckleOffRoad]

double triangulate 4 link FTW

[@OffroadMilitia]

I know this sounds dumb but. When you measure for your roll center percentage are you measuring from the ground up to center of gravity or from the bottom link mount up to center of gravity? I'll be running 39 to 42 inch tires but with beadlocks I run them at 1 or 2 lbs air so really like a 35

[@BustedKnuckleOffRoad]

ground

[@willleader538]

Could you go into more detail on suspension roll axis and roll steer? The offroad community needs to know.

[@BustedKnuckleOffRoad]

sure can

[@johnterpack3940]

Good video. But I do wish you had talked about the fact that lateral weight transfer still happens regardless where the roll center is. A vehicle will never "lean into" a curve. Inertia always pushes the CG to the outside. The easy way to visualize what's happening is to think of a pendulum where the CG is the weight and the roll center is the pivot. It will always move "out" when pushed. Putting the RC above the CG will just make try to go up and out rather than down and out. The problem there is that you have the geometry trying to lift the body while the weight transfer is trying to compress the suspension. Conversely, you are actively trying to lift the inside tires by trying to compress those springs while weight is being lifted off them. That's why a high CG only works at low speeds, lateral weight transfer isn't a factor then.

[@BustedKnuckleOffRoad]

come take a ride in one of our buggies and you will see the difference

[@DavidNJ1]

Umm...all those line are widely used to calculate a roll center, but it isn't the way it works. Each of the suspension links is either in compression or tension, which pull on the chassis at their attachment points. The lateral forces (we are talking roll center, so braking and acceleration aren't a factor) come through the tires and are more or less linear function of load (its not near the limits, but this is Indy, NASCAR, or F1). The front and rear are computer independently. The net is a vertical force on the body. The lateral acceleration causes weight to transfer to the outside wheels, and when the RC equal the CGH the forces in the links totally offset those forces. Lower roll centers don't. In people who do the lines for road racing and oval track cars it sometimes is a bit funny. They end calculating for the inside and outside wheels equally, while in some cases the inside wheel has no load at all (we've all seen pictures of a car on track with both inside wheels raised). This is an issue these days when even street tires exceed 1G lateral on pavement. Krawler KXs won't do that.

[@bustedknuckleoffroadllc5060]

I try to explain things so the average person can I’m understand. Most people would get lost trying to understand what you just wrote

[@BustedKnuckleOffRoad]

Don't want to talk over people's heads

[@Arykperry]

Hey Dave your killin my buzz .... now I gotta start all over !!! LOL

[@jamesdoughty1522]

How would leaf spring suspension in the rear affect roll center?

[@BustedKnuckleOffRoad]

absolutely

[@jvrkandc]

Another question I got : CRC - Constant Roll Center link. There's a company that fabricated it years ago already (bolt-on) , but for Long travel suspension cars the arms on the link can be fabricated longer as well as the center arm....I've read of cars with 14' of rear travel running CRC .... Question from me is Why Haven't we seen more on CRC ??

[@BustedKnuckleOffRoad]

Haven't ever looked into CRC

[@jvrkandc]

@@BustedKnuckleOffRoad Ok...thx for the reply....I'm just wondering if we can adapt it to a 14' + rear travel system.... Have a look at CRC.....I'd love to see your thoughts on it

[@Hairy_and_Scary]

Do a video for trailing arms!

[@Hairy_and_Scary]

Aaaaaaand I see you have one. Always great info jake

[@BustedKnuckleOffRoad]

ha yeah that is a good one

[@jockpc]

Hey Jake this Jock Burge miss can u mount the motor so the torque will force front down in stead of right rear like side ways

[@jockpc]

Or some kind of torque control to make all 4 have same ground psi if u prefect this u could rule Equalizer shaft or something they always go to the right the rut deeper on right

[@BustedKnuckleOffRoad]

sounds super complicated but possible

[@jockpc]

@@BustedKnuckleOffRoad thank you for the response yes I thank some could be in the drive line The direction it turns could make some difference in side torque love you guys I 59 would love drive one I see lines nobody tries

[@kdjwolf]

Will ori struts work to improve body roll.

[@BustedKnuckleOffRoad]

we recommend a sway bar and are not big fans of ORIs

[@Tboffroadfab]

Noob question here... but when you see a vehicle make a turn and they lift one front tire off the ground, what is normally causing that? Is that from Anti-dive? Or is that a roll center thing?

[@BustedKnuckleOffRoad]

Like a Trophy Truck?

[@Tboffroadfab]

Busted Knuckle Off Road yeah kind of, I always assumed it was just from power/torque but then I’ve seen guys do it in TJs and stuff too, with stock engines. After watching your suspension videos I’m thinking it’s more in how the suspension is set up now

[@jtv407]

how about roll center for a three link

[@dobermanracing]

You should put up on your website with the Calc how each thing affects the vehicle. I do much better with text.

[@BustedKnuckleOffRoad]

That would be a lot of information

[@dobermanracing]

@@BustedKnuckleOffRoad I just meant like a basic chart, higher roll center does x, lower roll center does Y.

[@bustedknuckleoffroadllc5060]

Doberman Racing ah, maybe i can figure out how to do a blog one day.

[@MayesBuilt]

can rear roll center help control roll from torque?

[@BustedKnuckleOffRoad]

yes

[@evo2racer8029]

Shock location in front of the axle , behind the axle, as well as angle?

[@BustedKnuckleOffRoad]

good question. straight up in down is your best bet for shocks. Slightly angled in is fine too

[@shaoyikai813]

Hello. I can’t understand, why dose high roll center having problem with high speed bump? Roll center should makes difference with “lateral force”, because the lever effect. but shouldn’t make much difference with “vertical force” .

[@BustedKnuckleOffRoad]

it unsettles your suspension and makes the vehicle want to roll

[@jeffreydavis5506]

Shit i chatted and no one else did!

[@BustedKnuckleOffRoad]

there were a few comments LOL

[@jeffreydavis5506]

@@BustedKnuckleOffRoad yea me😂😂😂

[@jeremy5641]

I wish he would have notated how the vehicle would handle if you were all Center sloped higher in the front and going down towards the back

[@breckfoster767]

Lmao this is becoming my struggle trying to set up an 08 Envoy with a 3 link front and retrofitting the 5 link rear with the 1 tons Speed and climbing is difficult to attain at the same time lmao

[@rickmarquart3277]

Did I miss how to find COG?

[@BustedKnuckleOffRoad]

center of the crank is a good starting point

[@mickhenson794]

Needs more micro link geometry

[@BustedKnuckleOffRoad]

we should have built a little scale model to help demonstrate

[@swstrand]

Can I come work for ya'll? Lol would be awesome

[@BustedKnuckleOffRoad]

We are always hiring skilled people.

[@FlowerSoap835]

Привіт! увімкни субтитри будь ласка🤘🇺🇦