Rear Suspension Series: Part 6 - 4-Link Basics
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- čas přidán 24. 07. 2024
- Part 6 in our series of tutorial videos that explain how to set up your rear suspension takes a look at basic 4-link set up and adjustments. Be sure to check out the other videos on Alignment, Pinion Angle, Pre-Load, Anti-Roll Bar and Ride Height if you haven't already.
Next week we will have a look at wheelie bars.
Learn more at www.timmcamis.com or www.dragrace.academy
Rear Suspension Series:
Part 1 - Rear End Alignment
Part 2 - Pinion Angle
Part 3 - Pre-Load
Part 4 - Anti-Roll Bar
Part 5 - Ride Height
Part 6 - Basic 4-Link Settings
The information contained in this video is based on the opinion of Tim McAmis and his 30+ years in the motorsport and manufacturing industries. Any action you take based upon the content provided shall be done at your own risk. TMRC and its affiliates are not liable for any losses and/or damages in connection with the use of this information. - Auta a dopravní prostředky
It's so nice to find someone who knows what they are talking about. Thanks ✌😁
Masterful geometry. Magnificent machines. Top shelf attention to detail/perfection👌
Good info. I finally put the car on a 4 post and got measurements of every adjustment hole and just plotted all the intersect lines on my cad software that way I have a file of every possible combo and we can rule them out for a particular scenario and keep the ones that work on file.
Wow great vid series. I was going to comment on every one but figured I would wait til the end. Very informative. Thanks for posting.
I race modified dirt, we really have alot going on with 4 bar! Great information!
Thanks for the great videos. Tim
It appears I don't know how drag car suspensions work because on a dirt car raising the front of the lower bar increases traction not removes it. Due to the differentials wanting to move in a counterclockwise rotation under power raising the front lower pivot point causes the weight of the car to prevent rotation of the diff which increases traction. Of course that's why most cars have a slight uphill angle in the bottom bar. All this info and much more can be easily obtained by reading on of the many suspension setup books available!
A four link is like a three link or ladder bar with a lot of adjustments and the advantage of have the shorter link bar they will react faster unlike a ladder bar that reacts slower so the car will move of the line faster with less need for front end lift to get the tires to hook.
Tim have you ever used a laser line tool in place of a plum bob for squaring things up with the rear crossmember? It’s a construction tool but It sure is beneficial in the shop as well.
How dose torque and the rear driving forward effect the weight transfer?
When the links are down there more weight on them to lift when up the weight is more on spring.
I think what confuses most dirt oval track racers is that on dirt the 4 link brackets pivot on the birdcages on the axle tube of the rear end. On drag cars the brackets are welded to the axle tube and don't pivot on the tube. Makes the 4 link bar adj basically the complete opposite than what they are used to.
awesome...
Thanks for the info, much of which I couldn't grasp, unfortunately. This was partly because I lack the required knowledge, but also because your video is entitled '4-Link Basics' (which is what I was hoping for and why I watched)
and yet it didn't really cover the basics at all. It went deeper from the get-go and assumed your audience is all professional racers and they are not. Thanks anyway, I'll do some more reading elsewhere and come back to watch it again once I have those basics to work from.
Get the 4-Link Wizard software to plot your Instant Center (Intersect Point). It plots all possible Instant Centers on the screen. You will see that moving one end of a bar one hole can make a tremendous difference in Instant Center. The software allows you to select bar positions to achieve small changes in Instant Center as you try to find the "sweet spot" for your particular car. The "spread" of the bars is more a side effect of which holes you have selected on the brackets and should not be the goal of your adjustment. The 4-Link Wizard program works with any brackets.
how much pinion angle change is there with this set up where there are to arcs in play? Is it too much to drive on the street?
I believe he is saying. if you do not have the traction you want then lower the front 4 link pivot one hole (near the cross member). But make the same adjustment to both upper and lower pivot points. To keep the same distance between the two adjustment rods. If the car is bitting to hard and will not let you counter steer through the turn. Then move up one hole on all 4 pivot points. (For more wheel spin. If I am wrong someone please correct me. SPI is a lower end tooling company. But I own a few of there products and have had no problems with them. This digital protractor seems to be very nice. The normal protractor will not hold the current angle. So that is a nice extra feature.
Hi Tim Alec from Melbourne,Australia. I have been watching with great interest in the 4 link setting up videos.Have a question ,is their any difference in setting up a 4 link on an 125" altered around 800 H.P than a pro stock car or the maths the same regardless what car,dragster altered is the same.
Hey Alec I have a similar setup here in New Zealand. I would be interested in knowing what numbers you are running and maybe settings?
Quickest 7.59. 172mph. C/AA .
The best I’ve done is 8.3 @ 158mph are you still poking out 800hp?
How do you determine the intersect point? He referenced a 60 inch interesect point and then backed off to a 55 inch and 6 inches high. I understand changing the angle to adjust tire bite.
I was wondering if you might be able to give some advise to another youtuber by the name Rather B welding. He’s a young guy with fab talent that is refining. He could use some help with a front end suspension for a project he’s working on. I’m just trying to get him in contact with the right people he can learn from. Thank you!
Raising and shortening the IC would add bite, lowering and lengthening the IC would reduce bite, prone to wheel standing and rear squat.Just look at radial drag cars, lots of bite from rear anti-squat with a high and short IC...
He seemed backwards to me as well. If the rear suspension extends, wouldn’t that force the tires into the ground and cause more bite?
He's speaking of a different animal where the intersection points are well below the neutral/anti squat line. Bite is coming from more or less load transfer and shock compression compression. If the car had half the tire on it for the same horsepower and track conditions as a car similar to these then you may go up around or above the neutral line and start pushing the tire to the track
not one mention of instant center
how do you make a ss454 chevelle hook up on goodyear polyglas?
🤣🤣🤣
Take 4 spark leads off👌
To bad this stuff probably wouldn't pertain to stock suspension type car cause you sure do explain things very clear
So, alittle tire spin is good? thats whats i getting from this video, it makes sense. I am trying to get an IRS cougar to hook with 10.5 Mickey T's. I know this is different i just cant get the fucker to hook. it only makes about 310hp to the tire. The tq is around 370lb/ft
still dnt get it
That's because he was talking nonsense mostly. "Spread" isn't a thing. The ideal angle of that lower arm is going to depend on the wheelbase of the car, the front/rear weight balance, and the design of the brackets. You can't just say the lower arm should always be X degrees. Look up "anti-squat" and you'll find all sorts of diagrams that will clearly demonstrate what he pretended to explain in the video.
hell, I dont even understand this much lol
+slowpoke96z28 man he confused me
Just a recap: the angle of your lower link changes transfer attitude. And here is a bunch of measuring points with a lot of rambling.
What?
Here's what it looks like in action on a dirt track... czcams.com/video/BQGXltGTsUE/video.html
You just confused me more
why not just make both the upper and lower lvl, it would give the maximum control for axle wrap, or wouldnt it
+nathan campbell i think they dont keep them parallel for anti squat purposes, idk its just a guess
he should be useing terms such as squat, anti squat, and instant center. theres alot more invalved and honestly from what i understand with bite he is saying it backwords but dont take my word for it. do reaserch on squat and anti squat.
I was hoping he would mention anti-squat the whole time and...nothing. I'm hoping he actually knows what it is, because trying to explain the geometry as "spread" between where the heims mount? That doesn't even mean anything at all..IMO. That's probably better explained by figuring out the instant center. It's possible he learned how to adjust this particular system to do exactly what he wants to do, without understanding the real physics happening or what the terms real engineers use to figure it all out. Again, adjusting "bite"? There is a much more complex, but correct way of describing what is going on there from the rest of the engineers that explain rear suspension setups. I'm still not an expert, so even I have a hard time explaining it properly. What I find cool is that some drag cars use over 100% anti-squat where the rear actually lifts on launch. The physics behind that are awesome.
You are correct, increasing anti-squat (raising the links on the chassis end of the 4-link) will in crease longitudinal traction (forward drive) because it keeps the CGH higher, the higher the CGH the more weight will transfer from the front to the back under acceleration. BUT, as is typical of the dirt track mentality, the affect that he is referring to, and probably why lowering the bottom link will tighten this particular car is because of the rear steering that occurs when you lower the bottom link. Rear steer tightens the car because of mechanical steering of the car, not because of an increase of traction in the rear, a huge difference. For more on this kind of accurate vehicle dynamics applied to dirt track chassis, visit www.hyperracing.com/ and go to the tech department.
@@mjodr are you really questioning the guy who's raced Pro Mod and builds some of the fastest doorslammers in the world? Are you the chassis man on a Pro Mod or Pro Stock team?
In English? Man lost me asap lol
HUH???
What the!!!
You should probably try to explain it in a way everyone can understand.
"If you can't explain it simply, you don't understand it well enough" -Albert Einstein
Magic mike Denton at @denton_arc_racecars says you should NEVER use weld in threads for suspension trailing arms. Why is that? Or is the guy just full of shit?