Watts-Link Geometry
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- Опубліковано 26 січ 2017
- The watts-link is a commonly used lateral locating device on rear link-type suspensions. The advantage to the design is that it can keep the axle centered throughout the entire travel range of the suspension. Understanding the subtleties of this design, which are necessary for the system to work correctly, are actually quite simple.
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My friends, there is a common error here for some applications. This is a great informational video with very sound information and advice and I have gotten some good pointers too.
The Watts link is a great piece of design. It can be used in different automotive applications in different ways.
However, if your application is racing on pavement and you are optimizing handling and traction, the atlas for the Watts link should be mounted on the chassis, NOT the axle. It may be important to mount it this way in other forms of racing also: off-road, drag racing, etc. Yes, it is often a little more difficult installation except for full tube race chassis but, there are many benefits to mounting atlas or pivot on the chassis. (see Paul Van Vaulkenburgh's book "Race Car Engineering & Mechanics".
First advantage of chassis mounting the pivot is a LOWER ROLL Center. The point through which the chassis will roll can be located lower relative to the chassis and center of mass and allow better management of cornering forces (suspension setup) so the tires can maximize grip. You are trapping yourself if you mount it on the axle. Locating it on the chassis allows a lower roll center point thus, better grip, and better handling because it allows a more compliant setup, which lets all four of your tires manage the cornering loads rather than dumping it all on the outside two tires.
The lowest watts link center location on my race car is 8 inches above the ground. Of course the critical dimension is how far is the roll center is below is the center-of-gravity/mass?
Second: the axle travels perpendicular to the link ends on parallel mounted links. So, if the link ends are mounted on the chassis and the pivot is mounted on the axle, the natural lean or roll of the chassis in turns means the line of travel is not vertical, it is at an angle although a shallow one. Most importantly, this means that there is lateral movement of the axle relative to the chassis and it is BUILT IN. This creates undesirable tuning issues that require you compromise otherwise optimized tuning to combat this thing that you may not even be aware of and may not be able to resolve.
Think how that is when cornering over bumps. The chassis is oscillating laterally through the turn, reducing the grip with mini lateral cyclical accelerations. That is grip that you can otherwise use to corner a bit faster.
If you are driving on the street with a street car, and driving carefully then, maybe how you locate it doesn't matter that much, maybe. But, if you are building a car for competition or want to maximize your car's performance in an on track environment NOT ON THE STREET then, this manner of mounting is proper and beneficial.
Thanks again for highlighting my comments.
There are a lot of watts link kits being sold that aren't optimal and may be even detrimental to the handling of the cars they are mounted to.
This and the book helped me tremendously building a truck here at the house for a friend. If not for this and Max I'd of surely not been able to optimize it like I did.
The best content and knowledge for suspension design. Get the book. You'll never regret it and learn a ton from it. I did!
I am finding this channel now. I love it. Thank you. I build an offroad car so it's give me the necessery information. :)
Great work! Nothing but the best knowledge from you like always!
Loved it! but dude, I really need part two because i would like to know how to build one of this in less than a month! It's an A+ for sure if I can do this. Please pretty please upload the rest, you will be my salvation. From Nicaragua, thanks a lot
These are the best explanations I’ve seen.
Love your site and videos. I'm ordering the book. You guys so much enlighting information. My latest project is a lifted 100 series Land Cruiser/LX. The information provided let me set Panhard bar correction to the original roll center angle. I didn't have a clue about this before I started the lift. The videos came along at the right time. For a big Cruiser that has been built and lifted for off-road use, applying techniques that I learned from these videos, let the truck handle like a sports truck on curvy paved switchbacks and perform extremely well on off-road whoops. Also, with the Panhard correction, I can hit railroad crossings at regular road speed without the read shifting around and giving that "heebie geebie" feeling. The off-road community can learn a lot from this site and these videos. I have three other cars with Scott-Russell rear link suspensions. If you would ever like some pictures of Scott-Russell / Torsion rear suspension just let me know.
Very informative. And a well produced video.
Subcribed just for how knowledgeable you are !
Simplest and best video on the subject !
Thank you very much 😁👌
Value added information- just subscribed ! Keep up the great work
Good video! I use one on my Street/Drag car which is working out great!
love love love! cant wait for more videos!
Watt's linkages aren't just for lateral location of an axle. Have a look at the rear suspension of the Alfasud - it has two Watt's linkages for longitudinal location and a Panhard rod for lateral, along with a twist-beam axle and some rather clever geometry to give roll-driven rear steering and anti-dive under braking. Saab used the same kind of setup on the 99 & 900.
Look up a circle track "Z link" pretty much obsolete now
Thank you so much for this video! It cleared up so many questions in my head.
A couple of questions that I still have are:
1) Does the link allow the axle to articulate? You showed the axle going up and down but not articulate.
2) can the center pivot be mounted on the frame and the side mounts go on the axle?
A properly designed watts-link should not limit axle articulation at all.
If you move the center point of the link to the frame, the roll-center will move with the frame instead of the axle. This is a much larger conversation, but for a driver, either way should work fine.
great video .. i like racing cars and something comes understand that a good suspension gives you good advantages , and it is very common in any type the vehicle including motorcycles .. currently i have a C10 Silverado 83 i have made some modifications .. and it has responded phenomenally .. cheers .
looking forward for.more videos about watts link！
Hi there, great video thanks! Can you tell me why the angle of centre plate is slightly off centre at half travel? Why cant it be vertical (perpendicular) at this point? Looking to add a rear trailing arm setup for a hotrod setup. (one each side)
Wow! Nice explaining :)
Just ordered the book.
I'm here because this video was linked in a "The Autopian" article about the new Ranger Raptor's rear suspension.
Good job... more knowledge now...thanks
Any information on the correct angle of the middle pivot?
Is there a ratio for link length?.. perhaps dictated by the span between chassis rails, and/or length of travel?
Great video, would this do anything for a 3/4 ton truck? I see talking about this only for cars. Just curious
This can work well in a number of applications. No reason it can't work on a 3/4 or 1 ton truck.
Great info went come the part 2 i want to know more to make this to my kp61
Question, in your book did you tech me from were I get the measurements and with all that info to built a watts link in my kp61?
Have you got any idea about why opel (or vauxhall) removed watt's linkage on astra? And what did they do to save the grip watts linkage provides?
great video.. Can u pls explain in you next video, on how the suspension reacts when one wheel goes through an irregular surface??
That is certainly something that we will address in the future.
Great animation...
I have a 41 Chevrolet with leaf springs a fairly decent set of shocks on an anti sway bar in the back end of the car still sways fairly severely for all the stuff I have. Could I just have two soft of springs, or maybe a combination of that and a higher center of gravity than say a more modern car?
So if one side of the link is damaged it will pull the axle to that side correct
First vehicle I seen fitted with this to the rear axle was the EF Falcon.
subscribed. nice video!
Nice video, easy with the music.
How much affect does a watts link have on over steer? I have a lot over steer.
What practical method would you recommend for finding total suspension travel ? It seems to me that rti ramp would be best. Run it up one side to max compression. Measure centre axle to wheel arch. This provides min arc length. Then reverse off and run other wheel up rti. Measure original wheel now at full droop. I can't think of any other reliable practical method. Please enlighten us?
Are you working with an air bagged suspension?
Is it worth it to construct a watts link for a static dropped truck with a panhard bar and factory four link that is only daily driven?
I personally think the Watts-link is unnecessarily complicated of 99% of vehicles.
what are the cons to watts 6 link over other set ups
Watts-links are overly-complicated for the majority of the vehicles out there. They certainly look good and will keep the axle centered in the chassis, assuming the geometry is correct, but in most cases, a properly setup panhard bar will offer great results in a far simpler package.
Enjoyed it. just designing a micro car, myself and needed a very basic set up for low speed i need the rear two wheels which are not driven to have a basic leaf preferably one leaf and shock absorber each side thats it.
Why does nobody seem to mount the outer (fixed-to-chassis links) level with each other ? I reckon it would reduce any error at the top and bottom ends of travel.
If you mount the outer pivots level with each other the axle won't move straight up and down. To determine the path of the axle centerline you have to find a position where the arms are parallel to each other. The path of travel will be perpendicular to the arms in that position.
If you mount the outer ends level with each other, the position where the arms are parallel to each other will not be one where they are level to the ground.
Would this set up prevent axle wrap please? From the U.K.
Utilizadas en los coches hasta los 80' , dejaron de emplearlas y ahora vuelven coches con esta vieja pero eficiente tecnología...
What type of steel should I use for my control arms in a four link rear suspension setup? Mild Steel, chrome-moly or stainless steel?
This is an impossible question to answer, unfortunately. There are too many variables to offer any sort of universal answer.
Pedantic Publishing, thanks for getting back to me.
Sean I used a watts link setup from a 2001 PT Cruiser. The bell crank and control arms. They use a tie rod end to the bell. I got them from NAPA there were 2 kinds of control arms, 1 had the ball joint welded into the bar, the other had the tie rod end threaded into the shaft. I kept ordering and returning until I had 2 threaded rods. There was no difference in the part numbers. I simply cut the rods to my length and rethreaded the tube for the tie rod. It is a very robust set up.
awesome !
This is like some learning PBS cartoon that teaches you history or something. But for people that build hot rods.... amazing lol
I liked the amendment. I liked that. I am from Sudan. I could tell you more progress. Thank you
thanks well made video..
Can a Wattls link be used on the front suspension?
I want to know hmm how body roll affects it.
Actually the left axle and hub seem to be slightly bent, you sure you didnt hit a curb with the left side?
dodge durango 2010 has that kind of rear suspension
Also make your links as long as practical; that maximizes the radius of their arcs.
What happens when just one wheel hits a bump?
Seems like it will force the whole axel to move instead of pivot.
Which is better?. A 4 link or Watts link?.
What about one sided bumps tho?
Getting the watts link for my 14 mustang gt 5.0.
Thanks!
Awesome 😎
Amazing! What's this song?
It's just a downloadable song for making videos and such. Nothing specific.
Wouldn't half travel of the axle simply be the car or truck at rest, on its wheels without any extra load?
No, that's the rest position. Often suspensions do not rest at half travel. There is an argument to be made that having the bars parallel at rest position is superior, though.
Great give me more please..l am building a special so will need some ideas...internal suspension using two A framed twin links..for my sidecar 🤪👍👍👏
So they can't help unbalance single side suspension.
What about a Mumford link rear end ??
I mean, why not? It's just a little complicated for the average driver quality vehicle.
I'm building one for my 77 Celica 👍quality all the way
Roll?
I'm going to guess without watching it keeps it centered?
Porschephile history buffs thank you
Lateral side force would not deflect axel by rotatation of center link...
Build a model and try...
Yeap!!! Greatings from russian north! Im building GAZ 24 with 4link and watt. Very very low car.
tam net rami 4tobi bilo stolko travela, lol
Pretty much a Chalmers suspension setup like in some dumptrucks.
I come up with this idea when I was 10 years old, then discovered Saab use this on 99 model
Hi, this is Kevin. I make LEGO Technic models. I just finished building a new car utilizing this type of suspension, and I’m making a video of it. I’m wondering if I could use a short clip of this video in my own video to show how this suspension works. I will credit this channel in my video and I will put a link to this video in my video descriptions. Thanks.
Absolutely! Hopefully, you already used it for your needs.
Yes
YES.....NEED MORE Input.....need more INPUT!!!
Look at this better watt’s linkage version:
ua-cam.com/video/dhX6NmkmVYo/v-deo.html
Roll center height can easily be changed putting center propeller pivot up or down.
There are many You Tube videos now about this suspension device. I think it's appropriate that I comment on this Channel, the Pedantic Publishing channel that all of these channels have it wrong, it is not a 'Watts link', his name is Watt not Watts. You could say Watt's link but definitely not Watts Link!
Opel astra j is with watts👍
Yeah, Astra and Chevy Cruze have a Watts link on the torsion bar for some reason.
Ok so earlier I went panhard rod stuff that Im running watts linkage... yeppa yeppa
Yea, I know how a watts-link works. It's in a PT Cruiser. It works like shit, and rattles like crazy after a while.
Explain with commentary n show inner posion
Mecanismo de Watts
I don't think it's all that important to keep the geometry the way to show in the video. There's at least 8 of different methods to mount a watts link off the top of my head and they all work fine. Equal length links with frame or axle mounted wishbone/pivot point, one short one long link with frame or axle mounted pivot. Top or bottom mounted links and pivot. As long as you don't cause bind in the suspension travel I think it will work fine keeping a rear end centered more accurately than a panhard bar at least. In fact a little "less than ideal" symmetry probably has its advantages in certain types of racing where you want to favor grip to one particular wheel.
Esta todo inventado! XD
Hü
Всем жигулистам на заметку
Кчему эта непонятная херня.
Basic animation...
Amateur thoughts...
Silly Cartoon music...
Information entry level...
Clearly useless to most...
And yet, visual effect has been accomplished.
Just not by you.
Comprehension is all
associated to THEE viewers ability !
YOU DO NOT NEED TO WAIT... VIEWERSHIP UNDERSTANDS NOW !
Sir - what have you posted on UA-cam with educational value? Please share the link with us.
maybe simply use your big boy words
Your video moves so fast you don't have time to read it. Have to re watch and re watch. Give ppl time to read.
Dodge stupid idea
Just for future ref... You can check into the name "Watts" and then look into vintage "steam engines".... at which point, you will discover, the relationship of where and when not only the name but the design and geometry came from... Beings, you intend on a future commentary of the subject matter... Good luck