watts link vs panard

[Tim.duncan]

found this while looking at watts link set ups, pretty intresting its 0.7 quicker threw the slalom!

http://www.youtube.com/watch?v=cpZdV4qcUKE&feature=channel_page

[ArbPotatoes]

cpZdV4qcUKE

[drift kid]

what does it actually improve on? ive never heard of a watts link setup before, looks allot heavier.

[hachi_dk]

lmfao 4.58... dirty azn

ive seen watts link setups on new holdens

[matt99]

what does it actually improve on? ive never heard of a watts link setup before, looks allot heavier.

Its does the same job as your panhard rod, however instead of moving a little to the side as it moves up and down, it allows the diff to stay centralised.

[Tim.duncan]

Cheers AB for you little magic window, you kids these days and your fancy intranet tricks

[Kid Karola]

It's pretty close to linear, in the mid range of it's motion. At limits it tends toward an eliptic path... (range depends on geometry)

http://upload.wikimedia.org/wikipedia/commons/9/93/Watts_linkage.gif

This effect is less obvious on circuit/tarmac application as say a rally/off-road due to generally longer suspension travel.

[matt99]

Edit: took a second look.

[Frak]

Good animation Karl

[Vance]

im suprised you dont have one frak.

i want one. how much and who supplies them?

[slide86]

lmfao 4.58... dirty azn

ive seen watts link setups on new holdens

please please enlighten me as to which new holdens you have seen watts linkage on

[Javal]

please please enlighten me as to which new holdens you have seen watts linkage on

Was about to say this.

[slide86]

how about ANY holden....

[Frak]

im suprised you dont have one frak.



Apart from the panhard rod moving the axle sideways I doubt there is much difference.

Roll centres are different depending on the setup (Watts link on axle or chassis) but how important is that?

If a low roll centre is required with a live axle, then a Mumford link is worth considering. This will give a low Roll centre without having hardware hanging down under the car.

Google should find you some stuff on a Mumford linkage. I have long ago dismissed the importance of 'geometric' roll centres.

Force based Roll centre's make more sense, though are difficult to measure or quantify. The easiest way I have found is to put the car on scales, then weigh it again with one side of scales lifted, say 50mm.

The difference in weights left to right will let you make some easy comparisons on what the Centre of gravity is doing relative to the roll axis.

Some trigonometry required but the results are better understood seeing as we are trying to control weight transfer. ..Why not measure it and then back engineer it? Drawing geometric roll centres on paper will help you avoid jacking etc, but I doubt it is of much value when setting the car up.

[hachi_dk]

how about ANY holden....

sorry, as you can tell, i dont know much about holdens.

didnt know you were so into them; that me presuming watts link was a new thing for em would offend you

[Buck]

^^^its more the fact that slide and javal are both holden mechanics...

[Tim.duncan]

Frak please bear with me as im trying to get my head around all of this.

i have looked into this mumford link and all the setups i can find are mounted well below the diff leaving lots of hardware hanging down under the car? is it posible to mount it higher and still achieve a low roll center with changing the angles of the moving parts?

and your saying that "roll centers" are a waste of time, and are a myth? (i read your link you posted)

[Kid Karola]

Haven't all bommadores been IRS since VP or are utes and wagons still live axle?
But we digress, I guess he means V8 Stupidcars use Watts link rear ends.

Ideally you'd install equal length rear 4-links on AE86 before (or at least at the same time as) considering a Watts linkage, otherwise you will not have the full benefit from it.

If you want to change rear roll center with much less cost and effort, you could by simply moving the mounting point of the lateral rod like so:

Jubiride bolt on http://www.jubiride.com/upload/FO02-20071228133924-1.jpg http://www.ae86drivingclub.com.au/dcimages/1/1/1/9/30934.jpg

Cusco/Revolver weld on http://www.turbowholesale.com/thumbs/t_6376.jpg http://www.ae86drivingclub.com.au/dcimages/1/1/1/9/30936.jpg Offsets 50mm

Although this still presents the same arching effect with panhard rod. Watts link can move roll center and keep diff cenrtal.

[Frak]

Frak please bear with me as im trying to get my head around all of this.

i have looked into this mumford link and all the setups i can find are mounted well below the diff leaving lots of hardware hanging down under the car? is it posible to mount it higher and still achieve a low roll center with changing the angles of the moving parts?

and your saying that "roll centers" are a waste of time, and are a myth? (i read your link you posted)


Hi Tim,
Have a good look at Mumford links, I haven't seen too many at all that hang low, changing lengths of link arms on a mumford changes position of roll centre.

Re-read both my post in this thread and the link AGAIN and focus on FORCED roll centre ;) When suspension is moving the roll centre is moving(all over the bloody place!), we all get transfixed on this roll centre being in a fixed position. When the penny drops on this fact you will then understand why I have said the things I have a few posts up.

Hey Karl, I'm quite sure the cusco rear weld on moves it by 25mm, I have one kicking around at home will measure up when I get home :))

[Kid Karola]

maybe, thought it was same as Revolver one? Can you take a pic of yours fitted for everyone playing at home ;)

[Frak]

Karl, if you look in the 4-link thread in technical, I have a picture of it there. How ya going mofo?

[Kid Karola]

Weld on piece made by Cusco, welds to diff side of panhard rod, lowers mounting point 25mm.

http://img130.imageshack.us/img130/7426/rearroll.jpg (http://img130.imageshack.us/i/rearroll.jpg/)

have you welded it on yet? (Thought you got this ages ago :yeah:) Also the body side mount should ideally be offset by equal amount.

http://www.ae86drivingclub.com.au/dcimages/1/1/1/9/30939.jpg

[Frak]

No I ended up doing something else ;)

[Javal]

sorry, as you can tell, i dont know much about holdens.

didnt know you were so into them; that me presuming watts link was a new thing for em would offend you

Oh, it doesn't offend. It's more that they've had IRS for the last 15 years, i'd have thought even the punter knew that.


^^^its more the fact that slide and javal are both angry holden mechanics...

fixed.

[Tim.duncan]

Re-read both my post in this thread and the link AGAIN and focus on FORCED roll centre ;) When suspension is moving the roll centre is moving(all over the bloody place!), we all get transfixed on this roll centre being in a fixed position. When the penny drops on this fact you will then understand why I have said the things I have a few posts up.


Tim sits scratching his head...... thinking..... pondering..... tink tink tink a small penny drops and lands on the ground

the roll center moves around and changes! man that makes sense. but at the end of the day isent being able to get the roll center (moving or not) as close to the ground as posible better? and this is easier to do with the watts or mumford link than the panard?

im wanting to change to latral system as all i have is a stock panard, id be keen to give the mumford ago.

the only info i can really find is from all the locust 7 boys who run there links below the diff center because of where the diff is mounted threw the back of the chasie

[Tim.duncan]

jIiEV0DILBw

mumford link in action

[DX20VT]

but at the end of the day isent being able to get the roll center as close to the ground as posible better?




you may be thinking of centre of gravity of the car,


I have adjustable roll centre on the panhard rod in my race car,
and if you wind it too far up or down it makes it a real handful to drive,
have to find a happy medium in the middle,

and it doesn't really matter how far the actual var is from the ground,
it only to do with the angle of a straight line between the the two pivots,
and horizontal.

We looked at watt's linkage, but we run the rod near parallel to the ground anyway, and there's so little up and down suspension travel on the track,
it doesnt move the diff left/right much at all.

[Sam-Q]

a bit of an update. I have been doing my measurements and I am going to go ahead with my watts link conversion. I am just getting the bits I need together and will slowly make the bits. I am in no rush so it will be a while before it's in my car.

[Tim.duncan]

you wouldent bother giving the mumford ago?

also with the watts are you going to mount the link on the diff? or on the car? some have mounted there link off the diff to keep sprung weight lower.

[Sam-Q]

I don't get the point of the mumford, whats the benefits?

I was going to put the link on the diff originally, I measured everything up and I could fit it without too much issues. Now I want to put it on the body. I think I will have a mounting mechanism off the bottom of the sub-frame that goes between either side of the car thats between the fuel tank and diff. This will mean I will be able to adjust it to see exactly how it affects the car.

The pivot points will have to be fairly low on the diff housing to clear the upper trailing arm mount on one side of the diff. Either that or I go shorter arms.

[fantapants]

http://www.performanceforums.com/forums/showthread.php?t=67233563&page=2

hey sam, check this thread for a good look at making cool shit :)

its an ex v8 supertaxi watts mount and he makes a tidy adjustable rollcentre mount also.

good for ideas :)

[Sam-Q]

yeah that is interesting, and thanks heaps for the link. For everyone else I will shamelessly nick these pics to post here:

http://www.ae86drivingclub.com.au/dcimages/2/5/2/34528.jpg

http://www.ae86drivingclub.com.au/dcimages/2/5/2/34529.jpg

http://www.ae86drivingclub.com.au/dcimages/2/5/2/34530.jpg

I didn't think they could adjust the rear roll center on the go, infact in my ignorance I didn't know that it was even that critical to justify the adjustment.

[Sam-Q]

found this:

http://texaslocost.homestead.com/files/img_0267.jpg

http://texaslocost.homestead.com/Suspension.html


and his drawing:

http://texaslocost.homestead.com/tp.gif

I don't get it


Also I have moved this to the tech section, seems more appropriate

[Sam-Q]

ok found out why:

http://www.bevenyoung.com.au/mumford%20linkage.htm

"The beauty of this thing is that the virtual point C is your roll centre. The astute will quickly recognise that if you shorten the distance AE, the roll centre rapidly disappears into the ground and below"


I will go the inboard watts link thanks

[ArbPotatoes]

I don't get the point of the mumford, whats the benefits?

I have no idea of any of this, but from what I've read with a mumford link you're theoretically able to get the roll center below the ground.

[Tim.duncan]

yeah from the little i understand and know it is a slightly superior system to the watts, in its adjustablity. i have also toyed with the idea of trying one of these 2 options for my car. Still not sure if all the hard work is worth it for a street or even track drivin car? some have said the diff dosent move up and down far enough that the panard rod has a negative affect. I would think you are very similar to me sam and want to do it just for the hell of it and to learn somthing new! so i might still have a crack to ha ha

have also read that article frak posted about roll centeres being a load of crap and not really that important?? my head just hurts after reading it is important and this is how you adjust it to who cares it means stuff all..... still trying to get my head around the whole thing.

either way I WANT PICS of everything you do sam, good luck with it

[Sam-Q]

yeah I consider all options and appreciate the suggestion. I had a think about it and it has too many design issues for me. I guess the main one is it's a pain to make something adjustable with it.

For mine I will either get a block of polyurathe soon or I will use a spare pan-hard rod bush for the center pivot. From here I will make my center section.

[blair]

you may be thinking of centre of gravity of the car,


I have adjustable roll centre on the panhard rod in my race car,
and if you wind it too far up or down it makes it a real handful to drive,
have to find a happy medium in the middle,

and it doesn't really matter how far the actual var is from the ground,
it only to do with the angle of a straight line between the the two pivots,
and horizontal.

We looked at watt's linkage, but we run the rod near parallel to the ground anyway, and there's so little up and down suspension travel on the track,
it doesnt move the diff left/right much at all.

This is probably the best post in this thread. Some first hand info!

And its also the thing that applies most to (i'd say) the majority of guys on here who are running 8/6kg springs, thicker swaybars etc...

How much do you actually think your shit's gonna move up and down to warrant going to a system where you dont get left-right movement because of this?

Or are people considering it for other major advantages?
(Ive read through the whole thread and cant really see any other significant pro's)

[Sam-Q]

yes there is one more significant advantage that is a greater thing for me than the lateral control. It's the fact that the bar when cornering doesn't push into the body and make the car tilt up on the outer edge. I do have a decent amount of travel with 4kg springs in the back.

I wish I could talk about more than just theory but it's all I have apart from some feedback from a guy I know. I plan on doing it and then reporting back on how it is.