Unusual Watts link design + general watts link discussion.

[slide86]

I was at the track today, stuck my head under a MK1 escort and spied this below. I remembered you talking something bout this not to long ago.

I took some pics for you to get ideas, sorry if they arent the best quality.

(Note: the engine in this car was a 200hp atmo Duratec engine...and this is still leaf sprung rear)

http://www.ae86drivingclub.com.au/dcimages/5/55539.jpg

http://www.ae86drivingclub.com.au/dcimages/5/55540.jpg

http://www.ae86drivingclub.com.au/dcimages/5/55541.jpg

[toygt]

the big question is how iy mounts to the diff its very similar to a v8 supercar and how there adjustable watts linkage goes

[Gunner]

That looks really complicated.

Did you get any shots of how/where it mounts to the diff? A wider angle shot maybe?

[H8CHIR6KU]

i dont know much about watts linkage setups but is it really worth the effort?

[Gunner]

from my understanding, it allows the rear end geometry to remain "square" throughout its travel. Unlike the panhard which travel on an arc. But I don't really know what I'm talking about so not sure.

[shift_rook]

yeah gunners right, it wouldn't make a maaaasdsive difference but it could possibly help shave 10ths off a lap time, under compression the rear end remains squars instead of moving sideways

[timbo]

keeps it square thus more traction. i'm sure you would notice the difference in a light weight car like an escort with quite a bit of power.

i think that whole piece behind the diff housing is actually attached to the diff itself.

cool pic here: http://www.brockeng.com/mechanism/Watt.htm

[pen15]

i remember seeing a kit you can buy on yahoo auctions for a watts link on t-series for ae86 in japan there is simpler ways to do a watts link than that setup i also know a bloke with a watts link setup on his ta22 i can get photos next time i see it

[Gunner]

http://www.ae86drivingclub.com.au/dcimages/3/5/550965.jpg

Something like this or like this, I think is a relatively viable option,

http://t3.gstatic.com/images?q=tbn:LVz_ZrfH856XYM:http://www.onelapcamaro.com/build/rearsuspension/LD%203-link.jpg&t=1

I don't think it is something that needs to be overly complicated, like the first series of pics.

[timbo]

^ exactly.

http://www.ae86drivingclub.com.au/dcimages/3/1/1/3/55551.jpg

http://www.ae86drivingclub.com.au/dcimages/3/1/1/3/55552.jpg

[Anthony]

I still think its better to try and put the pivot arm on the body, and the two pins on the diff.

Can I ask ppl's motivation for doing it? I thought the only real plus was the ability to keep geometric symmetry whilst adjusting the rear roll centre. Unless you have a circuit car, which is competition only, and you understand it well enough to go hunting for those last few tenths, it seems like a lot of work for not much gain :)

[timbo]

I still think its better to try and put the pivot arm on the body, and the two pins on the diff.

paint is your friend anthony! (mainly mine so i can understand what you mean...)

[timbo]

a cheap way of doing might be to modify a watts linkage off an au falcon (last with live axle).

[Gunner]

I'm using au gear as a base, though it will be set up as per those pics, with the pivot mounted to the body, so it will be adjustable.

My motivation is I dont want to worry about getting roll centre wrong, atleast if I build an adj. watts link it can be made right. Might be a piss poor reason, but with the lengths I have gone to, why te fuck not

[ke70dave]

just remember that the "problems" associated with 4 link with the arc are only evident if you allow the suspension to actually travel.

if you are going to be using the car for drifting, you will be using uber stiff springs that wont allow suspension to travel very far, thus you the geometry changes wont be such a problem.

also that first photo, since its still leaf rear end, all those pipes are just a glorified panhard rod. since leaf spring rear ends dont come with a panhard rod as such.

its just a way to keep the diff in the centre without inducing the diff to move in an arc, which happends with when you install a panhard rod.

that first setup is pretty sweet though, alot of thought has gone into it.

[Delazy]

i remember seeing a kit you can buy on yahoo auctions for a watts link on t-series for ae86 in japan there is simpler ways to do a watts link than that setup i also know a bloke with a watts link setup on his ta22 i can get photos next time i see it


http://www.rhdjapan.com/media/catalog/product/cache/1/image/5e06319eda06f020e43594a9c230972d/60906/Image/Normal/Image1.jpg

[toygt]

lol that pic of the white 86 with the watts on the hilux diff is my car!!

[Gunner]

http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fwww.ss-works.jp%2F


Edit: this is the one

http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fwww.ss-works.jp%2Fpartslist4.html

[H8CHIR6KU]

gotta love the japlish on that site

[slydar]

the advantage is roll center adjustment. as ant said. when you weigh it up. its not really worth it. especially when you consider a large majority of us run very hard suspension. and dont race. equal length 4 link is easier and will make a (much) bigger difference.

p.s. the escort still has leaf springs in it probably cos its an IP car. and theyre not allowed to fully remove/change things, but are allowed to add stuff.

[Delazy]

http://www.ae86drivingclub.com.au/dcimages/2/5/4/6/55579.jpg

http://www.ae86drivingclub.com.au/dcimages/2/5/4/6/55580.jpg

http://www.ae86drivingclub.com.au/dcimages/2/5/4/6/55581.jpg

http://img23.imageshack.us/img23/8494/p1010172c.jpg

using AU falcon watts link...

[mitchy]

thats a heaps simple design.

but with out the adj. roll centre i cant see the main advantage

mind you a setup like that is only a half day install.

[timbo]

delazy thats awesome! i see you are going equal 4 link too. what did you make the arms from?

[Delazy]

should have made it clear it isnt my setup....

actually one of the other local tassie boys...

http://www.ae86drivingclub.com.au/forums/showthread.php/17446-Tas-Ae86-s-Trueno-Track-Drift-Car-Build/page7

[Sam-Q]

slide 86, thanks for posting. I have been looking at the pics for quite a while now and I have just figured it out. This is not a watts link design, it's a pan-hard with an adjustagble roll cente design. Let me try and explain:

the horizontal bar on the left is the pan-hard. this joins to the pivot which is the internal hex countersunk bolt you can see through the slot. That's the roll center point.

This pivot attaches to an assembly which slides inside the housing, this inner assembly is supported by the sliding adjustable pivot on the bottom and the rod end at the top. The bottom nut is the adjustment point and in the photo is set to have the lowest roll center. All of the diagonal bars are reinforcement for the outer housing which handles half of the loads of the pan-hard. These, the top linkage and the bottom bolt do not move in driving use.

There is no doubt someone really switched on designed and made this but I am unsure about it, sure the person has made at adjustable roll center that needs only a spanner to move but it means that the pivot is moved to the center. Well assuming that it's originally off one far side he has halved the effective length of the bar. I think something bolted directly do the leaf spring saddle would of been better. He could make a few for different heights too, sure he couldn't adjust it in 5 mins like this one but it would of been lighter and stupidly simpler with half of the sideways diff movement. But hey I could be tottaly missing something here.

Edit: I now think for sure I am missing something as I am having trouble imagining how the force is transmitted to the diff housing through the top linkage alone.

[timbo]

oh haha cheers for the link mate! hope your build is going well!

[Delazy]

oh haha cheers for the link mate! hope your build is going well!
lol, no problem champ, my build has hit another hurdle, that of cash money...engine has well and truely drained the bank account at this point in time...so living on baked beans and noodles lol :s

[timbo]

living on baked beans and noodles lol :s

join the club!

back on topic, is there anyone else on here running a watts link setup on an ae86?

[Gunner]

slide 86, thanks for posting. I have been looking at the pics for quite a while now and I have just figured it out. This is not a watts link design, it's a pan-hard with an adjustagble roll cente design. Let me try and explain:

the horizontal bar on the left is the pan-hard. this joins to the pivot which is the internal hex countersunk bolt you can see through the slot. That's the roll center point.

This pivot attaches to an assembly which slides inside the housing, this inner assembly is supported by the sliding adjustable pivot on the bottom and the rod end at the top. The bottom nut is the adjustment point and in the photo is set to have the lowest roll center. All of the diagonal bars are reinforcement for the outer housing which handles half of the loads of the pan-hard. These, the top linkage and the bottom bolt do not move in driving use.

There is no doubt someone really switched on designed and made this but I am unsure about it, sure the person has made at adjustable roll center that needs only a spanner to move but it means that the pivot is moved to the center. Well assuming that it's originally off one far side he has halved the effective length of the bar. I think something bolted directly do the leaf spring saddle would of been better. He could make a few for different heights too, sure he couldn't adjust it in 5 mins like this one but it would of been lighter and stupidly simpler with half of the sideways diff movement. But hey I could be tottaly missing something here.

Edit: I now think for sure I am missing something as I am having trouble imagining how the force is transmitted to the diff housing through the top linkage alone.

Maybe it's a mumford link?

[Delazy]

more detailed pics of the ss-works japanese kit

http://www.ae86drivingclub.com.au/dcimages/1/9/3/55610.jpg

http://www.ae86drivingclub.com.au/dcimages/1/9/3/55611.jpg

http://www.ae86drivingclub.com.au/dcimages/1/9/3/55612.jpg

pics of the kai power japanese kit...

http://img227.auctions.yahoo.co.jp/users/4/2/9/7/ker9280-img600x450-1188451938ae86_wl-kit-1.jpg

http://img227.auctions.yahoo.co.jp/users/4/2/9/7/ker9280-img600x450-1188451970ae86_wl-kit-2.jpg

http://img227.auctions.yahoo.co.jp/users/4/2/9/7/ker9280-img600x450-1188452004ae86_wl-kit-3.jpg

[Sam-Q]

another point about watts links designs is that with a pan hard on cornering your car effectively pivots on the mounting point of the pan-hard pin.

I do think this has a place on the street, for me I have a decent amount of travel and drive through some rough corners at a resonable speed, I think it has a good chance of helping, on a track I doubt it would help much if at all.

I think that in ture tradition of making severly compromised rubbish products just for the sake of being bolt on the S.S works kit tics all the right (wrong) boxes. Unequal arms, expensive and the top mounts seem to be held on with two bolts and nuts! Hey whats the link for that video with that famous drift king guy where he shows it in action.


Gunner: those are adjustable roll center designs, this is what interests me. I have worked out a way that I have just enough room to clear my over diff exhaust

timbo: yours? unfinished I assume.

Delazy: I like the simplicity but I don't like how that guy made it on how the up and down forces feed into the housing and with that bracket. I think from the pics alone that it's going to have flex. Looks heavy too.

[timbo]

sam-q, mines still at mental stages! its a concept i've been thinking about for some time but always tried to weigh it up to see if its worth doing. mind you this thread has re-ignited my interest!

i would agree with you comment on the mounting on the bracket. not sure how those welds would hold up. most of the racing setups i've seen have a removable rear diff housing with a new one in place with the watts link mounting point cast as one. i'm still trying to find a picture of a v8 supercar diff, i'm pretty sure they use a EL falcon type rear end with watt link.

[Delazy]

Hey whats the link for that video with that famous drift king guy where he shows it in action.

i had it bookmarked...since been deleted due to "copyright" claims

[Gunner]

So I am curious as to why some of you guys have said that a watts link is somewhat pointless, are you talking specifically about drift cars, due to the use of a generally stiff set up, or any stiff car?

From what I can gather, we use a watts link when we want to adjust, rear roll centre, to move the roll axis of the car, thus affecting turning/handling characteristics. We mount the pivot to the body, so as the car travels on its suspension the rear roll centre remains somewhat perpendicular to the front roll centre, which adds stability to overall handling.

I understand how a stiff spring/shock/swaybar set up, allows less body roll, but how do you tune stability into the car if we can't adjust rear roll centre? And specifically keep it in line with whats going on in the front?

I know oversteer is desirable in drift cars, but what about a stiff road or race car, where we want to limit sideways action?

[Gunner]

ALso forgot to ask, moment arm is that actual body roll (of the chassis) or the lateral load on say a live axle?

[Sam-Q]

gunner: nah I know what a mumford look like and this isn't it.

Delazy: excellent pics, you posted while I was in the process of writing mine. I have never seen that kai power model before, look reasonable enough although it does look a little flimsy overall.

timbo: well it's looking good. The way you have braced your pivot is simular to what I had in mine for my own design before I decided to try and go for an adjustable design.

[timbo]

oh sam, that isn't my setup! thats just some google images i found that looked the goods!

but i would agree with its design, looks very strong. i have been reading up on the watts links on later model falcons and what tickford did to improve roll centre by lowering the diff mount by 20mm. would it be worth while running an adjustable setup with higher and lower mount points?

[Sam-Q]

I have no idea on any of it but I will go for an adjustable design. I was initially going to go for the diff pivot and have it braced just like the pic but I will do the other now. I decided on a center bar that has the pivots 60mm plus and minus on either side of the center pivot. This center pivot would be a polyurathe bush while the other 4 links would be spherical rod ends greased up inside rubber boots.

Speaking of boots I am looking at these on ebay:

http://cgi.ebay.com/ebaymotors/Seals-it-RERS-3-6PK-Rod-End-Rubber-Boot-Heim-joint-boot-/320594446603?pt=Motors_Car_Truck_Parts_Accessories&hash=item4aa4eb090b

http://i.ebayimg.com/23/!BOdH+6QBmk~$(KGrHgoH-CoEjlLlfZ3LBJu)GgcIwg~~_12.JPG

[timbo]

so where does it attach to the diff, either side of the rear housing?

those boots are a good idea!

[Gunner]

So I am curious as to why some of you guys have said that a watts link is somewhat pointless, are you talking specifically about drift cars, due to the use of a generally stiff set up, or any stiff car?

From what I can gather, we use a watts link when we want to adjust, rear roll centre, to move the roll axis of the car, thus affecting turning/handling characteristics. We mount the pivot to the body, so as the car travels on its suspension the rear roll centre remains somewhat perpendicular to the front roll centre, which adds stability to overall handling.

I understand how a stiff spring/shock/swaybar set up, allows less body roll, but how do you tune stability into the car if we can't adjust rear roll centre? And specifically keep it in line with whats going on in the front?

I know oversteer is desirable in drift cars, but what about a stiff road or race car, where we want to limit sideways action?

No one can answer this?

[takai]

You can mimic it by adjusting spring and shock rates and swaybar settings.

[Anthony]

Oversteer isn't desirable in any car. For drifting, ideally you want to have to really shock an inherently stable car into some brief oversteer, then produce relatively controllable understeer for a long period of time :) A circuit car too generally wants slight understeer on the limit.

Theres no doubt adjustable rear roll centre may help you achieve that setup, but there are many things which are easier to achieve which may be more helpful.Considering that adjustment will be performed once, twice if lucky, I just see a panhard drop as better value :)

[Gunner]

Ok thanks Anthony, I see where you are coming from. I'm still going to do it :)) For what I want to do, and the power I eventually want to put through the car, I think it is worth the bit of extra effort to have that bit more tunability.

Thanks guys.

[toygt]

this is what i'm using in my race car now14179

[Gunner]

pic doesnt work dude, try using photobucket or something to host it.

[mitchy]

how are you mounting that to the diff?

[Gunner]

Thats cool.

I would hazard a guess mitchy and say it mounts to the body, and the knob goes in the boot for easy adjustment, could be wrong though.

[mitchy]

what attaches to the diff then?

i cant really get my head around the adjustable setups?

[Gunner]

the two bars/arms

basically you just reverse is, so where the two arms mount to the diff usually, they now go to the diff, and the pivot on the body.

[takai]

Yup, its a pretty damned good design. Much easier to adjust than the pivot on the diff.

Who makes that center mount?

[Gunner]

Guessing it wouldn't be cheap

[roadsailing]

I'm going to try a satchell link on something, but i invented what i call the X link which is similar to the mumford link, but more symmetrical. satchell link is just about as simple as it can get.

http://www.vpmcobras.com/images/satchell1.jpg

http://www.vpmcobras.com/images/satchell3.jpg

[Gunner]

So its like a tri link? I was told that you would need a panhard rod or watts link to run that sort of set up, to achieve the right roll centre.

I wanted to run my rear end like that, but with the diagonal bars on the top, and the narrower point on the diff. Mainly so I didn't need to build a watts link.

Whats the chassis for?

[roadsailing]

nah its not like a 3 link, the lower links do the lateral and half of the fore/aft location. from some jag racecar some guy built.

looking at some other pictures you could use an equal length 3 link on a sprinter with a watts/panard and still kinda have two rear seats.

[timbo]

this is what i'm using in my race car now14179

by far the best design yet. easy to adjust and looks extremely solid.

[toygt]

the arms off the pivot mount to the diff the plate mounts to the body and the adjuster is in the boot i'm changing mine to remote adjuster like on a wilwood pedal box brake bias, the mount on the diff looks like two panhard rod mounts
just like a v8 supercar

and that one for sale on trade me for 3200 kiwi i machined mine at home on my mill it took ages but is worth it doing it yourself

[Momus]

The device mounted to the rear of the Escort at the head of this thread is a WOB link.
Much of it is hidden because the rocker that mounts to the chassis is in double shear and covered by the mount.
It consists of a vertical rocker pivoted at it's lower end (in this case by a Delrin bush) with a long rod ended link in the middle and a shorter one at the top.
Both the links are mounted to the diff and on the same, passenger side.
The roll center is the lower pivot point. WOB links behave very much like Watt's links but can be arranged to give a much lower roll center.

On the Escort with leaf springs and no trailing arms the roll center needs to be in sync. with the springs to prevent bind. On a decent 4 link set up they can go a lot lower. I run a WOB on a Sports Car with about 55 mm of ground clearance
The WOB is correctly mounted with the chassis pivot, as proper Watt's links also are. This is better structurally but the main reason is the roll center and center of gravity are fixed. This distance is what is being adjusted by the knob on the V8x unit pictured back a bit.
On a diff mounted Watt's, like a Falcon, the COG and roll centrer move relative to each other. This means, among other things that the leverage acting on the springs, stabiliser bars and dampers (shocks) is varying.

[Anthony]

Thanks for the info. that makes sense :)

[Gunner]

It looks alot more complicated in those pics haha. Must be some what of a dark art though as there isn't much info around.

A wobs link wouldn't be compatible with a 4 link rear? Wouldn't be able to hold anything on centre would it? So it is only for roll centre?

only pic I could find of a wob link, and thats how it appears to me.

http://www.lescanfield.info/images/AA_Woblink_intresting.jpg

[Gunner]

http://www.lescanfield.info/rear_geometry.htm

Some good pics of various rear ends and other stuff.

[Momus]

It looks alot more complicated in those pics haha. Must be some what of a dark art though as there isn't much info around.

A wobs link wouldn't be compatible with a 4 link rear? Wouldn't be able to hold anything on centre would it? So it is only for roll centre?

only pic I could find of a wob link, and thats how it appears to me.

http://www.lescanfield.info/images/AA_Woblink_intresting.jpg

The WOB is very compatable with a 4 trailing arm live axle suspension. The lower pivot defines the roll center and holds it.
The effectiveness of the lateral location and the holding of the straight line geometry is as good as the Watts.
They are very stiff and strong if designed correctly.

The Escort installation is overly complicated probably because it was his first go and he has put everything into double shear.

[Gunner]

Cool I get it, thanks momus. Welcome to DC.

[takai]

Whoah, Momus on DC.... valkommen zu.

[PRIMRK]

http://www.ae86drivingclub.com.au/forums/attachment.php?attachmentid=14180&d=1288128959

where can you get these units form? I've been looking for em but I'm not 100% what to call it to help my search...

[Sam-Q]

that's an in car adjustable watts linkage, looks like an ex "super-car" unit

[dustyae86]

INteresting to stumble across this thread, may be a while off but I am going to be doing this to my car. Luckily I have the help of alot of very very switched on guys. I will try to get a pic of a v8 supercar rear end tomorrow at work, it really isn't that difficult to make, it's just the setting up of the roll centre whihc is the issue, but as has been said. WHile you are at it you may as well have a 4 link and all the other bits that are going to add to it, if you are running standard arms and falcon shocks or soem rubbish it is fairly pointless, because YES you do get a better handling car but it is one of those finer things that could be done oh so right yet oh so wrong and make you have a lot more comfortable car to drive on teh limit

[DX20VT]

So I am curious as to why some of you guys have said that a watts link is somewhat pointless, Not that a watts link is pointless, more that a non adjustable watts link is pointless.

Putting the diff mount in the centre of the diff head is not always the right place,
without some up/down movement of the centre pivot you are only getting 50% the advantage for 90% of the work.

I run adjustable roll centre on a panhard rod on my car, as with the full length rod and the small suspension travel there was no advantage going full watts link when you can go adjustable with a panhard rod.
And it doesn't take much movement up and down for you to notice the difference,
so a watts link centre point would not have to be far out of place for it to be a backwards step for a lot of work.

[Gunner]

And thats why we make them bodymounted, and adjustable. My biggest hang up is the sideways articulation (cant think of anything else to call it) that a panhard generates throughout suspension movement. I'm no scientific engineer fella, but it would have to have some sort of negative effect on the car while moving through its suspension travel.

From what I can gather from all this suspensio hoo ha, is roll centre, and square geometry is whats important, although a panhard can give you correct roll centre, it can not give you square rear end geometry, its design will always lead to inconsistancies in geometry while travelling through its articulation.

I am probably way off, but its how it works in my head.

[fantapants]

holly shit momus on dc.... should be interestng :D welcome mate!

[DX20VT]

Not far off,

but in my case as the rod is near parallel to the ground when adjusted correctly anyway,
the sideways movement in normal suspension travel is less than a couple of mm,
so not worth building a watts link to correct that. Lots of other places to spend that time and money that will achieve more gain in my case.

Jack the car off the ground and let the diff hang full droop and the diff just about hangs out the side of the car though.

[Gunner]

Ah k, cool I get ya.

[PRIMRK]

Any ideas where one could source ex-super car watts link triangles from?!? ill be calling round tomoz to try find one but if some one here could point me in the direction to start with.

[toygt]

Any ideas where one could source ex-super car watts link triangles from?!? ill be calling round tomoz to try find one but if some one here could point me in the direction to start with.

http://www.trademe.co.nz/motors/car-parts-accessories/performance/suspension-braces/auction-390128175.htm

is that what your looking for?

[Sam-Q]

predictably expensive, two plates and multiple drilled holes works for me

[Gunner]

yeah my roll cage is not much more expensive ($3800), and that includes in car adj, watts.

[toygt]

its like anything you aint going to get topend stuff for nothing and anything ex v8 supercar aint cheap

[slydar]

who is momus?