[Chewy72ss]

Hello all,
I recently came across this company, Totally Polished. They offer a Watts link kit for around $500. I am seriously considering getting this setup for my '72. I would like to gather the thoughts of other, more knowledgeable TC members before I purchase anything.

What is your opinion on a watts link in a Chevelle??
What benefits would be had with this setup??

Check it out and let me know what you think...
Totally Polished Watt's Link Kit-

[Brettd85]

Thats really cool. I love the video. I dont really know much about the setup.

I assume it still uses stock control arms and such?
The watts link is just to keep side to side movement zero?

Wish I could help you, but all I have are questions.

[70L34]

In my experience, a well designed Watt's linkage will have the pivot anchored to the chassis. The Watt'slink pivot location is one of two points that defines the roll center height of the rear suspension. If the pivot is anchored to the axle, as these kits seem to be, the pivot point, and hence, the roll center height, vary with jounce and rebound causing variation in the rear roll stiffness. On another note, the converging 4-link rear suspension on the Chevelle will already react lateral stiffness, due to the inclined angle of the upper control arms. A Watt's link is not truly needed for it to function properly. If you're curious, a good Watt's link design is made by the folks at Lateral Dynamics: http://lateral-dynamics.com/. Hope this helps.

[jfman]

Originally Posted by Brettd85

The watts link is just to keep side to side movement zero?

.

Yes basically.

I have seen this in a new car as well. I think it was the newer crown vics

[vrooom3440]

Dodge Durango has one.

They are a lateral locating device so they keep the axle from moving side to side. Added onto a stock Chevelle they would move the rear roll center to the pivot of the center rocker arm. You would no longer need two upper links and could instead replace them with a single link for torque control.

To me this seems like a lot more hardware than is required to achieve almost the same results. I prefer a nice long panhard bar myself.

[Mark SC&C]

The problem with a watts linkage on a Chevelle is that you`d get conflicting roll centers,one defined by the upper control arms and one by the watts linkage as Tony pointed out. The advantages of mounting the watts to the chassis are IMO theoretical in this application (street car). Compared to the factory way too high rear RC that migrates all over creation the RC of a decently designed axle mounted watts is about an order of magnitude better! It`s still better than a good panhard bar. Of course it`s just as or more important to eliminate the stock C4L suspension`s non linear binding characteristics... Mark SC&C

[jfman]

Do you have a picture of a panhard setup ?

[vrooom3440]

Here is a backyard engineering example under a '68 El Camino:



One of our TC members "dennis68" did this one. Personally I would have mounted it a bit lower. The rear roll center (RRC)on a PHB is located where the bar crosses the center of the car. So on Dennis' setup the RRC moved from the top of the pumpkin (where the upper control arms intersect) to the middle.

[jfman]

Thanks for the picture...

Wouldnt this setup cause slight lateral(side to side) movement of the axle in relation to the chassis ?

The bars movement creates a radius and the lenght is slightly affect as the axle moves up and down correct ?

[vrooom3440]

Doesn't the RRC on a watts link run right through the center of the pivot on that middle link?

If so mounting that on the chassis would result in the RRC moving up and down as the suspension articulated vertically. A PHB would reduce this to 1/2 the movement. And mounting the watts on the differential would reduce it to zero.

I guess keeping the RRC fixed could be a good thing... any impressions or experience with how big a deal this is?

[vrooom3440]

You are correct. Of course it depends on the length of the PHB and angle at which it is mounted. Optimally the bar is long and horizontal.

Just for giggles let's do a bit of napkin engineering... For a 48" bar it will move 1* for every 0.84". If we use +/-3" suspension movement we get about +/-2.5* swing of the PHB. The cosine for 3* is .9986... meaning that the 48" bar just moved the axle 0.0672". Or not very darn much

[jfman]

Originally Posted by vrooom3440

You are correct. Of course it depends on the length of the PHB and angle at which it is mounted. Optimally the bar is long and horizontal.

Just for giggles let's do a bit of napkin engineering... For a 48" bar it will move 1* for every 0.84". If we use +/-3" suspension movement we get about +/-2.5* swing of the PHB. The cosine for 3* is .9986... meaning that the 48" bar just moved the axle 0.0672". Or not very darn much

The longer the bar, the better.. correct? As the radius made by the bar's movement increases, the sweep in degrees compare to inches of travel decreases so it affects the sided moveemnt less and less.

How much is the panhard setup ?

[Brettd85]

Thats an interesting pic. I also noticed he moved his lower control arms further out, and are at nearly 0 degrees. Why didnt he stay with the stock ones?

[Elusive_R]

That looks like a nice kit, but I'm not sure I'd go with the diff mounted setup. If you're going to do a Watt's link, you're probably planning on pushing the car hard, so you'd need way more bracing than this one provides. As mentioned, compare that to the LD design and you'll see which one is for show trucks and which one is for road racers. Either way, for a street car you really can't beat a Panhard bar for cost vs. impact. This is of course assuming that you're switching to a 3-link as well.

Ryan

[Elusive_R]

More pictures of a 3 link/panhard bar in my signature link. My PHB isn't optimal, either, but it works just fine for now.

Ryan