Watts Link or Panhard Bar...what do you think?
 

Scott, Roger, Richard or others help me out here:

I am addressing my rear suspension and I want to install either a Watts Linkage or a Panhard Bar on my rear end. What are your suggestions and why? What brand would you suggest? Aluminium or steel?

I am less than 2 seconds off the track record for a full bodied car at one our local tracks and I think I can get there with a little tweeking of my suspension.


Clois

Go with a Pahhard bar. Watts links are neat, but if your car doesn't have much wheel travel, they are a waste of time, effort and weight. Just make sure you have the track bar fairly level with the ground at ride height and right on your desired roll center. You could try brackets with adjustment holes so you could find out the right rc position for your car.

Go with steel tubing with threaded spuds in the ends to accept spherical rod ends. Or, just use a heavier-wall tube and thread it. Axle and frame bracketry will be the biggest fabrication challenge. I imagine you can find brackets from a stock-car catalog, then cut and fit as desired.

By the way, what are you using to locate the rear axle now? Assuming it's a bouncing axle, have you considered an IRS?:D

I am using a 4 link suspension with aftermarket upper and lower control arms. Kept the rubber bushings in the uppers and used the harder polyurethane bushings for the lower control arms.

I have considered an IRS but to fabricate it would be a nightmare since my car has been on the road six years. I do pretty good with a live axel but I still have options that can improve my handling.

IRS is definitely a better set-up but not feasable for my Cobra right now.

Clois

You are going to need about 4 seconds. I think I can get the record by at least 1 second!:D I am really looking forward to Hallet in June!

You can purchase a nice piece that bolts to the pinion support that gives you several holes to choose from that they use on stock cars, and also they have a box that the rod end fits in that allows adjustment that you can attatch to the frame...pretty easy stuff. I'm not sure of the name but I believe it is common to what all the local stock car guys are using. I can find out if you are interested....

I thought you might find this link, Dean. I think we may have something for the track this year!

Clois

Take a look at Levy Racing (Scottsdale, AZ). Gordon has about the best set up kit for live axle go-fast handling.
Dean

Clois,

I have built and driven both pan-hard and watts link axel locators. The pan-hard bar is definitely easier and cheaper to fabricate. However, there is a difference in how the car handles. The roll center on the axel side of the bar is constant. The roll center on the chassis side “floats” based on body roll. When you set up the bar, you adjust it to be parallel to the ground. In this position, the roll center is the same, when you turn the car (in the direction that causes the body to rotate about the chassis end of the bar) the body roll causes the chassis end, attachment point to dip, making it lower than the axle side. The result is different handling characteristics in left and right turns.
A watts-link has the roll center “fixed” about the center pivot point. It never changes left to right.
IMO, If you were building a combination street/track car with packaging and budget limitations. I would agree with the P-bar.
If you are going for track records, go with a Watts-link.
I don’t know what type of four link you run, but I have had excellent results with torque arms. They can really help put the power down coming out of the turns.
If your in the “buy” vs. “build” mode, I recommend Griggs Racing in Sonoma, Ca. They have a tremendous experience and a long winning history with stick axels.
http://www.griggsracing.com/

Jason

As Jason said,
Watts is the way to go.
My opinion Watts is better than IRS.
When a IRS car takes a turn the body/frame will roll and since the IRS unit is mounted directly into the body/frame it also rolls.
With the weight transfer from cornering and the body/frame/IRS unit rolls, the inside tire inherently wants to raise from the ground and causes loss of traction of the inside tire.
There are several way of correcting this kind of traction loss.
1.Adding suspension travel so that the tire doesn't loose contact with the ground when cornering.
2.Removing suspension travel by lowering vehicle.
3.Adding stiffer springs so that the suspension doesn't compress as much. This reduces roll and also causing a harsher ride.
4.Adding a swaybar, This reduces roll and also causing a harsher ride and DEFEATS the independant suspension.


5 Link (3link w/Watts)
The 5 link does several things.
The Watts link keeps the axle from moving from side to side(like a panhard bar but better).
The 5 link doesn't transfer minor road imperfection into the body/frame similar to the IRS suspension.
The Watts link keeps the axle housing horizontal with the ground and centered under the vehicle.
The Watts link doesn't transfer body/frame roll to the axle housing causing traction loss like the IRS suspension.
Meaning better handling.

Another option is a Mumford Link

http://www.susprog.com/images/Susp23.jpg

Tom,

That is an interesting diagram that to me almost looks like a double watts link. Have you ever used one on a Kirkham yet? By the way Deam Lampe will be very fast at Hallett in his Kirkham FIA. His IRS seems to be working quite well.

Clois

No our cars have an IRS rear suspension and the Mumford, Watts, etc only work with live rear ends. The Boss 429 show car that Ford built a few years ago had one, Superformance's Lotus 7 inspired car, and of course Mallock cars run Mumford links. It would be great to hear of any other cars using this system.

Jason and Rich,

Thank you both for your input and links. In my case budget is always a concern but I like to go for the best set up I can afford even if it means waiting a little longer. Also, I have found that hurried decisions tend to be re-thought, many times driving up the cost of a project. The two or three vendors I have checked with selling Pan Hard bars and/or Watts Link are not that far away in price actually.

Clois

Pinion Mount As John S Mentioned
 

Clois,
Attached are a few pictures of the mentioned pinion mount.
I was going to incorp the 4 link but found that I did not have the room behind the seat for the bars. I understand that for a four link to work properly, the lower bars need to be at least 17" long. Besides, everyone tells me the four link tends to bind up on road courses, but great for straight line.
I went to the three link with the panhard bar.

PS In the picture you will see I still need to notch my cross member in front of the pinon as the Winters quick change pinon is very low. This makes a pretty good set up with the PH bar..

Thank you, Alex
Cobracer

Clois,
Here's some other web sites for watts link suspensions.
www.evolutionmsport.com
http://www.levyracing.com/support/index.html

Thanks for the input now does anyone know where you can buy some mounting brackets for the 9".

locating a live axle.
 

C.H.

If I read right you have a 4 link locating a live axle. You don't mention the TYPE of 4 link you have...I can only assume that as you now have no locating devise (Watts, Panhard, ladder etc) that you have a NON-parallel 4 link....as there has to be a lateral locator for the rear housing. So then, assuming you have a short/long 4 link......2 upper bars splayed inward as they go forward, and two lower bars either parallel or slightly splayed inward at the front......that then, this system will control the lateral movement of the car as this design is intended to do.

A choice of what type of link to use might be determined by packaging. That is to say that room might be a deciding factor ..you might not have the room for one system or another seeing as tho the car is already together and you dont have a clean sheet of paper to work with. However in a well designed four link a separate lateral locating link is NOT necessary.

The pick up points of the ends of the four links determine what the car will do in bump/droop....and in the full travel /roll there should be NO lateral movement and no change in pinion angle. You should be using spherical bearings or metal bushings in these links, and not plastic or rubber.

There was another poster that mentioned 4 links bind in bump and droop.

This is correct IF the 4 links are parallel and then will bind only in cornering (roll). With a parallel 4 link there MUST be a lateral locating bar used.

Hope this helps you.......shocks are another complete movie.

Just found the article...

http://www.hotrod.com/featuredvehicl.../photo_12.html

Clois....what about a sway bar on the rear?????????

Stock Car Products or Speedway Motors will have all you need to fabricate one. You could also do a PM3L (poor mans 3 link) by adding the panhard rod and deleting one of the upper control arms. The uppers in the four link are notorious for bind.


http://www.stockcarproducts.com/rearsusp.htm