Steering, Suspension, & Brakes

Although this is not officially a Panhard bar by design as it does not match Panhards original eclecticism.
[bringatrailer.com]

This is an interesting and fairly easy way to reduce spring twist on an MGB. Pictures from my new car's underside:

Not near a panhard rod, it's a tramp bar! Won't stop lateral movement one jot!

David's right. We call 'em traction bars (or slapper bars).

A reasonable mistake for someone not familiar with this technology. The slapper bar is a traction device designed to prevent spring wind up and uses the counter torque of the axle housing to plant the tires on acceleration by applying a jacking force to the body. Useful in straight line acceleration but not helpful coming out of a turn. It helps to think in terms of the forces one is trying to counteract.

Jim



Edited 1 time(s). Last edit at 02/12/2012 12:02PM by BlownMGB-V8.

Thank you for the input. So, what is the best available true panhard bar for the MGB project I am presently building?

Are you looking for one that will just bolt in? Or, are you looking for DIY suggestions?

I would prefer to fabricate it myself. I'm a competent welder and have a small shop full of useful tools. Is there a tech posted here somewhere?

You might get some good pointers from this archived thread...
[forum.britishv8.org]

Robert,

Way back in the early days of the "MG V8 Newsletter" there was a very good how-to article. I don't think it was ever digitized here. A lot of us fabbed our own using ideas from it. The general consensus is to make the bar as long as possible, level with the ground, & even (or below) with the axle centerline. Lots of pics here to gather design ideas.



Edited 1 time(s). Last edit at 02/14/2012 09:39AM by MGBV8.

A couple more from the archives:
[www.britishv8.org]
[www.britishv8.org]

If your running real close tire to fender side clearance, consider the "arc" lateral movement of the rear end, as it travels up/down. Watts links, Jacobs ladders and Pickle forks, all used for controlling lateral location, do Not have "ark" traverse. Good Luck, roverman.

These two articles show particularly good installations, although quite elaborate:
[www.britishv8.org]
[www.britishracecar.com]

There are other options that you may want to look into such as the "Jacobs Ladder" or a Watts Linkage to control side to side movement of the rear axle. [www.spitzracing.com] or [en.wikipedia.org]

OK, thank you all for the links.

This is going to keep me busy cogitating and measuring for a while.
:)

Thanks for the "links" Bill. As we can see, either of these systems should provide a smoother ride and ehanced handling, with leaf springs, vs a panhard bar. It's easy to change rear roll center height with Watts linkage by having multile threaded holes (vertically), to mount central pivot point. This is also available feature for "pickle forks". Just say NO to lateral arc. roverman.

Quote:

Just say NO to lateral arc.

Art, the arc you're talking about is a function of Panhard bar length. The formula for calculating its size is given in the second article Graham linked to (above). With a 36" long Panhard rod, the arc effect results in a maximum lateral movement of only 1/8". (It would be a bigger lateral movement on an off-road vehicle, but MGBs just don't have that much wheel travel!) If an eighth inch is too much to suit you, you can make the Panhard rod even longer. So long as you don't make it shorter, the Panhard rod's effect on ride quality will be trivial. Watts links or great... but a Panhard rod will be cheaper to make and easier to install than any Watts link. If you want to play with roll center height, a Panhard rod makes that quicker and easier too.

I agree about the cost to build a panhard bar versus a watts linkage as I don't know of any pre made watts linkages on the market, but you can buy a Jacobs Ladder very inexpensively from such places as Speedway Motors. Still have fabrication work to do for the mounts, but you have almost the same with a panhard bar. I see it as a good option. The only downside for any of these is to get the best roll center and such the lowest mounting point needs to be pretty low and that might restrict ground clearance on a street car.

What I got from the ,"Jacobs Ladder vs Panhard Bar", is an 87" long panhard bar would generate approximately .100" of arc in 4" of vertical travel ? Is this more travel than a street use British sports car would use ? roverman.

I have a Watts linkage system; it's a little different but it came with my pinion mounted parking brake. I was trying to reduce the rotating mass mostly to increase MPG (and HP) but my main concern was the composite spring that I had purchased from Doug Jackson. There were some reports of spring shredding under high-torque. Doug Jackson which is now retired defended his product saying that the ones complaining refused to use tramp bars. Jim Stuart has this system with tramp bars for the past 8-10 years in his GT with the Buick 300 and has had no problems. I'm running a 331 FSB stroker, which, will test the springs to its limits.

I originally went with his system as no link bar system were available at the time. However, after I've called a couple of composite spring manufacturers, I understood the advantages of the composite springs mostly being the lightness and the fact that they react 8 times faster than steel springs.

I'm struggling every year to finish the project and I was thinking about replacing my DJ tramp bars with the "Slide-A-Link" tramp bars; the problem is that I would have to fabricate new front spring eyes with an extended area for the rollers to ride on (if you know what I mean). Again, the reason for switching to this type of bars is to free up spring extension for a better ride; as it stands now, only the back half of the spring extends with the swing of the shackles.

I'll attach a previous post that I had started depicting my concerns, it has nice photos. Take a look at the "Watts" linkage, the manufacturer assured me that they work great with narrow frame rails. The other photo with a top link is not mine; I was just questioning its usefulness.

[forum.britishv8.org]

Please, let me know your thoughts; some of you have great engineering minds and I could use the help.

Cheers,

Art, the point is that the panhard rod would have to be 87" long to equal the movement of the jacobs ladder, now I don't know of any sports car that's 87" wide so you wind up with most panhard rods being in the range of around 40" or so to fit between the springs in the rear. Not optimum length to minimize side to side movement. Would it be too much, not really, way too many of us running short panhard rods without problems. Just wanted Robert to know that there were alternatives that actually worked better and had less influence on the roll center.