Datsun Roadster Forum-311s.org

I'm thinking about making a bracket like this one for my RX7 rear end, and installing a panhard rod for more firm rear axle lateral location. I have volvo monoleafs, bilsteins, and the stock rear mounting bar. I'll be able to get about 15" on the panhard bar, and according to this video

, as long as I get it parallel to the rear even a short panhard bar should offer improvements. If I put in the panhard rod with the stock rear torque arm (is that what its called?) will I have any unintended negative consequences?

They are mostly for coil spring suspension -track bars
With No rubber bushing maybe noisy
If is raised like a bump ..it will shorten... thus pulling something
The frame ?

redroadster wrote: ↑Fri Feb 21, 2020 8:00 am They are mostly for coil spring suspension

Pan hard bars are for locating the rear ended laterally, this is actually done by the leaf springs in a car with leaf springs. Adding a panhard bar in a setup with leaf springs can cause binding since the axel is now forced to move in a slight arc laterally by the panhard bar, which the leafs will not like at all. I would not recommend adding the panhard bar to your setup. In addition if the torque bar is left in it will only add to the binding of the rear end. Some of the ways the get a “more firm” location are to:
- go with sniffer bushing in the leaf to frame connections; may put undo stress on connections
- add diagonal control arms. Some good math involved
- go with a four bar parallel, with panhard bar and coil overs like Alvins, lots-o-work
- go with four bar triangulated with NO panhard bar and coil overs like mine. Lots-o-work

The last three will greatly improve the handling but again lots of math

Cheer
Matthew

I know many leaf spring cars do upgrade to a Panhard bar, most noticably late 60s Mustangs. If I did go this route, I would be using the double adjustable bar from Ridetech:
https://www.ridetech.com/products/r-joi ... -link-bar/
Would it make a difference with the joints being able to articulate well in reducing any possible binding? What if I replaced the stock torque arm with a bar that was able to articulate also?

GoldHawg wrote: ↑Sun Feb 23, 2020 10:08 pm I know many leaf spring cars do upgrade to a Panhard bar, most noticably late 60s Mustangs.

I have never seen this done. I might try to reach out to the mustang guys and ask them. But I still don’t recommend it.

GoldHawg wrote: ↑Sun Feb 23, 2020 10:08 pm Would it make a difference with the joints being able to articulate well in reducing any possible binding? What if I replaced the stock torque arm with a bar that was able to articulate also?

Nope. The binding occurs where the leafs connect to the frame, at the shackles. If your going to replace those joints you might as well go for the four bar.

Cheers

Matthew

Matthew--thanks for the feedback.

EDIT: Matthew, et al, here is how/why the Mustang guys do it:

It has to move 1/4 " or slightly more using tie rod ends ( no give = panhard)instead of rubber bushings back and forth. Bet it ends up breaking the frame channel . if your set on it use a bushinged track bar. 1st

charlee0620 wrote: ↑Sun Feb 23, 2020 7:39 pmPan hard bars are for locating the rear ended laterally, this is actually done by the leaf springs in a car with leaf springs.

That may be the job of the leaf springs, but they do NOT do a very good job of it... In this particular car, the body does the locating, on the sidewalls of the rear tires. The leafs let the axle flex side to side like crazy.



.

Rock at one point did have a Panhard, although it was later abandoned for the V bar design. The V bar works beautifully with the leafs, and maintains the axle position.

Got a pic of how you did the v-bar? I can still do anything as I haven't powdercoated the frame and basically the rear suspension is in place. Anything I might ever want to do I'd like to do in the next few months. I'm happy with what I've heard from the volvo mono-leafs and the bilsteins re ride quality. If I can do anything to add to that to make the rear more stable that will still fit, I'd like to fab that up now.

EDIT: Just looking thru your thread, found it.

That is it. The front spring mounts had a third plate installed and drilled, so the bolt goes through the spring and the bar, then the nut holds it together. At the rear, the rectangle tube has a captured nut welded in, then welded to the bottom of the axle housing. The bar is bolted in from the bottom. It makes for a very nice compliant rear end, that does NOT move from side to side..

It looks like the V-bar setup would have no anti squat in it.

Long ago, I "imagined" or visualized exactly what RCMike has shown. I don't know $@#% about suspension etc, but I remember thinking that something like a Y bar would work, and there it is! Seems much less complicated than doing a pan hard rod, with a lot less fab and welding. I think I need one.

Actually I think making a panhard rod is easier. I also went out to my car and the muffler is in the way of the left hand forward bar. And I don't think I want it hanging that low, and I can't see how to get it higher. Any idea how much up/down travel on the rear end? By my calculations if I have a 16" panhard rod, the arc would only move the axle side to side by .125" with a 2" up/down (4" total travel). Goes to .29" w/3" (6" total travel). If travel up/down is limited, I don't think I'd have a bind with rubber bushings. But I'm also considering making some delrin bushings for the leaf springs; apparently that should take most lateral motion away.
Still cogitating on this....

Ah yes, the old exhaust... in my excitement I forgot about it. Probably why I never explored it further!

The longer the panhard the better off you are as you will get less alignment and handling change as the suspension travels (or body rolls). With the narrow frame rails on the Roadster, I would Go with a Watts link. It would be lots easier to package. Think Alvin has a watts link on his car though he has a full four link setup.