Sway bar on rear leaf spring street rods

[rick 36dodge]

Has any one put a sway on a rear leaf spring car ? I read an artical in Rod and Custom July 2004 about racetrack proven handling upgrades.
The '38 Ford had a rear sway bar. This is the first time I have ever seen one on a leaf spring car. Can you get a sway bar with rubber bushing ? The one in the artical has heim joints that seems like it would be harsh.
Thanks in advance for your advice.
Rick Harris  

[C9]

I have one in my 31 on 32 rails roadster.
The car's not running yet, but in my view it should make a big difference considering it has a transverse leaf up front and in the rear.

I have one in my transverse leaf front, coilover rear suspended 32 roadster.
When the sway bar is disconnected the car is easy to get rocking by hand.
With the sway bar hooked up there is virtually no rocking to speak of when rocked by hand.
I wouldn't drive the car without the sway bar.

I especially wouldn't drive a car that's sprung with transverse leafs both ends unless it did have a sway bar.

Sometimes it can be tough to get everything well packaged and working like it should, but a little thought will see you through.

There's a panhard bar on the rear of both roadsters.
The 32's is in front of the rear axle and the 31's is in back of the rear axle.
No special reason for the difference, just turned out to be the best place to put it in each car.
Make the panhards as long as you can.

You need a panhard up front with a transverse leaf, it adds a lot to steering accuracy and stopping the wandering bit in turns.

Sway bars on both roadsters are the nice little Deuce Factory units.
You only need a sway bar on the rear of these lightweight little cars.

Several other well experienced people have driven my 32 and all report that it handles and steers well.

[phat rat]

Not sure if your talking about buggy spring or parallel leafs. But on my 41 cpe I've got parallel on the rear with sway bar and the usual rubber cushsioned mounting. The front is Nova sub with the narrowed a-arms, in the narrowing process the sway bar mounting points were lost so a hiem joint set-up was used. Took a bit to get it set because of the new springs settling but once they took their set it was fine. Car handles like it's on rails.

[PeterR]

Assuming you are referring to parallel leaf springs.

When a vehicle fitted with parallel springs goes into roll, the springs are twisted and develop roll resistance.   Typically the twisting action increases the vehicle roll stiffness by about 50%.

I vaguely remember some years ago looking at the significance of that, and for a typical 3000lb vehicle the twist effect was equivalent to a .75" antiroll bar.

Putting this another way, if the leaf springs were replaced with coils of the same rated stiffness at the same place over the axle, an antiroll bar of about .75' diameter would be required to develop the same total roll resistance.

Adding a real antiroll bar will reduce body roll in high speed turns however a problem with very high roll stiffness on a road car is that wheel reaction to a bump on one side is resisted by the both the spring and the antiroll bar.   This forces the corner of the car to rise and the lateral acceleration of the drivers head results in an unpleasant ride.

A reasonable guide is to limit the roll stiffness of the antiroll bars to about half that of the springs, and parallel leaf springs already provide close to that.

Also fitting an antiroll at the rear alone will alter the balance of the vehicle making it more prone to over steer.

[rick 36dodge]

Assuming you are referring to parallel leaf springs.

When a vehicle fitted with parallel springs goes into roll, the springs are twisted and develop roll resistance.   Typically the twisting action increases the vehicle roll stiffness by about 50%.

I vaguely remember some years ago looking at the significance of that, and for a typical 3000lb vehicle the twist effect was equivalent to a .75" antiroll bar.

Putting this another way, if the leaf springs were replaced with coils of the same rated stiffness at the same place over the axle, an antiroll bar of about .75' diameter would be required to develop the same total roll resistance.

Adding a real antiroll bar will reduce body roll in high speed turns however a problem with very high roll stiffness on a road car is that wheel reaction to a bump on one side is resisted by the both the spring and the antiroll bar.   This forces the corner of the car to rise and the lateral acceleration of the drivers head results in an unpleasant ride.

A reasonable guide is to limit the roll stiffness of the antiroll bars to about half that of the springs, and parallel leaf springs already provide close to that.

Also fitting an antiroll at the rear alone will alter the balance of the vehicle making it more prone to over steer.

[rick 36dodge]

What I should have said was a panhard bar on the rear of a parallel leaf spring rear end. I have a 3/4" anti-roll bar now.
Thanks, Rick Harris.  

[Bob Paulin]

What I should have said was a panhard bar on the rear of a parallel leaf spring rear end. I have a 3/4" anti-roll bar now.
Thanks, Rick Harris.  

A Panhard bar used in conjunction with parallel leaf springs will result in the binding of the suspension as it moves up and down.

The Panhard bar moves the rear axle left/right  - slightly but measureably - as it scribes its arc. This would make the rear axle try and push the springs left/right - resulting in slight, accumulative binding at the Panhard bar mounts and the spring mounts.

Binds are not linear in nature, nor can they be assigned a "rate" in order to be factored into the overall suspension package.


Bob Paulin

[rick 36dodge]

Thanks
Rick Harris.

[rick 36dodge]

Please look on page 84 of July 2004 Rod and Custom. It looks like this '35 Ford has parallel rear leaf springs with a panhard bar. They call it a "hefty sway bar to keep a 9-inch ford in place".
Thanks, Rick Harris

[Bob Paulin]

Please look on page 84 of July 2004 Rod and Custom. It looks like this '35 Ford has parallel rear leaf springs with a panhard bar. They call it a "hefty sway bar to keep a 9-inch ford in place".
Thanks, Rick Harris

I don't buy most of the enthusiast rags these days because they offer nothing for me but pictures of cars.

There is really no solid tech that I'm interested in....mostly just bolt-on installations of advertisers' products.

Once you learn how to tighten and loosen a screw, these "how-to" articles take on a certain amount of redundancy.

I subscribe to RaceCar Engineering and Race Tech - two British publications that explain things such as how the latest hydraulically-interconnected front-rear sway bars work - not just how to bolt them onto your WRS car.


Now, if they have actually mounted a "sway bar" that is a horse of a different color from a Panhard bar.

But, I stand by my statement that a Panhard bar on a parallel leaf spring setup WILL bind.....regardless of who puts one together.

If they don't know the difference between a "sway bar" and a "Panhard bar", then you will begin to understand why I don't buy today's rags.

Maybe I'll skim through one at the book store next time I'm there.

Page 84, you say....?


Bob Paulin

[Bob Paulin]

So, here it is, July 16, 2004, 2 p.m., and I'm in the grocery store with my wife.

While she waits her turn at the deli counter, I figure it's a good time to skip on over to the magazine rack, and see if I can find the article Rick Harris was talking about from the July 2004 issue of Rod & Custom.

From a distance, I can see R&C on display.

I reach in, grab one, flip to page 84, and there's nothing, NADA, Zero, Zip about rear suspensions - let alone sway bar/Panhard bar.

Then, I go back to the cover to see that this is, actually, the September 2004 issue....in the middle of July!!!

That wouldn't be so bad if it weren't for the fact that down in the corner, next to the bar code, it states, "Display until July **, 2004.

Isn't this, in a world of reality and sanity, truly the July issue since it is slated to be off the newstands by the end of July?

Today's newspaper had today's date on it.....not next Friday's.

Why can't the magazine industry call a spade a spade, and make the issue that comes out and is off the news stand by the end of July, "the July issue"?

Actually, because I've worked in the business, I know the answer....

Publishers hope that the people who stock the magazine racks will look at the September cover date, and allow that magazine to sit on the shelf through September before taking it off the rack and sending it back for credit.....

.......a little Three Card Monte-like, sleight of hand, if you will.... "Watch the magazine...Which one is expired.....Keep your eye on the magazine at all times....Nothing up my sleeve...".

It's an old publishing ploy to extend the exposure time on the magazine rack.

Now, the more sophisticated stores caught onto this little trick, and they now ask for the little "Display until...." notation, based on the magazine's actual publication date.

You will notice that some magazines that do not print a "display until....." date on their cover, have had a sticker affixed by the store to indicate when the magazine has had a month's time on the rack.

So, isn't it time to "catch up" and call the issue that is scheduled to be pulled from the shelves at the end of July, "the July issue"?

But, since the publishers were already post-dating (that sounds just as bad for magazines as it does for checks) their magazines by  a couple of months - and they could'nt exactly have three consecutive "July 2004" issues to compensate, we're left trying to decide exactly which time cycle any one particular publisher happens to be using.

Is that September 2004 issue the latest thing out, or will the October  issue be in next week? After all, July IS half over, now.

And.......

Has anybody seen the current issue of Street Rod Builder which has a teaser on the cover, "50 (or some such number) Frame Detailing Tricks."

Thumb into the article and many of them involve sending the car out to someone else to do something such as powder coating.

Remember when at least half the content of these "50/100 ***** Tricks"  articles were things that the "average" car enthusiast could do himself with simple hand and power tools, and 90 percent or more could be accomplished in reasonably-equipped, back yard, hobby shops?

If the book  on the "dumbing down" of America is written before Americans all become to dumb to read it, one chapter will surely be, "I don't have any perceivable talent, but I DO have a checkbook that can make it appear as though I do."


Yes......

......I feel better!

Now, I'm gonna' go back into the dark corner of the shop and continue to sort a couple of coffee cans full of small nuts and bolts.


Bob Paulin

[58 Yeoman]

Bob, it's no different than new car mfr.'s coming out with next years model in June of this year; sometimes even a 2006 out now.  Remember when the 63 1/2 Ford came out? It was a different style mid-year. If they did that today, it would be next years car.

[river1]

Today's newspaper had today's date on it.....not next Friday's.

Bob Paulin

actually the paper i printed this morning had tommorows date on it.  we sometimes will print a section as far as two weeks ahead of time. most of the time it is for insertion timeing the causes it, tho sometimes for a large section(s) it is because that is the only time in the printing window to do it.

that said i get your point and agree with it. i think the mags could print a few days later each month til the date are more in sinc.

later jim

[SKR8PN]

Thank you Bob Paulin...........
I feel MUCH better after OUR little rant.............
Stuff like that,bugs the HECK outta me also.....................