panhard bar?

[got6spd?]

I did some research and didn't come up with a clear answer.

Is a panhard bar beneficial to a leaf spring car?

I'm setting up my rear suspension soon for my firstgen camaro and I'm for sure running hotchkis leafsprings, koni shocks, swaybar, and poly bushings. I plan on doing some heavy track driving but mostly street. The only thing left is if I'm going to run the phb or not.

What do you guys think?

[el-camino]

leaf springs sucks
its a big difference now in my Olds and my friends T/A
with the 4-link and panhard bar and coil overs the cars have a extreme good corner stability


aah, not all leafs are bad.

great stuff

[High Plains Mopars]

leaf springs suck

Hold on there babba louie. I'm willing to bet that a 1970 vintage trans am circuit car that is using leaf springs can put a hurtin on your coil over set up.

There is nothing inherently wrong with leaf springs. As a matter of fact, their design naturally resists rolling forces much better than a coil spring. Their biggest drawback in a competition environment is that they are heavy, and not easy to change rate on. However, I'd be willing to bet that a vast majority of coil over users on here do not use their car on a track often enough to really need to carry around springs that range in rate from 200 to 1000# in 50# increments, nor have the need to change wedge via spring height changes, so whats the point, really. Oh, well, they do look cool and are compact and light.

Yes, there is tremendous benefit to using a panhard bar on a leaf spring suspension, IF, you eliminate the potential for spring bind in the hangers so the springs can actually pivot and act solely as springs and not latral locators. If you use stock style bushings, poly, bronze, or aluminum, then you have the potential your leafs will bind up with a panhard bar. Use a leaf pivot and you can eliminate this potential bind. Once this is done, then the panhard can be used the same way as on a coil spring set up; to locate the roll center height and alter weight transfer characteristics.

[got6spd?]

sorry, but I'm not sure what a leaf pivot is. Can someone clue me in?

[High Plains Mopars]

Afco unit pictured below, around $40. Replaces front eye bushing.

[LowBuckX]

High plains Ive been looking fer those for a while just didnt know what to call em.. thanks... Id have to make a sleeve to run them in my Hotchkis leafs I think but Im not sure

[chicane67]

Leaf springs... if designed and constructed correctly... rule. And they even rule many IRS suspensions with ease.

The problem is... the cost of a properly designed leaf spring. Most of my FIA designs run about $850 for the leafs alone... and then you have to put bushings in them... which I only use Del-a-lum's in the standard set up for $200 or the Cat5 for a little more moola.

But dont think that a leaf spring sucks... because its too easy to prove that wrong.

[got6spd?]

I'm not really clear on what they're doing. Do they actually allow the the leafspring to move lateraly side to side to compensate for the pushing and pulling of the panhard bar?

[David Pozzi]

Yes, here's how it's done.
Install spherical joints like those in the front and rear leaf eye, also the top shackle position, at that point the axle can be shifted left-right a bit with little resistance except for the friction between leaf and axle perches. If the axle perch friction isn't excessive, then a panhard bar can control side to side motion with no conflicts.

Tom, - how much for a set of your leaf springs in Titanium!!!

[got6spd?]

How come more guys arent running this setup?
It seems fairly simple. Is it because the gain is minimal and not worth it?

My car is going to be a street car primarily yet I want it to handle well at track events. Basically, I'm confused on whether I should run this setup or just stick with running some poly or delalum bushings.

David, do you run this set up on one of your camaros, and if not is there any particular reason why?

Thanks for the replies and sorry to drag this on guys

[silver69camaro]

There is nothing inherently wrong with leaf springs. As a matter of fact, their design naturally resists rolling forces much better than a coil spring.

This is a draw back for me. In a coil spring setup, I can change the roll rate independently from the spring rate. Big plus.

When I had the Hyperco 'glass leafs on my car, my entire rear suspension basically weighed about 30lbs sans axle housing. You can't get much better than that. I had available rates from 180lbs to 250lbs/in, and had a pleasant ride to boot with reduced NVH. It would have been a killer setup with a panhard or watts and some front spring pivots.

For adjustability, link systems are great. Every suspension has their pros and cons and neither are better than the other.

[High Plains Mopars]

How come more guys arent running this setup?
It seems fairly simple. Is it because the gain is minimal and not worth it?

Because for years people have been saying leaf springs are junk. Because in a serious, somewhat unrestricted competitive environment it is not convienent to carry around 10-15 sets of leaf springs compared to 10-15 coil springs. Because leaf springs are a pain to swap out. Because leaf springs are not glamourous. Because there are a lot of drivers who want a better set up but don't want to take the time to understand the dynamics of it and realize they can get a decently adjustable set up relatively inexpensivley without a huge amount of fab work. Because aluminum coil overs look racey. I dunno, take your pick.

This is a draw back for me. In a coil spring setup, I can change the roll rate independently from the spring rate. Big plus.

That is the cool thing about going with the pivots and a panhard bar, it creates this exact situation with leaf springs.

[silver69camaro]

That is the cool thing about going with the pivots and a panhard bar, it creates this exact situation with leaf springs.

I disagree. While they do help, there will still be roll bind due to the rear shackles. Relying on bushing durometer for roll stiffness is an acceptable practice, although it can be somewhat unpredictable.

Another issue with leaf springs is the progressive spring rate do to "shackle jacking". Depending on the shackles angle in relation to the neutral plane, the spring rate will change..the rate distortion can be minimized by proper geometry, of course.

Don't get me wrong, I love leaf springs and have been very successful with them. They just have their lows as well.

[got6spd?]

I've seen a lot of dirt track cars with this setup.

Have you guys ever ran a similar setup on your pt cars?

[chicane67]

Tom, - how much for a set of your leaf springs in Titanium!!!

Dude... since 911, the price of American spring steel has quadrupled. I wish it was still pre-911 pricing... because at $136 per spring... I could sell a boat load for that.

Because for years people have been saying leaf springs are junk. Because in a serious, somewhat unrestricted competitive environment it is not convienent to carry around 10-15 sets of leaf springs compared to 10-15 coil springs. Because leaf springs are a pain to swap out. Because leaf springs are not glamourous. Because there are a lot of drivers who want a better set up but don't want to take the time to understand the dynamics of it and realize they can get a decently adjustable set up relatively inexpensivley without a huge amount of fab work. Because aluminum coil overs look racey. I dunno, take your pick.



That is the cool thing about going with the pivots and a panhard bar, it creates this exact situation with leaf springs.

Well said. Gotta have bling bling to make up for a small ding ding.

[David Pozzi]

All I can say is we have been having a lot of fun with our 73 Camaro with just some good leaf springs in the back. We started out with Hotchkis 175 leafs, then tried the Global West Cat5 which have spherical bearings in the front and rear eyes, but not the top shackle position. The leafs are 240 lbs, very stiff, the rear hardly moves but this seems to add stability and they do not increase roll stiffness. I drove the car at Buttonwillow and another guy was running a completly stripped race Camaro of the same year but with a 3 link rear supension. I beat his lap time by 4 seconds. This is not a fair comparison of suspensions by any means, but I was quite happy our street car with full interior and radio did that well against a lighter weight race prepped car. I have heard several guys rave about the leaf/panhard setup, and may try it some day, but I have to say I'm super happy with the simple leaf setup we have now. Instead of trying to build the ultimate rear suspension, we spent the time on the track and on figuring out other mods to improve the car.

The only thing about the leafs is, they are heavy and very stiff which affects the ride on the street. With street tires, it isn't bad as it is with the race tires, but the cat5 is not as nice as the Hocthkis leafs were or the L2 Global West leafs would be, and certainly not as nice as a glass leaf. I really wanted to use composite leafs but read of too many breakages from forum members, especially with higher horsepower levels. Leafs have inter-leaf friction and rising rates that makes them act different than a coil of the same rate. I'm pretty sure you'd need a higher rate composite leaf or coil to equal a leaf package. A composite leaf would have to be in the 250 range to replace a 175 steel leaf set. The composite leafs also move laterally more. The spherical bearing/pahnard bar setup might work very well with composite leafs.

My wife's car weighs 3600 lbs without driver, and has the GM crate engine with 425hp, but the GM rating is conservative, on normal speed shop dynos it would have around 440hp. At this hp and weight the leafs work just fine, no traction or stability problems at all. We have a 295/40/17 rear tire, we use the Kumho V710 slicks on the track and autocross.

My 67 will have very close to 600 hp and wider tires. I'll start out with leafs and may stay with them if I have enough rear traction. If not, I'll try something else, but it won't be Corvette rear suspension, it would probably be either a torque arm or 3 link.
David

[got6spd?]

sorry to keep dragging this on (last question).

David, how do you think running the same set up as the CAT5, spherical/delalum combo, would work except with my hotchkis springs instead? Would it be worth it or should I just invest in running delalums all the way around?

Also, it seems that for my application a panhard bar isn't really necessary so I think I can just rule it out. Any thoughts?