Hello everyone,

Quick question about mono leaf springs. I read the post a couple days ago about the gentlemen worried his mono leaf springs were too long. one of the responses to his thread was to get rid of the mono's you won't like them.
My question is what are people finding with the mono's are they not worth the cost? It seemed like a great idea to me until the question of others not liking them was raised. How does everyone like/dislike them? Pros and cons.....

Thanks Jeff

 

Well for one, if I break a leaf in the stack no big deal, you'll make it home. Break a mono your SOL.
If a mono leaf is such a great idea, why can't I think of a single ( no pun intended ) car manufacture that use's them.
Last one. Many who buy them so they can lower there trucks and cars, from others experience, they don't. I'm sure others will chim in.

 

The gent who made that comment is AX Racer and he knows what he is talking about. He's a big racing mucky mucky or something I can't remember at the moment.

I'm sure he will be along soon to expand on his opinion and why he made th ecomment. He is very good about providing factual rational for his comments.

 

I've never used them, but my understanding is they ride rougher than a cob. Instead of having several leaves that flex and slide to smooth out the bumps, you have only one super-stiff piece of metal to do that job.

The previous poster that said his mono leaf seemed too long and was bottomed out at the shackle, will have no give at all, and in my opinion, is in danger of breaking something. The whole point of the shackle is to take up the slack as the spring flexes and "grows" as it flattens out. With nowhere to go, something is going to give, somewhere. Given that choice, personally, I'll stay with 'old school'.

 

I think there are two types of mono spring?
A lot of modern european vans eg Renault master use a monoleaf in the rear - the van my work supply for me has this. Looking at the spring the steel is very thick however compared to a normal stack, and it tapers to each end.

 

Here's the best wrrite-up I've seen, by a spring manufacturer. Some will say they have a jaundiced view since they sell regular springs, I don't think so, but make your own mind up.

Mono Leaf vs. Multi Leaf Springs

 

I have a friend with monos and a big block in a 53 F100. He loves em, says he can accelerate hard with no wrapup, and the ride is excellent. I have not ridden in his truck, but trust his word. Joe

 

Good article, kind of supports my thinking on the subject.

 

Eaton is and has been a major spring supplier to the automobile manufacturers and aftermarket for many years, and is considered to be THE authority on springs.
There are two types of monos, the tapered leaf type Eaton describes and single thickness (basically just a heavy main leaf). The tapered leaf is especially prone to breaking because the majority of the flexing is done near the ends of the leaf where it's thinner rather than spread equally over the entire length. Think of an archer's longbow (a tapered monoleaf) where does the majority of the bending take place? Would a single thickness bow (spring) work well (most here have likely tried making a bow out of a sapling and a string)?
Along with the safety issue comes the secondary (but still significant) issue of wrap up.
Someone a while back was looking for the reason that drag racing cars would hop and chatter the tires on launch. They originally thought it was due to the tires of the day not holding traction, so they roughened up the starting pad. That made the problem worse. So that thinker decided to film the suspension and tires at high speed and play it back at slow speed to understand what was happening. What they saw was unexpected and very enlightening: indeed the tires were losing traction and regripping, but it was not due to the tires losing surface grip but the leaf springs (remember most cars in the day had parallel leaf springs in the rear) were being forced into a S shape due to the axle torque when the tires were hooked up, until the spring would reach a point where it would overcome the tire's grip and snap the axle rotation back the other way. This would break the tires loose until the spring straightened then the grip would be regained and the cycle would repeat. This revelation cause the invention of "traction bars" and similar devices to control this spring reaction or the spring "wrap up" as it was coined.
Fast forward to monoleafs. GM tried rear Monoleafs on a low end compact dubbed the Chevy II for a short time. This small lightweight inexpensive body/chassis was an immediate hit with the racers during the "gasser wars" and the oncoming altered wheelbase FX cars. But there was a problem! No matter what kind of traction bars were tried, the rear of the spring would still develop the dreaded "spring wrap". The invention and development of ladder bars helped a bit by physically restaining the rotation of the axle rather than trying to control the spring flex, but GM found that the manufacture of the tapered leaf and it's uniform tempering into a spring was problematic and expensive with a lot of rejects, and breakage on the street with the subsequent loss of control started raising it ugly head. The bean counters and legal eagles got together and said NO MORE! and in the next generation of the CII the monoleafs were replaced with coil springs.
FF again to the present: Rear mono wrap up isn't as big a problem on our beloved trucks especially if ladder bars are added, because our extra light a$$ ends and relatively narrow hard tires restricts the amount of axle torque we can develop. But wrap up once again rears it's ugly head with front monos upon braking. Many of us have upgraded our front brakes. When the brakes are applied hard the tire tries to move back and the weight transfer pushes the nose down, rotating the front axle against the spring. With the axle's drop and hanging below the springs the rotating axle has a lot of leverage and easily arches the softer front and rear ends of the mono. Two (or three depending how you count) things happen: 1. the rotation of the axle causes the front geometry to chang not good for control. 2. like the dragracing wrap up problem, the spring reaches a flex point where it overcomes the tire grip and pops the tires forwards breaking traction and causing the front of the truck to "dance around". There is no steering control when the tires have no traction. 2a or 3. the traction between the tires and the road are never equal side to side so this torque hop and is not going to be equal and simultanious side to side, so the axle is also going to rotate around it's centerpoint like the front of a child's wagon, and we all likely know how much steering control that has.

 

Everyone, Thanks for your info. Ax I always enjoy reading your posts because of the great detail info you give. Thanks to you for always lending such great advice/info.
I have heard that you can lower eliminating everyother spring from the original leafs. Has anyone had experince with this? I want to use the original axle and am looking for a way to lower the front and rear. Any ideas?

 

Is this for your Mustang or for a truck? If it's for a truck go here, http://www.roadsters.com/axles/

 

HD74 thanks for the link. I am working on a 49 F-1. I have tried to post pictures in my garage but so far have been unsucessful. I will try agian soon.

 

Your welcome, never tryed the garage thing. I would suggest going to your gallery and start an album.

 

I've had them for 6 years on my truck and like them. They ride well and the truck handles OK too. I'd buy them again.

 

I just had an email back from Dave Mann at Roadsters.com, nice chap, said there's no problem shipping a dropped beam overseas, the beam $350, dropped rod end adapters $60 (and only $140 shipping to France)

But currently (01/01/10) there is an 8 week waiting list on truck axles due to demand.

I had a company from California quote $238 to ship a pair of mono springs to me.

It would be interesting to know how much springs and axles weigh for shipping purposes.

Alex