Care of "flat" springs?

[ThomasBorchers]

What is the correct care for “flat” springs (leaf springs???) ? I don’t know the correct word but for example the Ford Model A has these springs and most of the brass era cars and a lot more. <BR>How do you protect these springs against rust? <BR>Thanks.<P>Tom

[Guest]

Tom ~ One of the things to keep in mind when restoring, maintaining or "prettying up" leaf springs is one of the principles by which they work, <B>FRICTION</B>. Do not do anything to reduce the friction between the leaves as this is what dampens the rebound action in a leaf spring. Too little friction + too much rebound = broken springs. <P>At least this is what I was taught by the manager of a spring shop who said, "Never get grease between the leaves of a spring."<BR> ~ hvs

[Guest]

I spray them with wd 40 periodically. Howard- Question I have also heard that leaf springs work through friction, but how does that explain the cars that have enclosures on the springs and a grease nipple to lube them? This has always confused me.

[Guest]

Terry ~ Me too. <P>I wonder if surrounding a leaf spring with grease is the same as putting grease between the leaves by extending them and inserting grease directly? ~ hvs

[ply33]

As I recall (it has been a long time since my mechanical engineering classes covered this).<ul>[*]Leaf springs break when they are twisted too much. Typically this happens when one wheel on an axle has a large deflection compared to the other (because the spring has to take up a twist between the frame and the axle). There are several ways of limiting the twisting or to allow the spring to handle the twist better:<ol>[*]Restrain the spring from large excursions</li>[*]Add a anti-sway bar to assure that the axle does not twist in relation to the frame</li>[*]Make your leaf springs very narrow (wider springs do not handle twist as well as narrow ones).[*]

</li>[*]Leaf springs have a fair amount of self damping caused by the friction between the leaves.</li>

On cars that are not fitted with shock absorbers all the damping (which limits spring travel) is in the friction between the spring leafs. Greasing the springs leaves on those cars might lead to breaking the leaves because:<ol>[*]The axle is damped less leading to</li>[*]increased axle travel leading to</li>[*]increased twisting of the springs.</li>

.<BR>On cars that are fitted with shock absorbers the damping is due to a combination of the internal friction of the springs and the shocks. Typically the leaf springs in this design require less friction and were often designed with anti-friction pads (oilite on Chrysler products) and/or grease fittings and/or gaiters to hold in lubrication. In these cases you are probably better off to lubricate the leaves. If fact, it may be necessary to get the ride quality that the factory intended.<P>Finally, newer cars often use a leaf spring with only one or two leaves. These have almost no internal friction. The need to have good shocks and probably a sway bar to keep the twisting down.<P>Of course, all of this does not apply to a transverse spring arrangement as used on the Model T and Model A Fords: To twist those springs you would need to rotate the axle and there are torque tubes and/or wishbones that prevent that. Simple vertical wheel motion on that type of suspension should not twist the springs. Thus they should be a little more immune to spring breakage. Probably a reason it was picked back when the roads horrible.

[Guest]

The grease fittings on each end of leaf springs are for the end bushings. My DB has two alemite fittings per spring rear end and one per front (this is true for both sets of springs). And if memory serves correctly the owner's manual has instructions on maintaining and lubing between the spring leafs. I'll reconfirm this tonite.

[Tom Deering]

Ford products of the '50s & '60s that used rear leaf springs, had insulators between adjacent spring leafs. If the vehicle had 5 leafs, there would be 6 insulators used: 2 per leaf, 1 at each end of the leaf located by slight depressions in the leaf.<BR>Originally a waxy substance was impregnated into a canvas type material that was about 2" square. Somewhere in the late '60s, plastic discs were substituted as the service part. I don't know when this began and ended. I know canvas (?) was used in '49 and pretty sure it was used at least through the '64 model year.<P> Tom

[Guest]

On many vehicles of the so- called "classic" era when shocks were offered on nearly every car { '28-'33} provision was made for lubing the leaves, the "sping spreader" a threaded device with 2 wedge shaped ends was a popular accessory still encountered, while some cars had metal sheaths covering the springs holding lube or leather "gaiters" serving the same purpose which I understand are being reproduced today. Just study the service manuals of the period and you'll see about spring care.

[ply33]

Some quotes about leaf springs and leaf spring lubrication...<P>From <span style="font-style: italic">De Luxe Plymouth Six Instruction Book</span> (Plymouth Motor Corporation, April 1933, page 67):<blockquote>The springs are equipped with Oilite inserts, placed between the three upper leaves, at the ends, and for the purpose of lubricating the spring leaves and eliminating squeaks.<p>When manufactured, the springs are treated between the leaves with a special lubricant. This lubricant should be replenished as required by a similar type lubricant obtainable at any authorized Plymouth Service Station.<p>Spraying springs with engine oil is not recommended.</blockquote>In February 1933 the British magazine <span style="font-style: italic">the Motor</span> on the export version of the 1933 Plymouth (called a Chrysler Kew Six over there):<blockquote>...Many more would have preferred to retain the confidence show by the public in road springs of great width, but Chrysler fits what he thinks is right, extremely narrow spring leaves which are capable of twisting without breaking and thus affording a far greater range of axle motion on rough roads than can ever be provided by the more rigid broad-leaved pattern.</blockquote>And finally some passages from <span style="font-style: italic">Dykes's Automobile and Gasoline Engine Encyclopedia</span>(1943 edition). From page 4:<blockquote><span style="font-weight: bold">The springs are secondary shock absorbers</span> and to get full benefit from the springs, which slide on each other when in action, keep them well and constantly <span style="font-weight: bold">lubricated between the leaves</span>(see pates 172, 762, 763).<p>Breakage of a spring means breakage of one or more of the leaves. Breakage almost always occurs in the expansion that follows a heavy compression, and not during the compression. In other words, it is the <span style="font-weight: bold">rebound</span> that usually breaks the spring.</blockquote>On page 174A:<blockquote><center><span style="font-weight: bold">Spring Lubrication</span></center><p>Sometimes springs are enclosed by flexible covers, filled with lubricant (see page 762). It is important to use a lubricant which will not dry out or separate.</p>Where the springs are not enclosed, they may be most conveniently lubricated by painting them with engine oil at intervals of 1,000 miles.^*<p>At some of the lubrication service stations, compressed air is used to force a spray of penetrating oil and graphite between the spring leaves, which lubricates the spring leaves, dissolves rust, and stops squeaks....<p>^*For later information on places to lubricate, kind of lubricant, and how often-- follow car manufacturers' instruction book. Spring-leaf lubrication periodically is not advocated by some manufacturers, one reason being it may cause excessive bounce and lead to broken springs....</blockquote><p>And now my fingers are tired and I will quit while I am behind. Or something like that. Sounds like my earlier post was pretty much on track. The main thing is to look at the service recommended by the original manufacturer. On my car that means lubricating the spring leaves (in addition to the shackles).

[RoadsterRich]

I always assumed the grease fittings were for the spring bushings, not for the springs themselves. Of course I have also learned that my 'common sense' (or is that lack of?) and reality tend to conflict on a regular basis. Basically my thought was that it allowed the end of the springs to move freely at the attachment points, as the springs flex I would assume (there the word is again) that the ends would move a bit, not the same as the springs 'sliding' over each other, rather I would think removing stress from the mounting point. Ah well, I sure would appreciate the real explanation now that I have shared my fanciful assumptions <P>Rich<BR><A HREF="http://www.1930Chrysler77.com" TARGET=_blank>www.1930Chrysler77.com</A><BR>Member AACA, WPCC

[bubba]

Speaking of Springs.....when jacking up a car with leaf springs for winter storage, is it better to have all the tires off the ground or just have them touching with most of the weight off them? I always heard not to raise them totally off the ground but a friend just told me it's better off so that the springs re-arc. INquiring mind would like to know.

[novaman]

Ply33, you didn't mention those famous ladderbars to keep the springs from trying to wrap themselves around the rearend housing for those people who like to do 0-60 MPH in five feet. <P>My Chevy IIs have the monoleaf springs on the rear. If you look at them that are really "thin" out by the spring shackle and the pivots under the rear seat. as you get closer to where the rear housing is attached the thick they become.

[ply33]

bubba,<P>If the springs on your car (or any car) could take a set from sitting or from being jacked up then they would never be able to be used as springs while you drive. The yield strength of those springs needs to be very large in relation to the vehicle weight to handle the dynamic loads encountered while driving.<P>I would not worry about the springs, jacked or unjacked on any car that is parked.<P>Now the tires are another story. Depending on the materials used for the "fabric" they can take a "set". The advice that makes the best sense to me is to jack the tire off the floor so there is no load on it. I have also heard, and it seems reasonable, that you should reduce the pressure in the tire to the point where it just holds its shape. The explanation is that there could be a slow seepage of air into the body of the tire that can cause oxidation and separation problems. I don't know how true that is, but it does not seem like it could hurt.<P>For myself, I live in a climate where it is nice enough in the winter that I can usually find one or two weekend days a month to drive the car. So, I don't jack it up for the winter. I just drive it.....

[Guest Hal Davis (MODEL A HAL)]

Bubba,<P>If you jack the car under the axles rather than under the frame, then the springs will stay in the same place as when it sits on the tires. In other words, the springs will still be supporting the weight of the body just like normal. <P>To all,<P>In the Model A era, Ford lubricated the leaves of springs before assembly. I don't recall exactly what it was, maybe a mixture of graphite and kerosene. It was something like that. I imagine the kerosene eventually evaporated leaving the graphite.

[cmj]

Jordan owners were told to "The springs should be lubricated regularly every 500 miles. ... it is only necessary to paint the sides with motor oil."This was to lubricate the springs and eliminate squeaks. from a 1930 owners manual. 1929 just says to paint the springs with motor oil every 500 miles.

[Guest]

I'm no expert, but can share my experience. My '64 Lincoln used the plastic-like insulators between the spring leafs, and I had to replace them regularly to eliminate squeeks. On my '35 Auburn, I sandblasted and painted the leafs, then greased them before assembly. No squeeks, and the car rides nicely. Originally, the Auburn had metal spring covers with grease fittings on them, and they were supposed to be greased regularly.

[RoadsterRich]

I was just browsing the owners manual for my 1930 Chrysler 77; it refers to the springs as "dry leaf type". Is it possible there are both "dry" and "lubricated" style leaf springs? Perhaps some are meant to specifically not be lubricated while others are meant to be? The wording caught my attention...<P>Rich<BR><A HREF=http://www.1930Chrysler77.com>http://www.1930Chrysler77.com</A><BR>Member AACA, WPCC