powdercoating leaf springs good or bad ?

[beaulieu]

Hi

I will be "restoring" the suspension on an old race car,
it has transverse leaf springs like a Model A Ford ,

They are rusty now from sitting 30 years,

So do I take it apart and powdercoat them ?
or is there a better idea ?

I assume the leafs move against each other, I have heard of some race cars putting teflon between the leafs....

what do you think ?

Beaulieu

 

[Keoke]

Hi beaulieu. I am, aware that zink fillers were used to separate the leaves in springs. Similarly a friend of mine who is a ME used Teflon spacers in his. However, I do not know what type Teflon one should use as Teflon has a nasty characteristic known as cold flow. This simply says if you put pressure on it it will move [ Flow } away from the pressure point.Certainly the faying edges of the spring ends may require champhoring as a minimum. I do not think powder coat is a good idea either if the springs deflection is high--Fwiw---Keoke

 

[Steve_S]

I've been thinking about this lately as I begin to plan the suspension rebuilt on my MG TC. Teflon strips are very common and work well. Heavy grease also works well, especially when wrapped for protection.

I've considered POR15 since it's self leveling, very smooth / slick and hard as nails. Still, I think that any coating will eventually wear off. I suppose once it's worn off then you still have nice looking springs, but I do wonder if the separated coating will cause additional friction.

 

[DrEntropy]

Pro'lly very little, Steve. I like the idea of POR-15 THEN the Teflon interleaving. Grease will tend to attract/hold dirt 'n grit then become abrasive rather than reducing friction... just my thoughts on it.

 

[roger_abbott]

The rear spring in a Triumph GT6 is a transverse leaf spring. It hangs out underneath the car, subject to road spray, mud and whatever else comes up off the road.

After removing and dismantling the rear spring on my GT6, I cleaned off fossilized grease mixed with mud. Once cleaned up, I discovered rust damage on some of the leaves. However, when I bolted up the spring and tested it for load in my h-frame press, it met the specifications set out in the Bentley manual. It appears it is still a good spring that needs rebuilding.

In this particular spring, Triumph inserted rubber buttons under each end of some of the leaves. These, of course, have worn flat. If I replace them with new buttons, there is a gap of about 1/32" between the spring leaves.

To avoid future contamination of the spring with road debris, I was thinking of wrapping the spring to seal it. I would appreciate your comments on (1) whether to wrap the spring and, if so, (2) what material to use for a wrap. Thanks.

 

[Steve_S]

Yes, possibly, but periodic maintenance of the springs was encouraged with pre-war and early post-war cars, especially in places like England where roads were often dirt. I've also considered greasing the springs and then wrapping them in tar tape, followed by rope. That outta be pretty water tight.

 

[Dave Russell]

IMO,
Anything you wrap the springs with will let "some" water in, but it makes it much harder for the water to get out so that things can dry.

A correctly built multi leaf spring will have each successively shorter leaf more arched than the preceding ones so that the main load points are on the tips of the leaves. All sorts of liners have been used between the leaf tips to reduce friction & squeaks.

Many factory springs use inserts only on spring tips which are made to retain the inserts. Other types of spring tips may require full length liners to keep them in place.

Although Zinc liners used to be used, the liners are now usually made of Teflon, Poly, or Nylon.

I think it's personal preference whether you use liners or not. It's not really going to help anything much except to reduce squeaks. Any liner or other "coating" will eventually wear through & need to be replaced.

Note - Spring leaf friction is not all bad, it assists the shocks in their damping. Less friction damping may require more shock damping.
D

 

[piman]

Hello Beaulieu,

I suspect that the extra thickness of the powder coating may cause trouble with re-assembling the spring, depending on the number of leaves and how they are put together.
What used to be common were spring gaiters made of leather which were fitted to the springs to protect them, some of which had grease nipples also so you could periodically grease the spring. (The spring would have had a heavy layer of grease prior to wrapping)

Alec

 

[Steve_S]

Moss used to sell those gaiters for the TC, long ago. They look kinda neat but I still prefer the look of cord wrapping.

 

[TRMark]

As usual Dave explains things very well. A good place to research this is the hot rod sites and vendors. The teflon liner material can be purchased in bulk and trimmed to fit, it's pretty cheap, about 10 bucks for a 2" wide by 20' ribbon. How about posting a picture of your old race car. I am working on mine over the winter, it has transversal leaves also.

 

[GregW]

McMaster Carr sells bondable Teflon in sheets. It could be glued on one side to keep it in place, not cheap though.

 

[DrEntropy]

On a street car you'd only need to do it once. Powder coat and Teflon glued to the underside of each leaf. Sounds a winner to me.

 

[mikeyr]

get the teflon liner and powdercoat them and be done with it for life. I did not use the teflon on mine and the powdercoating lasted longer than I thought it would.

Page 41 of this PDF at Restoration Supply (one of my favorites places to shop) has Poly-Slide, as I said I did not use it on my car but I have used it before and its great stuff. https://www.restorationstuff.com/Catalog/RSC%20No23%20web3.pdf