As with any multileaf spring they will fail if they are not maintained. If they have been in place for years, which is probably the case given your description, the spring will ac***ulate moisture and consequential rust between the leaves. This basically causes the spring to seize as the leaves can't slide over each other when it is compressed. Eventually, that will lead to a failure of a leaf. If not attended to the house of cards begins to fall and one by one the leaves will fail because of the increased load due to the failure of the first. I use a multileaf spring in my roadster. What I did with mine was to dismantle the spring to the individual leaves and linish them to remove all sharp edges. I then applied a liberal amount of ch***is greased on the leaves and also placed a needle roller from a uni-joint under the tips of the leaves as I ***embled the spring. Ithen tightened the centre bolt and the clamps. After that I then applied some shrink tube, the stuff that electricians use to seal outside installations to seal the area from adjacent to the spring eye up to and part way over the shortest leaf on both sides. This left an exposed area of about 8" in the middle which is more than enough to allow the spring to properly mount up to the crossmember. That arrangment flexes real well and allows the spring to function for many years without the grease drying out or becoming a dirt magnet and causing the spring to tighten up. Having had unsealed roads to navigate in my travels over the years this has worked well. This includes a couple of trips over hundreds of miles on dirt and corrugated roads to Lake Gairdner here in Oz for our speed trials. Anyone who has been there will know the conditions I'm referring to. I've never had any experience with a mono-leaf spring however, given the discussions here I don't think that is about to change anytime soon.
At one time, Mr Durant had Dayton Parts Company from Harrisburg PA. making all his mono-leafs. Mono-leafs and hyperbolic taper leaf springs have had a long successful life in big trucks & semi trailers. My understanding was that Durant was the first to step up with the money and order these limited sales applications ( compared to the heavy duty market). The minimum number of units required to make each part number was also substantial. In return for his investment, Dayton gave him exclusive rights or "proprietary part numbers" That only he could buy from them. Not even another big Dayton customer called Posie. Shot peening is considered to be an expensive step in spring manufacturing and all quality springs are shot peened to stress relieve the surfaces of them. Before I retired as purchasing agent from a large spring and truck parts company I tried to get some mono leafs from Dayton for my '56 F-100. They would not sell them to me because of their arrangement with Durant. They did however, buy me a set and give them to me as well as taking 6 of us to Booneville. I have no reason to believe any of these policies have changed including Dayton selling only quality, American made springs but if my mono leaf had not been shot peened I would suspect it of being off shore.
My questions: Why doesn't anyone offer a composite monoleaf that would eliminate the metallurgical (is that a word?) complications that come with these steel monoleafs? What are the "pros" of the monoleafs currently available for hot rods? Do they sit lower than a traditional leaf spring? A super-low composite monoleaf might be attractive. JH
I still am reluctant to "name" the mfg of the spring. Great people from Pete and Jake's got one almost overnight to my builder and I picked it up today. Failure on thursday night. Spring in Tulsa monday. Now thats service. Thank you guys at Pete and Jake's. If you haven't done business with them , get your act in gear. Great people, quality products and fantastic customer service. -----Nuf said!
I'm very happy with my front pair of Durant monoleafs. They are on my daily chevy 52 truck with a 650 lbs. cast iron 6, for the last 6+ years. I also got special designed gas shocks for the dropped 3", with lifetime warranty, also made in USA. I remember talking to James Durant over the phone at the time I got them, to hear what he thinks about safety of monoleaf springs. He came across very open, honest, knowledgeable and confident. I found the old thread with Durant's info .... http://www.jalopyjournal.com/forum/showthread.php?t=25217 After 6 years and very thorough use, I still think it was one of the best things I ever did to my truck. I always liked how smooth they ride for a truck and how much they flex, but never bottom out. The type and design of shocks also greatly determines the ride quality and reliability of the spring and should match the vehicle and use.
I installed a Durant monoleaf on a '40 Ford I owned. I put about 30K miles on it and never had an issue. Sold the car to a guy in Florida and the spring broke on him almost right away. Durant made it good and shipped him a new one no charge. Fortunately he was going slow when it broke and there was no damage done. He just had to throw his shorts away. The next car had a complete Pete & Jakes front end with a Super Bell axel. It rode just as good as the monoleaf and I felt more confident hiting those darn N.E. potholes.
I would be interested in hearing what people are doing to old springs to freshen them up. I would ***ume that sanding sideways would be bad, creating stress risers. chamfering edges seems to be a good idea. Fredeuce putting a needle at each tip sounds like it would localize the pressures across the face of the leaf, again creating a stress point. Aside from separating, cleaning, chamfering and ***embling with some sort of lube (anti-sieze, grease?), are there any other tips to make them work happily and live a long time? What about paint between the leaves? If you paint them ***embled, will the edge at each tip add friction/stiction?
had a Durant monoleaf in my A...had maybe 12000 miles on it when it snapped. I hit a pot hole, not particularly bad one and i was doing below 30mph. When it snapped the frame dropped on to the front beam axle and the right side front wheel jammed up against the front fender causing the car to cross the white centerline (im in the UK so drive on the left!!) and hit a car coming the other way....I had 2 kids in the car at the time too.....I will NEVER use another monoleaf what ever it's made from.. the breakage photos you have posted are exactly the same as mine looked, small initial stress crack, small spot of rust and then a clean break, even the profile of the break is the same!
You make a fair comment about the stress point . However the way it did was to chamfer the ends of the leaves inconjunction with the needle roller. This prevented the end of the spring leaves from galling at the ends on the leaf below in much the same way that some aftermarket springs have pad and relief in the spring to locate it. The indivual leaves made full contact with the leaf below.
This is an old thread, but was surprised to find so many others who experienced failures also. I cant believe this company still sells this product. I dont mind saying their name out loud. DURANT>>>DURANT>>>DURANT! Per my experience with their company, I wouldnt run another one if they paid me $5,000 to install it. I was traveling at 75 mph on a smooth highway at night (E470 SW of Denver) when mine broke back in 2001. When I called them to let them know I had one of their 2 piece springs, he replied he doesnt have 2 piece springs and none have ever broke. I told him he cant claim that going forward, but obviously he still does. I hung up on him when he told me he wouldnt stand behind his "unconditional guarantee", but he would sell me another one at a discount. I hope he experiences a failure for himself one day so he realizes how dangerous his product is. Buyer beware... As for me and any friend who will listen, I will only buy Posies going forward. At least they stand behind their product...and they have always been nice to deal with also. I regret to have been talked into straying away from their product. Never again.
I dont see how multi leafs would make any difference in the outcome.The main leaf is the only one that has the eyes on it and when the end snaps off,single leaf or multi leaf will be flopping around.
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