Bronze Bushing Wear

[flyfshrockies]

Cate&Rob TucsonJim Again not being an engineer I am uncertain of many aspects of suspensions. Two things come to my mind regarding springs and bushings. These bushings are subject to an increased debris load due to their proximity to each other and being behind the tow vehicle as well, no fenders to speak of and no slash guards. It would seem that in these conditions the addition of grease without seals to protect from grit etc. that the grease may attract, hold grit and form a fine grade abrasive that works into the bushings during movement, thus causing abnormal/accelerated wear. I know that on heavy equipment we greased the fittings at least once a week to expel dust and grit regardless of need for lubrication, due to no seals. I don't know. As for the springs being multiple vs. single leaf, the multiple springs in varying lengths might actually create hard spots that are detrimental to the life of the springs as well as creating an increased harshness of ride as each different leaf takes load. Again I do not know about this stuff, just spinning it around. A single spring that is varied in thickness and tapered from the center to the tip with a welded on, alignment bored fitting on the ends would be far superior to a multi leaf arrangement, probably more costly but longterm cheaper due to reduced maintenance and repair. Many aircraft have a single leaf spring landing gear, they are great for rough conditions where the softer portion works well for uneven conditions with a fast response and the progression in strength farther up (think axel position) soaks harsh sudden impacts. Does any of this make sense? I am the curious sort so am trying to think this through.

Dave

[Cate&Rob]

Jlawles2
Hi Joseph,

What you suggest makes perfect sense . . . except that we are going to have to find correct dimension springs with bigger eyes. There is not room for the better bushing that you describe, between the ID of the spring eye and the OD of the bolt.

Rob

[Jlawles2]

Cate&Rob Rob, the nature of the spring eye since it is spring steel, just force it in there with a decent interference fit. the eye will flex since it's not a solid piece.

flyfshrockies Dave, welding and the quality of steel for springs can be done, just not cost effective. I wonder if going to dump trailer (big rig stuff) where the spring is center supported and the ends of the leaves are attached to the axles would be a better system.

[Guest]

Another issue is the size of the pin. A much larger spring eye with a steel tube for a pin would spread the load more evenly over a much larger bushing. A grooved bushing would also help to distribute lubrication where these small diameter pins with a poorly fitted bushing just pushes the grease away from the load bearing region. The other issue is the short length of these springs. There is much more motion at the bushing as compared to the much longer springs found on a pickup.
An automotive style spring eye and bushing on one end and slippers on the other end would also take care of the wear for an alternate choice.
There are also low cost torsion systems out there.

Jim

[flyfshrockies]

Guest Good points Jim, hadn't thought about the length of the spring increasing motion. To your point about the poor fit and bushing contact defeating the grease dispersion, perhaps double spiral fluting of the bushing would better distribute the grease if there were two ports from the hollow bolt core end at the zerk fitting. That would probably be reasonably cost effective vs. the constant parts replacement. It would seem that some enterprising person might do this if the opportunity was brought to their attention. A past acquaintance had a cnc machining business and that stuff could do amazing things in a hurry once programed. Good discussion.

Dave

[Guest]

An automotive spring flexes primarily in its rubber bushing where the steel on steel bushing and pin are not factors. They can get away with this due to the increased length of auto type springs. For these cheap across the pond springs with a poorly shaped spring eye and no way to hold grease its a failure waiting to happen. It may be possible to use epoxy in the spring eye or JB Weld as gyro suggested to bring some stability to the bushing but it would need to be greased prior to each trip at a minimum. Wondering if Eaton/Detroit spring could make up a set of quality springs with proper spring eyes or even rubber bushings to retrofit to our Ben Hur suspensions.

Jim

[JCR GD]

Shoutout to @JD JCR . Well that sucks, only my tag for TucsonJim worked.....

Pat

Hey Pat... Gotta get the name right JCR GD

[Cate&Rob]

. . . our Ben Hur suspensions.

Jim

Ain't that the truth !

Rob

[Dave27]

Cate&Rob Hi Rob, is there any way to determine the wear other than take it apart? I am well past 20,000 miles with the Moryde replacement suspension. If this is how they all wear, I will be replacing them every other year. Are the bushings a standard size, and where is the best place to get replacements?

thank you for bringing this to our attention.
Dave

[Lonestar]

When Brian and I were at MorRyde a few months ago, I specifically sought out one of their technical staff and asked them how long I should go before replacing the bushings. His answer was "as long as you keep them lubricated, they should last the life of your trailer".
Jim

The lubrication of the wet bolt bushing concerns me. With only one small hole in the bushing from which the lubrication escapes, it just doesn't seem like there is going to be a good distribution of grease inside the bushing. Seems like the grease comes out the hole and heads straight down the bolt toward the end(s) of the bushing in the path of least resistance, leaving about 90% of the bolt un-greased.

Maybe I'm looking at this wrong.

A more efficient solution might be spiral grooves running the length of the bolt on the bolt's diameter, so that when the grease came out of the hole it would spiral around the bolt in both directions, effectively greasing the entire I.D. of the bushing. If kept well greased, it seems like this would allow the bushing to last a long time.

[Jlawles2]

Lonestar better option may be to put Teflon washers between the straps and the spring to forma seal which will help he lubrication stay in place better. the spiral grove only works well when the tolerance is tight and the parts rotate 360 so the lube gets drug around the perimeter. With a spiral if the wet bolt is clocked upward, the grease will follow the same path as with out the groove. If clocked downward, you may get a little in the center around the hole, but it will follow the groove up then the same path as before.

Ideally a wet bolt or bushing with poly inserts may be a getter option.


if the image does not work: http://www.nationalbronze.com/News/h...onze-bearings/

[Lonestar]

I really like your idea of the washers, and the plugged bearings look great. I just can't see how the current crop of wet bolt bronze inserts can last that long since they just do not seem to distribute the grease very well. Still better than the old nylon inserts, but bet if they were checked very often we would find they need to be replaced frequently even if kept greased.

[Guest]

If the springs were made with quality in mind and had a well sized eye, a bi-metal bushing would be all that's needed. This is a steel/bronze bushing with pockets to hold grease and to distribute evenly. Also the spring hangers that are much too wide would also need to be corrected to aid in a tight gap to help distribute grease.

Replaced many of these in springs as well as in king pins in my younger days. Here is an example of a bi-metal bushing.

https://www.truckspring.com/products...__OGB-RNK.aspx

Jim

[Cate&Rob]

Cate&Rob Hi Rob, is there any way to determine the wear other than take it apart?

Hi Dave,
There is no way to determine the condition of the bushings with out removing the spring. They are completely hidden within the assembly.

Improving the fit between the hanger and the sides of the spring or ends the bushing seems like a good idea . . . but there is a problem with this. The spacers would have to be carefully sized because the nut has to come up against the shoulder on the bolt to reach proper torque. If the nut reaches torque against the side of the hanger, the back and forth motion of the spring might unwind it. This is why hanger reinforcement (V-Clip) has to leave some flex in the hanger sides. The design intent (if you can call it that) is for the hanger to bend inward until the nut torques against the bolt shoulder. This creates a final assembly where the hanger sides are not square to the ends of the bushing It is what it is.

Rob

[Lonestar]

Cate&Rob

You are so correct. Also if the hangers were formed to exact measurements, or spacers were used, it seems it would be so tight you could never get the spring ends in and out of the hanger.

If a bushing holding grease such as Joseph or Jim suggested were to be used, along with a way to add grease, I bet they would last a long time. I guess this is all a moot point since we are probably never going to see springs from the factory with well formed/sized eyes.