Bouncing/teeter tottering suspension bounce depending on the road

[oddshot]

Odd thing

Ahem. That's "shot", as in ... "OddSHOT". Think of it as random "plinking", or perhaps the single flyer of an otherwise tight group of 6 shots.

I collect firearms, and used to write a column about unusual firearms or short stories that mentioned odd firearms in them. The name of the column was The Odd Shot. I kinda like odd things ... guns, cars, trucks, aircraft, music .... and, I guess any number of folks consider me a bit ... odd. Perhaps they are right. As a Humber owner, I'm sure you know how that goes. I had a chance to buy a Snipe once ... but I passed it up to purchase a Rover 2000TC. The Rover was a nice car ... not quite as odd as the Snipe, but OK in its own way.

I'm always at a loss when it comes to screen names and passwords and such like. Unfortunately, once you put it down and hit enter, you're stuck. You should see some of the others I've been stuck with.

AS I think on "Odd Thing" ... its has a ring to it, I guess. Sort of British, I suppose. Certainly a lot of odd things going on over there.

 

[gimpyrobb]

Absolutely correct. Here's a power point that explains it.

http://www.google.com/url?sa=t&rct=...=VJ5csOBI79-9fO3fiWSWPA&bvm=bv.84607526,d.cWc

Its a good power point ... but the first 10 pages explain what you want to know.

Quote: When assembling multi-leaf spring packs, never paint or lubricate the contact surfaces of the individual leaves. The result would limit the self-dampening characteristics of the spring.


ALSO ... In the 40 or so years I've been repairing cars, I have seen countless shock absorbers that "looked good" ... some even looked almost factory fresh. But, when I disconnected one end and compressed the shock ... there was NO pressure, the shock was dead.

One more thing. When I bought my Deuce home, it pretty much did the same as your truck over similar surfaces. I replaced the front shocks and everything was fixed.

I have since bobbed my truck, and to my rear-end, the ride quality decreased a bit. A set of shocks for the rear is on my list of stuff to do, but its not real bad so its not real high on the list.

Page 16 helped a lot. I will start there when I get a "round-tuit".

 

[rustystud]

You can add shocks to the rear without ever having to disconnect them. Start with a mount that affixes to the sling load point on top of the tandem pivot using the 1" pin to hold it in place. You need this bracket to fit snug in that pocket and protrude from the top about 1/4". Take a piece of 1/4" wall 2"x2 square tube and weld to the top of that parallel with the leaf spring pack and cut it about 4" short of the leaves on each end. Weld on a tab mount for the top of the shock on each end of the tube at a slight upward angle so the shock can be mounted at an angle, then build another simple bolt on tab mount from plate that you can bolt to the leaf end pocket on each axle. You will need to use short shocks, but this way the whole thing pivots with the axles and won't put a bind on the shocks. The springs don't flex so much so I can't see pulling one apart either. This is just preliminary thinking on my part. I haven't actually entered the design and measuring phase yet. It should help dampen things a bit anyway.

Jeepsinker, could you provide a diagram showing what you just said. I have a hard time visualizing things. I have dyslexia. No I'm not kidding. I was lucky enough to be involved in a special experimental program out of the U.W. university in the 1960's which helped me tremendously, but it still is difficult to take the written word and describe a mechanical thing for me.
Thanks.

 

[Csm Davis]

Okay I will not debate whether leaf-packs need to be lubricated or not as I believe nobody will lube them anyway. But I do believe that cranetruck gave us the design we are looking for. I don't believe the suspension we have can properly control the axles at speeds we travel with little or no loads on board. So to add shocks I will copy this design pretty close.

 

[rustystud]

Okay I will not debate whether leaf-packs need to be lubricated or not as I believe nobody will lube them anyway. But I do believe that cranetruck gave us the design we are looking for. I don't believe the suspension we have can properly control the axles at speeds we travel with little or no loads on board. So to add shocks I will copy this design pretty close.

The only problem is the limiting of articulation. Yes you can make some kind of quick-disconnect system, but it would be a pain in the butt to have to crawl under the truck to do it. The walking suspension system in a deuce is a wonder of mechanical ingenuity, and I for one would like to keep that ability. With all the 4X4 hot rod shocks available someone must have a shock that will help our deuce's.

 

[cranetruck]

The problem stated by the original poster, is probably not solved with the addition a shocks, I was fully loaded when experiencing the "phenomenon" and I have seen Aberdeen testing (vintage videos), showing the effect when driving on a wave-like road. It has to do with distance between axles more than anything.

Before going through the trouble of adding shocks to the deuce rear, calculate the existing damping already provided by the 12-pack leaf springs.

 

[Csm Davis]

The only problem is the limiting of articulation. Yes you can make some kind of quick-disconnect system, but it would be a pain in the butt to have to crawl under the truck to do it. The walking suspension system in a deuce is a wonder of mechanical ingenuity, and I for one would like to keep that ability. With all the 4X4 hot rod shocks available someone must have a shock that will help our deuce's.

What is the overall travel of the axles? Think you can find a shock that can be used without any problems or disconnect needed.

 

[welldigger]

What is the overall travel of the axles? Think you can find a shock that can be used without any problems or disconnect needed.

The problem isn't finding a long travel shock absorber. The problem is everyone throws a hissy fit when they find out they are north of $350 each!

 

[gimpyrobb]

Yup.

 

[cranetruck]

Check out NOS M37 shocks...

 

[skinnyR1]

I am going to take the advice given, and change the front shocks to begin with. I'll start with the easy stuff 1st.

 

[rustystud]

The problem isn't finding a long travel shock absorber. The problem is everyone throws a hissy fit when they find out they are north of $350 each!

Did not know that. Your right, that is a lot of money !

 

[Lonnie]

One thing that can contribute to this is the big singles, combined with no weight in the truck.
Your tire pressure is low enough, maybe too low though. Too high they bounce like basketballs, too low they flex & spring back.

I had a similar event with my 5 ton when it was still a tractor. The large tires, stiff springs & no weight in the back would make it buck when you hit expansion joints at bridges & especially on concrete highways. If you got into a certain rythm (based on road speed) with the expainsion joints, it would seemingly keep increasing in magnitude.

Basically the tire is being more of the suspension than the spring is & you cannot dampen the tires. Unfortunately, they are going to do what they want & all you can do it try to control what you feel in the truck with shocks etc.

One thing I found to help was to run different pressures in the 2 rear axles. Since they react at different frequencies they wont bounce at the same rate. This can cause a cancelling effect instead of an increasing resonance.
Try 35 in 1 set & maybe 45 in the other. Also try higher pressure in the front, since this is where more weight is concentrated. Maybe start at 45 there as well.

Experimentation is key here. It is also a no cost item.