939 bouncing

[BenRoberts]

Has anyone fixed permanent weight in the bed to help with bouncing when driving? If so I wouldn't mind seeing your pics. I also could have a tire out of balance. I understand they are a rough ride but seems like after a bit of time in the seat a seemingly healthy guy could develop a case of hemorrhoids in a quick fashion.

 

[Jason O]

I had the same issue with both of my trucks. My tires were out of round, and out of ballance. Weight will help a bit, but not correct the situation. In my case I had the tires shaved down (loosing a bit of tread) to get them true. I also added ballance beads to the tires.

 

[Suprman]

You would need alot of weight in the bed to make a difference with the bouncing. The leaf springs are really stiff and heavy.

 

[M543A2]

If you can determine if it is coming from the rear you might try removing one outer rear wheel at a time and turning it 180 degrees then driving it to see if it helps. You can do this to the other three until hopefully it gets better. This can orient the wheels so the out of round or out of balance on a dual set offsets each other. I have also found the tire that is out of balance and had luck with de-mounting it and rotating it 180 degrees on the rim and trying balancing it again. This may offset a tire/rim balance problem, again helping each offset the other.
Is it possible the truck has sat in the same place for a long time, making the tires develop flat spots? If so, they may come out with time or rotating one rim 180 degrees on each dual set as mentioned above might help until they do. Unfortunately if those attempts to solve it with little cash outlay (hopefully you can do the wheel removal and replacing yourself) does not work you will have to spend the $ to do something like what JasonO suggests.
Regards Martin

 

[Aruba1]

You can go old school and add a pint of coolant to each of the tires to make it ride smoother. I am planning to do that soon to mine.

 

[BenRoberts]

All 10 tires look almost new the spare also looks new. i may have to utilize it

 

[MuleMac01]

Just a note I spoke to a guy that drove M923A2 in the army about the bouncy tires and he says that's norm if you run empty. Mine has a slight bump on them.. I put 4 14R20 tires in the back and hauled my M105A3 trailer around and the bounce stopped I don't know if this will help everybody but... just saying.. Hope this helps.

 

[Csm Davis]

Ben take your M923 to a big truck shop and have them balance the tires and see if that helps and also don't run them fully inflated, try lowering the rear tires air pressure 5 psi at a time, probably no lower than 50 psi, if you think your M923 is bad try a tractor M931.

 

[BenRoberts]

Ben take your M923 to a big truck shop and have them balance the tires and see if that helps and also don't run them fully inflated, try lowering the rear tires air pressure 5 psi at a time, probably no lower than 50 psi, if you think your M923 is bad try a tractor M931.

Ill try lower the PSI a bit. When I picked it up I did not have this issue and the tires were a bit low,not dangerous but about 10psi or so. Since then ive aired everything up an it got real bad. Never put 2 and 2 together

 

[Tinstar]

Remember your driving a empty cargo truck.
It's gonna bounce. A lot.

Mine had flat spots but after driving enough to really get the tires warm/hot, it helped a LOT!

Now I have zero tire bounce issue

Does it still bounce while driving? Of course! They are empty cargo trucks.

My suggestion is pick a warm day and do a road trip of several hours total.
This will give the tires a chance to heat up and "reset" if their able.

Worked for me.

 

[Tinstar]

It worked for me on the super singles.

If it will work on the dual tire setup, I don't know.

 

[BenRoberts]

I noticed a significant improvement when the outside temp was 30F cooler than the initial bouncy day. rule of thumb 10F = 1psi or so difference in air pressure so I had a roughly 3psi air drop which id say took 75% of the issue away. I would of never thought that slight of psi change would effect something that large. im also getting it out more which im sure helps. Ill be taking Tinstars advice here soon.

 

[WYomer]

I had the same issue with both of my trucks. My tires were out of round, and out of ballance. Weight will help a bit, but not correct the situation. In my case I had the tires shaved down (loosing a bit of tread) to get them true. I also added ballance beads to the tires.

Do ballance beads interfere with CTIS at all? I know guys used to use airsoft pellets in rock crawlers but they break down.

 

[Jason O]

Not sure about the beads and the CTIS yet. I have a feeling that at some point a few will get stuck in a wheel valve, prevent it from seating, and deflate a tire. I'm going to try something bigger on the other truck - maybe golf balls.

 

[Aruba1]

Not sure about the beads and the CTIS yet. I have a feeling that at some point a few will get stuck in a wheel valve, prevent it from seating, and deflate a tire. I'm going to try something bigger on the other truck - maybe golf balls.

Golf balls will eventually compress in a cube pattern and it will destroy your tires from the inside. Beads will require to break the tires. Have you done one? I have tried, the easy part was to remove the bolts with a 1" impact but it's still lay behind the garage. It take a lot of work with the tire hammer to separate the tire from the ring. It's a process, lol, eventually I will be there although I am thinking of using the backhoe.

 

[Jason O]

Aruba-

I injected the Counteract beads through the valve stem w/o splitting the wheel. A few of my wheels need new o-rings installed and I figured I may have to use the loader bucket to get the ring free from the tire.