daily doubler build

[kroussinoffroad]

You guys drive at highway speeds? How does that not drive you crazy? Every vehicle should go down the road smooth - regardless of tire size.

.

great in theory its just too bad NONE of the roads are smooth around here. rescently voted worst roads in america. ive never had to drive this rig over 10 miles on the road. wouldnt even have enough time to drive me crazy. if i could ever really tell they were out hahaha

 

[Sasquatch_Ryda]

An unbalanced tire cyclically loads bearings. Whether it caused failure or not, it probably shortened it's life. Granted we're not very nice on our vehicles anyways (offroading in general), but I try to eliminate any unnecessary abuse whenever possible.

You guys drive at highway speeds? How does that not drive you crazy? Every vehicle should go down the road smooth - regardless of tire size.

Yes, I drove mine at highway speeds, and will again on the 40's.

You ever driven on a set of bias swampers? Balancing doesn't make them smooth.

 

[Bray D]

I was curious so I threw a 500lb side load on it. Looks like the new design is stronger in that direction as well (40%). Win.

 

[Bray D]

Yes, I drove mine at highway speeds, and will again on the 40's.

You ever driven on a set of bias swampers? Balancing doesn't make them smooth.

My truck sees a LOT of road time. Bias ply tires don't belong on it.

Balancing will reduce the stress on bearing, steering, and general axle components. You're correct though, it's not going to make an egg shaped tire round again.

 

[Bray D]

Aaand just for fun, because I'm bored tonight.

Old assembly. 38lbs model weight.

New assembly. 50lbs model weight.

Hopefully the additional 12lbs yields the increased strength that I've been seeing in model space. Only one way to find out! I can't wait to beat the piss out of these things.

 

[Sasquatch_Ryda]

For sure. I drive mine on the road because I enjoy driving it, not because I need to. And radials have no place on our trails here lol.

New sliders look good!

 

[Josh40601]

Old design support to frame. 4" separation at frame. 2" left unsupported. 1" sch. 80 round pipe.

New design support to frame. .125" thick wall. 4" tall at frame, taper to 2" tall at slider. 1.125" wide.

I 'fixed' the mount at the frame, and applied a 2000lb load at the free end.

Old design deformation plot. 1.31E-4mm max displacement.

New Design displacement plot. 9.45E-5mm max displacement.

Granted the displacements are in mm, we'll look at percentages to get an idea of relative rigidity.

Looks like the new design will deform 72% as much as the old design under these loading conditions. 28% improvement? Not bad at the moment. I investigated adding another layer of strap to the top and bottom to make them .250" thick. It added some strength, but I'm not sure if it's worth it yet. I'll probably add some gussets as well that may add strength. I'll keep playing with it for a while, but this will be essentially the new geometry - as defined by spatial constraints.

Can you explain this a bit? I'm still pretty green when it comes to stress points and all that junk.

 

[Bray D]

Can you explain this a bit? I'm still pretty green when it comes to stress points and all that junk.

Sure. Those plots are pretty basic. I modeled them in SolidWorks (3D modeling program) and applied a material to them. That way SolidWorks knows all of the mechanical properties of the material (tensile-yield-elongation, density, poisson's ratio, etc).

Then I did a 'Study' in Simulation. Simulation is a FEA (Finite Element Analysis) program that is integrated into SolidWorks. It's called Finite Element because it breaks the part up into a finite number of nodes, then performs calculations at those nodes (stress, strain, deformation, etc). You essentially select how many nodes there are by how you mesh the model (jargon - I know). The more nodes, the more accurate; but the longer it takes to calculate a solution. More isn't always better. The key is to mesh the model such that you obtain an accurate answer in the shortest amount of time.

For this particular Simulation, I placed a 'fixed' constraint on the flat plate that will be attached to my frame. That made it so that plate wouldn't move when I put a load on the part.

Then I placed a 2000lb vertical load at the end of the part, simulating close to 1/2 the weight of my truck pushing up at that location (essentially 1/2 of my truck sitting on my slider, but my slider only being supported by one 'support').

For this analysis, the amount of load isn't as critical as the comparison of the results. I wanted to make sure my new design was stronger than my old design; so I placed both the new and old design under the same loading conditions.

Simulation will tell you pretty much anything you want to know (stresses, strains, and displacements in any direction and at any point), but for this study I only looked at displacement. I had SolidWorks tell me the location and the value of the maximum displacement under these conditions.

Of course, the max displacement happens at the end of the support, where the load is applied. I just looked at these values and found that the new support will deform 28% less than the old design under these conditions. The new support is lighter too, so it's an all around win.

The colors depict the severity of the deformation. Red = more. Blue = almost none. The visual deformation that you see is an exaggeration of the real world deformation, scaled by a value that you input (or it does it automatically if you want it to). If I looked at the actual deformation, it would hardly be noticeable. You would just see the colors.

If this were a stress plot, the colors would depict areas of higher stress. Red = more stress. Blue = almost no stress. You can see that in the pics where I analyzed the main members of the slider.



I welded the reinforcement strap on the bottom of one of the sliders yesterday, and it warped it pretty good. I'm researching thermal straightening to see if I can pull it back straight.

 

[Shran]

I haven't really been on TRS much since you started building your doubler. Looking good!

You guys drive at highway speeds? How does that not drive you crazy? Every vehicle should go down the road smooth - regardless of tire size.

I've never balanced my 35's. I'd like to but I keep gutting them and I'm sure it would take a lot of weight to balance a tire with a section vulcanized in. I also have never balanced the 285/87/16's on my tow rig... doesn't shake at all until you hit about 65...but it never sees 65 anyway

For you guys running bias plys - are you using lead/sticky weights, or what? Some of the local guys are using water, antifreeze, airsoft BB's, etc. Or do you just run them unbalanced?

 

[Bray D]

I haven't really been on TRS much since you started building your doubler. Looking good!



For you guys running bias plys - are you using lead/sticky weights, or what? Some of the local guys are using water, antifreeze, airsoft BB's, etc. Or do you just run them unbalanced?

Thanks man.

As for the balancing question, just like your local guys, there's going to be guys on here that run anything and everything. If I were driving them on the street, the first thing I would do is get them on a balance machine. Then at least you have some info to base your decision on.

 

[Sasquatch_Ryda]

I'm going to be running BB's in my 40" LTBs.

 

[wahlstrom1]

With the amount of weight you have on yours Bray, I'd copper BB balance them as well.... best thing is it also accounts for torn tread, mud in rim etc and is always 'dynamically' balancing the tire.

 

[Bray D]

With the amount of weight you have on yours Bray, I'd copper BB balance them as well.... best thing is it also accounts for torn tread, mud in rim etc and is always 'dynamically' balancing the tire.

I agree with everything but this.

The inside of the carcass of a tire is pretty concave, right? I think that will have a tendency to pull all of the media (bb's, airsoft pellets, sand, dynabeads, etc) to the center of the tire. The geometry of the inside of the tire prevents it from locating where it needs to be along the axis of the wheel to properly dynamically balance it.

I don't know for sure though. I never will until I try I guess. All I know is it works for some guys and others not so much.

I should've tried that before dynamically balancing with stick on weights. Definitely would've been quicker and cheaper. If it didn't work then I could've gone the stick on route. Oh well, I'll run em for now.

Do you run bb's Andrew?

 

[Sasquatch_Ryda]

Pretty sure he had them in his 37" mtrs

Sent from my GT-S5830D using Tapatalk 2

 

[wahlstrom1]

I've run BB's in everything from 31's to 44's and for me it's worked great. Flip a pop/beer can upside down and fill the dish with BBs, just over level for 31-34/heaped for 35-38's/heaped and a bit for 39+....

If you have a small scale (I don't, just used what I had on over 15 different sets of tires) you could work out the weight and make it perfectly even, but it really doesn't matter as it'll balance itself out, and the tire as long as you have enough in each.

I use these: