What supporting mods to run 40s

[Kevin8086]

what are the weak points of the Truck? I’m on 37s now and want to go 40s but I wheel pretty hard and afraid it may be too much stress. I have
-part time kit
-4.88
-25% tcase reduction
-HD tie rods
-chromolly birfields/axles
-DC joints and drive shafts
-adjustable rear upper and lower arms

What else needs to be beefed up?
Hydro assist needed?

 

[-Spike-]

Wheel it 'till you break something. Go from there.

 

[White Stripe]

14 bolt axles front and rear, hydro assist.

 

[chap79]

@jcardona1 @ajax1 @js93cruiser @Camino @AMMO @PKP80 @nukegoat

 

[Kevin8086]

14 bolt axles front and rear, hydro assist.

That’s needed to wheel on 40s?

 

[baldilocks]

That’s needed to wheel on 40s?

No. I believe you got the correct answer from @-Spike- because the answer to your question is purely subjective. Therefor, this thread will probably go on for pages.

One thing is fosho; your gonna need a Sawzall.

 

[White Stripe]

That’s needed to wheel on 40s?

You said your wheeling hard, so one ton axles should be considered in my opinion. Could the toyota stuff hold up? Your pushing the limits, especially if your hard on the gas pedal.

 

[LandCruisinMy93]

You have more going than I do and I've been on 40's for years and when I wheel I beat my rig like it owes me money and slept with my old lady. I would say truss the front axle if you're going to run the stock housing. I somehow bent the short side lol but it still drives alright; I just go through more inner seals on that side lol and have a bit more camber on that tire. As it's been said, wheel it until something breaks and address it as it happens.

 

[nukegoat]

I wouldnt

 

[-Spike-]

I wouldnt

Says the guy who did.

Also, you let me down ng. Perfect opening for your usual spiel. Are you going soft?

 

[nukegoat]

Says the guy who did.

Also, you let me down ng. Perfect opening for your usual spiel. Are you going soft?

Oh. Well, I wouldnt do it on an 8" ring gear and 30 spline shafts. And certainly not without stacking a few head gaskets in the engine

 

[Kevin8086]

I wouldnt

Why wouldn’t you? I’m seriously debating it and just want to keep it reliable

 

[nukegoat]

Why wouldn’t you? I’m seriously debating it and just want to keep it reliable

OK, here's why: When you run close to the limits of metal things, especially those subject to lots of stress reversals, then it's a matter of time before you fatigue them to failure. So you may get a few trips on the whole setup but then it may fail when you're not getting on it that hard and/or in the middle of nowhere and/or during a long trip you expected to really enjoy.

I'd rather engineer things to last effectively indefinitely (unless they're easy to replace/repair and/or the failure modes are non-critical).

Google S-N curves

 

[baldilocks]

You are venturing into big money territory if you really do wheel hard and often. I have seen a couple of your videos and your style seems to be defined by optimistic enthusiasm.

You don’t mind using the skinny pedal. Do you see where I’m headed with this?

 

[Kevin8086]

Sadly this is the reality of 40s. I was hoping it wasn’t so but in the end it really isn’t a good idea.

 

[nukegoat]

Sadly this is the reality of 40s. I was hoping it wasn’t so but in the end it really isn’t a good idea.

Well, I'm a naysayer, but several members on here are running 40s on OE axles: @ExpoMax , @northwesttaco , @LandCruisinMy93 - I just wouldn't do it. But I have very little free time to risk "failures in the field" and enjoy engineering projects so swapping axles was a no-brainer for me. Not for everyone, though.

 

[jcardona1]

But I have very little free time to risk "failures in the field"

I'm in the same boat, which is why I think I'll stick with 37s for a while. The idea of 'wheel it till it breaks' seems good on paper but in reality I would hate to deal with that. Suffering from a pretty serious drivetrain failure in the middle of Rubicon or Fordyce would suck bad. Getting the truck off the trail in 2WD would be a nightmare, getting it home would be another hassle depending how bad the breakage is.

With that said, if you wanna go forward with it, I would at least consider adding hydro assist. After that you should be ready to go out and efficiently start breaking stuff.

 

[joez]

Been on 40's for over 4 years now.

RCV's up front, chromoly rear shafts, 5.29's, hydro assist, RCV drive flanges, rear hubs drilled for more dowel pins, the list goes on.

Have I broken anything big? Not yet. Do I know I am going to? Yes. Front ring gear is my bet on what will finally grenade, for the reasons listed above. Metal fatigues.

Would I say don't do it? Nope. I ran 42's on my minitruck, and while I did break a few ring and pinions, I would still do it again. I love the balance and ground clearance I get with my current setup.

It does help that I'm willing to pull cable when it doesn't feel good. I don't force it.

 

[retrofive]

So where is the need/want to go to 40's coming from? Every Starbucks I've been to 37's have been fine.

 

[nukegoat]

Been on 40's for over 4 years now.

RCV's up front, chromoly rear shafts, 5.29's, hydro assist, RCV drive flanges, rear hubs drilled for more dowel pins, the list goes on.

Have I broken anything big? Not yet. Do I know I am going to? Yes. Front ring gear is my bet on what will finally grenade, for the reasons listed above. Metal fatigues.

Would I say don't do it? Nope. I ran 42's on my minitruck, and while I did break a few ring and pinions, I would still do it again. I love the balance and ground clearance I get with my current setup.

It does help that I'm willing to pull cable when it doesn't feel good. I don't force it.

View attachment 1581883

Love the cage