RHS size for transfer case crossmember...?

[smaddock]

I bent my transfer case crossmember on my 4runner a couple of months back, not too bad but got me thinking about making a lower profile one. Since every mob that makes the low profile hilux ones say they don't suit 4runners, I'll be making my own.

I've got some 70x25 RHS in 2.5mm thick, do you think that'd be sufficient in strength? I would think it would be, but any other opinions would be good. I'd probably prefer to go something in a 3 or 4mm thick, but this is what I have for now.

Thanks,

[stock 4runner]

mate where is frankston im pulling my low profile off my 4 runner and its up for grabs

[DamTriton]

Frankston is out near "put playin"

(SE suburb of Melbourne actually)

[lukethedork]

I used 100mmx50mm it's 3mm wall.
I can guarantee this will bend very fast on my sub 2,000KG Jeep.
I am going to sheet it with 3-4mm sheet (making it 6+mm where the crossmember is) and then 1/2" (12.7mm) UHMW.

If you look at Lukey4x4s and Buds customs Hilux crossmember/skids they are both folded 10mm. Your RHS will resist bending more, but 3mm will still DENT very easily. I would go for 6mm minimum if you are just going to have a piece of RHS sitting in the open.

Luke.
PS. If it is purely to hold up the transfercase/transmission and you are leaving the RHS intact (ie. not cutting pieces out of it), Then I think it is plenty strong.

[smaddock]

Yeah I was afraid the 2.5mm wall might be a bit too thin. It won't be a straight piece of RHS, I was going to notch it where it needed bending and weld it at the bends with extra supports on each bend, but yeah, I didn't really think of how easy it would bend when contacting rocks I was going to make up a skid plate to attach to it too.

But maybe I should go for a 100x50mm with a decent wall thickness (4 or 5mm if possible), that is if I don't happen to come across one for sale soon

Cheers guys!

[smaddock]

Alrighty, got the RHS sorted. Ended up going for a 75x50mm with 4mm wall thickness, looks plenty strong enough for what I'm planning. It won't be a straight piece between the chassis, what I've done is got a piece coming out straight from each side off the chassis, then one length mounted to the bottom of these, joining each side, welded with extra plates also mounted over the welds to make it stronger. Here's a lovely Microsoft Paint pick of what I mean



Basically, I'll gain an inch clearance underneath, but will have a crapload more protection, which brings me to my next question, what thickness sheet metal would you recommend for a skid/bash plate? The plate will cover the transfer case, and a little bit of the tranny. I was thinking 3mm thick?

[lukethedork]

what thickness sheet metal would you recommend for a skid/bash plate? The plate will cover the transfer case, and a little bit of the tranny. I was thinking 3mm thick?

Can you tell us what size tires you have and whether you bash on the rig or just want to get to the good camp spots and back home?

Like I said, I am going to do 3mm with light bracing behind it AND then either 1/4 or 1/2 UHMW over that... so it is substantially stronger than just plain 3mm plate.

Quote from TJM website 'TJMs range of Sump, FUG and Transmission guards are made using 3mm thick steel'.

Hope this info is helpful.
Luke.

[smaddock]

what thickness sheet metal would you recommend for a skid/bash plate? The plate will cover the transfer case, and a little bit of the tranny. I was thinking 3mm thick?

Can you tell us what size tires you have and whether you bash on the rig or just want to get to the good camp spots and back home?

Like I said, I am going to do 3mm with light bracing behind it AND then either 1/4 or 1/2 UHMW over that... so it is substantially stronger than just plain 3mm plate.

Quote from TJM website 'TJMs range of Sump, FUG and Transmission guards are made using 3mm thick steel'.

Hope this info is helpful.
Luke.

Tyres at the moment are 32x11.5x15, but am planning on getting 33's next. So them themselves will give me another 0.5 to 1 inch, but still want a little bit more protection. I don't go rock crawling or do anything extreme, just like to get out once every month or two to go round the local tracks. Last time out on Deep Creek 1 track in Walhalla, there's a rock ledge entering a creek bed that bent my stock crossmember, hence why I'm wanting something stronger with a little more clearance and a nice skid plate. The stock one is only around 2.5 - 3mm thick I'm guessing, and it didn't bend that much, but did nonetheless. 4mm RHS should be a bit stronger, and with 3mm plate acting as a skid plate, I'm tipping I'll just slide over the rock ledge next time... Why am I doing it considering I don't get out that often? Well, its only cost $25 so far, all I need now is the skid plate... Hmmm, cost of nothing from the factory behind ours, done and dusted for a whole $25, thats why I'm doing it

Thanks for the replies too... I'll let you know how it goes, tomorrow I'll be finishing it off!

[lukethedork]

From the sounds of it you will be ok with the crossmember and then a plate of 3mm steel. If you want to strengthen it slightly then put a little bend at the front and back of the steel plate, this will help stop it from bending.

Luke.

[904Runa]

... Since every mob that makes the low profile hilux ones say they don't suit 4runners, I'll be making my own.

That might not be right. When I swapped a G52 and transfer case from a solid axle hilux into my 4runner to run crawler gears (the standard transfer is chain drive and no crawler option available), the original crossmember was fine, the only thing that needed changing was the case mount.

[smaddock]

... Since every mob that makes the low profile hilux ones say they don't suit 4runners, I'll be making my own.

That might not be right. When I swapped a G52 and transfer case from a solid axle hilux into my 4runner to run crawler gears (the standard transfer is chain drive and no crawler option available), the original crossmember was fine, the only thing that needed changing was the case mount.

Yeah but it was more of a case of the way I was told that their crossmembers wouldn't suit, they were all quite rude and wouldn't even think of fitting one to a 4runner... That, and I really didn't feel like paying $300+ to see if it would fit. Nah I've almost finished mine, will be fitted this weekend, and only cost $30 all up, time will tell how strong it is