Welded or Bolted 1

[waskillywabbit]

Which do you think is stronger or perhaps more appropriate when attaching "sliders" to the frame of a 4x4? Why?

I've always welded on my sliders using some "scab" plates for spreading out the loading on the frame rails. I've never liked the idea of having more holes in the frame and I've also seen lots of modifications done where the bolts were tightened too much and pulled in the frame in those locations.

FYI: Sliders are tubing that protrudes perpendicular from the frame out from underneath the body between the axles to protect the rocker panels on a 4x4. Generally I make mine out of 2"x3"x3/16" tubing for the main rails and supports to the frame w/ 2"round tubing for the outriggers that turn up and protect the rocker panels.

Brian

 

[metengr]

waskillywabbit;
An interesting question. From my perspective (that deals with pressure retaining items), when one can reduce or eliminate the number of openings, the component will exhibit less stress concentration – which is desirable. Otherwise, openings in components need to be accounted for in design by either increasing the thickness of the component or by adding reinforcement.

This is not to imply that welds are better than bolts, because each joining method has to be carefully evaluated for the specific application. So, to indirectly answer your question, by reducing the number of openings using welded scab plates for the sliders, the frame will have less stress concentration.

 

[MintJulep]

Properly designed, either a welded or bolted attachment could be appropriate, and either could be made "strong enough". In more general terms, a bolted or welded joint could be designed to be equally strong, provided other factors do not impose constraints on the design.

Imporperly designed or executed, either a welded or bolted joint could cause the frame to fail.

As you noted, a bolted joint that spans a hollow section could deform the section. Carelessly drilled holes could introduce stress risers, or serve as crack initiation sites.

A poor weld design, or poorly performed weld could serve as a crack initiation site. Poor welding could blow a hole through a frame member (likely to lead to a repair attempt by buttering more filler metal over the hole).

So, the answer to your question is either of the above, provided the design and fabrication is good.

 

[diamondjim]

If the parts do not need to be disassembled
welding is the way to go. You do not have
to worry about loose bolts.

 

[DanEE]

Depending on which way you end up going, these references may come in handy.

This document published by the Australia DOT does the best job I've seen in dealing with welding on frames.. It is written with heat treated frames in mind, so makes good advice for taking a conservative approach on a mild steel frame..

http://www.dotrs.gov.au/transreg/vsb/PDF/vsb_06_h.pdf

If you want a look see at some practical experience with mounting sliders you might want to take a look at this site..

http://www.4x4wire.com/toyota/tech/sliders/

The frame cradle included in the article is mine.. Way too much work, but it's how I wanted to do it on a relatively new vehicle..

Depending on the strength of your frame, you need to consider its resistance to twisting as the sliders are slammed upward e.g. when sliding off a boulder. I added a very rigid cross span on my cradle design for this reason.

Many people just line the slider up with the rock panel weld seam and let the slider make contact on severe upward loads..

 

[waskillywabbit]

DanEE,

I'm quite familiar w/ 4x4wire and other assorted 4x4 forums and I've read most of the opinions relative to this discussion. I have a locked/lifted/etc. 85 4Runner (

http://www.drawhorn.org)

and I'm currently in process of fabbing/purchasing some sliders. I was just curious for some input from those who have a more objective approach. Thanks for the references.

Brian
Pressure Vessels and Autoclave Systems

http://www.mcabeeconstruction.com

The above comments/opinions are solely my own and not those of McAbee Construction.