What grade bolts for front winch bumper mounting?

[asinor]

What grade bolts should I use to mount a Protofab winch bumper to the frame rails.

 

[ObscureMachine]

I use Grade 8 for just about everything that needs any strength at all.

 

[surfer-b]

I used Gr 8 but I also beefed up the frame where it mounts and added 2 more per side.

 

[BRONCO26]

I just mounted a hard Knox get and used grade 8 w lock nuts.

 

[xcntrk]

Another here for Grade-8. Use them everywhere. Home Depot, Lowes, even the auto-parts store generally have a decent selection. But typically when I'm starting a new project I order them online. Way cheaper and you can buy an individual bolt if necessary:

http://www.boltdepot.com/Default.aspx

Just use a good size and thread pitch gauge to determine what you need up front...

 

[blubuckaroo]

If you're bolting to the stock bumper holes, grade 5 is plenty. You'll tear the holes out before you could break a 1/2" grade 5 bolt.

 

[Broncitis]

If you're bolting to the stock bumper holes, grade 5 is plenty. You'll tear the holes out before you could break a 1/2" grade 5 bolt.

I generally use Gr 8 on general principal and since they really do not cost all that more, but the above statement is accurate.

The best local place I find to get bolts is at Tractor Supply where they sell them all by the pound. MUCH cheaper than any of the hardware or home improvement stores.

 

[asinor]

Did you weld plates above and below or add some type of channel around the frame?

Just did the calcs on various diameter grade 5 and 8 yield and ultimate shear strengths.

Grade  |   Diameter   |   Yield (LBS)    |   Failure (LBS)
-----------------------------------------------------------
   8   |        1/2   |         3,508    |         17,870 
   8   |        7/16  |         2,056    |         13,679 
   8   |        3/8   |         1,109    |         10,050
   5   |        1/2   |         2,891    |         14,725

So reinforce frame rails / mounting.
4 total shear surfaces.
Mount Bumper with 1/2 Grade 8 bolts.
Mount Winch with 7/16 Grade 8 bolts (or lower for a known failure point to save frame horns and winch internals?)

Not that I'm going to be doing any wheeling that will need to pull a solid 12k load with a winch, but its nice to know I'm safe regardless.

 

[sprdv1]

When in doubt... Grade 8

 

[surfer-b]

Did you weld plates above and below or add some type of channel around the frame?

I cut a .25" plate the same dimension as the frame all the way back to the crossmember, welded it to the outside of the frame, drilled and taped the horns on the bumper and bolted it up. I wanted to use 2"x4"x.25" and slide into the frame as I did in the rear but the design of the frame wouldn't allow it to go far enough back for my likings

 

[ilovemaui]

Ace hardware has a great selection of grade 8 for cheap.

 

[ObscureMachine]

Ace hardware has a great selection of grade 8 for cheap.

x2 That's where I get all mine.

 

[bknbronco]

If you're bolting to the stock bumper holes, grade 5 is plenty. You'll tear the holes out before you could break a 1/2" grade 5 bolt.

I agree!! The winches my dad and brother just got only came with grade 5, 3/8"x16 bolts for mounting. They also got one of these lock bolts to detur the ripoffs!

http://www.factor55.com/

The prolink they sell is a great add on also. Dad and bro got the same thing from another company but you have to feed your rope through theres. factor55 just came out with these and they use a pin so you can use them with cable also.

 

[knack]

OK, somebody has to disagree.

I usually stick with grade 5 for situations like this. Grade 8 bolts are ultimately stronger - but when they break they snap. A slightly softer bolt will stretch or bend before breaking. In some cases that can make the difference between a broken part turning into missile, or just tearing loose and falling in the mud.

 

[hucklburry rev2]

OK, somebody has to disagree.

I usually stick with grade 5 for situations like this. Grade 8 bolts are ultimately stronger - but when they break they snap. A slightly softer bolt will stretch or bend before breaking. In some cases that can make the difference between a broken part turning into missile, or just tearing loose and falling in the mud.

X2

Grade 8 are brittle, grade 5 will bend.

We put overhead cranes together with either structural bolts (99.99% of the time), or I have seen grade 5 used (not often). I never see grade 8.

The forces that will create a problem are when shocked, where something gives way and creates a shock load, that can cause an instant/momentary force up to 5x the actual load. Thats when a grade 8 will snap, and you hope the grade 5 will give and not fail completely.

But I am no engineer, just what I've been taught, it could be wrong.

McMAster sells structural bolts if you want some real strength

 

[nabes68]

I used grade 9 a friend of mine worked for CAT and he got me some but that was on my heep tj

 

[Madgyver]

Unless the bumper has tabs that go into the framerail and bolted up, The ears on the stock framerail for the bumper will fail before any grade 5 or grade 8 1/2" bolt.

 

[asinor]

It's a Protofab bumper, basically 4x3 tubing that slides into the frame rail.

Looking at the numbers, it really doesn't matter what I use. The winch will burn up before it breaks any bolt or bends anything. I'll use grade 8 for the bumper and grade 5 for the winch and tow hooks.

 

[Madgyver]

This is what I meant about the extention that goes into the framerail.
Pics are from a Ballie Bilt winch bumper, center section.

 

[asinor]

Gotchya.