Tire Carrier Hinges - again

[pcampbell]

Interestingly, there have been quite a few votes in the "other" category. If you vote that way, it would be helpful to elaborate on your choice if you haven't already. Perhaps you have something specific in mind? I would modify the poll if I could to add a few more categories. At least one that was "other spindle type" or "other non-spindle type"...but I can't modify it.

 

[pcampbell]

I don't know that it matters when people are using 1" bolts only supporting a couple hundred pounds at the most.

Good point. That's a massive bolt no matter what the grade.

 

[getlost4x4]

a 1" grade 5 bolt has a clamp load rating of 38616 lbs.:Wow1:

http://www.derose.net/steve/resources/engtables/bolts.html#largebolts

i think it'll work well with my 300 lbs back there.:elkgrin:

 

[sasfrontier]

I vote for 2 heims.

I am in the process of building a rack to go over my bed and plan to build a swing out carrier that attaches with one heim at the top of the rack and the lower heim to the bumper to help distribute the load. Check out qscomponents.com for cheap heims. I have used their budget heims in stuff like this and have never had a problem.

 

[Mayne]

As far as bronze and other bushings, McMaster Carr also carries a WIDE selection at reasonable prices. You'll have to spec out the matterial, and it takes some time, but it's worth it. I built a swing out on a 1750lb spindle, and I'm redoing it in favor of a double shear. I just never felt good about the sing shear point.

Mayne

 

[SAR_Squid79]

We adapted a heavy duty trailer axle bearing assembly for my tire carrier hinge. I would wager that it's stronger than any of the options you listed.

 

[AKRover]

We adapted a heavy duty trailer axle bearing assembly for my tire carrier hinge. I would wager that it's stronger than any of the options you listed.

What makes that trailer spindle different than the ones listed in the first post?

 

[SAR_Squid79]

What makes that trailer spindle different than the ones listed in the first post?

I guess I didn't read close enough. The one we did is almost identical to this one from the 1st post:

http://www.comp4x4.com/tire_carrier_hinge_kit_2000.html -- This one is interesting. They have incorporate a sleeve that you weld to the bumper which alleviates any welding on the spindle itself. This should help the issue of creating stress areas on the spindle and prevent breakage. It's a 1.75" spindle too, which is the same as the Slee adn 4x4Labs spindles (a proven size). However, the spindle is then located with a roll pin. They suggest tack welding the spindle for further insurance, kind of defeating the purpose of their design IMO.

 

[ntsqd]

Mostly posting to bookmark this thread (thinking we need a sub-forum directed to rear bumpers).

One comment on the grade 5 vs 8. I know many people who believe that the 5 is a better choice in a sheer situation and that an 8 is too brittle in a sheer load. YMMV.

I don't know that it matters when people are using 1" bolts only supporting a couple hundred pounds at the most.

The way that I've seen the argument laid out is that a G5 is more likely to plasticly yield (Bend) where a G8 is more likely to shear off if/when subjected to an impact load. On the surface the idea has merit, but the numbers don't support it. The G8's shear strength is still significantly greater than the shear strength of a G5. Need to keep in mind that Shear Strength, in steel, is roughly 57% of the alloy's tensile strength.
If the bolt is critical, use a real bolt like a Holo-Krome SHCS, any of the various Aircraft specs, or an F911 and not an SAE graded bolt.

Trailer spindles of any sort are single shear. I'm coming to dislike them all. I'll take a big pin in double shear & fixed to not rotate except against the bushings, with flanged polymer or oilite-bronze bushes inserted where ever appropriate.

 

[TangoBlue]

Like the Iron Pig offering?

 

[Willie G]

....Trailer spindles of any sort are single shear. I'm coming to dislike them all. I'll take a big pin in double shear & fixed to not rotate except against the bushings, with flanged polymer or oilite-bronze bushes inserted where ever appropriate.

While I see your point, and agree in part, I think a lot of the breakage can be aleviated by the way the arm is supported when closed. My thinking is that probably 98% of the vibration happens there, not in the 2% when the arm is swung open.

I built a carrier for my TJ using a 1.5" spindle and had no problems in 100k miles - still worked fine when I sold it. It was "shimmed" at the free end by a small ramp that held it with zero movement, then secured by a bolt/t-handle - not a very quick release design, but it worked and didn't break.

 

[AJsArmor]

Not to try and sway any results...seriously! We've been in business going on 10 years now and up until last year I used strictly the spindle/bearing setup like what has been shown and is in the poll. Basically a trailer spindle with tapered bearings and sleeve.

The failures I've seen pictures of online (not on my stuff) I always attributed to improper installation or design. The breaks looks crystallized and grainy which is usually a case of the metal becoming brittle through rapid heating/cooling. What a lot of guys were doing is cutting a hole in the top and bottom of the bumper, put the spindle in and weld it. Created very localized heat and if they tossed water on it or anything would make the problem worse.

What I did for the longest time was to cut a slit in the face of the bumper so that it would GREATLY increase the weld area. I also added a chunk of 2" x 3/4" thick steel that protruded to the backside of the bumper. I preheated, welded it in in small sections to raise the heat up slowly, then covered with heavy leathers to cool slowly. This has worked fine with ZERO failures.....

Until last year. Then I had 2. One bumper was 3 months old the other was at least 2 years old. One did have some significant bearing play as a sign of lack of maintenance but but sheared off. One looked brittle 75% of the way through then had a clean break, like you'd expect to see in an example of a typical shear. That crystalline break, never sat well with me. When I dug into it deeper through the vendors I found that this isn't uncommon, that there's a failure rate on these even in the trailer industry. So to use them in this application....well they could last forever or they could fail at anytime.

That was enough for me to never use them again and design our hinge. And I'm still not 100% happy with it and plan on several more designs. I like it, but it's too complicated.

 

[GreenXJ]

Casper: What size of Heim joints did you use? And where did you get the spacers that you put between them? I originaly had a 1000lb trailer spindle on my bumper and it sheered completely off at a gas station... good thing nobody was near by! So needless to say I don't think I wanna go that route again.

 

[R_Lefebvre]

I'm going through this currently as I'm building my tire carrier right now. I'm still humming and hawing...

Here's what I've got:

I'm going with delrin bushings instead of axle bearings. I've machined two top hat bushings that will get pushed in to the arm, leaving vertical bearing surfaces on the top and bottom. I've got a 1" dia cold rolled steel rod that will get welded through the bumper top and bottom. Then a steel spacer ring will get welded over the rod to provide a nice bearing surface for the delrin in the arm. I've cut a chamfer on the bottom ID of the ring to allow clearance for the weld bead around the rod.

At the top of the rod, I've drilled and tapped a 1/2" UNC hole, to which I was going to use a simple bolt and large washer to retain the arm. But... I've been thinking more about this, and maybe I should make this double-shear. I will have a structure welded to the bumper beside the arm anyway, as I need to replace the OEM plastic corner finisher which I won't be using. It wouldn't be much of a stretch to make this suitable for supporting a top plate.

The issues I have at this point... if I was going to go double shear, I wish I'd made the bearing section in the arm much shorter. I left it long for lots of bearing area, and then welded that diagonal in. If I'd done it shorter, I'd need much less of a vertical stand-tube on the bumper for the double-shear plate. That horse had left the barn already. I could still do double-shear, but the whole thing will look a bit clunky now.

On the latch side, I dunno yet. I was starting to think about using a paddle-latch as used on a truck/trailer. I'm wondering if I had a striker plate on the bumper to vertically support end of the arm, and an adjustable stopper so that the gate must be slammed to latch, and then the stopper will push the gate against the latch.

Either that, or what about an automotive latch? It could support the end of the arm both vertically, and keep it from opening.

 

[AKRover]

On the latch side, I dunno yet. I was starting to think about using a paddle-latch as used on a truck/trailer. I'm wondering if I had a striker plate on the bumper to vertically support end of the arm, and an adjustable stopper so that the gate must be slammed to latch, and then the stopper will push the gate against the latch.

I have used these pull action latches in the past and they have always worked well.

http://destacoclampstore.com/pullaction.htm