Rear Bumper Started (trying some new, your opinions please!) Pics!!!

[Boston Mangler]

Hey Guys

The rear bumper project has begun and took a weird but possibly good turn. Curious what you all think.

I had 2 custom mounting brackets made out of 3/4" plate (can you say overkill?) and the machinist making them goofed on one of the dimensions (kind of my fault the way i had the dimension diagram drawn). These were fairly expensive to have made, so we wanted to "Make Em Work"

Here is what we did:

The hole for the D-ring mount was drilled to 1 1/2" instead of 1". I know this is no big deal and there is still AMPLE amounts of meat there to support pulling the rig if needed (the plates are 3/4"!!!!). My problem was that the hole was way too big and the D-Ring was bouncing around like mad and making a racket. Looked kind of 1/2 assed too!

Anyway, the machinist and i designed these bushing out of some poly stock he had laying around the shop. At first i thought the idea of pulling such a heavy vehicle in this manner was a little hokey, but he assured me that the poly is plenty strong enough and now i am starting to think this might turn out to be a very good thing for a few reasons!

The bushings were machined for a very snug fit both into the hole of the 3/4" plate and for the pin of the d-ring.

The theory behind this idea (besides trying to make these work) was to eliminate the loud rattling and to protect the powdercoat.

Here is the link to my little writeup:

http://www.yankeetoys.org/mangler/80rearbumper.htm

Here are some pics. Please give me your opinions:

The bushings shown here are just made out of some plain white stock he had laying around and also have a large diameter "shelf" to them. If i decide i want to use this method in the final design, we are going to make a set out of black poly with a much smaller "shelf"

 

[Cattledog]

You say poly, but what type of poly? Need to be more specific, there are many type with varying mechanical properties. I like the idea of keeping the mounts and rings quiet, but why not install the D-rings at the trail head and scrap the bushing?

 

[e9999]

nice, but you can also get bigger anchor shackles...


interestingly, the bracket is exactly what I was proposing for the front and rear recently and was poopooed about....

 

[Mickldo]

What are you planning to do with the rest of the bumper?

 

[RavenTai]

nice, but you can also get bigger anchor shackles...


interestingly, the bracket is exactly what I was proposing for the front and rear recently and was poopooed about....

why? have seen very similar done by a friend of mine and it worked great.

only thing you have to do is make sure your connection to the frame is good.

your "shelved" bushings are generally refered to as "hat bushings" as they look similar to an old time top hat.

if the poly gives you any trouble have them remade in bronze sligly oversize on the OD and freeze fit them. liquid nitrogen is handy here (machine shop should have) final size the ID after install with a remer. if the fit is good it will not rattle.

 

[Boston Mangler]

You say poly, but what type of poly? Need to be more specific, there are many type with varying mechanical properties. I like the idea of keeping the mounts and rings quiet, but why not install the D-rings at the trail head and scrap the bushing?

Yes they would only be installed at the trailhead, but installing them at the trailhead wouldnt solve anything. The hole would still be too big, they would bounce all over the place and be loud as hell and do a # on the powdercoating.

 

[Boston Mangler]

Also, forgot to mention, there will be a 1/4" plate on the other side of the frame as well to "sandwhich" it

 

[Cattledog]

I like RavenTai's idea of bronze and freeze fit them.

Who cares if they rattle on the trail. You are running 6000+ lbs over rocks and through dirt, noise is going to happen. If you use the bumper for offroad and recovery it won't stay powdercoated long.

 

[Josh83]

I did brackets like that for my bumper, but I also made a plate that bolted on where the stock tow loops bolt on and welded the two brackets together. And I made mine out of 1" plate

 

[-Spike-]

Nice, you now have a 5* departure angle. At least you can use it as a plow.

-Spike

 

[alia176]

I think he's using Poly as a generic term for UHMW. If you're looking for a simple recovery point, I can think of other more elegant solutions! But, creativity is fun to watch in progress!

Ali

 

[Beowulf]

I would buy shackles that fit. Crosby is an excellent choice.

They have a 1-3/8" shackle (1.5" pin diameter) that would fit perfectly in that bracket.

My concern with the poly bushings would be with deformation during a hard recovery. If the material is hard enough then that might not be an issue. Bronze would be better. Have the guy make black poly washers that would fill the gap between the insides of the shackle and the custom bracket; one on each side.
That would stop the side-to-side rattle.

-B-

 

[Rich]

If you feel compelled to stick with polyethylene, then at least go with black, formulated with UV inhibitors appropriate for outdoor use.

Me, I would machine steel plugs of the appropriate size, weld 'em in, and grind 'em smooth.

 

[Boston Mangler]

My concern with the poly bushings would be with deformation during a hard recovery. If the material is hard enough then that might not be an issue. Bronze would be better. Have the guy make black poly washers that would fill the gap between the insides of the shackle and the custom bracket; one on each side. That would stop the side-to-side rattle.
-B-

Yeah, as of now, this is just some early testing! I am going to do some testing to try to simulate being stuck and tugging on it. If there is no deformation at all and they work great then i will have a black set made with a smaller hat and be done with it. If there is deformation, i will either buy new shackles or do what RICH said and machine some plugs and weld them in and grind smooth!

Thanks for the feedback!